FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: jayb on March 01, 2015, 11:25:28 AM
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Over the past year I've been helping some friends of mine with a father-son FE project. We finally got it on the dyno this weekend, with pretty good results. It was a typical dyno session, with unanticipated problems that had to be solved, disappointing results at first, and then happiness all around when we finally got the engine working right. Its been a while since I posted one of these blow-by-blow accounts, and there's always something to learn from this stuff, so I thought I would detail it all here.
First, here are some specifications on the engine. It is based on a 0.060" over 391 truck block, and has one of the standard 4.25" stroker kits installed, for 451 cubic inches. The kit uses a Scat crank and rods, and forged pistons whose manufacturer I don't know. Compression ratio is 11:1, and we wanted the engine to run on pump gas, so a fairly large cam was selected. We picked a Comp solid roller, with lobes from their High Energy Street Roller series, #4220 on the intake and #4221 on the exhaust. Lift and duration on the intake is 255@.050" with 0.650" lift, and 262@.050" with 0.650" lift on the exhaust. Advertised duration is 300/308, and the cam is ground with a 112 lobe separation angle, and degreed at 108. We chose Comp 943 springs to use with this cam. Also, a Harlan Sharp roller rocker setup was used, with their rockers shafts, stands, and solid spacers.
The heads are the normal Edelbrock 428CJ heads, and they are essentially stock; no significant porting work was done, and although there is no flow data available for them, I'd be surprised if they flowed more than 270 cfm on the intake. They use the stock Cobra Jet sized valves. The heads are definitely a bottleneck in this combination, and if there had been more money available for the build I think it would have been well spent on a street/strip porting job, to get the intake flow up to 300+cfm. But that can always be done later...
This engine uses one of my intake adapters (#002), and a Weiand tunnel ram for induction. For carbs, the guys selected 450 cfm Holleys. I haven't had great luck with those carbs, so I was a little skeptical on this choice, but they got a good deal on them used, and then had them revamped with a Quick Fuel metering plate in the back, that allows jet changes in the secondaries. So those were the carbs we used.
The engine was finished off with a set of my adapters and a CVR electric water pump, a Milodon 7 quart oil pan, and an MSD distributor. We ran Hooker street headers on the dyno, with the normal 1 3/4" primaries. We got the engine set up on the dyno in a couple hours on Friday night. Here's a picture of it at the end of the day on Saturday, after we swapped on a different pair of carbs:
(http://fepower.net/Photos/Posts/Dusty390.jpg)
Saturday morning we were ready to go at 9:00 AM. We filled the engine with water, and, good news, there were no leaks. The same could not be said for the fuel, unfortunately; the back bowl on the rear carb started shooting fuel out of the vent when the pump was turned on. I removed the bowl, and the plastic baffle that goes around the needle and seat assembly on these side hung float bowls was just laying in the bowl, not positioned correctly. It was preventing the float from coming up and compressing the needle against the seat. Apparently the local carb "expert", who had gone through these carbs, had not assembled this correctly. Fortunately it was an easy fix, and after re-assembling the rear bowl the leak was gone.
The engine fired right up when we cranked it, and we set the timing as it warmed up, and varied the load somewhat with the dyno in order to help break in the engine and seat the rings. Since the cam was a roller, there was no need for a cam break-in period, so after running the engine for 10 minutes or so, we shut it off and pulled the valve covers to lash the valves. They were all a little loose, because they had been set at the specs with the engine cold. With aluminum heads, as the engine gets hot the heads expand, increasing the distance between the lifters and the rocker arms, and thereby increasing valve lash.
After getting the lash set to the specs, we started the engine back up and ran a cruise test, just to load the engine in the lower RPM range and see if everything sounded and looked OK. Looking at the cruise test data everything looked pretty good, but there was a disconnect between the dyno's A/F reading and the reading from my wideband O2 sensor; the O2 sensor looked pretty good, but the dyno reading looked lean. I wasn't sure which one to believe at this point, so we decided to run the first dyno pull and look again. We ran the pull from 3000 to 4500 RPM to be conservative. Here's the first dyno sheet:
(http://fepower.net/Photos/Posts/DusPull1A.jpg)
Obviously the horsepower and torque numbers were very disappointing. On the sheet, the left side O2 sensor (LambdL) was not hooked up. The right side O2 sensor was reading in the mid to high 12s, which is just what you wanted to see, but the dyno's A/F numbers looked lean. The engine sounded OK, but not real strong. We decided to double check the timing, and run another pull; the timing was still set at 33 total, and the second pull looked pretty much the same as the first.
Based on the power numbers I was beginning to suspect fuel as the culprit, but we decided to do one more pull and advance the timing a little as a test. On the dyno we were running 110 octane race fuel, which allows you to advance the timing quite a bit past the optimum level and not hurt the engine, so we went to about 38 degrees this time. One thing that we had been noticing about setting the timing was that the distributor was really hard to turn; it was a real fight to get it to move, and then once it did, it didn't move smoothly, so it took us several tries to get the timing where we wanted it. Back in the pull, we actually lost power with the timing change, so it was time to start looking at the jets in the carbs.
Of course with two carbs its a pain to do the jet changes, but we got started on that and after disassembling the first carb on the primary side, we found it had #59 jets. This just seemed way too small to me. I decided to overkill on the jet sizing just to see what the dyno results looked like, so in one carb we replaced the #59 jets with #68s, and in the other we went to #70s (I only had two of the #68 jets in my box). After re-assembling the engine we started it, and then reset the timing back to the original 33 degrees total, again struggling with the distributor to get the timing set correctly. We ran the pull, and the engine sounded soggy at the low end but better after 4000 RPM. The horsepower and torque numbers were a dramatic improvement, as shown in the sheet below:
(http://fepower.net/Photos/Posts/DusPull4.jpg)
Here's a graph of horsepower and torque, before and after the jet change. Still looking pretty ragged, but a big improvement:
(http://fepower.net/Photos/Posts/Dusjetup.JPG)
That was a little more like it! But now, according to the dyno A/F numbers, we were running way too rich. We decided to do another jet change, and this time we looked at the secondary side as well as the primary side. The secondaries of the carbs had been fitted with #67 jets. I decided to ignore the power valves in the carbs and square jet them to make it easier, and work with the selection of jets I had on hand. So, we put #64 jets in the primaries of both carbs, and #65 jets in the secondaries. This picked the power up substantially again on the next dyno pull, and we were now pretty close to the optimum 12.5:1 to 13.0:1 A/F range. Here's a comparison chart of the pull with the new jetting, and the previous pull that was pretty rich:
(http://fepower.net/Photos/Posts/Dusjet2.JPG)
The power levels were finally starting to look like they should. We decided to do one more test of the timing, and again began struggling with turning the distributor. I couldn't help but think that it shouldn't be acting like this; it seemed like the body of the distributor was too large for the hole in the block, to allow it to easily turn. Then I started thinking about the distributor gear itself, and thought to ask whether they had replaced the stock cast iron gear that comes on the MSD distributors with a steel gear, to match the billet steel cam. The question was met with an "Oops!". They had forgotten to do that. Well, now the distributor had to come out, and I was worried that we'd find that the stock cast iron gear had been all torn up, and that there would be a bunch of shavings from that now in the engine.
The distributor was really tight and had to be pried out with a pry bar, but we were all relieved to see that the gear did not appear to be significantly damaged. You could just barely feel the start of a wear line on the gear. It wouldn't have lasted long, but fortunately the amount of material that had worn off was really small, so I don't think it caused the engine any problems. On the barrel of the MSD distributor you could see wear marks, where the body of the distributor was in tight contact with the block, so that was the reason why the distributor turned so hard. I plucked an MSD distributor with a steel gear out of my vast archive of FE parts ( ;D), and installed that one in the engine. My distributor turned easily in the block, so the distributor that the guys have will need to be sanded down a little with an emery cloth before it is reinstalled (after a new steel gear is put on the shaft). That should solve all the problems. Hindsight being 20/20, its a good thing that distributor was tight; otherwise I would have never asked about the gear on the distributor, and it would have worn itself away eventually, potentially damaging the engine.
After all that screwing around, we advanced the distributor from 33 to 35 degrees, and got virtually no change in power from the engine on the next pull. We ran one more, to a little higher engine speed; here is the data and a graph of the final pull, with the 450 Holley carbs:
(http://fepower.net/Photos/Posts/DusPull8A.jpg)
(http://fepower.net/Photos/Posts/Dus450.JPG)
I thought that 520 horsepower and 525 foot pounds of torque wasn't bad, given the heads. And the torque curve was nice and flat, and close to 500 foot pounds even at 3000 RPM. This engine is going to be mated up with an automatic and 3500 stall converter, which should be just about perfect for it. But with that cam I was kind of surprised that the horsepower seemed to be peaking in the 5500 RPM range; I'd figured it would be more like 6000 RPM.
By now it was just after noon, and I'd been telling the guys all day that I thought the engine would make more power with a pair of 660 center squirter Holleys, and I just happened to have a pair of those. So, given that we had a little more time to run the engine, we decided to swap on my carbs. Those carbs are jetted for a lower horsepower engine (my 428CJ, which is around 460 horsepower), but we decided just to bolt them on and run them, and see what happened.
To say that the engine liked the bigger carbs would be an understatment. According to the dyno A/F reading we are running a little lean with these carbs, pretty much as expected, but the engine still picked way up. Also, it seemed to want to run higher in the RPM range than before. We ran a few more pulls, up to 6400 RPM on the last one, and now the engine looked like it was peaking at 6000 RPM, as expected. Here's the dyno sheet, and a comparison graph between the 450 and 660 carbs.
(http://fepower.net/Photos/Posts/DusPull11.jpg)
(http://fepower.net/Photos/Posts/450vs660.JPG)
I think that 547 horsepower and 544 foot pounds are really, really impressive numbers given the stock Edelbrock heads. A street/strip porting job on the heads, getting the intake flow up to 300 cfm, would make this an easy 600 HP engine. Even as is, its a great hot street engine. It idled on the dyno between 900 and 1000 RPM with a nice lope, and seemed to have really good throttle response, especially with the 660 carbs. Can't wait to see it in its new home, a '64 Galaxie...
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That's a neat build. Great power with non-exotic parts, and it'll be great fun in a street car. I like it a lot. Nice write-up as well.
JMO,
paulie
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Very cool. Interesting that you caught the tight dizty. I had thought they might have installed the intake w/o sliding in the ditzy first to align the intake before tightening it down. Obviously this was not the case. Lucky they are due to your experience to have caught the wrong gear!
The carb swap as an eye-opener too. Once again dyno testing, and having your massive stash of speed parts nearby (!), proves that bigger is sometimes better.
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Thanks Jay
Really enjoy your in depth write ups.
Congrats on the engine.
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Nice healthy build and some solid numbers. Just goes to show that some good power can be made with stock CJ heads, but I'd agree, some head work would really make that thing live up to it's potential. I hate those 450 carbs. I've never been able to make them acceptable, performance wise, on any engine. Hopefully they'll change them out permanently. Also, it's nice to see the adapter/tunnel ram combo used. That's what I'm planning on for my next build. That should make for a fun street combo, with enough left over for some good strip fun also.
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A pair of 450 carbs was nowhere near enough airflow, and they are really miserable little carbs to boot.
Consider that Ford put a pair of 600ish carbs on a basic passenger car 428 in the Shelby cars and considered them good enough to have a warranty and be an everyday driver package.
Tunnel rams rock!
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Really nice build Jay.
Great to see your parts in action.
If it is a 391 @ .060" and the 4.250" arm would it not be 446.70 cid ?
Don't want to be short changing the guys . ;D
Imagine if the heads actually had a proper valve job. ::)
How much do you think the engine would loose with a switch to a much more modest fuel, say 91.
I'd be going with the Black Cap when they put it the car.
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Howie, my calculator says 451.1 cubic inches. 4.11" bore and 4.25" stroke. Check again, buddy ;)
I don't think it will lose much, if any, with the switch to the pump fuel. I've often seen engines on they dyno pick up power. Usually you've got to jet up some though, because of the ethanol in the fuel around here. But the pump fuel is oxygenated, which should help power if anything.
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So I did.
I plugged the numbers into the Wallace Calculator the first time (obviously a misstroke on a key) and got an incorrect answer, but
did not check my work. Always a mistake when doing a math calculation.
And did not put my dollar store reading glasses on, even a bigger mistake. ::)
You are correct Jay.
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Good stuff!
How well will the tunnel ram fit in a '64 Galaxie? Are they running a hood scoop? Just curious, as I have picked up one of your MR intake adapters, and am thinking about how and where I can use it.
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I assume they are either going to use a hood scoop, or just let the carbs poke through the hood. When they get it installed I'll post some pictures of the car.
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I have a matched set of those 450cfm holleys that came on the Shelby 8V intake, origional fuel line, and small air cleaners. Now I am rethinking using them even for an origional nostalgia build. I think a pair of 600cfm would be much better, and look identical to the unknowing. Neat dyno test! About time you warmed up the air a tad for us. LOL. Joe-JDC
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Nice looking setup, looks just like mine, I would guess the carbs would sit way above the hood, even with the bubble hood based on my 63 galaxie. Jay I noticed you are running the carbs "reversed" from the normal Ford setup, would this affect the numbers any because of fuel dist? Just a thought.
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Jay, excellent writeup, and a nice Father-Son project! A question on the heads; were they run basically out of the box except for the springs? Any additional valve seat work over what Edelbrock provides?
Btw that Weiand tunnel ram looks right at home.
Thanks,
Bruce
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Excellent write up. Minus the tunnel ram it sounds very similar to the solid roller 445 I'm building for my '64. ;D
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Sweet! Did you happen to get a video?
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Jay, appreciate the writeup and detail. It's very good to see the potential for these heads when "fed" in this manner. Shows much can be achieved in basically "out of the box" configuration with only a spring change as I had hoped.
Even though they eventually become the limiting factor the numbers generated make for a very healthy street thumper. Its info and data like these that help in planning my next (inevitable ::) upgrade.
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Jay I noticed you are running the carbs "reversed" from the normal Ford setup, would this affect the numbers any because of fuel dist? Just a thought.
I don't think so, although I suppose it is possible with the 450 carbs because they are vacuum secondary carbs. The plenum of the tunnel ram is supposed to help equalize the shot to the runners, so I kind of doubt that it had a big effect. On the 660s, they are square bore, mechanical secondary carbs, so there wouldn't be any effect with those.
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That is really cool Jay!!! I had to share your write up. Thanks very much for posting it!
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Jay, excellent writeup, and a nice Father-Son project! A question on the heads; were they run basically out of the box except for the springs? Any additional valve seat work over what Edelbrock provides?
Btw that Weiand tunnel ram looks right at home.
Thanks,
Bruce
My understanding is that the heads were run with the factory valves and factory valve job, and that the entrance to the port was cleaned up with a cartridge roll. You know how the entrance of the Edelbrock intake ports is machined for the first tenth of an inch or so, and then you get into the cast part? Sometimes there's a ledge there, and that was probably cleaned up. Otherwise, new springs, spring seats, retainers, and locks were all that was done.
I agree, by the way, that the FE looks awfully good with a tunnel ram...
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Sweet! Did you happen to get a video?
No, but we may run it again this weekend. If we do, I'll be sure to get one.
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Nice build Jay , thanks for posting all the results ..Bud
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Just to be clear, I don't get the credit for building this one. A couple of local friends of mine did all the work. I picked out a cam for them, and helped them a little with the stroker kit, and that's about it. They did a great job, IMO - Jay
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Jay interested in your opinion of running different headers with different motors in the dyno room. You obviously do not run the same header or shall I say have the one size fits all "shop header" that goes on every dyno'd motor . Obviously your doing the Mexican Hat Dance with dozens of headers for your book helps with being able to run different header configurations, but it surprises me that more FE specialists don't offer up running the same header or at least a similar header to what their customer will be running. When running a header that the owner will run vs a shop header, how much could a tune (jetting, timing) be potentially harmed when the customer drops the dyno tuned motor into his own chassis with his own headers?.................
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I just read this post and enjoyed it very much. Now I have a question how do you think, or have you ever tested a similar combo with Edelbrock 750 carbs? I have a combo much like this one only with more compression and a flat tappet cam and I have put the 750 edelbrock carbs on it for the "nostalgia" look that I am aiming for with my 466 (385 series) engine that is going into my 63 this summer. I know its not an FE but I do the best I can with the limited budget that I have to live with. :(. I guess I am asking how much hp am I going to lose with the 750 ed's versus a pair of generic 750 Holley's.
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Jay interested in your opinion of running different headers with different motors in the dyno room. You obviously do not run the same header or shall I say have the one size fits all "shop header" that goes on every dyno'd motor . Obviously your doing the Mexican Hat Dance with dozens of headers for your book helps with being able to run different header configurations, but it surprises me that more FE specialists don't offer up running the same header or at least a similar header to what their customer will be running. When running a header that the owner will run vs a shop header, how much could a tune (jetting, timing) be potentially harmed when the customer drops the dyno tuned motor into his own chassis with his own headers?.................
I don't like using dedicated dyno headers just for the reasons you mention. I try to find a header that is similar to what will be going in the car. As far as tuning, though, unless the headers are radically different between the dyno and the car, I don't think you'd be talking a big difference, especially on an engine under 600 HP.
One reason why some shops use dyno headers is that they fit the dyno. My dyno has been modified to allow use of most headers, but I had a set of Crites headers once that just would not fit; they were too tall, or hung down too low, and I couldn't get them mounted on the engine without interfering with the dyno cart. If you are running a dyno shop, do you want to screw around with every different header style you come across to try to make them fit? Probably not, and I'll bet that's why a lot of shops have dedicated dyno headers.
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I just read this post and enjoyed it very much. Now I have a question how do you think, or have you ever tested a similar combo with Edelbrock 750 carbs? I have a combo much like this one only with more compression and a flat tappet cam and I have put the 750 edelbrock carbs on it for the "nostalgia" look that I am aiming for with my 466 (385 series) engine that is going into my 63 this summer. I know its not an FE but I do the best I can with the limited budget that I have to live with. :(. I guess I am asking how much hp am I going to lose with the 750 ed's versus a pair of generic 750 Holley's.
I hate those Edelbrock carbs, Phil ;) I lost 20 horsepower over a pair of factory 600 Holleys on a 425 HP motor when I tried them. I don't know how much you will lose on your engine, but I don't think they'll perform as well as a Holley...
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I have a pair of generic holley 600 carbs that I modified many years ago to have mechanical secondaries. And if these don't work I will have to rebuild them and give them a try. I ran this engine with these edelbrocks on my test stand and they started and idled fine. But haven't dynoed this thing yet. I will have to ask Ron if he has a set of holleys or maybe even use my one 750 and buy another one as it is just a 3310 750.
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Wish I could understand the steel distributor gear with the steel roller cam. Not long ago it was run a bronze gear with a steel roller cam. I believe stock Fords ran cast iron against cast iron. But why is a cast iron gear against a steel cam a recipe for disaster? Just can't grasp why steel to steel works and bronze to steel works and cast iron to steel does not?
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Like materials, work best , Bronze is a self sacrificing deal and it works ( for a while ) the Steel ( steel compatible is a better description ) came out after Bronze , and Composite is also available , BUT very Pricey , I have no life span info on them
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We ran this engine one more time today in its current configuration, prior to the next "experiment". Here is a video of the dyno pull:
http://youtu.be/-fN8KkLvT-4
Peak torque this time was 550 foot pounds, and peak horsepower was 549. For what it is, this is a really strong engine.
Quite a while back, the guys building the engine thought it would be cool to make it rat-roddish. They bought some parts that were popular back in the day, but thankfully I and some others talked them out of using them. But there they were, sitting on the shelf, and curiosity got the best of me I'm afraid ( ;D), so I had them bring these pieces over so that we could dyno the engine with them, just to see. As I understand it, these parts are referred to as the "Poor Man's Tunnel Ram":
(http://fepower.net/Photos/Posts/poormanstr1.jpg)
(http://fepower.net/Photos/Posts/poormanstr2.jpg)
Just looking at this setup cracks me up. It took us an hour and a half to work out the throttle linkage issues, but finally we got everything set and did the dyno pull. Ed "Big Daddy" Roth was attending in spirit ;D As expected, with these things (whatever the hell they are) on the engine, it was down on power, but not by as much as I'd figured it would be. That is, until the engine hit 6100 RPM. At that point the engine started to pop and stutter, and barely made it to 6400 RPM. The horsepower and torque graph tells the tale:
(http://fepower.net/Photos/Posts/poormanstr3.JPG)
I just can't even imagine what's going on in the intake tract with these things on the engine, but at the end of dyno session, the guys were kind enough to give them to me, for the wall of shame LOL! Maybe I can use them somehow in the plumbing in my house, and at least I can cross this dyno test off my bucket list. The overachieving engine is off the dyno now, and slated to go into the '64 Galaxie soon, I hope. Should be a great combination...
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Lately, I've been thinking about putting some of those "tubes" on an Edelbrock cross ram. It could be an fe version of the old Dodge cross ram 413. I still don't think it would get to the inner fenders like those were ;) Don't have parts for any of it, just one of those goofy thoughts in my head. Later, Travis.
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No wonder the power plummeted at 6,200 they're supposed to go in-line! ............... Just kidding but fill us in on the details are the Poor Man's Tunnel-Rams divided into runners or just a big plenum?.......Astonishing how they made power to a point then died.
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Just a big, open plenum. Pretty weird performance characteristic, all right.
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Can't remember what those were originally made for - but I've seen them.
I do remember a friend having a cast "V" shaped deal that converted a single 4 bbl intake into a dual quad. I bet that would be a strange critter on a dyno as well....
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Nothing is totally worthless....you can use one of those to move your toilet over a few inches.
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I can honestly say I've never seen a combination like that before. :)
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Good thing it isn't productive, talk about distracted driving. Can you imagine trying to see around that setup while cruising down the interstate? Or maybe you're just supposed to look under it..... ???
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Here is a test with those adapters on Ted Eaton's dyno last year. http://www.eatonbalancing.com/blog/2014/01/17/y-block-ford-dual-quad-testing-on-aluminum-heads-part-ii/
Check it out. Joe-JDC
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A question for those who know. What et will this engine
do in a stock wheight -64 Galaxie
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This might give you an estimate if you know the car weight.
http://r.search.yahoo.com/_ylt=AwrSbhDwiP1Uz5IABsBXNyoA;_ylu=X3oDMTEzc2R1aDNrBGNvbG8DZ3ExBHBvcwMzBHZ0aWQDVklQNTgyXzEEc2VjA3Ny/RV=2/RE=1425930609/RO=10/RU=http%3a%2f%2frobrobinette.com%2fet.htm/RK=0/RS=Tr7df_hDFtvllNHcCnZPPCb2woI- (http://r.search.yahoo.com/_ylt=AwrSbhDwiP1Uz5IABsBXNyoA;_ylu=X3oDMTEzc2R1aDNrBGNvbG8DZ3ExBHBvcwMzBHZ0aWQDVklQNTgyXzEEc2VjA3Ny/RV=2/RE=1425930609/RO=10/RU=http%3a%2f%2frobrobinette.com%2fet.htm/RK=0/RS=Tr7df_hDFtvllNHcCnZPPCb2woI-)
Nick
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Here is a test with those adapters on Ted Eaton's dyno last year. http://www.eatonbalancing.com/blog/2014/01/17/y-block-ford-dual-quad-testing-on-aluminum-heads-part-ii/
Check it out. Joe-JDC
Wow, that is interesting that those things actually helped on a low end intake manifold. He says that the combination is still way down on power compared to a good intake by itself, though. I doubt he would get the same results if he stuck them on a good intake.
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Here is a test with those adapters on Ted Eaton's dyno last year. http://www.eatonbalancing.com/blog/2014/01/17/y-block-ford-dual-quad-testing-on-aluminum-heads-part-ii/
Check it out. Joe-JDC
Wow, that is interesting that those things actually helped on a low end intake manifold. He says that the combination is still way down on power compared to a good intake by itself, though. I doubt he would get the same results if he stuck them on a good intake.
I think a passage from this Chrysler site on the old Sonoramic (1st non-Hemi cross-ram) intake make help explain why the Offy adaptors help the low end....and not so much the top end.
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I had to have this whole thing explained to me slowly before I got to the stage where I could at least give the appearance of knowing what's going on. But the way I understand it, it works much like water flowing through a pipe in that the water wants to keep moving even after a valve or faucet is closed. Sometimes, water even hammers when it begins to pile up against the valve. In the SonoRamic Commando, the fuel/air mixture in one of the tuned arms of the manifold works in the same fashion; it wants to keep moving even though the mixture is obstructed by the closed intake valve. The fuel/air mixture is literally "rammed" up against the closed intake valve of the engine, instantly available to charge the combustion chamber when the valve comes open. This is the "Ram" part.
The "Sono" comes from that compression wave that the service manual talked about. Those 30-inch passages were carefully designed to maximize the resonant effect of that compression wave so that it hits that intake valve at the very instant it is opening. This provides an additional force to push more of the fuel/air mixture into the combustion chamber until the valve closes.
The kicker in this equation is that the passage length of the manifold directly affects the rpm range at which the optimum boost is achieved. Since these compression waves move at some 1100 feet per second, if you want your maximum boost at the middle range of engine operation, the tubes have to be longer for the wave to take more time to get out and back in sync with a intake valve opening to give maximum boost at 2800 rpm. If you want that engine to scream at 5000-5500 rpm, the passages have to be shorter as you want that wave to get out and come back quicker.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
http://www.allpar.com/mopar/sonoramic.html
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No, the results would not be as dramatic on the regular 8V intake. What those adapters did was cover the low end torque loss with poor fuel distribution from the hogged out plenums. Anyone who thinks it is cool to open up a plenum on a dual plane 8V intake should be very careful. It ruined that intake for use. What someone thinks will work like a single plane intake, does not work the same when modifying a dual plane plenum. Also, cutting the divider out of a dual plane will drop the torque down over the same intake with the divider left in place. We lost 12-14 ftlb torque with two ported intakes that were very similiar except for the divider. That was a tiring 3 day testing session, but very gratifying!
On edit, if you read down to the bottom of the article, you will see that the adapters lost 26hp on the best intake combination. Down from 378hp to 352hp. Joe-JDC
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Joe, many years ago---1968 or thereabouts---I put together a 427 for my '67 Cougar. I scrounged for parts and chose an 'XE' Sidewinder for an intake manifold. In order to fit Low-Riser heads it had been filled at the bottoms of the runners/head interfaces and although cast with an open plenum it had had a fore/aft divider welded in. The engine used a new 'AA' cam and very high compression due to the pop-up pistons I used because they were available for the right price. I put in a water injection system because even 260 Sunoco tended to want to crackle.
The manifold was 'bootie' from support for John Corrunker's Super 'E' automatic CJ Mustang. We held the MPH end of the NHRA record for most of that season.
The combo, in my XR7 GT Cougar, was massively torque-y. In fact, I had the opportunity to have several street face-offs with street hemis in various 'Cudas and so on and had no trouble getting a fender-length or two on all of them.
KS
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I have the dyno sheets from testing back-to-back manifolds with divider, and without/modified divider cut down similiar to the one Barry R. ran on his EMC engine. On another EMC engine the cut down divider lost 12-14ftlb torque, causing the overall points value to be lower, so the manifold with divider was run, and it produced the best point value in the EMC competition. I have a 351C Torker intake that has a divider welded in that I would like for Jay to test when he starts comparing different intakes on one of his adapters. Joe-JDC
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I've seen those Offy goose neck carb adaptors at a local swap meet for cheap. No wonder they were so cheap huh? They would make a neat ratrod two hole outhouse perhaps? ;D
Now these deals look like they would be worth a go on the dyno.
http://www.ebay.com/itm/Fits-Weiand-Tunnel-Ram-Aluminum-Spacer-Gasser-Ford-351C-Cleveland-Riser-2-Tall-/231452891480?pt=Vintage_Car_Truck_Parts_Accessories&hash=item35e3aad958&vxp=mtr
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Joe, do you consider that to be a given on most all dual planes? Because I seem to remember someone testing the Edelbrock RPM with a "notched" divider that made more power. It seemed to help pretty well if I remember correctly, but I can't remember who or where it was done.
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Is this what your thinking, Doug?
http://www.fepower.net/Dyno%20Results/dyno_results_6.html
Edit: Can't get the link to paste right with my BlackBerry. >:(
Fixed it for you - Jay
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I have done testing with the divider notch, and without the divider notch. It seems that with a spacer on some combinations the notch may work. I have also seen on the dyno where there was a dip in the torque and hp curve at an unusual rpm that did not make sense, and it was because of that slot. When a manifold without the slot was used, the dip on the graph went away. It all comes down to testing, and trying every conceivable combination to find what works and what does not. I also find that on my flow bench when flowing dual plane intake manifolds that the ports nearest that slot have a turbulence, and lose flow at higher flow ranges on the bench. I believe that is the cause of torque fluctuations on the dyno. Depth of the plenum is also a factor because the deeper the plenum is, the more space is available for the airflow to turn into the runners instead of bouncing off the floor and having to make a right turn to get into the ports. Ted Eaton has done extensive testing with spacers with and without slots, and he has a lot of good information available on his web site. I have helped/watched several of these tests, and can verify what he prints there to be true. Joe-JDC
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That must have been it. Failing memory syndrome I guess ::)
But the test seems to back up what you say, since the spacer seems to be the bigger factor in that test, even if the notch did help.