FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: JimNolan on June 01, 2015, 12:56:34 PM
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Friends,
I'm getting ready to change head gaskets on my 410 to a thicker gasket. Thus, I have to change cams to bring my compression (DCR) back up to where I want it. I'd like to get as much cubic inch use out of it I can get on 87 octane. I've already got a cam that would work well and give me what I'm looking for but it's a comp cam ( 110/106) and to get what I need it needs to be a 110/110 cam. Can I just get a timing set with multiple degree crank gear and use the 4 degree retard keyway.
I've always used a degree wheel to insure the results of ICL but I've never really used a crank gear with multiple keyways. This 4 degree built in stuff has me talking to myself. Thanks guys.
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Jim, if you want to increase the DCR, you advance the cam timing, not retard it. You're trying to decrease your static compression ratio with a thicker gasket, but want the DCR to stay the same, right?
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Jim, if you want to increase the DCR, you advance the cam timing, not retard it. You're trying to decrease your static compression ratio with a thicker gasket, but want the DCR to stay the same, right?
Yes and no. the cam I have now with a thicker head gasket would lower my Static Compression from 9.6 to 9.25. At the same time that bigger cam I have now will lower my DCR to worthless value. I've got a cam that will work but if I use it straight up the DCR value will shoot up past what I want. By retarding the cam to 110 ICL instead of 106 straight up, that will bring my DCR back down to a useable value. The part I don't get is the built in advance of the cam. I feel like I'm changing something that wasn't meant to be changed. confused
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You are mixing terms here, first "straight up" isn't dot to dot, its when ICL, ECL, and LSA all are equal. Dot to dot is just dot to dot and at best it is equal to what the cam card says.
106 is 4 degrees advanced from "straight up" which would be 110 ICL (equal to the LSA)
So, to get it to 110, you have to retard it 4, just like you originally said.
In other words, you are trying to install the advanced cam in its straight up position. So you have to "undo" the ground in 4 advance by retarding it 4 degrees
I will say this though, with all respect intended, it's a goofy way to do it. Better to run thin head gaskets and early cam timing than to run thick gaskets and late cam timing.
Also, I have to ask, is everything cc'd and any other clearances carefully measured? If not, chasing DCR numbers to the specificity you are is sorta worthless
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Jim, if you want to increase the DCR, you advance the cam timing, not retard it. You're trying to decrease your static compression ratio with a thicker gasket, but want the DCR to stay the same, right?
Yes and no. the cam I have now with a thicker head gasket would lower my Static Compression from 9.6 to 9.25. At the same time that bigger cam I have now will lower my DCR to worthless value. I've got a cam that will work but if I use it straight up the DCR value will shoot up past what I want. By retarding the cam to 110 ICL instead of 106 straight up, that will bring my DCR back down to a useable value. The part I don't get is the built in advance of the cam. I feel like I'm changing something that wasn't meant to be changed. confused
DCR isn't the be-all end-all. It's just a tool. I completely agree with MY427Stang in that a thinner gasket with a more advanced cam is likely better than a thicker gasket with late cam timing. It'd be better to run the higher static compression, and higher DCR, in most cases.
Can you tell us the two cam's specifications, with your static compression ratio, current and proposed head gaskets, along with
your deck clearance? That would make it a lot easier to sort out.
JMO,
paulie
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First off, everything was cc'd and measured before assembly so I could rely on calculations. I have a Cam Research 282/288 adv, 216/225 @.050, .515/.540 lift, 110/106. .052quench which gives me 7.5 DCR and 9.58 CR and using a 750 Holley. This is all well and good for peak horsepower at 5000-5500 rpm. But, I'm not going to run my car up there again. That's over. I want gas mileage now and more horsepower and torque at lower rpm where I can possible get better gas mileage cruising at 1850 rpm (65mph) with the Tremec. I can gain about 42 lbs of torque and 20 hp at cruise with a cam that is more compatible with peak horse power coming in at 4500-4800 rpm.
What I planned on doing was using a XE256 comp cam, that's 256/268 adv, 212/219 @.050, .487/.493 lift, set on 110/110, .063 quench which would give me a 7.78 DCR and a 9.25 CR using a 570 Holley for carb. I think I need to stay within a + or - 4 degrees of a 208 @.050 Intake duration cam that I would need for a 9.25CR.
Now, some of you guy's helped me with this engine before, I'm going to hang onto everything you guy's say, it's worked before. Tell me what you'd do to get what I'm looking for. Thanks.
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My opinion is that you should keep the tighter quench and higher static compression ratio, and then just choose the best cam you can. I would tend toward a single pattern cam if you want low rpm drivability and mpg. Maybe one with less aggressive ramps than the Comp XE cam you mentioned. The XE's are reputed to be noisy and the short advertised duration is hurting you with respect to DCR. There is a limit to how low you can go on duration without having detonation issues, but maybe you can thread the needle so to speak.
How about this Howards cam? 263/263, 209/209, .490"/.490", 111 LSA. If you installed it with an ICL of 110 the DCR is around 7.86. I think this on the small end of what you can do with 9.58:1 compression.
http://www.summitracing.com/parts/hrs-250021-11/overview/make/ford
Or the Crane 266 Energizer? 266/266, 210/210, .516"/.516", 110 LSA. I think Crane measures advertised duration at 0.004" as opposed to the more usual 0.006", so the advertised figure might be a couple of degrees higher if measured as other cam manufacturers do. It's also not much different than the cam you have now (High Energy 268?) in advertised duration, but has less duration @ 0.050", so maybe not much to gain there.
http://www.summitracing.com/parts/crn-13404/overview/make/ford
The Lunati Hi-260 is 260/260, 210/210, .508"/.508", 110 LSA.
http://www.summitracing.com/parts/lun-10330205/overview/make/ford
The Comp High Energy 260 is 260/260, 212/212/, .484.484", 110 LSA
http://www.summitracing.com/parts/cca-33-222-3/overview/make/ford
Go any bigger than those and I don't think you'll see an appreciable difference from your current 268H cam. A decent rule of thumb is every 2 degrees of cam duration @0.050" will change the rpm peaks by 100 rpm. Maybe that will help you decide.
JMO,
paulie
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I'll run them through the computer. But, the 265DEH gives me a lot of hp and torque at 2000 rpm. It's an 8.0 DCR though.
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Jim, what are you running for heads?
I like the idea of tight quench better, but that .063 quench / 256 cam combo will run ok, I sure don't expect it will be that strong unless you have a serious set of heads, but it'll likely work OK
You may be gaining some torque using a calculator, but don't forget that overlap allows torque once you get off idle due to scavenging of the chamber pulling more into the cylinder. That 256 cam has very little overlap and probably wont perform as well as the dyno programs say it will. Although I do think it'll be a nice cruiser and get good gas mileage
Once you respond with which heads and what has been done with them, I will give you my 2 cents. I do think with 410 cid though, you need to have an efficient set of heads and intake to fill the cylinder well with a small cam
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Ross, Please do. This is the 410 engine you helped me build. It's got the Edelbrock RPM heads and Edelbrock intake with the 750 on it. Yes, give me your 2 cents. Thanks
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Jim, a couple of things
I can't get to your numbers, but I can stay under 8:1 dynamic with the 256 on 110 ICL with the .052 quench. To make a very mellow cruiser I think that would work, although I don't think you need to go as small as 570 cfm, it'll likely do OK for a Sunday drive through the hills car.
If I could figure out were our numbers differ, I may be able to see why you want to do both the head gasket and the cam.
BTW, if you are serious about top gear torque at low RPM, a change to a Performer from the RPM might be wise, but then you'll lose even more at the peaks
Have you ever though about just regearing what you have to get 5th more usable? In my case, going from 3.70s to 4.11s gained mileage and allowed nicer cruising, as well as in town being much happier, I forget which TKO and rear you have, but maybe match the gearing to the use rather than detune the motor
FWIW, the reason I am coming at it at a different direction than you is that to really do a "truck" motor like you are trying to do, the heads and intake are not really perfect and you may be spending more than you need to to make a happy cruiser
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BTW, if you are serious about top gear torque at low RPM, a change to a Performer from the RPM might be wise,
LOL Ross you know I'm smiling.
Seriously, I am learning so much from these posts.
Thank you Jim for your posts and the rest of you guys for the great insight on this and others.
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Ross, what do you think about a 265DEH cam. That'll give me about 13 more horsepower and 33 ft. lbs torque at 2000 rpm. It takes away about 25 horsepower at 5000 rpm but I don't want to go there anymore anyway. The only bad thing is if I put it at 110/106 I'll have a 8.0 DCR. I don't mind that as long as it don't get to 8.1. My 406 has 8.1 and it teeters on 89/91/93 octane depending on where you get it. And on a trip that sucks. I think 8.0 DCR would be secure with 89 octane. What do you think, leave the motor as is and change the cam. Also the 265DEH intake duration at .050 is 211, which would be right on for 9.58 CR.
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BTW, if you are serious about top gear torque at low RPM, a change to a Performer from the RPM might be wise,
LOL Ross you know I'm smiling.
Seriously, I am learning so much from these posts.
Thank you Jim for your posts and the rest of you guys for the great insight on this and others.
His may...yours no no way :)
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OK, so first, whats the difference between your 406 and this 410? Quench, heads, piston design, intake, ignition, carb, gearing etc.
The reason I ask is that like Paulie said earlier, DCR is just a tool, I run 8.35 on the Mustang and 8.2 in the truck and neither has fuel issues, matter of fact the Mustang is easier on fuel choices than the truck
So 8.0 vs 8.1 really is not significant, something else is contributing.
So for the use of the car though, I think the 265DEH on 106 would be OK, I'd probably run a 268H Comp though (for no good reason LOL) to peak around 4800-ish and I'd leave the quench tight. I'd look at the timing curve and mixture if it pings at that point. Typically the DEH cams are not very well loved for power, but it'd probably do fine for your needs.
Is your car a .64 OD and a 3.70?
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The car has a 3.50 true trac and a .64 5th gear on the tremec.
The 406 has a .030 quench with 10.7 CR and a 8.1 DCR. I had trouble with pinging going to Tupelo last month. I ended up using 93 octane down there and it still pinged some. When I got back to Warsaw I lowered the ignition timing from 17 to 14 and I'm running 89 again with no pinging. I run a Lunati 282/296, 214/224 @.050, .500/.500 lift, 114/110 LSA/ICL in it. PS, I've got a new 268H with new lifters on the shelf but it has a 218 @ .050 intake duration on it. I figured that was too much for 9.58 CR.
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I thought you were currently running a 268H in your 410 and wanted to move the power band down? And I thought you had the Cam Research 282/288 in hand, and were considering getting the XE256? I'm not sure if I got that all correct.
The 268H is not very big for a mild 410 and is not too much cam for a 9.58:1 compression.
What's in your 410 now?
paulie
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Also, those dyno programs aren't perfect either. They'll get you in the general range, but they don't give you the exact power you are going to make. My experience is they can be close at the power peaks, but they can be way off at other points in the power curve. That could be particularly important in your case if you want good power at the very low end of the range.
JMO,
paulie
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I don't understand this cam stuff like you guys but I ran a 265 DEH in a 428 engine and was unhappy with it. It didn't come on until much higher RPM rather than being a good low end torque cam like it should have been. I later came to believe that this cam needs a fair bit of static compression to work properly, and I was running low 9s. So I would not go that direction with your lower compression.
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Rockhouse66, you got real time information. That's what I was looking for. I read all this stuff on cams, run it through a computer dyno program and all you get is a comparison between the different cams you input. That's like figuring what octane you can run. The information from a engineering firm ( or credible looking website) says 7.6-7.8 DCR is good for 87 octane, 7.8-8.0 DCR is good for 89 octane, 8.0-8.2 DCR is good for 91 octane, 8.2-8.4 DCR is good for 93 octane and anything above that you need racing fuel. We also know from experience the aluminum head and a low quench will aid in preventing knock. Now I just got through putting 1600 miles on a car with an 8.1 DCR with iron heads but a quench of .030". I use 89 octane because of the quench, I'm sure of it because depending on which gas station I got gas from my engine would ping on that trip. I get 13mpg so I used a lot of those service stations along the way.
Anyone can study information, some of it fits my calculations, some of it don't. But the reason I get on here is for real time information and the experience you guys have got. That makes two of you that don't like a 265DEH. I don't like it either now.
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With the added info I would say a few things
- Paulie gave you good info on the 268H, it matches what you want. I also think its a better cam than the 265DEH. I do not understand why you are concerned with the .050 value and compression, but it's not an issue. That's a nice match with the tight quench
- You may need to tweak your distributor with the new cam, so be prepared, you are changing intake valve closing time significantly, and although you are accounting for it with the DCR calculation, it is different and may like a slightly slower curve.
- Your 406 wasn't pinging because of too high of DCR, it was too much initial timing for that motor (or too quick of a curve)
- That 570 will be way down on peak power, and a smaller carb doesn't make more torque, so expect power loss, but if you like the way it cruises and it gets a little better mileage, go for it. Make sure you don't lean it out too much, a lean motor is more likely to rattle. Don't be afraid of the 750 though, when not hammering it, they can get good mileage
Last...
3.50 X .64 = 2.24 final drive.
That is going to be very tough to be where a 410 wants to be all the time. If you are unhappy after the change, consider changing to a 3.89 gear. 11% more mechanical advantage would be significant and would free up power everywhere while still having a 2.49:1 final drive. It would likely even get better mileage. I probably would have done this first
Heck I'd even consider 4.11s, but I assume your tire is pretty short, so first gear may get a little short when horsing around
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Jim, I don't know if you have considered this, but widening the LSA to 112 or 114 will broaden out your torque curve and get you a real smooth idle which helps save gas.. The old mileage maker cams from the 70's were short duration wide LSA. You could also consider (forgive me Jay) the old Sp2p manifold. it makes more torque below 3000 rpm than any other manifold
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I just remember somewhere in my files i have some dyno data on the Sp2P vs a regular Performer on a truck 416 that I did years ago. That had a small Isky cam in it Something around 260. I will see if I can find it.
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I'm with the idea that 5th is drastically undergeared. I saw this problem in my forum years back. Can you drive some without using 5th at all? Check mileage after a bit and I think you'll see it's better without. If so, the change to 4.11's will lower off-the-line stress, too.
Mileage and 410/428's don't really go together.
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I'm with the idea that 5th is drastically undergeared. I saw this problem in my forum years back. Can you drive some without using 5th at all? Check mileage after a bit and I think you'll see it's better without. If so, the change to 4.11's will lower off-the-line stress, too.
Mileage and 410/428's don't really go together.
I second the gearing thing. Lugging them down to try and save gas causes "piston rattle".
It's going to get 12 to 14 no matter what you do. So keep the rpm up in the power zone.
And stop trying to cheap out on gas.
You guys down south don't even know what expensive gas is. ::)
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Howdy Jim.......Hope things work out for ya.
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Well, time's up. I'm going to go with the 268H cam and keep the rest of the motor the same. I'll gain 8% in HP and Torque at 2000 rpm and only loose 5% HP on top end ( if you can believe the computer dyno). It may not be accurate but it does give you the same comparative reading on different cams. DCR on this cam installed 110/106 is 7.9. Thanks guys. Now I've got a bigger problem with the True-Trac differential.
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I think the 268H is a good choice. And I also agree that more rear gear might help. I don't know what your tire size is, but with a 3.50 gear and a .68 overdrive the rpms are going to be awfully low for most carburetors to deal with.
If you have 27" tall tires, at 70 mph you would be turning about 2073 rpm. That's not easy for most carbs to deal with. I'm not an EFI guy by any means, but very low rpm fuel metering is where EFI really excels, in my opinion.
A carburetor has to have a certain velocity/volume of air passing by the boosters to make them meter fuel well. That means more rpm. Annular boosters can help that situation, but not nearly as much as EFI. So if you get your cruise rpm up a few hundred rpm, it might work better with a carb. With 27" tall tires at 70 mph with 4.11 rear gears and a .68 overdrive you'd be turning about 2435 rpm. That's likely pretty close to the sweet spot for a good carbureted engine.
JMO,
paulie
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Paulie,
At 70 mph I'm turning 1950 rpm. My 5th gear is .64.
The last truck motor I had was a 74 DTE 105 390. In this same car with same rear end and transmission. All I did was buy a new set of timing chain gears to get the retard out of the cam and I got 20 mpg with it on trips. My 1/8 mile times were the same as the 410 I have now (same tires). It went through the quarter in 15.2 sec. That's not bad for a 250-270 horse engine. I did put a 570cfm 4V carb on it and used the stock heads and stock exhaust manifolds. Making this 410 achieve what the old 390 did is impossible though. Too much engine, stroke , heads, exhaust and intake. I think this 268H cam that gives me another 8% hp and torque at 2000 rpm might let me better enjoy a trip as well as enable me to keep beating my buddies Bullitt Mustang.
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Well, you're mixing together so many variables, different cars, engines, cams, carbs, etc., it's no wonder you can't make heads or tails of it. Okay, so your current overdrive gear is 0.64. Got it.
I still think carbs like to (or are only able to) cruise efficiently at higher rpms than a good EFI setup. A smaller carb relative to the engine size will help this. That is because a smaller carb will have a higher velocity past the boosters for a given rpm. But then you pay a price in the mid-range and top end. Like I said, I'm not an EFI guy, but I acknowledge the benefits.
Bottom line is, getting your cruise rpm up a few hundred rpm will likely help both mpg and performance.
JMO,
paulie
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Jim..when I had a 410 in my truck with a Baja Beast cam ment for a lower C/R,I just kept the distributor lose and swung as needed.Worked out well.But then I'm here due to papal dispensation.
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But then I'm here due to papal dispensation.
LMAO!! ;D ;D ;D