FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: CV355 on August 20, 2019, 07:50:16 AM
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I am curious how reliable my current engine build is. Earlier in the year I was contemplating swapping heads but was advised it may make some of the conditions worse. I have a '69 Mach 1 with a 428CJ. Bore is 0.030" over, decked 0.005". I haven't checked compression yet, but calculations are pointing at a near-stock 10.6:1 static. Dynamic, we assume the cam is a Lunati 10503, still set up as flat tappet. It runs to a ~2800 stall TC, C6, and 4.11 rears (so, drivetrain is somewhat loose). The previous owner said it ran fine on 91 + a gas station shelf octane booster. Thankfully I have 93 around here and that's all I run in our vehicles. I drove the car three times in cold weather and had no issues with pinging, but we don't get many 50 degree days in SC.
I've been stuck trying to figure out what I really want to do with this thing- my goal is just a fun, reliable cruiser car for maybe 500 miles a year. Period correct is ideal, concourse not. After hitting a few snags I decided to leave the original heads on it if the compression ratio isn't too high for modern pump gas.
Before I send it to the carb tuning guys and zip the thing up for a while, is there anything I should consider doing? I'd like to avoid a cam swap if I can.
I do appreciate all of the help and input you guys have given me along the way. I'm looking forward to actually being able to drive this car in the Fall. 2 years of lifts and jack stands is a sad existence for this car...
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What is the timing set at and have driven it in 80+ temps. yet? I would think 10.6 if your figures are correct would be pushing it for 93 pump gas with iron heads. Cam duration and Lobe Separation Angle will also determine cylinder pressures.
Have you done a Cranking Compression test yet?
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What is the timing set at and have driven it in 80+ temps. yet? I would think 10.6 if your figures are correct would be pushing it for 93 pump gas with iron heads. Cam duration and Lobe Separation Angle will also determine cylinder pressures.
Have you done a Cranking Compression test yet?
At the risk of sounding unprepared, I am unsure what timing is set at. I've had everything disassembled for 99% of my ownership of the car, and I've only cranked the engine 3 times in the last 16 months. I'm looking at having the timing checked and cranking compression test done at a local (trusted) performance/resto shop next week. 10503 cam is 224-232-114 I believe, but that's still speculation. *edit* Hey my memory served me right https://www.jegs.com/InstallationInstructions/600/638/638-10503.pdf
I have never run the car in weather over 50 degrees. It's a calculated risk right now- if we think that the current build is "tune-able" for 93, then I still have to invest a chunk of money getting the intake machined to match the head plane, plus reassembly. If there is ample concern with this setup, then I don't want to waste my time and money machining the intake. Right now there is a substantial step between the intake and head plane where the valve cover seats and it was the cause of an oil leak.
If I swap heads, most aftermarket heads appear to have a smaller combustion chamber. 72cc vs 68cc I believe? That pushes me into thinking I may have to tear it down and get the pistons swapped, which really gets into territory I was trying to avoid. Scope creep from hell.
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I have a close combination in my 68 Mustang daily driver, 30 over 428CJ, stock cast iron CJ heads, 10.5:1 compression ratio, a Comp 294S solid cam, FPA headers, and one of my intake adapters with an Edelbrock Torker intake and a Holley double pumper carb. I run 12 degrees initial timing and 36 total, all in by 3000 RPM. 4.11 gears and a T-56 Magnum transmission. Coolant temperature always stays in the 170-180 degree range, and no fresh air induction, so it does get pretty hot under the hood. I do have an electric fuel pump with a return style fuel system, which solves a lot of the hot weather problems.
I only get 91 octane here, 10% ethanol, and the car runs fine on that fuel with no octane boosters, in weather up to 90 degrees (which is about as hot as it gets here). No pinging or any other fuel related problems. I don't know your cam specs, but as long as its not a super mild cam, and you have a good solution for fuel delivery that will keep the fuel cool, I think you should be fine on 93 octane.
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I have a close combination in my 68 Mustang daily driver, 30 over 428CJ, stock cast iron CJ heads, 10.5:1 compression ratio, a Comp 294S solid cam, FPA headers, and one of my intake adapters with an Edelbrock Torker intake and a Holley double pumper carb. I run 12 degrees initial timing and 36 total, all in by 3000 RPM. 4.11 gears and a T-56 Magnum transmission. Coolant temperature always stays in the 170-180 degree range, and no fresh air induction, so it does get pretty hot under the hood. I do have an electric fuel pump with a return style fuel system, which solves a lot of the hot weather problems.
I only get 91 octane here, 10% ethanol, and the car runs fine on that fuel with no octane boosters, in weather up to 90 degrees (which is about as hot as it gets here). No pinging or any other fuel related problems. I don't know your cam specs, but as long as its not a super mild cam, and you have a good solution for fuel delivery that will keep the fuel cool, I think you should be fine on 93 octane.
That is encouraging. I'll have to verify compression ratio then before I commit to anything. The cam sounds relatively rough for a supposed "stock class cheater cam." Plus the loose converter and high rear gear ratio will help keep the engine under lighter load with most conditions.
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Its all in the tune up and how the head chambers work along with the quality of local pump fuel. I can "drive" the 10.5:1 351C around on 91, but it has a decent sized hydro roller and such. BUT - at the track, 91 is no-no because it peppers the plugs every pass. So I pretty much stick to VP110. If we had 93, that might be OK for cruising. I have mixed, fuel, but the result is extremely gummed up intake runners.
Note my "street car" is 28" tires, 4.56 with a spool, 4600 stall converter and a decent sized cam, runs high 11s at 3250 lbs, 8 point roll bar, air shifter, etc. Open the trunk and pump fuel in the fuel cell LOL.
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Its all in the tune up and how the head chambers work along with the quality of local pump fuel. I can "drive" the 10.5:1 351C around on 91, but it has a decent sized hydro roller and such. BUT - at the track, 91 is no-no because it peppers the plugs every pass. So I pretty much stick to VP110. If we had 93, that might be OK for cruising. I have mixed, fuel, but the result is extremely gummed up intake runners.
Note my "street car" is 28" tires, 4.56 with a spool, 4600 stall converter and a decent sized cam, runs high 11s at 3250 lbs, 8 point roll bar, air shifter, etc. Open the trunk and pump fuel in the fuel cell LOL.
Oh I've been there before. In 2009 I had a street/strip car that was set up far more for strip than street, but I drove it and being younger didn't care about missing the creature comforts. My mindset has changed since then. I watch a video of a concourse 428CJ and go "wow, look at how smooth and quiet that engine is!" I just sold my GT500 recently and I'm missing an angry exhaust and kick in the pants.
It sounds like my plan should be to get the dynamic compression tested then make a decision on whether I want to leave it stock and machine the intake to match, or if I need to do a teardown
In the event that a teardown is necessary, is CR the main variable to play with here? What is key to getting these FEs running on pump gas without making it a slug in the process?
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If the specs are correct, it's a whopping 304/324 degrees advertised duration.
The reason it sounds good is that it's got overlap for days.
That long 114 LSA also helps, because the ICL is relatively high as well.
The DCR calculator shows it should work. DCR stuff is theoretical though. In reality, if it doesn't ping, I wouldn't worry.
I'm curious to see how it operates the power brake booster though. 86 degrees of overlap, if the specs are correct.
FE's are the same as any other engine when it comes to making them run on pump gas. It takes a combination of static compression ratio, the right cam, the right timing, etc.
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If the specs are correct, it's a whopping 304/324 degrees advertised duration.
The reason it sounds good is that it's got overlap for days.
That long 114 LSA also helps, because the ICL is relatively high as well.
The DCR calculator shows it should work. DCR stuff is theoretical though. In reality, if it doesn't ping, I wouldn't worry.
I'm curious to see how it operates the power brake booster though. 86 degrees of overlap, if the specs are correct.
FE's are the same as any other engine when it comes to making them run on pump gas. It takes a combination of static compression ratio, the right cam, the right timing, etc.
That is also encouraging. Not sure how much vacuum it pulls at idle, but likely not a considerable amount. I'm swapping out the booster and master cylinder, and might have to run a vacuum pump. I've run manual brakes before and really did not care for it.
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From experience, 64-65 degrees of overlap yields about 14-15 inches of vacuum on a well-tuned engine. You're sitting at 86. If those specs are correct, I can't see how it would have any vacuum and a reservoir will probably be necessary.
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>My mindset has changed since then.
LOL, did I mention that I'm 63 and still run 3" bullets on 12" of collector extensions. I like it loud. My other car runs methanol, and I'd love to get this one converted over.
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From experience, 64-65 degrees of overlap yields about 14-15 inches of vacuum on a well-tuned engine. You're sitting at 86. If those specs are correct, I can't see how it would have any vacuum and a reservoir will probably be necessary.
Sounds like a pump and reservoir is what the doctor ordered then. The few times I did drive the car, the brake pedal felt an awful lot more like my old manual setup than an 8" dual bendix... This is good info!
>My mindset has changed since then.
LOL, did I mention that I'm 63 and still run 3" bullets on 12" of collector extensions. I like it loud. My other car runs methanol, and I'd love to get this one converted over.
That's why I like your generation better than my own age group. Believe me I like it loud too- I've had plenty of straight-pipe supercharged / turbo cars that you could hear from miles away. :)
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You don't necessarily need a vacuum pump, but just a reservoir would work.
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I am not sure where you came up with 68CC. Factory information shows 72.7-75.7CC on the C80E-N. Might be a good idea to check compression.
-Keith
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I am not sure where you came up with 68CC. Factory information shows 72.7-75.7CC on the C80E-N. Might be a good idea to check compression.
-Keith
Aftermarket heads. TFS has 70cc, Edelbrock has 68 and 70 I believe. That'd just make my compression issue worse.
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Barry's survival heads and the BBM heads are at 75cc I believe and have a modern heart chamber . Way more forgiving on pump gas .
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>My mindset has changed since then.
LOL, did I mention that I'm 63 and still run 3" bullets on 12" of collector extensions. I like it loud. My other car runs methanol, and I'd love to get this one converted over.
You're old and deaf. It's the only way you know the engine is running... :D :D :D :D :D
I am around jet engines all the time. However, on the flight deck, However, when I do my walk around inspection they're still loud on the ground at the gate and in the alley.
-Keith
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Barry's survival heads and the BBM heads are at 75cc I believe and have a modern heart chamber . Way more forgiving on pump gas .
Good suggestion! Just looked those up based on your recommendation and they look pretty dang good! Looks like my cam would be compatible too. I might give those guys a call and see what they recommend.
Ok, been perusing their site. Now I have the itch to start from scratch on an engine stand, but my wife may kill me. Probably going to just continue as previously stated- static compression test, dynamic compression test, determine if the numbers look friendly for pump gas. If so, keep it as-is, mill the intake to fit, button it up, tune the carb and go. If the numbers are too high for reliable use on pump gas, I may say screw it and just build a new one from scratch...
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I understood you were running stock heads. TFS shows 70. Edelbrock offers 72 and 76 and the speed master heads are 76CC. I just went though this with the head change ordeal. Because of my piston change. 72CC with 22CC inverted dome JSE pistons. I wanted to maintain no less than 9.8. compression. I'm glad I can get away from the VP if I don't want to run it.
-Keith
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I agree with your plan. Just put it together and see how it runs on pump gas. Worst case you may need to add a bottle of octane booster to each tank. If you only drive it 500 miles a year that’s only 3 bottles or $36 per year.
Just get it running and enjoy it.
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Do you know the Distributor Curve , Has it been recurved , I see "
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I had a iron head 390 with 10.7:1 compression in my Galaxie before. C1AE heads heavily worked, comp 294s cam, 4500 stall converter and 4.11 gears. Ran fine on pump 93 in upstate NY. I believe I ran my total timing around 38.
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Get an otoscope and watch the plugs. Center ceramic will tell you what's up real quick. "Pepper" is no es bueno
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It's going in the shop in two weeks. Worst case scenario, I have to swap heads and intake to drop CR. Should be interesting
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A fresh valve job where you cut the seats, and dress the valves will increase the combustion chamber volume a bit, helping lower the compression ratio without affecting the quench area. Slow down the initial advance in the distributor by increasing the spring tension on the smallest spring, and that should help with detonation at slower speeds. Joe-JDC
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If you have that 304/324 cam in there and it's at 110 ICL, you will be able to run any cheap gas you want without detonation, and even likely with an aggressive curve. In fact, I'd say in street driving, that cam would likely handle 11.5:1 It's a big boy if that's the one
I wouldn't sweat it, if anything I'd advance that thing to about 104 if you are really at 10.7:1 and give it a reasonable curve with a big initial.
That cam won't be fussy (if that is indeed the cam in it)
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I've run my 428CJ motor in my truck for decades. .04 over, 10.5/1, .59 lift Crower flat tappet, med riser 2x4 with mildly worked stock heads. Run it on 91 or 93(whatever I can buy) and have beat it to pieces for decades with no ill effects.
It has gotten a dose of 110 on random days if I have some left over juice from the wagon I need to burn up. I run 40* total and pretty steep initial. Starts easy.
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As always, I really do appreciate the input!
Sounds like it may be good as-is with a little tuning. I'll know for sure next week when we run compression tests and get it dialed in.