Compression
Senior User
Joined: Jul 2001
Posts: 111
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Compression
[QUOTE]I'm looking for a V10 project motor to modify, probably won't be built to anyone elses standards, but hey, different strokes.
Golly gee, maybe you can bump it to 16:1 and run it on corn squeezins'...[/QUO
What's your problem? Maybe alcohol is a good alternative fuel, for the engine.
Golly gee, maybe you can bump it to 16:1 and run it on corn squeezins'...[/QUO
What's your problem? Maybe alcohol is a good alternative fuel, for the engine.
Senior User
Joined: Jun 2001
Posts: 480
Likes: 0
From: Alabama
Compression
I'm running a 10.0:1 compression with forged pistons, mild cam, 272/282 I believe or similar, its a custom made cam by an engine builder. I run 93/92 octane, actually around where I live its hard to find the 92 anymore everyone seems to sell the 93 but it does not make a differnce. Now I tried to back the timing down and run 87. It would cruise alright, but would diesel sometimes when you shut it off. And the power was gone. Not worth it to save 20 cents a gallon.
But anyhow, I think you will be fine running high grade pump gas with 10.5.
chris
79 F-150 Ranger Lariat, 2wd, RC, LB, 460 (intake, headers, cam), C-6(shift kit).
79 mustang (work in progress...its just slow progress)
98 Chevy 4x4 (work truck)
95 Lexus SC300 (wife's baby)
But anyhow, I think you will be fine running high grade pump gas with 10.5.
chris
79 F-150 Ranger Lariat, 2wd, RC, LB, 460 (intake, headers, cam), C-6(shift kit).
79 mustang (work in progress...its just slow progress)
98 Chevy 4x4 (work truck)
95 Lexus SC300 (wife's baby)
Tuned
Joined: Jul 2001
Posts: 430
Likes: 0
From: Deatsville, AL
Compression
I found the following specs for a Ford Marine/Off road Cam:
M-6250-A460 Camshaft; requires Anti-pump-up lifters.
Duration 269 degrees intake, 274 Exhaust
Valve lift: .493 Intake, .503 Exhaust
Taken from the 1986 SVO Catalog.
Bob
'66 7 Litre, top loader, 3.25 Traction-lock, Sidewinder Intake, SCJ Exhaust
'88 F150 LWB 4x2, XLT Lariat, 302, 5 speed, 3.08
'99 Ranger, 4x2, 3.0, 5 speed, 3.73 posi
M-6250-A460 Camshaft; requires Anti-pump-up lifters.
Duration 269 degrees intake, 274 Exhaust
Valve lift: .493 Intake, .503 Exhaust
Taken from the 1986 SVO Catalog.
Bob
'66 7 Litre, top loader, 3.25 Traction-lock, Sidewinder Intake, SCJ Exhaust
'88 F150 LWB 4x2, XLT Lariat, 302, 5 speed, 3.08
'99 Ranger, 4x2, 3.0, 5 speed, 3.73 posi
Posting Guru
Joined: Aug 2000
Posts: 2,416
Likes: 4
From: PacNW
Compression
The new 2002 water cooled Harley Davidson 4 stroke engines are 11.3:1 compression ratio on premium gas! What would prevent a truck engine from running 11.3:1?
Posting Guru
Joined: Aug 2000
Posts: 2,416
Likes: 4
From: PacNW
Compression
I have some idea how the others effect the CR, but how does EGR effect the maximum compression?
EGO (Exhaust Gas Oxygen) sensors measure the amount of O2 in the exhaust gas and tell the computer to adjust the fuel delivery and spark timing accordingly.
Postmaster
Joined: Aug 2001
Posts: 2,882
Likes: 0
From: Nevada
Compression
That'll depend on how aggressive you get with your timing. If you have a lot of initial advance with the remainder coming in at lower rpms, you'll get detonation (pinging). Stock 429s and early 460s, at and above your C/R, run fine on premium pump gas with factory static timing and vacuum advance distributors.
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Junior User
Joined: Jul 2001
Posts: 86
Likes: 0
Compression
[font size="1" color="#FF0000"]LAST EDITED ON 14-Aug-01 AT 09:59 AM (EST)[/font][p]I'm going to join the discussion here. Your last response brings up a problem I have with my slightly pumped 429(dove heads). I'm using a Mallory unilite mechanical advance distributor. When I give it the intitial advance that it wants to really run, then I get detonation. Our premium is 91 octane. Couple of questions, would a vacuum advance be better? Never curved the mallory, I haeard once that they were basically curved for a Chev, would it help if I adjusted the curve? Thinking of switching to an msd and a using a timing adjuster in the cab! Suggestions, Help? Hate runnning around with all that cubic inches, and then having the power fall off because I've backed off the timing to prevent detonation.
Thanks
Dennis
55F100
Thanks
Dennis
55F100
Tuned
Joined: Jul 2001
Posts: 430
Likes: 0
From: Deatsville, AL
Compression
I always use a vacuum advancce on a street engine for drivability and economy. But then I'm an old goat and forgot more than I know ...
but the rice burners stay away from me, don't want to be embrassed again.
Bob
'66 7 Litre, top loader, 3.25 Traction-lock, Sidewinder Intake, SCJ Exhaust
'88 F150 LWB 4x2, XLT Lariat, 302, 5 speed, 3.08
'99 Ranger, 4x2, 3.0, 5 speed, 3.73 posi
but the rice burners stay away from me, don't want to be embrassed again.
Bob
'66 7 Litre, top loader, 3.25 Traction-lock, Sidewinder Intake, SCJ Exhaust
'88 F150 LWB 4x2, XLT Lariat, 302, 5 speed, 3.08
'99 Ranger, 4x2, 3.0, 5 speed, 3.73 posi
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