[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.

 

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)

 

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

 

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?

john

 

I don't know a lot about newer H-D engines but I believe they run aluminum heads which by themselves allow between a half and a full point increase in the C.R. Other factors which allow higher compression (in cars & trucks specifically) are computerized ignition/"closed loop" fuel injection which allows the use of EGO & spark knock sensors and adjustable timing & fuel delivery. However I don't believe Mr "12:1" has any of this on his truck.

 

I have some idea how the others effect the CR, but how does EGR effect the maximum compression?

Thanks,
john

 

EGR or EGO? A malfunctioning EGR (Exhaust Gas Recirculation) can affect the driveability and cause pinging because it uses inert exhaust gas to cool down the combustion temp of the F/A mixture and reduce NOx emissions. Obviously it doesn't do a anything to enhance the performance but it can be detrimental if it's not working correctly. Theoretically I guess you could run a higher C.R. with an EGR system since it does reduce pinging but it's always been an emissions reduction system AFAIK.

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.

 

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.

 

[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

 

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