Just wondering what you believe is the ideal quench for a 390 with 2291 pistons? And what deck/head gasket combo are you running? Id like to be running at or a little over 10:1 CR. I would like to keep it on 93 pump fuel. Right now the pistons are .013 below. I'm still playing with Numbers on head gaskets to figure out about what i would want. If i have the shop cut .010 from the deck i should be around 10.1 CR with the 72cc head and the gasket i have picked out. Any pointers/opinions would be appreciated.

 

Ok, with the piston deck hight being .013 in the hole, and this gasket 1132G from mr gasket would give me about a .033 quench. This is about what I am looking for. Has anyone used this gasket? The above is assuming that the deck will not need anything to be trued up at the shop. If it needs done i want him to take the min just to square it up. How do you feel with a .030 quench?

edit. I just noticed the bore of that gasket is 4.220 Is that to large for a 4.080 bore?

 

Not leaving you hanging, your just in over my level of knowledge and I would hate to give you bad info Hope someone responds soon that knows about this stuff. Best of luck.

 

No problem. I just dropped it off at the shop this afternoon. I forgot to take the flywheel so i'll have to drop that off. ETA is 4-5 weeks.

I told him to only take off the deck was necessary. That way i can stay above .030 quench. And for later when i have my heads redone if they need some shaved i'll still be safe CR wise.

 

Out of curiosity, are those flat top or dished pistons your running? Just thinking that if they are flat tops and it needs a little more shaving you could switch to dished piston or something that has the wrist pin a little closer to the top of the piston.

 

flat tops. They have the 1.776 compression height, so with out anything being taken from the deck and the .020 head gasket i'll have about a .032-.033 quench.

Speed Pro ZL2291F - Speed-Pro Forged Pistons - Overview - SummitRacing.com

Most likely it won't need anything off the deck more than just a few thou. So that should still let me in range. Atleast i'm hoping. If not i'll find a larger gasket or have them shave it more so i can get the quench i want.

 

I am running my 418Fe at .036 quench and it has seen 8000 rpm before. I actually am using a 428 crank and 390 pistons that I had shaved down. The pistons sit .004 over the deck of the block. Click on my links you can here it run I have made some 12's passes with this engine in a truck

 

Are you running pump gas? if so what are your specs on CR and cam and heads. I'm trying to get a good quench to help ease the use of pump fuel. I'm just afraid of going to far and getting it to close at higher RPMs. But if you spun it to 8k before i should be fin with .030 or so with a 6200 max.

 

.035 is the min quench one would run on a street engine
.045 is the max you should run

Now some do claim to run less....but not for long...Most engines that see 6500 rpms with less than .035 will find the piston has been kissing the head lightly...as the bearing clearance grows and the rods stretch danger gets close ...

Keep your quench .035-.045 you will have a safe efficient engine.
390 fords are very efficient with proper quench..

I seen you throwing around a 10:1 compression ratio..make sure you have some overlap in your camshaft and not more than about...8.25-8:5 dynamic compression with aluminum heads and no more than a 8:1 with steel heads

Or a Pinging condition will result
A stock camshaft with steel heads and a REAL 10:1 compression is Not good

A for the guy who claims 8000 rpm with a FE..i would like to see your engine

you have a very rare FE...Most wont turn over 7000

you must have MUCHO money in that engine

Most race FEs with a stroke over 3.78 only turn 7000 max and peak power is at 6500
after watching your videos I think you have a 6000 rpm engine at best..
Nice truck and good times for a truck....But 8000rpms ....maybe in neutral and then bending the rods
Barry makes FE's SING..and at 7000 rpms and LESS
You might consider putting that engine in the Jegs engine master challange if its a 8000rpm engine
you would have won three years running

 

Well the the 8K number is not all the time. My engine is more designed to run in the 6500 range. But when I took it out to the track and before I had a revlimiter. During a burnout throught the lights it wrapped up past 8k in 2nd gear. YES OUCH!! It made one of my push rods look like a "Z" . NO its not a constant 8k engine but it has hit it more than once on a burnout prior to putting a rev-limiter on it. I agree .035 is the closes I would go. I have C8AE-H that have been machined some. Estimated 68-69 cc heads. Run 390 flat top pistons with minimum valve relief. Estimate compression is 11.5 to 1 and yes I do run pump gas 93 octane when I drive it around town. And run 105 octane when I race. .030 is pushing your luck. I had all new bushings put in my rods. My engine is balanced. It has a custom grind solid lifter flat tappet cam. I had it ground at Delta Cams. I had this truck at the track last summer, Made a torrque converter change (smaller stall 2500) and installed taller gears 4.22 Truck ran 13@106 on a 100 degree day. Had a tuning issue with the carburator. It had a dead spot the first 60ft. Pro-Systems built the 950 i am running on it. Found out about a week later(after I finally called them) that they had air restrictors in the back fuel circuit (this softend throttle response) so took them out now I can't keep the truck straight. Have to wait till I get home to get my cam specs.but will get them

 

Mine is going to be, h-beam rods, i believe the same pistons as you, 427 crank and balanced. It will have a rev limiter on it set at 6k. I just don't want to be pushing my luck too much, thats why i started this post. I'll have to do some checking on gaskets and see what i can come up with without dropping a 100 bill every time i want to pull heads.

Polcat are you running Ford Racing M-6051 head gaskets?

 

I am running ford rods. Can't remember the casting number but are the same as the 427/428 performance engines run. The bigger and heavier rod. I have a Scat 9000 cast steel crank(brand new), I studded the mains, and the heads. I have larger arp bolts for the rods. The cam I am running is a custom grind. 247/255@.050 110 lobe seperation .611 lift on intake and .629 lift on exhaust As far as head gaskets I am running the Felpro Q1020

I really like your idea though on the Quench. I did alot of research on that same subject while I was building my engine. I did find out alot of circle track guys run the .030 quench cause the engine are at more of a constant speed. Drag racer stick with the .035. But also make sure your valve to piston clearance is good. .100 minimum especially on the exhaust valve. I think in my gallery their is some pictures of my build. good luck