Is it possible or practable to use two head gaskets to lower the compression on an FE? If yes, how much would it lower it? One point? a half point? I know, change the pistons is best, but I don't really want to or have the time. What say you Ford guys?
BEEP, Head gaskets are sold in different thicknesses, you may be able to buy a thicker gasket than what you already have. I would have to drag a catalog out to give you a list. Try a search on your favorite catalog speed shop or mine. I have seen head gaskets doub;d up before but not will good success. I doubt what you would gain from the extra gasket would be worth the trouble that it could possibly cause. If you are ponginmg and you are already below say 10:1 you may snag a cam with closer lobe centers or more overlap to make it bleed off at low RPM.
I don't know because I haven't tried it. But with the way the intake mainafold and heads go togeather I would try to avoid raising the heads much.
Its possible but not a god idea for several reasons wich FE, wich heads you got now, why you want it lower? one head gasket is about 10 cc depending on thicknes
Ford made FE heads with many different cc sizes. Changing heads could lower the compression. Which heads do you have? Cast between the center 2 exhaust ports.
If memory serves me, most of your later model heads have the lower compression. Believe 76 was the last year for the FE in pickups. I'd say any D3T or even the C7AE or C8AE heads will have the larger chambers.
69 is right. Any of the late model '72 to '76 Pickup heads were low compression. Bad part is that those heads also had small ports and didn't flow well at all. Beep, a little more info on why you want to lower the compression would be helpful. I am imagining a 6-71 with a bit too much boost????
What not to do! I got a set of 427 FE Lowriser heads in trade for some welding. The heads had been worked on by Mondello in 1971 and had been fitted with HR valves (2.19 intake & 1.73 exh) as well as the chambers were opened up. (not necessarily by Mondello) Well the machining was done with some disregard & the exhaust bolt hole burned through on all 8 chambers. These heads came out of the Sacramento or SF area so i expect they were on a Blown hydro/drag boat. Cost to fix is approx $1000 with new valves -- They are being done now. So the simplest idea may not be the best. You can see the hole at the bottom of this photo.
OK, I'm pulling the heads tonight. I will check casting number and get back on here with the information. I do not know what kind of pistons I have yet (flat, dished, ?) since I didn't build the engine. I will find out tonight. I bought it running. She has 225 lbs of compression when I do a compression check at cranking speed. She has a fairly mild comp cam hydraulic cam and edelbrock intake. The reason I want to lower it, if it is too high, is because it runs hot over time on the road and If the timimg isn't set perfect and I don't use high test gas with a booster she pings bad when I go under load. If I retard it to stop the ping, she gets hotter quicker and performance goes down quickly. As to it running hot. I have a four core radiator that is in perfect condition and it has been tanked, rodded and checked twice . A cool flow high volume water pump, 180 thermo that works well, and I have triple checked air flow over the radiator to make sure 99% of the air is forced through the radiator. The only thing I have not checked is the head gaskets being on upside down which can happen on an FE. That is why I pulling the heads. To make this final check. If the gaskets are on correct and I have dished pistons and/or large CC heads, I give. Out comes the FE and in goes a sbf.
those are some high compression numbers, or at least higher then what ive fooled around with. I am a newbie compared to alot of the FE guys on here, but post up what heads you have. You can drop a good bit by swapping heads. Around here truck FE's are a dime a dozen so maybe you would have the same luck. Too bad im not closer, if you went to a sbf id take that boat anchor off your hands.
Can be to lean fuelmixture to Is the distributor working corectly?vakum advance? Wrong advance curve? 4-10 initial. max 36-38 full advance most fe heads have 72-76 cc cambers give 8,5-9.5 with most flat tops that wont be to high either you have domed pistons ore 360 hp 352 heads with 50something cambers ore both
OK, here we go: Heads are: C8AE-H w/oversize intake valves and all steel seats Pistons are: Flat tops & marks on top are 05-012-01-B and L2291 040 I ***ume this means .40 over How much static compression does that give me? Cranking compession = 225 by-the-way. Head gaskets were on correctly. water opening to rear.
Typical C8AE-H "door stop" heads have 72cc chambers..give or take a couple of cc's. Depending on deck clearance you're in the 9.5-10.0:1 compression ratio range if you're using the usual .041" thick head gaskets.....slightly higher if the motor is zero decked. 225psi cranking compression is too much for pump gas (usually). You'd like to get it down to 180-190psi. More cam with a later intake closing spot willl help bring the cranking compression down and get you better suited for pump gas. My 428SCJ had more compression than this motor and I was able to squeek by on doctored up pump premium running a Crower 297HDP cam. With any cam over 0.500" lift in the FE you'll need to swap to an adjustable valvetrain and machine/set the heads up for the appropriate valve springs.
Can anyone tell by the markings on the top of the pistons who made the pistons. 05-012-01-B and L2291 040
L2291 --- Checked (searched) on the FEForum & they were listed as TRW It was also noted ther in one place that L2291-F are forged but thats a fact I can't prove.
Hey Beep, any more info on the FE overheatng issue? I'm running practically the same setup in my 31 coupe. Have only run it on an engine stand and in the ch***is so far, its not been driven, but my temps are peaking around 180 with just an electric fan over the radiator at about 2000-2500 RPM. Have not checked my cranking cyl compression yet. Brad Outlaw
I had a very similar one recently, a '66 390 block/2291's/ 390GT-428CJ juice cam- except used the early large-chamber C1 heads that are very similar to a 427LR.428CJ head but with standard valve sizes. The later heads have smaller chambers, and the C1/C4's run around 74-76 cc and also have the early "high" exhaust port. The C8's are indeed not the most desireable head. BTW, early 390-4V's came with a thin steel shim gasket- my '62 ragtop with the original one with C1's runs just fine on unleaded regular with no ping or heating. Methinks most of your problem is probably excessive quench with the pistons down in the hole- measure how far down they are, and the thickness of your old gaskets, you want around .040 total or just a touch more, but not less. If you have a lot more, that will make it rattle and get warm, and the early heads will drop the compression a bit. The one I had went into a '66 Country Squire and is towing a large trailer with no pinging or heating problems
Hey Big Chief, here is what I found. Can you tell me about what compression I had and what I will havwe when done. CURRENTLY: 390 FE bored .040 C8AE-H heads, milled .020 to get them flat. Head gaskets were .035 thick Pistons are .015 below deck, flat top with one set of eyebrows NOW: Same heads Head gaskets are .045 thick (before compression) Pistons are .125 below deck, flat top with two sets of eyebrows & small dish (.025 deep) Thanks
In 62 the 409 Chevy engines came from the factory with 2 shim gaskets. I giess they did it to cut down warrany claims and/or detonation. It sure pepped them up when you changed them to 1 shim gasket so I know it will work
Here's a toy you can use to figure it out. http://www.kb-silvolite.com/calc.php?action=comp Are you sure the piston tops are 1/8" below deck?
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