Can you run two head gaskets on an F.E. to raise compression, I got a set of free pistons that are 13 or 14 to 1 according to the guy I got them from, they are 40 over 390 pistons, If it is possible how much difference would the extra head gasket make?

You are asking for trouble using two gaskets. The possibility of leakage is too great and the compressed thickness would only yeild small gains. Consider taking them to a machine shop and having them cut down to the ratio you are looking for.

http://store.summitracing.com/partdetail.asp?part=SCE%2D034158&autoview=sku

Why do you want the thicker gasket? Are the pistons going to be out of the hole or are you trying to drop the compression a bit? If you are trying to reduce the compression, don't forget about the quench/squish distance. High compression and a big squish space can be hard on pistons.

Why not find a good machine shop and have the domes
cut down on a lathe

I ran a short calculation and got that drop in ratio assuming you'd start with a 20cc net dome, .020 deck, .040 gasket, 72cc head.
For a $100 rebuild, I've done the 2-gasket trick, since the cost is only about 1/10 of machining, and it's less permanent too, once heads are milled (or a block), done is done. I guess I had good luck, no blowouts, but limited experience so maybe just got lucky.

In your case, my GUESS is that the reduction in CR from say 13.58 to 12.12 would be of more benefit than the detriment of a loss of .040 quench. In general though that tradeoff is a tough call.

But if you're building even a 12.1 cr engine, hopefully it's not a $100 special, so I'd go more for one of the suggested solutions, best maybe to mill the piston tops if they are thick enough, I assume they're forged being popups like that?
Any identifiers on the pistons? Some popups "work", and some do not work - the added compression just barely makes up for the power losses due to worse flame travel. I do recall that you could mill the "Muscle Parts" Ford piston domes flat, they were thick enough to do that.
Hope this helps.

...12, 13, 14:1 compression are all gonna need race gas to run anyway. Compression is your friend...it is power. Some of the newer water/alcohol injection kits that the "tooner" crowd is using makes these "sqeeeze" numbers useable with pump gas. Painless Wiring makes one, and so does Snow Performance. VERY unlike the old Holley set-up I tried to make my 11.3:1 429CJ happy on 91 octane.

If those pistons could be milled flat, either 10.6 (1 gasket) or 9.74 (2 gaskets) are pump gas territory.

But I didn't know about the advances in water/alcohol, I did the same kind of testing on my 429scj way back, water thru an under dash valve. Too hard to control so I gave up back then.

I am not saying that all these suggestions aren't good, its just that you need to ask yourself "how important is it that I build the engine around these free pistons". Sometimes it is just better to spend the money on the right pistons and build the engine you want in the first place.

I am not saying it can't work with the pistons he has, I am just saying that sometimes it is good to take a step back and consider that the free pistons might not be so "free". Especially if you have to spend a bunch of other money trying to make them work and you have to make compromises on the engine specifications at the same time.

I bought that back in the eightys for $18.00 from PAW in Ca. I used to color the water different every time I ran the car...freaked people out since I had clear lines from the WI to the carb's...........I agree that in his and my situation that Snow water injection is the way to go, if fact there is an article about it in this months MMFF mag., Mike U.

327 chibbie engines used to come from the factory with two SHIM gaskets. They were advertised to have 11:1 compression---but not with two gaskets. And the warrantee disappeared if the engine had only one gasket per side. Note that these were shim gaskets of less than .015 thickness and no one ever talked about quench at that time.
KS

Todd, if you are wanting less than these popups will give, would you consider trading or selling them to someone like me ? I am wanting to build a 390 with at least 12 to 1, more is better, to run on alcohol. 14 to would be perfect for me. What compression are you looking to have ? Maybe we can do something for each other. Cal

I agree, rather than chop up useable high compression pistons, and possibly ruin them, I think a better idea would be to see if anybody here has some lower compression pistons to swap. That way, we may have 2 happy guys.

428 powered Fairmont drag car, Best ET:10.03@132.11MPH, best 60 ft: 1.29
59 Meteor 2 dr. sedan 332, Ford O Matic
74 F350 ramp truck 390 4speed

I want to be able to run on pump gas, This will be a driver as well as a drag car. The problem is I already had the machine shop put the pistons on the rods and the are balanced.

Todd, my unfortunate guess is that even with tripled gaskets, you compression is going to be too high for pump gas, AND your quench distance will be way too big, which causes detonation. Even if the pistons are already hanging on the rods, an FE has full floating pins, so disassemblig them from the rods is a two minute deal. If your shop already balanced the rotating assembly, they or you should have a card with all of the weights listed on it. I'm thinking you may have a set of TRW 2292s, which are heavy. If you switched pistons, your machinist would have to take more weight off from the conouterweights of the crank- easy to do- much easier than if you would have to add. Are you thinking you want something like 10 to 1 ? Cal

That would be good as long as I could run pump gas in it and still make good power.