Is there any good reason to put '86 pistons in an E7TE block? I looked again at the pressures I was seeing with compression check. Pressures were 130s-150s except the rusty one at 108. One cyl read 155 on two different gauges. Isn't that 10+:1? Is that possible with flat-top pistons? Could a head shave do that? I haven't cleaned the gasket material off the heads but didn't see anything stamped to indicate a shave. Think Ford used up some old pistons when assembling this engine?
20% difference across cylinders indicates a much needed rebuild. the block is still the same either way but what u have is an 86 motor. heres what u need........
But .. but .. but .. what about the E7TE cast in the block???? That can't be an '86 block. I'm guessing that's a stroker kit in your pics. Tempting!!! I ridge reamed it and got the rotating assemble out today. Next I'll hone it to see if all the cylinders will clean up. Then take the bare block, crank, cam and E7 heads to get everything cleaned/miked/checked. See what the machine shop suggests. Then I'll think about the options. If I have to bore it (new pistons) or do crank work (expect they'll at least want to polish it) a stroker kit might be the way to go.Lots of options -- gotta get some numbers to compare. Thanks for comments.
th is is very strange. 86 pistons and 86 heads with an e7 casting on the block. If I had to guess, its probably a VERY early 87 motor, and was used in the end of the lineup on the 86 mustangs, or the very first of the 87 mustangs. either way, you won't clear e7 heads or gt40 heads with those pistons without cutting valve reliefs
Not good news but I'm VERY glad you mentioned that. Didn't know there was a problem putting e7 heads on earlier 302s with stock cam and rockers. Thanks. :Handshake No markings on the cam other than "XXXXX 5.0" cast in between the lobes. But, the cam has been out before. One of the bolts holding the cam end plate was definitely not original. I'll borrow a dial indicator and check the rise.
IF it is a stock 86 type bottom end, then 50% of the time e7's won't clear...gt40's won't for sure. I've had two friends personally run into piston to valve clearance trying to swap e7's onto flat top 86 style clearance. "some" have been able to fit...it's that close. You've got to clay everything up. they sell a piston notching tool, which from what I've heard, really isn't that difficult to use
my buddie has an 86 bottom stock and had factory e6 heads. when he was running that, he had a f303 cam w no clearance issues. then swapped to gt40s and went back w factory cam and has no issues whatsoever. so gt40s and e7s do work but usually not w additional mods like a big cam or high ratio rockers.
THEY WILL NOT WORK 50% of the time or more...that is a fact. I've been dealing with these 86 mustangs for 15 years now. i've already stated that clearances are such that "some" 86 blocks will indeed work, many WILL NOT. you have to clay everything up first. I've had 2 friends literally try to upgrade heads on a stock 86 shortblock and have the valves touch the pistons when they clayed it up. clay it up, or you'll be very, very sorry 50% of the time..that's a BIG risk
Seldom do we get such a thread that brings out so much good info. Kudos to all involved. Even more interesting because I just did the 302-to-5.0 swap, but my pistons had valve recesses in them, so my gt40 heads had LOTS of clearance. Someone mentioned earlier that you can determine compression ratio from compression numbers. I always assumed this, if the rings are tight and not letting any pressure leak by. If this works, what is the general equation for getting CR from psi?
the 85 roller and 87-01 5.0 blocks ALL had valve reliefs...all except the 86 blocks ...which sucked for me, as I have several 86's.... FYI also, those 86 mustang flat top pistons ARE forged...so it "could" be worth re using those pistons, especially if you want to spray.
Mine was a reman engine with .040 over pistons, so I have no idea what it came with stock. But the .040 overbore pistons had the valve reliefs, which, according to some other threads, was a lifesaver, since the gt40 heads and bigger cam/1.7 rockers seem to be an issue with flat top pistons.
I always heard that on the 86 5.0's there was valce clearance issues. What about an 87-88 Bronco 5.0? I have one I can get free along with the rest of the truck. Are they worth messing with? I know it's not a roller. clint
I thought '86s had "true" flattop pistons.Those look like they have a dish to them.My Comets motor is a bastard-'85 block,'86 pistons/E7 heads.Running a B303 w/no clearance issues.Of course the block/heads have never been decked to the best of my knowledge.
