I bought a 1990 mustang about 3 months ago. The guy had it for about three years. No one knows how many miles are on the engine. Probably alot but it runs fine. It does have an oil leak, I believe from the rear main seal. I plan on replacing the clutch soon and I'll take care of the leak then.
Anyway, on to my question. Is it ill advised to upgrade to some gt40x heads on an engine with (maybe) alot of miles?
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you'll get mixed replies, but generally IMO if there isnt significant wear in the cylinders when you pull the heads off and you keep everything clean as to not introduce debris into the motor (like in the cylinders between the piston and the cylinder wall above the top ring) you'll be alright with a new set of heads.
i agree with 68 on doing the compression test, if they all check out ok, and you have no major oil leaks or rattles or knocks, then sure go for it, ive torn 5.0s down after 100,000 miles plus and they still had the cross hatch pattern on the walls, so they hold up really well if taken care of. while your at it throw in a new timing chain and gears, hell while your that far might as well toss in a different cam too to really take advantage of those new heads. and dont forget the factory intake is very restrictive and will be a major bottleneck with those heads. remember its all in the package. have fun!
i agree with 68 on doing the compression test, if they all check out ok, and you have no major oil leaks or rattles or knocks, then sure go for it, ive torn 5.0s down after 100,000 miles plus and they still had the cross hatch pattern on the walls, so they hold up really well if taken care of. while your at it throw in a new timing chain and gears, hell while your that far might as well toss in a different cam too to really take advantage of those new heads. and dont forget the factory intake is very restrictive and will be a major bottleneck with those heads. remember its all in the package. have fun!
+1, at the very least buy a new 35.00 double roller cloyes timing chain.
just tear it appart lightly hone it ...put new bearings and rings in it and re gasket motor and oil pump..when it's all said in done you'll have around 400.00 in it..= overhauled motor= good for a while
do what mjr46 says he is very skilled in these areas and i have taken his advise more then once, and also have seen his green and silver stangs run and there both fast, (his wife drives better then him)[sm=owned.gif]
im doing what your doing exept i got me some GT-40P just check your heads good before you use them, maby change the springs and grind the valves and port them!
mjr i'd just be worried about someone without experience doing the bottom end incorrectly and ending up with something worse than when they started, knowwhatimeanvern????
mjr i'd just be worried about someone without experience doing the bottom end incorrectly and ending up with something worse than when they started, knowwhatimeanvern????
And this is my situation. I'm learning but I'm not ready to rebuild my current engine. My other option was to buy an already rebuilt shortblock and slap my heads and upgrades on there. But, if my block is still good, I'd rather save the money.
Upgrading heads on a high mileage block
