1968 ford 302 boreing question?

1968poney · 06-12-2009

this prob seems really stupid but whats the max boreing size on a 1968 ford 302, and i mean max. is it possible to bore it .09 over or is that just plain stupid. if so would it be posible to put 390 pistons that are .03 over size in the 302 or are they too long. the reason i am asking this stupid question is cause i was going to make a 302 engine with a 302 block but use a 289 crank and rods. that way i get same displacement but higher rpms cause the crank doesnt have to turn as far.

prob a stupid question please dont give nasty answers i already built a 302 and i have a block left over and just want to use it with out wasteing parts the block is a 1967 december 29 302 with a 289 setup

Thanks Tom

"its just one of those wondering things or what if"

cindys_sn95 · 06-12-2009

.030 is about max on a 289/302. and yes they are to "tall". if you use a 289 crank, rods, and pistons it will be a 289. but thats o.k. you are only talking 13 cubic inches! if you are looking for more power save up and get a 331 stroker kit, it will still rev like crazy and make plenty of power with the right combo of parts.

kens67mustang · 06-12-2009

anything over .40 over on a 302 block& you are asking for heating problems. How would i know this? I had a 40 over 302.........ran great. You COULD take it 60 over if you are brave enough......but, i wouldn't. 40 is max.

L3K · 06-12-2009

I have my 289 at .60 over and to be honest I've never had a issue with it. no over heating problems or anything i just upgraded all of my engine cooling items and its fine.

1968poney · 06-13-2009

not looking for more power just reving easier. strokeing an engine key word makes a longer stroke so the engine has to pull the pistion further down to get the extra cubic inchs. im sure if i realy want i can do this it would be cutom though there are aluminum 302 svo blocks that you can bore .125 over the pistons would have to be custom when you stroke an engine you lose the fast rpms but gain the power what you want is a bigger cylinder with a nice size stroke. the big blocks are only .04 bigger bore then a stnd 302 (the 390). whats the difrence is the cylinder length and the stroke. the bigest bore size stand on a big block that is a ford is a 4.36 a 302 is a 4.0 the stroke on a 460 is 3.85 and the 302 is a stroke of 3 when you think about it it takes more power to turn a 460 then it does for a 302 but the 460 clearly has more power cause of its displacement what i want is for some way to intertwine. big bore and a small stroke high rpms quick responce and of power. it was just one of those concepts of what if and was wondering i pretty much new the answer was just seeing if i was wrong.

as far as heating problems ford is known for that. but you can fix that by makeing sure all your ports are clear and the gaskets are all ligned up and of course polish and port.

if i want power i dont want to be on a small block i could get a 460 and stroke that out to a 512 but any ways thanks for the info. nothing against small blocks in fact i have 2 302s one in my f150 and my 68 mustang both are awsome.

Thanks Tom