I'm thinking of keeping my 302 a 302, or re-bore to 306 instead of stroking it. I think 5l is big enough in my 1200kg maverick and would rather spend the money on performer heads, roller cam and forged pistons- with the intention of plumbing in some giggle gas! Question is- where are the typical weak spots on the 302's, and would I need to put a girdle on the bottom end as it is only a 2 bolt mains and will be pushing for a good 400bhp!!
Reboring it to a 306, instead of stroking it? You won't notice any difference in power. a 306 is just a 302 that's been rebuilt due to worn cylinders. There's proboally a million running around. I do agree with going w/ the cam, heads, etc instead of the stroker. You can always stroke it later, but w/o decent heads/intake/exhaust it's pointless to stroke it. As far as a girdle, it never hurts to have it. I'd buy a set of light weight quality pistons/rods and go from there.
Depending on the blocks vintage and where its made... They suffer from weak main bearing webbing (unless its a mexican block) as well as thin cyl walls (early roller blocks) Heads are the main limiting factor on a small block ford. I would stud the mains (loose the bolts) to limit cap walk and use a girdle if your gonna rev the wee out of it. Stock crank will handle 400hp, rods need stronger bolts.If you are serious about the bottle feeding...Stud the heads too and "O" ring the heads for better sealing. Stock blocks tend to saw themselves in half at the 600 HP mark, soo you should be golden at 400HP. Good luck!!!
Sorry I know a 306 is only a bored 302- but unless its in perfect condition when I strip it down it will get a bore to tidy it up- never meant for extra power sorry for the confusion! So what pistons and rods would be a good combo? Would I get much benefit by getting longer rods in there or not worth messing around with? I would always ARP the heads and mains, con rods too, are there some good off the shelf girdles to buy or are they custom jobbies? Sorry I'm only used to Rover/Buick V8's as they are the only ones common as muck in the UK!!!
your heads cam intake idea is good. choose a well matched combination. i dont belive in girdles. ive seen the blocks still split in half with them. its not pretty. a long rod should give you beter torque production wich is a problem with the 302s short stroke so it would be a good idea to get longer rods. sence your replacing the rods and pistons any ways. put money into your valve train so it can spin some high rpms. thats where the money will really pay off.
To girdle or not is hard to answer. I have seen people swear by them, and others who havent. Personally I dont think its the horsepower that matters in your case as much as how you plan to drive your car. Adding a girdle doesnt cost much money but to do things right you need to replace the main studs and should re-alignhone the block which can be an additional cost. You didnt mention which year block you have which can make a difference too. As for rods and crank, keep in mind machine shops are getting expensive. Make sure you price the cost of having your crank and rods redone before you do it, because in some cases for a few extra bucks you can buy stroker cranks and rods for less then having your parts re-conditioned.
Agree with brainsboy. First rebuild should be checked for line-bore. Recon rods good, if I was gonna spend $ onrods, I would stroke it.
You have a point- with the cost of H beam rods and pistons- a stroker kit might not be much more. How much metal has to come out of the block with a 331 stroker crank? Roller cam & lifters sound good
Great point, last crank I had ground cost about $120 and that was a long time ago. With cast Eagle cranks around $200 on ebay that makes the difference pretty reasonable.
One more added cost of a main girdle in a Mav/Comet is a new oil pan. The stocker ain't gonna clear the rear main studs pokin below the girdle.
i didnt have to clearance my block for my 331. a 331/347 is a much longer rod as well so....i think to make a long rod 302 w stock crank would be just as expensive as a 331/347.. since u were planning on boreing it anyway. but a 302 w afrs or trick flows..etc will make plenty of power.
Even with a 302 you can go big with the heads if you use the right cam to control them, AFR185s, TF TWs, etc. I would buy a Scat crank before an Eagle, they usually need less machine work. A girdle won't keep a block from splitting but it might contain those expensive engine parts so they don't fall all over the ground when the block does split.
