302 Swirl port heads vs 340 X heads

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gipperco

gipperco

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So I have a set of 302 Swirl port heads currently on a 318 that I am building as a seat time race engine. Hope to run 13's high 12's in our Dart. I just found a set of 340 X Heads that are available. Would they benefit us on 318 for some extra HP? If so what is a fair price to pay for them?
 
Not really enough info,but the 340 heads will help top end h.p and kill the bottom end tq.Engine doesnt really have enough cid to use ported 340 heads. I'd buy em anyways if it's a good deal.
 
they are 69-70 heads disassembled. the 318 is basically stock with roller cam. HE doesn't know what he wants for the heads. wants me to make an offer.
 
You will lose compression because 302's are closed chamber and the X-heads are open chamber about 68-72cc's originally. The big valves will also hurt.
If they're in decent shape and you can get them cheap, do it. But not for your current combo.
 
To be completely honest I have absolutely no idea. It was in it when I got it, we inspected everything and it all looked good with very little wear and decided that it would be good to go to get her some seat time. She has never driven down the a race track yet so a 13 second car is a great place to learn. After a year of that and saving any money that we can we will build up from there.
 
will 302 heads work on a 340 with 11.5 pop ups cam is a solid 528 with 248 duration
 
pat d said:
will 302 heads work on a 340 with 11.5 pop ups cam is a solid 528 with 248 duration
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Most likely, no! 302's are closed chamber and the dome or squish/flat part of the piston will hit the head.

As for the cam, the right way to do it is to check piston-to-valve clearance with everything in place. Too many variables to "guess".
 
gipperco said:
they are 69-70 heads disassembled. the 318 is basically stock with roller cam. HE doesn't know what he wants for the heads. wants me to make an offer.
Click to expand...

you have to buy the heads..plus they are bare which will require springs...valves and probably guides..

I would buy a set of Engine Quest heads..EQ...small chamber like a 302 head...bigger ports like the X heads..better combustion chambers then X heads....flow alot better then a X head...

and probably cheaper went all said and done...you can get them with the LA intake bolt pattern...and just go to junk yard and get rockers off any magnum engines...
 
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