Thread: 302,347,351 which one should i build

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hey i got a 302 now that 30 over mid cam summit raceing intake but im pulling it out i need MORE POWER .plus it recently its started to have a lot of blow by i mean alot so whats your opinion on what build i should do well u know i have the block for building up a 302 or 347 but the 351 i can get for $200 bucks but 302 i would be puting on gt40p heads so i will have header problom but i would just get some made the 351 will be a very tight fit in my 63 1/2 comet the 347 i just dont know much about on building one the 302 if i would build it will makeing about 400 to 450 hp depending what options of parts i go with. the 347 and the 351 i haveent checked on parts yet but my goal is no less than 400 hp with good torque. so what do u think.

My choice would be the 351 with a stroker kit to 408. You can get big numbers out of a 302, but reliability and longevity will suffer. There's no replacement for displacement!!!!

what do u mean reliability longevity will suffer

Building a 302 to that high of a horsepower level requires running the engine right on the ragged edge. The bigger displacement offered with the 351 as a base for a stroker kit would probably be a better choice. Pumping a 302 to 400+ hp takes all premium parts and a whole bunch of rpm!!!

ok thanks im going to look in to a 351 but i got to see the cost difference is between the 2 but this is stuff i want to hear

times 2 on the 351 stroker...

Not much difference in stroker kit prices. Heads will work on either, too... Pat McCarthey right here on CHR has some great prices on internal engine pieces, might want to check with him, too!

Originally Posted by slepper63

what do u mean reliability longevity will suffer

Slepper63, I saw a nice little Mustang at a shop a while back that had the 302 block split right down the middle. He was pushing something like 650 hp at the rear wheels with blower & nitrous, and it simply could not handle the power. I'm at 425hp and have been told that I should not push it much more than 450, 500 tops and that is a risk. Others may disagree.

im really not going to race the car its more for cruisein and going to car show like what i do now but i have race couple of times when some pulls up to me u guys know how it goes. i really dont plan on beating on it.

i have a c-4 trans but i was going to rebuild it to handle the power will it still work with the 351 if i would go with it and if not what trans should i get . if i go with the 351 should pull the tran out the same car

A C-6 makes a good street tranny, C-4 is lighter, eats up less horsepower, and can be built into a good drag trans. For the street if I have to run an automatic, C6 would be my choice!

i was planing on puting in a shift kit in the c-4 but why is the c-6 better than the c-4 for the street

Not necessarily a better trans, but the C6 is a more heavy duty trans, and from my experience will give years of service and stand up to a considerable amount of hard use.... Your car is probably light enough that a C4 would also last a long time if setup and maintained correctly..... If you already have the C4, then that would be another point in it's favor!!!!

thanks dave i do have a c4 thats whats in now.

I've been involved with the 302 vs 351 discussion 2-3 times in the last few months and what it all boils down to is what you want to do with the car in the end. If you want an all out street - strip car, then for sure you want to go the 351W route. The 302 is about done with cubic inches somewhere in the 347 range while the 351 will go to 427 and more. There are a couple of areas that might cause you concern in your Comet - spring towers if you still are using that suspension. The 351 is an inche plus taller and two wider at the top then the 302. These are close - http://www.mustangsandmore.com/ubb/E...imensions.html.

Then of course, the cost - a 351W based engine is significantly more expensive - 15 to 25% more, something like a SB Chevy vs a BB Chevy.

The engine in my current car is based on a 302 crate motor with many additions. It was relatively inexpensive. My last car had a 351W .030 out to 355 and was a high end used engine build - and cost a fair amount more then my 302W. Given the chance today and knowing what I could have put in my car now, which was an unknown, for sure would have stepped up to the 351W.

And the C4 - never had a problem with either car. The C6 is a great transmission - but big, heavy and fairly expensive. A possible better choice with gas continually getting more expensive might be an AOD - and with them, there are "good" ones and "not so good ones" and that's the limit of my knowledge of AOD's.