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351 with 302 heads
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http://www.clubcobra.com/forums/small-block-talk/129187-351-302-heads.html)
| Bryan Wilson |
06-04-2014 08:09 AM |
351 with 302 heads
Does anyone know of any problems with putting 302 heads on a 351 block any pros and cons are welcom.
Cheers,
Bryan
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| Rick Parker |
06-04-2014 08:19 AM |
As long as the compression ratio is acceptable you're OK. Some applications have valves that are smaller than 351 OEM spec but the architecture is the same.
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| Igofastr |
06-04-2014 09:00 AM |
Doesn't the 351 use larger head bolts?
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| Bill D |
06-04-2014 09:09 AM |
Quote:
Originally Posted by Igofastr
(Post 1304429)
Doesn't the 351 use larger head bolts?
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Yep! OEM 302 heads have 7/16" head bolt holes. 351 heads have 1/2" holes. Most if not all aftermarket heads have 1/2" holes |
| diverrick |
06-04-2014 09:13 AM |
Years ago when I used to run fast, I built a 302 up from scratch. I used 351 heads on the 302 block. That gives you bigger valves as well as a bit more volume. Then I added pistons that had to be machined to fit. It all adds up to more power. Not sure why you go the other way and put 302 heads on a 351 though. Maybe for higher compressions?
Trying to remember if the 351 heads didn't have stronger valve springs as well.
One note though. If you are planning on pushing the engine, make sure you swap out the pressed in rocker studs for threaded no matter which head you use, or the pressed in ones will pull out, particularly with a high lift cam. BTDT
That motor tried to kill me more than once. I finally totalled the vehicle and told the insurance folks from my hospital bed to keep the motor. I am guessing some one got themselves one hell of a motor. Bottom end was balanced within 1/4 gram!
That thing spun up like an electric motor.
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| Igofastr |
06-04-2014 10:48 AM |
Quote:
Originally Posted by Bill D
(Post 1304430)
Yep! OEM 302 heads have 7/16" head bolt holes. 351 heads have 1/2" holes. Most if not all aftermarket heads have 1/2" holes
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Thanks for the confirmation.
My point is that the holes in the heads will be too small for the 1/2 inch bolts that the 351W block needs. I would assume that the heads will need to be machined to fit the bolts through. |
| k98dave |
06-04-2014 02:47 PM |
The Ford Racing GT40X alum heads have the 1/2" bolt holes. I used them on a 302 with the bushings that come with ARP bolt kits.
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| Mark O'Neal |
06-14-2014 12:02 AM |
Or, Edelbrock has a bushing you can use instead.
Part number 9680 at about 55.00 a set.
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