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Old 11-01-2002, 11:37 AM
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Post Opinion on 302/351W heads

I found these on ebay, was wondering what people thought of them.

<a href="http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=1870983196" target="_blank">http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=1870983196</a>

They have sold several sets, and I have emailed the buyers to get their opinions, but was wondering if these would be a better addition to the 302 I'm building rather than the set of stock 302 heads (D3 casting number).

I was also wondering if anyone had any info on the size of the intake and exhaust valves on a D3 cast 302 heads.

Thanks,
Ryan

[ November 01, 2002: Message edited by: 66StangBoy ]</p>

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Old 11-01-2002, 12:31 PM
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Based on what it says, these heads would give you no performance gains over your heads that you have now. The stock 302 heads have the same sized valves as these heads that are for sale. They don't say anything about combustion chamber size, which is pretty important if you are looking for performance. It is obviously not early 351 heads becuase they have bigger valves along with bigger intake ports. If it is off of a 351 windsor, its probably 69cc and if you put it on a 302 it will actually take away performance becasue of a compression ratio of about 8:1. The ports are identical also to 302 heads. Also, if its off a 351 and you put it on a 302, you need head bolt bushings to make the holes go from 1/2 to 7/16"
If it is off of a 302 the combustion chamber volume could be anywhere from 53-67cc. I can't tell you because they didn't give the casting numbers. The only condition that I would buy these under is if it had under 60cc chambers to give you 9:1 with flat tops. Otherwise you really don't have any gain over stock heads except for those stiffer valve springs. If you have a stock cam it wouldn't make a difference anyway.
So, ask them what the casting number is. You say that your heads are D3XX, which means they probably have large chambers becuause of the gas crisis and smog laws during those years. You might get a performance gain from compression using these afterall if they have smaller chambers.
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Old 11-01-2002, 12:33 PM
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oops, i mean with 60cc chambers you will get 9.5:1! . . .with flat tops
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Old 11-01-2002, 12:58 PM
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Is there any way for someone like myself (hardly even a backyard mechanic... more like I just found the backyard, hehe)to determine the size of the combustion chamber size or would I have to take them somewhere to have them checked?
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Old 11-01-2002, 04:10 PM
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I have one other question about heads... I've now had the info that perhaps putting some kind of larger chevy valves into 289 or 302 heads would be a really good way to get the engine to breathe.

Anyone that could elaborate on that?
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Old 11-02-2002, 02:36 PM
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yes you can put larger chevy valves into your heads and it will help upper rpm hp. It may effect your low end torque too though, im many cases with pushrod engines you will have a tradeoff with low end torque or upper rpm hp. This pertains to cams, heads, and intake. So yes you could, it takes a lot of work though i would have a good machine shop do it. Its up to you if you would rather have low end torque or higher hp.
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