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heads for a 283

 
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aharris05
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Joined: 07 Sep 2011
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1444.66 points


1968 Chevrolet Camaro

PostPosted: Fri Jul 25, 2014 9:26 pm    Post subject: heads for a 283 Reply with quote

Thinking about using some of our spare parts lying around and see how it runs. I have a standard 3.875 bore 283 short block, and a set of 186 fuelie heads, 2.02 intake valves. and a 282S comp cam (.495 lift). Does anyone know if I can put these heads on the small bore block, or will I have clearance problems?
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clay
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Location: South Carolina
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1972 Chevrolet Nova

PostPosted: Sat Jul 26, 2014 10:56 am    Post subject: Reply with quote

I did some searching around on 307's which share the same bore size and it does appear the 2.02 valve will clear the bore. As a quick check stick a head on a bare block, flip it over and have a look. Some interesting reading also shows some 283's can go 0.125" over giving you a 302. You'd have to test the block of course but it would open up the world on piston selection. Clay
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Big Dave
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PostPosted: Sat Jul 26, 2014 12:13 pm    Post subject: Reply with quote

Yes the valves will physically clear the bore but they will be shrouded by both the combustion chamber walls and the cylinder walls. It is for this reason that the factory engineers chose a 1.94 valve for the 283 and held off on the 2.02 inch valve till the introduction of the four inch bore.

You can grind a notch similar to the one used on the 396 that stays inboard of a line showing the head gasket seal, and above the top ring to aid in breathing as well as grinding to relieve shrouding of both intake and exhaust valve in the combustion chamber. (David Vizard's book on head porting covers that detail very well)

Big Dave
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af2
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1933 Willys Coupe

PostPosted: Sat Jul 26, 2014 5:43 pm    Post subject: Reply with quote

The 186 heads for the most part are 1.94/1.5" IE.

I would be surprised if you have 2.02/1.6"


All 283's had 1.72/1.5" valves. The first 327 had 1.94/1.5" valves or 2.02/1.6" on the Corvette dual quad/FI cars.
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aharris05
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Joined: 07 Sep 2011
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1968 Chevrolet Camaro

PostPosted: Sun Jul 27, 2014 9:45 am    Post subject: 283 Reply with quote

Most everyone seems to agree that the drop in CR and shrouding of the big valve would make this a waste of time. Too bad, because Camquest calculated about 400 hp with this combo. Alotta guys tell me that the Vortech heads would work well on this motor. I will keep these bigger valve heads for a bigger volume motor. I have a .030 350 block out in the shop. And yes, they are definitely 2.02 intakes - I measured them to be sure.
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Paul P
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1971 Chevrolet Chevelle

PostPosted: Thu Aug 07, 2014 11:02 am    Post subject: Reply with quote

400hp with a 283 is something I would like to see. Buzzing to the moon to do it. That is 1.41HP/CI.
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