Ported Chevy 487x heads

[Carnut1]

It would be good to see how these compare to 441's

Sure just keep loading the work on. I have a good set of 441's somewhere. They have the 441 on the bottom 90 degrees from normal 441. I am not sure why these are supposed to be the better castings.

LOL, sounds like you have a good collection of heads!

Last count 28 sets.

[Ks Fats]

Any 520's in your collection? I'd be interested in their flow characteristics; working on a set with 1.94 intakes now and finding a lot of variation of the bowl roof height relative to the seat. Pretty short on runner volume also but it will be a 2bbl deal; don't want to highjack the thread but I'd like to hear their pro's and cons.

[Carnut1]

Any 520's in your collection? I'd be interested in their flow characteristics; working on a set with 1.94 intakes now and finding a lot of variation of the bowl roof height relative to the seat. Pretty short on runner volume also but it will be a 2bbl deal; don't want to highjack the thread but I'd like to hear their pro's and cons.

I do. Completely stock. k-line guides and a three angle valve job.
When I was researching my flowbench to see if it had been upgraded and I spoke to the owner of Jamison equipment, nice guy, and we got into cylinder heads a bit and he spoke about his 60' wagon he races with 292 Chevy with 520 heads and stock valve sizes. Turning 8000 rpm. I never mind a thread highjack, I would say I would try to throw them on the bench for you but I don't think I have a single 1.72" valve. This is what happens when you move, all the junk you have been keeping gets dumped and then you need it!

[Ks Fats]

"This is what happens when you move, all the junk you have been keeping gets dumped and then you need it!" X2; I'm sure we've all been there. Thanks for the offer; maybe someone else can shed some light. I had heard of some of the small engine drag guys using them so there must be something there.

[Carnut1]

"This is what happens when you move, all the junk you have been keeping gets dumped and then you need it!" X2; I'm sure we've all been there. Thanks for the offer; maybe someone else can shed some light. I had heard of some of the small engine drag guys using them so there must be something there.

It is a small port but has a nice shape by eye.

[Carnut1]

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I never did any work to the exhausts on these. The 90's porting was pretty good on flow. The ssr is very tall on these heads and the port has a nice overall shape.

[Carnut1]

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90's bowl. Smooth finish

[Carnut1]

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Modern bowl slightly enlarged and finessed. Cuttered finish.

[Carnut1]

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Modern intake and 90's exhaust port flow. This head has a very high ssr in the exhaust and flows quite well even with my 90's porting.

[Carnut1]

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Modern intake and exhaust. Very deep intake bowl. (nearly as deep as my iron bowties) sonic checker said bowls still have lots of meat (I don't trust it). Increased pinch and lowered ssr on both ports. High lift gain on both. If I was running a low lift cam 90's porting actually averages higher cfm.

[Carnut1]

0505161956.jpg

Modern intake and exhaust with increased pinch, lowered ssr. Averaged from .1 to .7 lift and .1 to .8 lift. High lift gains come at low lift losses.

[steve316]

If you are running a exhaust with more margin; radius chamber side of exhaust. those are very good number .

[Carnut1]

If you are running a exhaust with more margin; radius chamber side of exhaust. those are very good number .

On the 049 head thread the radius on the chamber side of the exhaust was worth quite a bit of flow. Thanks.

[wyrmrider]

speaking of margin, which I like for my builds because they live longer
straight or break the sharp corners or full radius
when and why?

Nice work Carnut
I've never progressed much beyond your "old school" (starting from "hog them out big")

[Carnut1]

speaking of margin, which I like for my builds because they live longer
straight or break the sharp corners or full radius
when and why?

Nice work Carnut
I've never progressed much beyond your "old school" (starting from "hog them out big")

I would need to do some testing to answer the radius question. It does seem to increase flow, maybe decrease cone size around valve. Will also change your overlap flow, I would think increase overlap flow.