Valve sizing

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Bubblhead
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Valve sizing

Post by Bubblhead »

With a reasonably mild 4.7 build based on a 99 block and 0630 head, i had considered bumping the intake valve size up to 1.94 or 1.97, probably a swirl version and a swirl stock size exhaust. is this even worth the trouble? I am guessing any gains would be negligible and maybe not worth the cost? Any thoughts? TIA
Randy Bobandi
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Re: Valve sizing

Post by Randy Bobandi »

There isn't much issue with the stock valve diameters. The bottleneck is the throat and the ID of valve seats.

Most cylinder head pro's like to see the throat between 90%-92% of the valve diameter. Stock Jeep exhaust throat is 85%, Intake is 88%. This is why I don't like to run larger diameter valves on the stock valve seats. Tucker Valve Seats makes excellent oversize seats for the Jeep cylinder heads and your local machine shop would have no problem installing them. They allow up to 2.00" Intake and 1.600" Exhaust valves. If that's too much work, you would be better off porting the head that you have and slightly opening up the bowl and the throat to work well with the stock valve diameters.


ID OD H ID OD H
Stock Jeep Intake Seat - 1.675 x 2.00 x .21875 Tucker T-301+031 Intake Seats - 1.750 x 2.0365 x .21875
Stock Jeep Exhaust Seat - 1.285 x 1.5642 x .1875 Tucker T-952 Exhaust Seats - 1.375 x 1.625 x .21875
Russ Pottenger
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Re: Valve sizing

Post by Russ Pottenger »

Doing a LS Chevy valve upgrade it’s pretty straightforward.

You’ll have to have your machine shop hone the guides and Machine the valve spring seats for a 1.700 Install Spring Height. This will also allow you better choices for camshaft selections. Opening up the bowls and doing a pocket port will help give you the biggest bang for your buck.

For under $300.00 your getting 2.000 intakes, 1.550 exhaust, LS springs, matching chrome Molly Retainers, and a set of valve locks.


Any questions you’re welcome to reach out to me.

Russ Pottenger
Bishop-Buehl Racing Engines
531 N. Lyall Avenue
West Covina, California 91790
Work (626) 967-1000
Cell (626) 673-2203
Email: [email protected]
Bubblhead
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Re: Valve sizing

Post by Bubblhead »

so it sounds as if a combination of both of advice will work well for me, Thanks!
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