Need help finding the correct intake valves for my #6 cylinder heads. I am looking for bigger valves in the 2" area. I have seen articles and vendors offering the following sizes: 1.995, 2.02, and 2.07. Which one is correct/best? Any part numbers would be appreciated.

I am going to stick w/the stock size (1.562) exhaust valves, but cannot find a vendor that sells them. Any help on this would also be appreciated.

d1

 

The correct "larger" SBO intake vales would be the 1.995 set. 2.02 are SBC and the 2.07 are BBO.

 

I'd think the 2.07 woud be the best - a good shop should be able to increase the seat to the correct location with only the grinding stones!
A nice 'bowl blend' after installation would help take advantage of the larger valves, too!
Same applies to the exhaust!

 

Grinding stones!!!!!
Take them somewhere that has a Serdi or similar seat machine. A much better way to do them. Plus they can cut into the bowl area equally from valve to valve. Makes it a lot easier to blend from there.

 

Thanks, did not realize the 2.02 was chebby.

What does a "bowl blend" accomplish exactly? Is it simply smoothing out the combustion chamber around the valve seats for better flow?? Does bowl blending negatively affect CR?

I should probably enlarge the exhaust side, but I am going to keep the exhaust manifolds (with dual exhaust). Trying to keep costs down so I can apply it to the 425 I will have shortly.

Does the seat machine cut the diameter first to accommodate the valve and then cut the angles 30,45, 60? Or is it done all at once?


d1

 

All at once. Bowl blending is the area below the valve commonly referred to as the valve pocket.
Unshrouding the valve in the chamber area is most beneficial to low lift flow. Depending on how much you take out of or smooth the chamber will determine how much compression you lose. You can always cut the head to achieve whatever compression ratio you're looking for.

 

C'mon you guys - a lot of us grew-up in the "stone" age!! [NOT 'stoned']
We even used calipers to measure, and got the job done!!
No shop I've worked for could afford anything more than a good Quik-Way setup.

 

We used to ride horses and use pay phones, too. Remember when high 13s was fast?

Dual-pattern cams, multi-angle valve jobs w/porting was super-secret race stuff back in the day, now it is common-place. Keep up with the times!!!

 

Most hops will use some sort of "bowl hog" to open up the bowl for a larger valve. A stone can do the same thing, but the stone wears down, and changes shape as it cut. Stones wear out, and they cost money. An experienced machinist can only equal what a Serdi machine can do, but he really must be on top of his game. There are some things a Serdi can not do, also. A Serdi can not cut the bowl with any bias (professional head porters know there is airflow to be found having one side of the bowl deeper than the other), this can only be done by hand, or with a CNC.

But the 1, most important thing a Serdi will do, is cut everything exactly the same height, and same size, as long as the operator correctly sets the plunge depth.

Valve, and port work always comes down to who is using the equipment, no matter how outdated it is.

Jim