[PAUL K]

A while ago we started working on some Pontiac aluminum heads for a pretty stout factory block build. The valves I wanted to use for the project were on Covid back order and took more than eight months to receive. So I could move forward on the project I used a couple of popular brand, nice looking "bargain" intake valves for seat work, port development and flow testing. The bargain valves were the same dimensions as the valves we were waiting for. I wanted to flow test the correct valves for the project and found the results interesting, so much so, I reflowed the bargain valves back to back to verify my data was correct. I thought I'd share the results. An added plus is the "good" valves are more that 10% lighter than the "bargain" valves.

Good valves / Bargain valves

Lift CFM CFM

.100. 81 81
.200. 151 141
.300. 222 206
.400. 282 266
.500. 330 318
.550. 342 335
.600. 361 353
.650. 363 358
.700. 366 361
.750. 366 366

[steve25]

Thanks for the report Paul!

Could you give more details between the two brands?

45 seat width?

Margin height?

Is one stem under cut?

Does one have a chamfer on top of the margin?

Is one more tulip then the other.?

The flow gains between.200” and .400” should make a fat difference in how long the motor holds on to peak HP for.

[Tim Corcoran]

That is very interesting who thought that a valve could make that much difference in airflow. I also am interested in what valves were the good valves and the bad valves. Also what about on the exhaust side? Was this with E-Heads of high ports?

[PAUL K]

Originally Posted by steve25

Thanks for the report Paul!

Could you give more details between the two brands?

45 seat width?

Margin height?

Is one stem under cut?

Does one have a chamfer on top of the margin?

Is one more tulip then the other.?

The flow gains between.200” and .400” should make a fat difference in how long the motor holds on to peak HP for.

Thanks Steve

Your questions in order

One brand we sell the other is sold by many including Pontiac specific shops.

Seat width .060 vs .085

Margin .060 vs .050

Both undercut stems

Both chamfered on face one is small radius other is small angle cut

Both 12° back angle

[PAUL K]

Originally Posted by Tim Corcoran

That is very interesting who thought that a valve could make that much difference in airflow. I also am interested in what valves were the good valves and the bad valves. Also what about on the exhaust side? Was this with E-Heads of high ports?

Hi Tim

I'm not going the mention brands. Most valve manufacturers offer different series of valves. Series X might flow great but Series Z might suck (lol) or one part number in the same series may be a good or poor flowing valve ..... I wouldn't want folks running out a buying poor flowing valves.

Exhaust has custom titanium which flow good.

Wenzler Series 2

[PAUL K]

Both valves were tested out of the box. Both valves would most likely show improvement with basic modifications. Obviously one has a lot more room for improvement.

[steve25]

Are they 2.19” valves Paul?

[PAUL K]

Originally Posted by steve25

Are they 2.19” valves Paul?

2.25

[steve25]

Thanks!
So using the valve diameter Xs .2 math it’s clear that the non bargain valve all the way up to .450” lift likes that seat geometry and the chamber exit geometry your using a good amount more!

[Stan Weiss]

Originally Posted by PAUL K

Thanks Steve

Your questions in order

One brand we sell the other is sold by many including Pontiac specific shops.

Seat width .060 vs .085

Margin .060 vs .050

Both undercut stems

Both chamfered on face one is small radius other is small angle cut

Both 12° back angle

Paul,
The actual flow area (curtain area) is smaller for the same valve size and seat angle with a wider seat at any given lift. If you have the time could you near the 0.085" down to 0.060" and see what the difference is?

Stan

Stan

[PAUL K]

Originally Posted by Stan Weiss

Paul,
The actual flow area (curtain area) is smaller for the same valve size and seat angle with a wider seat at any given lift. If you have the time could you near the 0.085" down to 0.060" and see what the difference is?

Stan

Stan

Hi Stan , sorry can't make that happen. I'm two years behind. I could spend a day and fix the bargain valves then I would be two years and a day behind. Regardless, it would be considerably heavier than the better valve even if I fixed the flow deficiency.

[Skip Fix]

Paul even though they have under cut stems are they the same diameter and same length of undercut" I have seen a wide variety of different dimensions there as well as different amount of "tulip" even on flat valves. Since the bargain valves are heavier I wonder if larger in those areas.

[slowbird]

Nice info. It pays to pay attention to details. People don't seem to understand why their cars don't perform as they think is usually because they didn't pay attention to the details. They paid more attention to $$, the small things matter. In this case yes what valves that are in the heads matter.

[PAUL K]

Originally Posted by Skip Fix

Paul even though they have under cut stems are they the same diameter and same length of undercut" I have seen a wide variety of different dimensions there as well as different amount of "tulip" even on flat valves. Since the bargain valves are heavier I wonder if larger in those areas.

Hi Skip, you are correct that is definitely part of it. The valve actually looks pretty nice until you look at it closely or compare it to a good valve.

[Stan Weiss]

Hi Paul,
Did you do any pitot probing with the 2 sets of valves?

Stan

[PAUL K]

Originally Posted by Stan Weiss

Hi Paul,
Did you do any pitot probing with the 2 sets of valves?

Stan

Good morning Stan, lot when developing the port.... None with the better flowing valve.

[Stan Weiss]

Originally Posted by PAUL K

Good morning Stan, lot when developing the port.... None with the better flowing valve.

Paul,
Thanks. I was thinking with the big difference in mid lift flow looking at the velocities at those lifts might give an idea of how / where the good valve had improved flow.

Stan