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Here’s the intake port flow tests I ran on the stock SM head, the CNC SM head and the TF head.

Very nice work. I love the shape of your flow curves - that’s tough to do! You are a talent for sure.

Ok. Try again.

What heads do you have and what heads do you need? I have some stuff laying around.

Maybe this is the source of some confusion. I have stated several times that I am trying to find the flow limits of a 2.02 valve. But that is not the same as saying I believe more flow is always better. I'm trying to understand what exactly is going on the the port that stops flow at the...

Point taken, but not necessarily agreed with. I do appreciate having my thinking challenged. It's how we learn new things. Now here's why I say I don't necessarily agree. I am thinking street head which means less overlap. A 50 degree seat will help prevent reversion. A 40 degree top cut...

What heads do you have so far? OOTB or ported?

I have never flown a port backwards. I’m not saying you are wrong, but I heard Darin Morgan say to fight reversion with velocity and cam timing, not seat angles. I do know this. The steeper top cuts fight reversion both on overlap and the short side reversion that occurs at high intake valve...

Here's a few pics. Since the new valve job is not centered on the old seat insert, it's a little confusing to look at since each angled cut goes in and out of epoxy, aluminum and insert. Hopefully the color coding helps identify each cut. Cuts are 40/50/65/75/80 with the 80 blended. The red...

No difference. This is just the first step - move the valve centerlines. I've been trying to find the flow limits of a 2.02 valve, so I want to stay at that size for a while. The exhaust valve was moved more than the intake in the hopes of testing something larger than a 2.08 at some point in...

Do you have a dyno date scheduled yet, or is this something out in the future? I think there are many folks that would love to see these results.

I’ll post some tomorrow. Seats were not replaced. Epoxy was used to form part of the top angle in the chamber and to form part of the throat. This is one port in a test head.

I sure wish this test were with some PBR prepped heads. The CNC Speedmaster heads seem to be all over the map with quality. The head I have for testing is 200cc, 93% throat and flows 266 cfm.

Here's before and after data from the same port on a stock Speedmaster SBM head, not CNC'd. Before: OOTB stock 15/45/60/90 valve job with Ferrea 30/45 valve, 90.2% throat. No modifications to port or chamber. After: Intake valve shifted 0.060", exhaust valve shifted 0.080". Valves sunk...

I agree, and I’ll never be able to make that distinction on the flow bench. Plenty of people with success with both the 45 and 50 degree seats. I have learned that a top cut angle of 5-10 degrees less than the seat angle helps flow in the mid to high lift zones while marginally hurting low...

I will eventually get there with the throat size. Starting small and working my way larger. This is the 5th or 6th valve job so far on this port, but also the best as far is the flow bench is concerned. The tight throat controls the flow separation longer. I realize that is not the ultimate...

Not quite sure what you are saying with the first two statements. Care to elaborate? I have read some of the theories behind large bowl/slower air speed/higher pressure/better throttle response/more torque. Is that what you are referring to? Your last statement is certainly true even just on...

Thanks for the kind words, but I think we can both look at the flow graph and see there’s still a lot of work to do to stabilize the port. On another note, I’ve had a machinist friend move an intake valve 0.060 and an exhaust valve 0.080 in another port on this head. Don’t know when I’ll get to...

He and his posts have been a big help.

Been working on this port for 5-6 months now as time allows. The objective is primarily to learn, so I take liberties with epoxy and clay that would not work at all in a running engine. My goal is this - to find the flow limits of a 2.02 valve and to learn why flow increases stop. After all...

I wonder what the results of a Dykem wet flow test on the bench would be. It looks like some of the air from the cyl center side is being used to push the fuel back toward the cyl wall side. This is the lean and detonation prone area according to Darin Morgan. I've never liked the idea of...

Earlier in this post we discussed the purpose of the vein in the TF head. Eric touches on it a little in this video:

Does anyone know of a reduced diameter head stud for the SBM? I have seen them for motorcycles and a few other auto engines, but can't find anything for the Mopar. It would have to be 1/2-13 on one end, reducing to 7/16 or less on the smooth shank and top threaded portion. Looking for a way...

^^^Agree^^^ The PR pinch complicates things, but it is capable of well over 300 cfm without relocating. 2.02 valve can flow 290-295 by 0.550.

Kingsport. You can probably hear me typing.

In the flow testing I have done, I have always been able to find some flow increases around the valve guide. Get it right and there are 10 cfm on the top end and a few cfm throughout the range. Behind the guide accounts for about half of that. I have always found a knife edge airfoil shape...

TF bowl is 1.996 or 98.8% at the tip of the bronze guide. That is the widest point and it tapers toward the throat. Factory CNC Speedmaster is 1.904, 94.3% at the guide and 1.923, 95.2% between the guide and the throat. I would enjoy the opinions and theories on bowl sizes. I have several...

Max bowl width is 1.930, so 95.5%. That occurs about half way between the throat and the tip of the bronze guide. It's a little smaller at the tip of the guide.

Back on the Speedmaster head with a few changes. I increased the width of the port on the cyl center side at the apex which brough the velocity at the apex of the SS down to 360-380 range. It was almost 410 at peak. Flow did not change much, maybe down 5 cfm from previously. I also undercut...