Performer RPM Gasket Matching

[rockhouse66]

Jay's book says that gasket matching didn't have much affect on the Performer RPM intake, but please take a look at what I have and comment.  The gasket shown is a perfect match for my ported C6AE-R heads so do I at least blend the one tall side of the port that is a mismatch?  I seem to recall that blending the bottom of the port is not a good idea??

[turbohunter]

I’m certainly not the end all be all on the subject but I don’t like the way that gasket fits.
Understand it fits your head.

I think you’re right to stop and question.

When I was at Jays last summer we went through a few manifolds where it did not matter a lick if there was a reasonable step to the manifold but none of them were as misaligned as that one.

Hey Rock, why is the manifold discolored a bit behind the mating surface by 1 and 4? Has it been worked on?
Sorry I have no answer for you but questions I have.

[Joe-JDC]

Just blend the sides and top, leave the bottom as is.  Only go in about 3/4" or less and blend in.  Be careful not to cut the pushrod tube holes  The bottom on the tall port C6AE-R heads is not important there for flow.  It will be fine.  Also, you probably noticed that the Reintz gasket ports are not all the same in width.  Joe-JDC

[turbohunter]

Is that a normal deal Mr. Joe?

[Stangman]

I think that gasket needs to be flipped the opposite way. The heat riser is on the other side, gasket might sit differently

[Joe-JDC]

Every Reintz that I have seen for the FE has one end port that is narrower than the rest.  Just the way they are made.  If your heads are larger than the gasket, I would try to open the gasket up to match the head on the inside turn side.  If the heads are the same size as the gasket on that port, leave it alone.   Try to match the intake manifold on that port to the gasket, and not larger like the other three ports.   Joe-JDC

[rockhouse66]

I will flip the gasket and see what happens - good thought.  I have other gaskets to test fit as well.  I like the moderate blending approach, sides and top.

This is a used manifold I got with some other parts (some of you may remember SOHC Bob from the other Forum) but it does not appear to have been tampered with, just "used".

[338Raptor]

I’m in the leave it alone crowd.
I would bet that manifold (untouched) will drastically outflow your heads.  If this is the case, opening your manifold ports will only slow the air/fuel charge velocity.

I know this isn’t exactly apples to apples but my 557 BBF has the same mismatch with Kaase P51 heads and an Edelbrock intake manifold.  Jon Kaase’s guy told me to leave the manifold alone.  That motor makes 900hp and 801 torque with untouched manifold and heads.

[falcongeorge]

If that gasket matches your heads, and the gaskets orientation is the same as when it matched the head, I would suspect that intake has some core shift. The alignment is pretty inconsistent from port to port, the end runners sit higher than the two middle runners by a fair whack. I would expect some port-to-port variation, but that's all over the map.

[rockhouse66]

falcongeorge - I see what you are saying and I will go back and repeat this more diligently.  However, other than double and triple checking to be sure I am transferring the dimensions from the head to the intake properly, if the large overlap on the tall side remains I think I will blend it back a bit as JDC suggested.  I mean, after all, it is what it is, regardless of the reason.  Or did I miss your point?

[turbohunter]

Hey rock, what falcongeorge said is where I was trying to get without the ability to spit it out.
I fully understand just runnin it. It’ll prolly be fine with a blend. Especially if it is a 300 hp workhorse. What f’george said is why I was asking about the manifold history. It seems odd to me that manifolds would core shift but stranger things have happened. I’d almost trust the gasket before the manifold. In your photo it seems that the bolt holes are off also. Did flipping the gasket have any alignment affect?
I’m just curious about your deal, I’ve never seen alignment that far off but I haven’t seen boat loads of engines. Maybe the guys that do lots of engines have.
Color me curious.

[falcongeorge]

falcongeorge - I see what you are saying and I will go back and repeat this more diligently.  However, other than double and triple checking to be sure I am transferring the dimensions from the head to the intake properly, if the large overlap on the tall side remains I think I will blend it back a bit as JDC suggested.  I mean, after all, it is what it is, regardless of the reason.  Or did I miss your point?

Im sure its usable, but it does kinda stick out when you look at it. FWIW, in my experience on the flow bench, the air within the last 1/16 of the runner wall in generally not as active anyway, so its probably not a big deal, but I generally port match everything anyway, force of habit more than anything else. One thing you DONT want is to grind so much that you create a big increase in the CSA at the runner face. You only want to increase CSA on sharp turns, like at the turn into the bowl, other than sharp turns, you want to maintain a fairly consistant CSA.

[rockhouse66]

I did a more diligent job of aligning the gasket to the intake and I think the result is within reason. I am matching to just inside the scribe mark on the sides and bottom and leaving the top alone as suggested.