Exhaust Port to Header Flange

GeorgiaSnake · #1 (**permalink**) 05-21-2003, 07:26 PM

I was fitting my header gaskets tonight and realized my Edelbrock Aluminum Heads (which have been ported) have exhaust ports that are approximatly 1 1/2" h x 1 3/8 wide. My headers measured inside the flange is 1 1/4 " h x 1" wide. What to do - I don't think I can grind enough off the header to get it the same size. This seems to be a rather large restriction, almost 50% and wondered how much power I might lose. Any suggestions appreciated. Most of the area inside is weld bead and I'm afraid if I grind it out the header may fail.

Randy

xlr8or · #2 (**permalink**) 05-21-2003, 11:27 PM

I would look at some larger tube headers. That much blockage and you are sure to lose some significant power.

You may find other problems as well. Since they are so much smaller you will probably have issues with exhaust leaks at ports since there isn't much material near the edge of the port.

Scott

Tony Radford · #3 (**permalink**) 05-22-2003, 03:50 AM

Randy, I though Bill used TFS heads on his small blocks. Did you specify Edelbrocks? I had to mill my copper gaskets out quite a bit to avoid port restriction, but the header to head connection looked pretty close with respect to sizing. Did Clyde have a similar problem?

GeorgiaSnake · #4 (**permalink**) 05-22-2003, 05:00 AM

Scott - Got any ideas where to get some larger tube headers or get mine modified. The flange has planty of meat that can be removed, it's the tube and welds causing the restriction.

Tony - Bill uses both I think, either way he opens up the ports. I think Clyde was in such a hurry to get on the road he didn't worry about port matching.

Randy

zipzip · #5 (**permalink**) 05-23-2003, 11:45 AM

I did the grind job on my headers to smooth out the transistion. There was some pretty large weld beads on the inside of the header tube. For my 302, larger diameter tubes were out of the question to leave clearance for the bolts - the tubes were already flattened to be able to fit the bolt! I'm not concerned with failure because there is still weld filling the interface between the tube and flange and for equal thicknesses, weld will hold up longer than the steel tube anyway. I think a good blending job will be more important than making the holes match exactly. Take as much out as you feel comfortable with, up to flush with the inside of the tube, then make a nice smooth transition.

Todd

GeorgiaSnake · #6 (**permalink**) 05-23-2003, 03:17 PM

Zip I have the same condition - bigger tube won't clear the bolts. I'm sitting down with the grinder this weekend to smooth out the headers and open them up as much as possible and improve the flow.

Randy

xlr8or · #7 (**permalink**) 05-23-2003, 03:35 PM

Randy if there is a bolt clearance problem on the tube sizing then a smooth transition as mentioned above is the way to go. If you can provide a a bevel type of grind and radius the corners, that would be best flow wise I think.

If you have plenty of flange and weld to work with it shouldn't be a problem. The restriction issue is all in the transition. Look at what most cars exhaust ends up with at the back of the car versus the front. They just keep transitioning down in size but never have a blunt blockage it's always smooth.

ToyCollector · #8 (**permalink**) 05-23-2003, 03:40 PM

I would try grinding. Hedman Headers is in Alpharetta where they make some custom pipes. They told me to go fly a kite though when we asked about doing custom headers for my Hemi. They said they had no 354-392 hemi flanges and it would be $1500 if they did. I don't think they wanted the job basically.

Hello Sandersen Headers!