Headers to fit AFR heads?

[WHP]

I am putting a 302 in an early 260Z. I bought the Summit blockhugger headers because they look like the best fit in the engine bay. But they do not match the larger exhaust ports of my AFR 165 heads. The flange is the correct size, but by the time the pipes are inserted and welded they are .1" undersize all the way around the port. Would it be possibe to weld around the outside flange and grind out the tubing from inside? Any suggestions?

Thanks!

Will Piatt

[blueovalz]

If only to radius the entrance. If you were to cut much material at all, the 18-16 gauge tubing would be long gone if you went back into the tubes any appreciable distance.

[WHP]

What I was trying to describe, is weld the tubing to the outside of the flange and remove it from inside the flange only. I was not looking to thin the tubing. It seems all too common for header mfgers to cut the flange to match the port then stuff the tubing inside that. Well that was a MSA header I once threw away was.

[74_5.0L_Z]

The process you describe will probably work. The problem that you may encounter will be clearance for the header bolts. They are usually pretty close to the tube to begin with.

[WHP]

I basically will have to make a .1" transition in the thickness of the flange. I contacted AFR and was very disappointed in their answer. Basically they made a large port with no provisions to connect properly to any off the shelf exhaust system. I would think a smaller port but smooth connection to header would outflow bigger connecting to smaller= turbulence? Here is their reply:

 

Hey Will,

 

You are not going to find any headers off the shelf that will completely clear the port. The problem is the stock 2" bolt pattern, then factor tube thickness, weld thickness, then room to actually remove and install the bolts. Just doesn't leave manufacturer's much to work with. Feel free to contact me again by phone or by e-mail with any further questions.

 

Thank you for choosing AFR,

Jason Dow

AFR Tech./Sales Dept.

(661) 257-8124 Ext. 124

 

Am I too much of a perfectionist or is this mismatch an expensive mistake on my part?

[blueovalz]

It won't matter at this point, but this was one issue that I looked into on my Ford heads, and that was an acceptable exhaust bolt pattern. Currently I'm running the old Alan Root (J302) heads on my 289. They have a dual pattern, one OEM, and the other similar to a Cleveland pattern, which is the one I use. When I chose a new head, the AFR 205, I made sure it also had a dual bolt pattern as well. The factory pattern simply will not allow a wide tube right off the exhaust.

[WHP]

Well I sent an email to AFR bashing them for building heads that no exhaust fits and they admitted they blend the step just like I was planning to do. So plan well guys. I spent hours researching heads, but I don't remember anyone mentioning this problem.

[lilredZ]

I have heard of bolt on flange kits that allow you to attach a much bigger (1.75 or 1.875 inch for example) header to a stock bolt pattern. It fits the stock pattern then space transforms (flanges out) to a bigger pattern. What I don't know is if this will allow enough side clearance for the headeres to still clear things.

 

Ideally I'd love a 1.875 set of tri-Ys that have the identical shape to what I have now...since these fit like they were built for the car. The passenger side needed the collector shortened but this only cost me $100 at the local exhaust shop.

 

I am going to look into that flange kit (adaptor) and report back if I find anything decent.

 

LilredZ