I just finished elongating the holes in a set of NA performance headers I bought from another F-Chatter. They are reasonably well done, made of 321 SS, but they didnt fit! In fairness to NA performance, part of the problem might be because they are one piece, no joint at the collectors to accommodate misalignment The left side took about two hours of Dremeling. SS is hard to cut with a Dremel Tool! The right side was another story; some flange holes were almost an eight of an inch out. All in all I was able to align only two flanges, and those required Dremeling. I have made perhaps a dozen headers out of both 306 and 321 and have had them power coated. I have never had a set of headers come back from the powder coaters with this kind of distortion. In fact they all came back with no discernable distortion. I made a template from the original manifold and a couple of dowel pins to locate it on the new headers selectively to get the least hole deviation of the eight holes. Then I set up the header in the mill, and milled down through the template. At this point I am undecided whither or not to install them. There is no discernable evidence of failure in the original headers, but at least now they will fit. (After raising the right side of the engine about an inch up from the cradle) BTW Kevin, when you have these powder coated, have the coater mask the threads on the air injection. I had to chase them because of the coating. Fortunately I have a 24 X 1.5 thread chaser Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
How close are the ports matching? BTW, the factory part doesn't have a joint, and the mounting flange is one long uninterupted piece.
I have seen those headers before.... I think one reason they did not fit is that the collectors were welded to the primaries. Reducing the available adjustment to almost zero. NA normally has a slip-fit collector. Funny thing I was told they were on the car but the owner did not like the way they looked ???? Does every 355 cylinder head different?? I don't believe so.....but I could be wrong
The ports will be mismatched by the same amount that I had to elongate the holes, there is nothing I can do about that, which is only one of the reasons I may not use these headers. And yes, the factory flange looks like it may be an investment cast piece, its very nicely done.
Yes, I was also told they were on the car, but I can guarantee you they have never seen the inside of an engine compartment, and no youre not wrong about cylinder heads.
I hope you got a break on the price, considering the extra work you have put into them. I personally took a magnet to the plasma cut flanges and it stuck! Meaning they are VERY poor grade stainless or not stainless at all, hmmm . The tubing itslef IS stainless though (magnet did not stick). I also did not like the way the welds that attach the collector could not be completed around the tubing due to interference. I Like the standard slip fit better, it allows for normal thermal expansion.
Just tried it, and you're right, not stainless. Anyone want to buy a set of headers that are guaranteed to fit? of course after what I've said, who would?????????
Headers fitted, ........well at least they're in place Image Unavailable, Please Login Image Unavailable, Please Login
I'd sure want a heat shield between that pipe and that alternator. Not going to do the oil hoses a lot of good either.
I totally agree, I don't think I am going to use these headers, but if I were to a heat shield is mandatory on both sides. I have some ideas about that already.
Looks good, though heat shields strategically placed would pay dividends! Good luck and keep posting on these.
What's the physics behind placing the air injection connections so close to the block/valves rather than closer to the cat? Somehow I was under the impression that an air leak (perhaps even air injection??) near the exhaust valves could burn valves and valve seats.
Good point! Though I beleive the reason would be since the car is not warmed up yet, they are aiming for the "hottest" point in the exhaust during start up/warm up to get "maximum" fuel burn.
