A little over a year ago, I purchased my '69 cutlass. It was someone else's project that came with a pile of parts. One of those parts was a set of American Racing stainless headers. I recently installed a 455 and TH400, but can't for the life of me get the headers to fit without the #3 and #4 tubes hitting the backside of the engine crossmember. It's like the motor is either just a touch too low or too far forward. It's very, very close...I have now been able to get the headers to physically bolt to the heads ('71 G heads), but still touching the crossmember. I have remflex gaskets I was hoping to use, but there's no way I'd have enough room to install those. It has the original "small block" frame mounts with new anchor 2261 engine mounts. I also used a new anchro 2268 trans mount with the stock trans crossmember. I even swapped out another set of 2261 mounts from my '64, but with the same results.

I called American Racing this morning and they didn't have any ideas other than that I could send the headers back to them for them to check in their jig. I'd rather not do that (time and expense), but from everything I've heard these should fit without issue. Before I hit them with a torch and hammer, does anyone have any other ideas?

 

I would modify the crossmember before touching a $2000+ set of headers.

 

That thought crossed my mind as well. The problem is that I really shouldn't have to do either one.

 

Bernhard wrote:
If it was my car I would source big block frame pads and ensure I have the correct mounts. I would also make sure that the frame pads are correctly positioned on the frame and that the mounts are correctly positioned on the block. Before I touched the headers or the cross member. I would also check the frame for collision damage to ensure that no other factors are at play.

 

I agree. Ask them to cover the shipping up front. And if they find that they’re ok then you pay it back to them.
I know everybody on here loves ARH, but I bought two sets years ago. Product is great, customer service not so much.

 

Reading through this thread, the OP states clearly he has a 455 mounted to small block engine mounts - both statements in Post #1. Am I missing something? Things that make you go "Hmmm......"

I think Bernhard in Post #4 is on the right track.

 

There is no such thing as big block / small block mounts. It depends on the year of the chassis, the engine the car was built with. As long as you use the same style mount that was originally used with the frame pad the engine sits in the same place.

 

Just so we're clear, these headers are for a BBO and not the SBO that would have come in a Cutlass, right?

 

Just a quick update. After having the engine in and out about a dozen times, I was able to get to the point where i have about an 1/8” clearance on both sides (but still without gaskets) These are the 1 - 7/8” primary/ 3” collector 455 A body headers. I’m not comfortable with such little clearance, so I’ll probably end up with one strategically placed dent on each side. Attached is a pic of the passenger side #4 tube to frame crossmember clearance. The only thing I've found a little off is that the frame pads appear to be the ‘70-‘72 small block style rather than the ‘64-‘69 style. I wouldn't think that should matter though?

 

Dimensionally those frame pads are equivalent, so the 2261 motor mounts put the crank centerline in the stock location. Presumably you have new motor mounts?

 

Yep, new mounts. I’ve actually tried two different sets of new mounts with the same results. It’s almost like the motor/trans is tilted down too far at the tail shaft. Anything I should be checking for there? It’s a new trans mount as well.

 

The car would have had a Jetaway or T350 behind the small block. Do yo have the correct transmission cross member and mount for the 400.
You might also want to consider a mount that will not fail under spirited driving there has been good feed back on this set up bellow.

 

The crossmember is the same for any offered trans. Only the location is changed due to the longer TH400

 

Running out of options as to why they fit so poorly. They are such well made header it would be a shame to have to dent them. I would be tempted to send them back before denting them up. I seen a set on Facebook that someone took a hammer to.

 

While denting them may be disappointing, rest assured a few small dents will not adversely affect horsepower.

 

Completely agree - and having to make some small modifications seems to be pretty normal with most headers. I just wanted to see if anyone in this group could think of something I hadn't.

 

Figured I'd update the group. I decided the last thing I'd try before denting tubes is double check that the trans mount is as expected. I ordered a second Anchor 2268 mount from RockAuto (the first came from Summit), and to my surprise, the two mounts were totally different. The one I got from RockAuto had 2268 stamped into the rubber (the one from Summit did not) and was about 3/16" taller, the metal was shaped differently, and so was the rubber. I swapped that out, which gained me a little clearance. It still wasn't quite enough to get the headers in, so I put a small dent in the #3 and #4 tubes where they go over the crossmember. And when I say a small dent, I mean SMALL. I basically flattened the crown of the tube by about 1/4" in that area. That gave me just enough room to slide the Remflex gaskets in and tighten everything up with about 3/16" clearance on both sides. Now on to everything else so I can get this thing on the road this summer.

Thanks to everyone that provided input.