[428GTO70]

I have a 70 GTO with Hooker Super Competition D port headers and have a slight issue with clearance of my A/C box. As you can see the #6 exhaust pipe juts way out up and over coming scary close to the bottom of my A/C box. I would say it is around 1/4" of clearance, I can't fit my finger in between.

I know this is too close, right? what would be a comfortable distance? Presently there are a few things I can do to try and pick up some clearance here.

1. My frame is slightly bent up on both sides from people using floor jacks in the wrong locations which I believe is slightly raising my trans crossmember mount location, I plan on bending these back straight when I can get it on a hoist which should lower the crossmember along with everything else tilting down behind the motor mounts, but how much I don't know.

2. I have the original rubber body mounts still, not sure how crushed they are but I would imagine that new ones would lift my body a bit from the frame.

3. I'm not sure but it LOOKS like I could maybe try and pry that pipe in towards the engine which should pick up some space if it bends easily enough. Although I don't want to stress any welds by the head flange or crack off any of the ceramic coating.

4. I have installed the 1/4" motor mount spacers that were being sold through here, I would definitely gain some room if I removed them, but I may create problems elsewhere by doing this and they would probably really suck to remove now. I have good clearance everywhere else and these seemed to help with that.

Anyway here are the pics. what do you guys think is a safe distance to maybe at least use some kind of heat shield in between?

[HJones1313]

I have the same car/motor/header setup as you, but no A/C. I think thats veeery close! When I changed the body mounts to poly I gained 1/2" which should give you the clearance you need. Off topic, but noticed you cut the header flanges. I already did mine, but haven't tried them yet. Does it make them easier to bolt up? (Which is why I did mine).

[geeteeohguy]

Too close, IMO. If you had another 1/2-3/4", I think you'd be fine. That would be enough of a gap to dissipate heat. Nice looking install, BTW.

[428GTO70]

Originally Posted by HJones1313

I have the same car/motor/header setup as you, but no A/C. I think thats veeery close! When I changed the body mounts to poly I gained 1/2" which should give you the clearance you need. Off topic, but noticed you cut the header flanges. I already did mine, but haven't tried them yet. Does it make them easier to bolt up? (Which is why I did mine).

I was thinking about poly mounts , think I will look into them further since I could for sure use new body mounts anyways its a good place to start!

And yes the cut flanges IN ADDITION TO a set of ARP 100-1109 header bolts make it much easier to install the headers. Those header bolts use the smaller 5/16" head giving more room to move a wrench around them. Suggest getting a good 6 sided box end wrench to use for this. with starter out you are able to tighten the 3 rear bolts on each side from below and the front 3 from the top. It's still some reaching but works out pretty well. I also used remflex gaskets and cut them into 3 pieces each also and slotted the center one to install just like the slotted header flange hole, which is the first bolt you start with to get the headers hanging.

I had the headers already under the engine since I dropped them in at the same time, but it only took me about an hour to get all the bolts and gaskets in and bolt them into place completely on the heads. About a days worth of work improvement over the last time I did it

Hope this helps a little. good luck!

[428GTO70]

Originally Posted by geeteeohguy

Too close, IMO. If you had another 1/2-3/4", I think you'd be fine. That would be enough of a gap to dissipate heat. Nice looking install, BTW.

Thanks! now to get that 1/2" to 3/4" somehow....hoping body mounts and fixing my warped frame gets me there.

[misaac]

X2 on using the 5/16 hex head bolts on headers. Check them frequently, they do get loose over time.

[428GTO70]

Hey HJones1313, what poly body mounts did you run? I am having a hard time finding them, and I have also seen some posts on here that say some poly body mounts are actually thinner than stock rubber mounts and DROP the body 1/4". Let me know and thanks again!

[TSMartin]

Originally Posted by 428GTO70

I was thinking about poly mounts , think I will look into them further since I could for sure use new body mounts anyways its a good place to start!

And yes the cut flanges IN ADDITION TO a set of ARP 100-1109 header bolts make it much easier to install the headers. Those header bolts use the smaller 5/16" head giving more room to move a wrench around them. Suggest getting a good 6 sided box end wrench to use for this. with starter out you are able to tighten the 3 rear bolts on each side from below and the front 3 from the top. It's still some reaching but works out pretty well. I also used remflex gaskets and cut them into 3 pieces each also and slotted the center one to install just like the slotted header flange hole, which is the first bolt you start with to get the headers hanging.

I had the headers already under the engine since I dropped them in at the same time, but it only took me about an hour to get all the bolts and gaskets in and bolt them into place completely on the heads. About a days worth of work improvement over the last time I did it

Hope this helps a little. good luck!

Just another option on the bolts. I got some 5/16" 12 point head bolts from McMaster Carr when I put headers on the Bonneville. Combined with a 12 point wrench you have less angle to get through to get another bite on the head.
TS

[HJones1313]

Originally Posted by 428GTO70

Hey HJones1313, what poly body mounts did you run? I am having a hard time finding them, and I have also seen some posts on here that say some poly body mounts are actually thinner than stock rubber mounts and DROP the body 1/4". Let me know and thanks again!

Good idea on the ARP bolts. I've actually used allen-head socket screws on the ends and 7/16" 6-points on the center, but I'll try the ARP's. I went thru my receipts and of course can't find the one for the mounts, but I know they were Prothane brand. I've attached a pic of the installed height. My originals were absolutely destroyed, and it's a real fun job to replace 'em, but it's one of the more rewarding projects.

[Don 79 TA]

i personally prefer the 5/16" ARP 12 point header bolts
especially on the d port, just made it that much easier
and i used a nice moon type wrench along with the 5/16" SK 1/4 swivel socket/extensions

as for cutting the tubes, i know when i had the dougs d ports on the ED's (dport e-heads) i was using, it was a little bit of a pain to install the bolts by myself, those tubes were a MOFO to get down, i'd say leave the flange as is if you are using a good quality header and new heads
perhaps header studs would have been better/easier????

for round ports, the regular ARP 3/8 header bolts have plenty of room, PLENTY, didn't need the 5/16", at least on my TA it did. now 2" or larger tubes.. that could be a different story

if i were to do it again.... header studs...
I did them on the wifes 05 vette... OMFG made it soooooooooooo easy...

[HJones1313]

Originally Posted by 428GTO70

Hey HJones1313, what poly body mounts did you run? I am having a hard time finding them, and I have also seen some posts on here that say some poly body mounts are actually thinner than stock rubber mounts and DROP the body 1/4". Let me know and thanks again!

One more thing, since you've already doen the flange mod, I wanted to see how close mine are to yours. Any leak problems, alignment issues. I'd like your opinion on my hack job.

[David Jones]

Bolt a piece of steel to the area you want to straighten back out. Let that piece of steel poke out from under the car and get a floor jack under the end of it. Jack it up until the frame is back straight. Done.
If the crossmember area is bent from careless jacking then that'll fix that and probably give you the clearance you need. No lift needed.

[428GTO70]

Originally Posted by David Jones

Bolt a piece of steel to the area you want to straighten back out. Let that piece of steel poke out from under the car and get a floor jack under the end of it. Jack it up until the frame is back straight. Done.
If the crossmember area is bent from careless jacking then that'll fix that and probably give you the clearance you need. No lift needed.

Damn, good idea! LOL I was trying to think of different ways to do this and I like this one.

Thanks!

[428GTO70]

Originally Posted by HJones1313

One more thing, since you've already doen the flange mod, I wanted to see how close mine are to yours. Any leak problems, alignment issues. I'd like your opinion on my hack job.

Well I'll be honest with ya, I bought them used cut that way already, lol. But I will have to say they lined up just fine even though they are cut apart, AND they have been ceramic coated and put through a tumbler polishing machine since I've had them and didn't get bent out of shape. the nice thing is even if they don't line up just perfectly they can be flexed into place pretty easily if you are having issues lining up a bolt hole. I had to flex one pipe just a hair to line up, nothing bad at all. I haven't started it yet but the way it bolted up I feel confident it sealed just fine.

[70455HOVert]

Those headers are looking good! Probably the best set of headers I've owned in terms of sealing and staying sealed.

I'll fill in the rest of the story. I too bought them used, but being a newbie to Pontiacs at the time, I was told that unless the flange was cut, I'd have sealing issues. Since they were such a B!tch to put on, I didn't relish the thought of dealing with that, so I cut them.

Also, my A/C box has a nice hole in it where the header tube torqued into it. Your 455 looks to be significantly stouter than mine, so you might want to take it easy with it unless you have solid motor mounts.

[428GTO70]

Originally Posted by 70455HOVert

Those headers are looking good! Probably the best set of headers I've owned in terms of sealing and staying sealed.

I'll fill in the rest of the story. I too bought them used, but being a newbie to Pontiacs at the time, I was told that unless the flange was cut, I'd have sealing issues. Since they were such a B!tch to put on, I didn't relish the thought of dealing with that, so I cut them.

Also, my A/C box has a nice hole in it where the header tube torqued into it. Your 455 looks to be significantly stouter than mine, so you might want to take it easy with it unless you have solid motor mounts.

Hey! Ah yes, the headers have changed a bit since last you saw them lol. I cut off the old collectors and welded on ball flange collectors and got them ceramic coated. They turned out pretty good!

So you say this same set of headers did in fact contact and break your AC box in this spot? Good to know, I'm not sure what I'm going to do to fix that but I will figure something out. I wish I would have been able to test fit them before getting them ceramic coated, I would have shortened that tube a bit and rewelded it.

[70455HOVert]

Here's my take on it.

1) My A/C box was broken inward in that spot. Clearance was tight.
2) Might have been broken before I installed the headers, but I doubt it.
3) Pass side motor mount was basically torn when I pulled the engine two years ago and put on RA manifolds

I'm assuming the engine torqued over and contacted the box, thus caving it in. I didn't witness that though for obvious reasons.

[428GTO70]

Do you happen to remember how much clearance there is from the bottom of the ac box to the evaporator inside? Is there enough room to cut away a portion and make a sheet metal patch to gain some clearance?

[70455HOVert]

As I remember there's not much. I could easily see the evaporator. Maybe 1/4" at most.

[428GTO70]

Originally Posted by 70455HOVert

As I remember there's not much. I could easily see the evaporator. Maybe 1/4" at most.

Yeah that's what I kinda figured. I guess I'll start with fixing my bent frame rails and go from there. Thanks again!