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1972 cranberry red 454 ps,pb,at,ac
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Discussion Starter · #1 ·
the bb is in my 72 went to install 2" headman headers pass side hits factory ac box cutting box not a option. Spent a lot of money. All conponets are new heater controls everything!! Really don't want to tare dash and all conponets out to put in vintage air. any help out there?
 

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the bb is in my 72 went to install 2" headman headers pass side hits factory ac box cutting box not a option. Spent a lot of money. All conponets are new heater controls everything!! Really don't want to tare dash and all conponets out to put in vintage air. any help out there?
Factory AC to me is worth a lot more then a set of headers.. I suspect you are not a racer. Your post is really broken up and I suspect you are saying you will not cut the factory AC enclosure where the headers are hitting and do not want to modify your dash. Do you have a picture showing where it is hitting so someone can help. Maybe a different engine mount kit or reposition that frame motor mount a bit.
 

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I don't know what headers you have, but several years ago, we put a built 402BB in my son's 71 with factory air cond. We used Dynomax ceramic coated headers and everything fit and cleared the AC box with zero issues.
 

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hi
Have the offending tube cut out and reweld a new section in . I hope u have not ceramic coated them yet .
Best to use a header fab experienced guy.
In my GM car I ordered 1 7/8 adapter plate set and had the fabricator tack welded the primaries to the flange plate in case of air- con clearances issues [a/c box or compressor/ bracket etc ].
 

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1972 cranberry red 454 ps,pb,at,ac
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Discussion Starter · #7 ·
Factory AC to me is worth a lot more then a set of headers.. I suspect you are not a racer. Your post is really broken up and I suspect you are saying you will not cut the factory AC enclosure where the headers are hitting and do not want to modify your dash. Do you have a picture showing where it is hitting so someone can help. Maybe a different engine mount kit or reposition that frame motor mount a bit.
no not a racer but motor has been built and dyno with 2" headman headers. I have removed half ac shell headers hit evap. Mounts are stock height
 

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Factory AC to me is worth a lot more then a set of headers..

Boy do I agree with that statement. To each his own as the saying goes however for me I won't even consider headers for any car I will ever own. WAY WAY TOO MUCH B-$hit involved. I almost torched a car because the headers and the positive battery cable got too friendly. It hadda be seconds away from a "burn it to the ground" car fire.

Don't see the benefit on the street anyway plus all the surface area of the headers (particularly so close to the A/C evap hsg) is just gonna raise under hood temps and compete with the A/C evap function. I get it that headers are part of the hot rod / performance vibe but never ever again for this guy...A/C or no A/C.
 

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1972 cranberry red 454 ps,pb,at,ac
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Discussion Starter · #10 ·
Get different headers. You don’t need 2” pipes for your use case.

Hedman 68198 fit in my ‘72 big block car with AC perfectly.
the problem is #6 cyl pipe comes out then back towards firewall hitting ac box. After looking at pics of differant brands dougs all tubes go down is anyone using these? Engine builder built this engine using 2" pipes it's over 600 hp
 

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the problem is #6 cyl pipe comes out then back towards firewall hitting ac box. After looking at pics of differant brands dougs all tubes go down is anyone using these? Engine builder built this engine using 2" pipes it's over 600 hp
I had no headers on my 2014 Shelby and it made 725 net hp with stock exhaust and 4 cats. Sometimes you have to compromise and just because that is what he used to dyno does not mean you have to. Are you using the exhaust system he used. That factory AC will be a lot of $ in your pocket when selling time comes around. Not sure you have noticed but many members are installing AC and you did it right and fixed the factory stuff. Even if you lose 10hp do you really think that is gonna make much of a difference with 600hp. How much more do you think the car is worth with 2 inch versing a smaller tube header, my guess is it will make no difference and then you have all the other clearance issues to deal with after you fix this one.
 

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the problem is #6 cyl pipe comes out then back towards firewall hitting ac box. After looking at pics of differant brands dougs all tubes go down is anyone using these? Engine builder built this engine using 2" pipes it's over 600 hp
As Bill said - for your use case (street car, not racing) you will not notice a difference with a 2" vs a smaller tube header.

Your tires will hate you either way as traction on the street will be your issue and you are not going for all out performance since you aren't racing the car.
 

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Also headers work best with velocity. They make their HP by the fired pulse pulling out the next, scavenging effect. If you lose that you will lose HP on a street machine. I ran 1 5/8 headers on my LT1's and many ran 1 3/4 and I beat them for that reason. Sometimes bigger is not better especially on the street. It's amazing that we are running header tubes that used to be the tailpipe size when these cars were built. Yes I know they were stupid small and to make matters worse there was only two and you have 8 on a set of headers. :oops:
 

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I've been running headers since I could drive. If you have a basic understanding of a few things they can give decades of trouble free operation. They came stock on many cars over the years including fox body mustangs after '84.

This is my '68 with 1 7/8" headers and factory A/C box. Not sure if it's the same since my car is older. My headers do not hit the box. There's plenty of room in there.

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1972 cranberry red 454 ps,pb,at,ac
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Discussion Starter · #17 ·
Also headers work best with velocity. They make their HP by the fired pulse pulling out the next, scavenging effect. If you lose that you will lose HP on a street machine. I ran 1 5/8 headers on my LT1's and many ran 1 3/4 and I beat them for that reason. Sometimes bigger is not better especially on the street. It's amazing that we are running header tubes that used to be the tailpipe size when these cars were built. Yes I know they were stupid small and to make matters worse there was only two and you have 8 on a set of headers. :oops:
afr heads were flowed intake flowed all needs to work together talked with engine builder he sugested looking into 17/8. we both feel look for header that all pipes go down as i said befor #6 pipe runs back towards firewall then down.
 

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1972 cranberry red 454 ps,pb,at,ac
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Discussion Starter · #18 ·
I've been running headers since I could drive. If you have a basic understanding of a few things they can give decades of trouble free operation. They came stock on many cars over the years including fox body mustangs after '84.

This is my '68 with 1 7/8" headers and factory A/C box. Not sure if it's the same since my car is older. My headers do not hit the box. There's plenty of room in there.

View attachment 720518
I've been running headers since I could drive. If you have a basic understanding of a few things they can give decades of trouble free operation. They came stock on many cars over the years including fox body mustangs after '84.

This is my '68 with 1 7/8" headers and factory A/C box. Not sure if it's the same since my car is older. My headers do not hit the box. There's plenty of room in there.

View attachment 720518
do you know what brand and tube size?
 

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1972 cranberry red 454 ps,pb,at,ac
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Discussion Starter · #19 ·
As Bill said - for your use case (street car, not racing) you will not notice a difference with a 2" vs a smaller tube header.

Your tires will hate you either way as traction on the street will be your issue and you are not going for all out performance since you aren't racing the car.
Trying to find if dougs d316 will fit looking for dougs teck.
 
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