I have a 67 Firebird 400 with D port heads, the stock manifolds are pretty much done and was looking into headers, Doug's, Thorley, seem about the best but I'm also liking the Sanderson block huggers, I would prefer Tri Y but seems no one makes them, trouble is there seems to be a complaint about every header and fitment. I've done headers on other vehicles his time I'd rather do some research.
When you say 'stock manifolds', do you mean logs? There is nothing better than a Poncho engine with long branch manifolds. (LBMs) RARE makes an excellent repop of the original LBMs. Butler sometimes sells the RARE ones for less than RARE has on their website. There are other companies that also make repop D-Port LBMs, but they are not as nice and clean as the ones RARE sells.
You can also get the hardware from RARE, and have them ceramic coated, although it only lasts 5-10 years.
I used to be indecisive. Now I'm not sure. I feel like I am diagonally parked in a parallel universe. 1968 400 convertible (Scarlet) 1976 T/A - 455 LE (No Burt) 1976 T/A New baby, starting full restoration. 1968 350 - 4 speed 'vert - 400 clone (the Beast!) 1968 350 convertible - Wife's car now- 400 clone (Aleutian Blue) (Blue Angel) 2008 Durango - DD 2008 GXP - New one from NH is AWESOME! 2017 Durango Citadel - Modern is nice! HEMI is amazing! 1998 Silverado Z71 - Father-daughter project 1968 400 coupe - R/A clone (Blue Pearl) (sold) 1967 326 convertible - Sold 1980 T/A SE Bandit - Sold
The oil filter change amounts to one bracket that RARE also makes. Its about a five minute swap.
I used to be indecisive. Now I'm not sure. I feel like I am diagonally parked in a parallel universe. 1968 400 convertible (Scarlet) 1976 T/A - 455 LE (No Burt) 1976 T/A New baby, starting full restoration. 1968 350 - 4 speed 'vert - 400 clone (the Beast!) 1968 350 convertible - Wife's car now- 400 clone (Aleutian Blue) (Blue Angel) 2008 Durango - DD 2008 GXP - New one from NH is AWESOME! 2017 Durango Citadel - Modern is nice! HEMI is amazing! 1998 Silverado Z71 - Father-daughter project 1968 400 coupe - R/A clone (Blue Pearl) (sold) 1967 326 convertible - Sold 1980 T/A SE Bandit - Sold
yeah I know, I just don't like the angle, I prefer to prefill my filters at oil change, nothings perfect eh?, I kind of liked the style of the Sanderson block huggers, seems they be good for low end torque, but someone wrote at Summit that they had to fabricate a 3/4" lift to the motor mount on the drivers side and grind a corner off the steering box?? maybe they screwed up, but stock RA would fit
I currently run these: https://www.summitracing.com/nv/parts/hed-35276/overview/year/1968/make/pontiac/model/firebird with copper gaskets and I'm very happy with them. I mated this to a Flowmaster complete exhaust system. I will probably upgrade to Doug's solely for the purpose of going from a 2.5" exhaust to a 3" exhaust to better handle the spent gases from the 474ci I'm currently running (previously Pontiac 350). These headers are short length headers with a ball and socket reducer they tuck up near the subframe which I really like.
I have hooker super comp headers on my 68. They slide in and out no problem and have clearance to get the oil filter on and off. But do not know what year they were made and if the new ones are made exactly like mine. I have a friend with a 69 bird and he has Doug's. I had to modify his drivers side header and move one of the tubes because his Pittman arm was hitting the header tube and preventing full steering turning.
I have used Hedman 35270 headers in several 1st gens, street and strip. They are the uncoated version. These have very short collectors. So, I used collector extensions on all our drag cars. They have 1 3/4" tubes. Never had any complaints with them, at all.
Only clearance problems I ran across was when the car had a straight pittman arm. I think the V8 cars had curved arms. So, I assume that all the straight six cars came with a straight arm. Not sure tho. I'm sure there are lots of 1st gen experts here that know for sure.
I've read that the '69 arms had a hole on both ends, and are not made today. Again, I'm sure some of these guys know. I never built a '69, because of the flat top rear fender well. I liked the '67-'68 round wheel opening, which allow the tires to stick out, without rubbing. I suppose this was/is a low-budget deal. Those with plenty to spend use to run a narrowed rear end with big wheel tubs, so that they could run big fat tires, inside the body lines. I always had to go the low-budget route.
I have also heard that the Headman with 1.75 primary is good for the money, but are thinner at 18ga. I just ordered a set last night, and after test fitting, will bring to a local shop to have coated. If this was not a street/strip car, I definitely would be using cast long branch manifolds!