Rebelrob

Hello,

I am now looking at some after market aluminum heads for my 454 build.

I am considering the AFR 290cc oval port heads to replace my cast iron rectangular heads.

One of my concerns is headers fitting properly. I have previously picked out these Hedman Headers

http://www.summitracing.com/parts/HED-68096/?rtype=10

due to lots of happy customers with BB Vettes and there easy fit and good height underneath the car. They are 2 inch primary tubes.

AFR advertises that their exhaust ports are raised 3/8 inch higher than stock big block heads. The tech at Hedman, told me I might have fit issues, based on concerns of the deck height of the heads and longer head bolts. I need to ensure that the header port covers the the entire sort of D shaped AFR exhaust ports. AFR also claims there raised ports are the one of the shortest lenghts compared to many after market aluminum BB heads.
I talked to an AFR tech and showed him the Hedman header link and he said they should fit to the head with no problems, but warned that I might run into other issues with the header hitting part of frame/steering assembly,etc. due to raised ports.
So both vendor are contradicting each other.

Looking for advice, or if anybody has run into this problem or if Hedman is just being overly cautious.

Hard to make a decision, and I do not want to spend big $$$ on custom headers.

Thanks,
R

Shark Racer

I'd recommend headers with a 3/8" flange and thicker steel.

Rebelrob

I am not sure what the flange size is on the Hedmans. I am open to other options on headers but need to first understand if these headers fit these heads without any issues or custom fabrication.

Shark Racer

These are 1/4" flange. 3/8" will be less likely to have bolts back out. (and it'll still happen :| )

I personally don't think the 3/8" lift from the heads is going to affect anything, but I'd check with some of the other big block builders. (632C2, and the guy who just did the tri-power build)

I'm sure they'd have some good advice. You might PM them and direct them here...

73, Dark Blue 454

I'm also considering those head on a summer project (BTW, they don't give them away, do they).

'm thining 3/8" of an inch shouldn't present a problem with header fitment. But again, we're talking headers,..BB headers,..in a Vette.

I'm also curious to know if any C3'ers have run these heads with headers.

427Hotrod

I'm sure some will chime in...but I know there are several here that have used the AFR's with little issue. They raise them a lot less than say the Brodix race heads and about the same as Dart's. We just did a 555" with the Darts and had no issues with 2-1/8" tubes.

Depending on the cam you use and RPM range, you might be happier with some 1-7/8" headers on a 454. 2" won't kill you...but they are a little big for it. Check Hooker for some nice ones.

You would think all of these would fit by now...but expect to put a dimple or two on them possibly. I think the Hedmans and even the small tube Hookers are tight by the idler arm and there is sometimes a little interference on the #3 tube by steering box.

My 2-1/8" Hookers actually fit better with my .600" raised port Brodix heads than they do with the stock heads. Raising them up clears things better. Go figure!

Don't forget...the Brodix Race Rite heads have exhaust ports in stock location.

JIM

Rebelrob

Jim, thanks for the info.

Hedman tech support concern was will there header port opening cover the entire port on AFR head. I was not able to get the dimensions of the AFR ports, they just told me they were almost D shaped. Do you think they will? The other concern Hedman had was since the AFR head bolts are longer they were worried about the Header flange possibly hitting the head bolts.

I plan to use the locking header bolts to keep them from backing out. If have to dimple a few areas to fit, that should not be a big problem. The header bolting to the head is my main concern with those raised ports on the heads. I do not want any metal covering the head ports and losing flow.
Thanks,

DRIVESHAFT

I would think that AFR should be able to tell you about the exhaust port line up. There isnt anything odd about the Hedman port location.
So if they say a 2" tube is large enough, and I cant imagine it not being, you should be fine.
I did have to grind the bottom of my header flanges on my Hedmans with stock heads because of the head bolts I was using, but since the exhaust port is raised on the AFR I bet that isnt an issue.
The only worry that I might have would be floor clearance, because the Hedmans tuck up pretty tight. But with the tube height moving up less than 1/4" vertically, I bet it really isnt an issue.
Of course if you would like to buy the AFRs and just ship them to me, I would be happy to try them out for you and let you know how they fit with the Hedmans.