GTD headers

Howard Jones · 11-04-04, 02:33 AM

Here is a before and after shot of one of my GTD headers. The left is the header flange that came with the original GTD headers. The right one is a new flange that is port matched to a SVO GT40X alum head.

This picture clearly shows how much of the heads exaust port is blocked by the old header flange. Mine you this is the best flange match of the batch and it has been ported to make it as big as possible. You can see that the roof of the left post has been shaped as much as possible without grinding thru the pipe and the bottom is protruding almost a 1/4 inch into the port opening.

If you are going to use the orginal GTD 4 into 1 single side headers with a modern head then you should check into this for youself.

I believe this is where Fred lost most of his power when he dynoed his motor.

Julian West · 11-04-04, 06:23 AM

Howard,

Nice work! Did you manage to retain the stock header flange & 'port' it, or did you weld new flanges on the existing pipe?

I wonder what would be the best diameter pipe for that same engine?

Howard Jones · 11-04-04, 03:13 PM

It's a little hard to see here but the left flange has been cut off. The right one is part of a one piece 4 port flange and will now make each side header 1 piece. I had them all cut off about inch up stream from the port. Then mated up the new stub that was welded to the flange and then welded into place. The new flanges are also 3/8" thick whereas the orginals were 1/4" thick.

It's hard to see in a picture but at least two of the GTD flanges mated up so badly that the exaust port on the head extended below the bottom of the old flange causing a exaust leak that I thought was valve train noise. It really did, really.

I think that the GTD headers are ok on diameter. The shop that did the welding builds 6 and a half sec pro stock cars and the engine guy said they would be fine up to about 450 hp or so. The restriction where the old GTD muffler was welded to the merge collectors was worth 25 RWHP on freds car. I would think that the port mismatch at the other end has to be worth at least 10-15 hp or more. Overall these headers are done well except I wish that the time spent forming the pipes had been followed thru on when making the flanges and mating up the muffler.

I will also tell you that this fix was not cheap, but not nearly as much as some of the header prices quoted here on the forum. This was a project that I could not take to work and do myself. The car was needed to act as a jig and my boss would have had a fit.

I just think that it is a shame to spend a couple of grand more on good heads and then stop them up with badly mated headers.

Iron Sheik · 11-12-04, 10:17 PM

Where the hell is my set??! So, my 347, Victor Junior heads, "Webered" Carbs are gone put out 220RWHP?! [img]/ubbthreads/images/graemlins/frown.gif[/img] [img]/ubbthreads/images/graemlins/mad.gif[/img]

Howard, how much for these? Can we get a two for one set? How much?

Your engine is no good anyway [img]/ubbthreads/images/graemlins/shocked.gif[/img] [img]/ubbthreads/images/graemlins/shocked.gif[/img], why not let me have the headers [img]/ubbthreads/images/graemlins/grin.gif[/img]

Howard Jones · 11-12-04, 10:30 PM

Fred, You will need the same job as I did. your heads have a different port shape than the SVO heads so you will need to use a different header flange thats all.

You will need to be seated when I tell you how much. Here's a hint, mine took 16 hours labor. You will have to guess the hour/rate.
Again, be seated my brother.