D port long branch
 

I have just received a pair of D port long branch i got off of eBay and the passenger side outlet is 2.5" and the drivers side outlet is 2.25" they are supposed to be factory. is the side with heat riser supposed to be larger or is this a reproduction

repos dont have a heat riser if I remember?Tom

Heat riser flap side is always larger at least on the standard log manifolds. The opening for the flapper is machined to about 2.10’’ and the other side as-cast opening is about 1.90”.

On some of the earlier style log manifolds manufactured without the flap there’s still that same difference in outlet size between the right and left manifolds.

It wouldn’t surprise me that the openings are different by about 1/4” on the long branch manifolds.

Agree with Tom S. I'm pretty sure the repros do NOT have heat risers.
 

Unless someone has started reproducing them EXACTLY.

And remember that the 1969-up long branch manifolds - like those on our (two) 428HO 1969 Grand Prixs - didn't have the flapper either.

We've got an extra pair of manifolds off another 428HO GP - I'll dig them out and measure the outlets.

And, as a side-note, Lance has listed an NOS RH manifold WITH the flapper - for the extremely hard-core restoration. $2800.

https://www.ebay.com/itm/11455443956...AAAOSwTEpamuEN

Thanks fellas. glad i didn't get shafted .. is the thermal spring that's supposed to on the flapper still available to buy its non existent on mine. also while looking into this there is very little mention of a cast # 9779494 that I have ..only 9779493 and 9779495 and I do not have a cast date on the 9779495

This is exciting. I think I’m picking up a pair of these gran prix manifolds in a couple weeks. I saw them in the old mans garage but too much stuff to get to them. Just yet. I’m stoked I won’t be paying retail. I’ll keep you guys posted on my hunt.