[Randy Frazier]

I have a '60 Tri-power that is listed in McCarthys book as a Super Duty unit. It is cast iron and has casting #535544. I know the NASCAR SD was an aluminum 4 bbl. Can't figure out why Pontiac would produce a different casting number manifold for the 363 horse 389 if there were no physical differences in the RPO manifold 3 deuce unit. Any info appreciated.

[Randy Frazier]

I have a '60 Tri-power that is listed in McCarthys book as a Super Duty unit. It is cast iron and has casting #535544. I know the NASCAR SD was an aluminum 4 bbl. Can't figure out why Pontiac would produce a different casting number manifold for the 363 horse 389 if there were no physical differences in the RPO manifold 3 deuce unit. Any info appreciated.

[carbking]

Randy - I have compared the two side-by-side, and can see no obvious differences.

The following is undocumented hearsay:

Pontiac issued a block of numbers for the SD motors, so there is a different number for the SD. Even though the SD casting has a lower casting number, they were cast after production started with the standard 1960 3x2 manifold.

End of hearsay.

I have restored a number of what I believe to be original 1960 setups. The production 1960 tripowers that I have seen all had steel fuel lines, while the SD units that I have seen had aluminum. This tends to lend credence to the hearsay, as Pontiac went to the aluminum lines (mostly) for the 1961 production year.

Incidentally, there seems to be about as many of the SD manifolds as the standard manifold.

Jon.

[Randy Frazier]

Thanks Jon. By the way...thanks for the carburetors too - they are good ones.

[carbking]

Randy - glad you are happy with them. Tell all your friends. With slightly more than 150,000 in stock, if I sell one a day, I need to live an additional 574 years I need to sell the more common ones in bunches.

Jon.

[63gpstanley]

How about 2 Roch. 4 Jets. I need some for a dual quad set-up, can you help?

Dave.

[carbking]

We have lots of 4GC's. Like other carbs, they come in a multitude of sizes; MOST of which are too large internally unless you are building a race engine 389 or 400, or a 455 or larger street engine. If you are building a factory 1956 2x4, about the only carbs which will work well are the factory carbs; and they make SD dual quads seem common!!! If you are building a race version of the 1956, the 1955 Cadillac Eldorado 2x4 can be calibrated to work, again pretty pricey.

Jon.

[63gpstanley]

The garden variety should work OK as it will probably end up on a 421. It isnt a factory set-up just an old Offy intake that I picked up. How much would a couple of carb's be worth?

Dave.

[carbking]

Let me know exactly by tag number which ones you want. Remember if trying to match a non-original manifold that there are three different flange arrangement, not to mention the different sizes. Would suggest the use of Pontiac AFB's instead of the 4GC's.

Jon.

[63gpstanley]

I have no idea of tag no.s, I have no carbs on this intake. The bolt pattern for the carb flange is the small rochester type, early GM cars had them I believe. I have seen adaptors available for small rochester pattern available somewhere in the US and the measurements were the same so I am figuring that it is a 'common' type.
I will measure the spacing if neccessary and post again.

Dave.

[63gpstanley]

Sorry for the delay in getting back, been a busy week. The carb spacing is 3 7/8 between the centres and square spacing all round. Is this any help.

Dave.