Nick's old 61 4wd GMC Truck

[Nick]

Hello everyone , my name is Nick and I am a new member...
I have a 1961 GMC four-wheel-drive truck.
The motor is a 305 a V6 that has been totally rebuilt by a race engine builder 20 years ago , it has sat without running since then .
Finally working on it to get it running again and finding out that that 61 305 a seems to be a rare Motor because some of the parts were exclusive to that year.
It seems that year was the only year they use the holly one barrel and also the only year that they use the Carter M3599 fuel pump , both of those items seem to be hard to find.
Questionnaires to are you smart mechanics is there alternative replacements to those two items ?

Thanks
Nick

[bigblockv6]

You have a 305A with the 1bbl Holley it's not a one year only availability, tis engine was offered in 1960 through 1961 and midyear the 305D 2bbl version was introduced, the 1bbl version was just not adequate for these engines and it's been said many were converted to a 2bbl. my suggestion is get a 2bbl manifold and retrofit it with the Holley 500cfm 2bbl carb and Mr. Gasket #1937 adapter. As far as the Carter fuel pump, most likely the original pump was an AC fuel pump and replaced with the Carter during the rebuild.

[AZKen]

Does it have a carb or a fuel pump on it now? Are you missing both? Are you trying to build and exact restored pure truck? or a daily driver?

[George Bongert]

Originally Posted by Nick

Hello everyone , my name is Nick and I am a new member...
I have a 1961 GMC four-wheel-drive truck.
The motor is a 305 a V6 that has been totally rebuilt by a race engine builder 20 years ago , it has sat without running since then .
Finally working on it to get it running again and finding out that that 61 305 a seems to be a rare Motor because some of the parts were exclusive to that year.
It seems that year was the only year they use the holly one barrel and also the only year that they use the Carter M3599 fuel pump , both of those items seem to be hard to find.
Questionnaires to are you smart mechanics is there alternative replacements to those two items ?

Thanks
Nick

Greetings, Nick!

In my humble opinion, you would be money ahead and much better off with a Two Barrel Carb and intake manifold. That One Barrel carb and manifold setup would be like you trying to do hard work with only one lung.

[Nick]

Originally Posted by bigblockv6

You have a 305A with the 1bbl Holley it's not a one year only availability, tis engine was offered in 1960 through 1961 and midyear the 305D 2bbl version was introduced, the 1bbl version was just not adequate for these engines and it's been said many were converted to a 2bbl. my suggestion is get a 2bbl manifold and retrofit it with the Holley 500cfm 2bbl carb and Mr. Gasket #1937 adapter. As far as the Carter fuel pump, most likely the original pump was an AC fuel pump and replaced with the Carter during the rebuild.

Thank you very much for your knowledge and suggestions.
I will try to find a two barrel manifold and do some research on the AC fuel pump,in the meantime the motor does have the One barrel Holley that I rebuilt 30 years ago and I do have a rebuild kit for it and did finally find the Carter fuel pump and should have that in a week and it is also on the motor but it’s not functioning.
I’ve had this truck for 50 years and a anxious to get it on the road again.
Thank you very much for your knowledge and input.

[GMCNUT]

I want to see some pictures of your GMC - post them here! I am just about to begin working on my own 61 K1000 and am interested in seeing everyone elses

[Nick]

Originally Posted by bigblockv6

You have a 305A with the 1bbl Holley it's not a one year only availability, tis engine was offered in 1960 through 1961 and midyear the 305D 2bbl version was introduced, the 1bbl version was just not adequate for these engines and it's been said many were converted to a 2bbl. my suggestion is get a 2bbl manifold and retrofit it with the Holley 500cfm 2bbl carb and Mr. Gasket #1937 adapter. As far as the Carter fuel pump, most likely the original pump was an AC fuel pump and replaced with the Carter during the rebuild.

Thank you for the info ,, could you please tell me where I may find a two barrel manifold and a Holly two barrel carburetor .

Thank you again

[Jim A]

I think GM put the one barrel Holley on for a reason.
Mine has worked fine, if a little uneconomically, for fifty years.

[George Bongert]

Originally Posted by Jim A

I think GM put the one barrel Holley on for a reason.
Mine has worked fine, if a little uneconomically, for fifty years.

Greetings, Jim!

There was a reason that GM went to two barrel carbs on on these engines, and that reason was for performance and increased power. A one barrel carb on these engines was a disservice to the performance of these engines, and the GM engineers finally realized their misguided mistake. Even the early Buick 231 C.I. V-6's used a one barrel carb, and were soon updated to the two barrel version for the same reason. They developed more horsepower, and performed better. A two barrel conversion to Nick's engine would be a vast improvement over that outdated one barrel setup!

[Jim A]

George:
What do you suppose that my truck failed to do with the Holley?