6066 (1960-1966) GMC Truck Club
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6066 (1960-1966) GMC Truck Club (https://6066gmcclub.com/index.php)
-   GMC V6 and V12 Engines (https://6066gmcclub.com/forumdisplay.php?f=9)
-   -   Holley 500 conversion? (https://6066gmcclub.com/showthread.php?t=50307)

Funky61 August 22nd, 2020 09:01 PM
Re: Holley 500 conversion?
 
From the Archives section; I jetted down as well to 68's and liked it.


Quote:
I am running a 305 with 9:1 compression and Magnum components. Plus an HEi using full manifold vacuum. It seemed to be not running as well it should. The engine was operating too rich. The Holley carb comes with 73 size jets and i changed to size 65. This made a noticeable difference in performance. The only problem was a sight hesitation at cruse speeds.
I increased the jet size to 68
and it is smooth for all RPMs. The std 73 jets may be fine for 401/478 motors, but the smaller 351/305 may need some tuning.
Edwin Erlbacher Dallas TX

1965GMCK1502 September 4th, 2020 03:24 AM
Re: Holley 500 conversion?
 
No mods necessary. I used the stock jets that came with the Holley

RedElvis September 12th, 2020 01:07 PM
Re: Holley 500 conversion?
 
Quote:
Originally Posted by 1965GMCK1502 (Post 68856)
Current setup is the 305v6 with a Rochester 2G that’s working fine, especially after swapping in new Taylor wires and platinum plugs..
Does the 2G bolt right on to the intake with the same bolt pattern or is a conversion plate needed? I have a rebuilt 2G from a 283 and would like to try if it's an easy swap.. Just want to get this truck running good, nothing fancy or high performance.

1965GMCK1502 September 12th, 2020 02:03 PM
Re: Holley 500 conversion?
 
Quote:
Originally Posted by RedElvis (Post 73033)
Does the 2G bolt right on to the intake with the same bolt pattern or is a conversion plate needed? I have a rebuilt 2G from a 283 and would like to try if it's an easy swap.. Just want to get this truck running good, nothing fancy or high performance.
Yes it should bolt right up if it’s the 2G with the close bolt pattern.

bigblockv6 September 12th, 2020 05:54 PM
Re: Holley 500 conversion?
 
I've seen quite a few 305 V6's with the Rochester 2G used to replace the stock WW carb. It is said that GMC actually used some 2G carbs on the 305 V6 in 1967 because there was a shortage of Bendix/Stromberg carburetors since Chrysler also used these carburetors in large numbers on their 318 engines.

RedElvis September 12th, 2020 07:18 PM
Re: Holley 500 conversion?
 
Great, thanks for responding. It's the smaller base.. Stock air cleaner fits the top hole.. 2 3/8 or so.


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