Holley 2bl on a GMC 305 V6 ???

[rcbildr]

I'm getting ready to install a Holley 500 cfm 2bl carb on my 1960 GMC with the 305 V6. I was wondering, is there a noticeable improvement in power, how about mileage, how much tuning was required....I read on the 60-66gmc website that not much was needed to get them running good. Any help will be greatly appreciated. Thanks.

[jbgroby]

RC,

I've done the switch and although I can't report the mpg prior to the changeover, I can tell you AFTER I'm getting 16-18 mpg, IF I stay at or under 65mph. that seems to hold at 1900 rpm'ish with 3.23 gears on a Dana 44.


The only thing in addition to the carb swap is that you will need to build a new pedal linkage. I traded my last one to a club member, but see the picture. I used a 1/2" wide 1/8th" thick flat aluminum bar from Home Depot. rounded out where she rides over the nuts and bolts of the bell linkage and gave her a dog leg bend to align, took me 15 minutes to fabricate.

I've also upgraded to Petronix ignition, which I believes helps. I've attached a few pictures.

[jbgroby]

This is the first run in.

First time Start-up of a GMC 305 V-6 - YouTube

This is the second longer start stop.

Start up of GMC 305 V 6 - YouTube

[61_FL_Apache]

Nice flame thrower!

[jbgroby]

yep, first time it happened, scared the crap out of me. Then I did it again thinking it wuz cool, till I saw I burned off the paint -

[rcbildr]

Awesome. Thanks!!! What kind of tuning did you have to do to the carb? Was it just a mixture adjustment or more than that....I know almost nothing about Holley carburetors.

Thanks for the tip on the linkage, I work maintenance in a machine shop that makes parts for Boeing so I'm pretty sure I can come up with something. I'm hoping tomorrow I can pick up the a stock intake/carburetor gasket so I can finish up the adapter. A friend of mine gave me a spacer that has the bolt pattern for the holley and I think I can drill the holes to bolt it to the intake once I get the gasket.

I'm not exactly sure what rear gears I have, all I know is that its posi of some sort, and my mileage is around 9....but I didn't rebuild the stock carb when I got the truck....figured I would be replacing it soon.

I haven't upgraded to pertronix yet, just didn't have the funds when I was giving her a tune up...but it is on the list.

Thanks!!!

[jbgroby]

All my friend did was turn the mixture screw he tuned by ear. Sadly he took his life about a year after that was shot. He was a great friend and I do miss him terribly. Mike was one of the old school mechanics that could fix ANYTHING.