New member introducing myself and Holley carb

[AZKen]

Hello David. Glad you found us.
Well well well, fancy that..........even Holley says the 500 is the wrong carb. 350 is all it can use. Like many of us have said many times. It falls on deaf ears because 500 is such a macho number. Then you fiddle and diddle and tune and tricks and change everything to make a 500 run and get no better gas mileage and still max out a 4000 RPM., same tranny, same differential, same gearing, same cubes, same speed. Oh gosh!

Now Holley is wrong....YOWZA! Bada Bing, Bada Boom! Rim shot please. I'm gunna put one on my 5HP Briggs and Stratton.

David, I would try to find a Bendix-Stromberg WW carb per our Carburetor Data Page. Easy rebuild and kits/videos available.

The "upgrade" to a Holley, described by Jolly, is on a 351. There are folks out there who have done it to 305's and have seen no improvement but are scared to say so. Actual testing has been done and shows no improvement in performance, but ignored. Holley Tech says will not benefit, now being ignored. It seems that the benefit is a perception. That's OK. So I do agree everyone should do what they wish as long as they hear all sides of the story.

[David]

Hi Ken,

Thanks for your reply. Unfortunately, I still haven’t gotten to working on the carburetor, so I don’t have current experiences to report to add anything to this forum.
But this is valuable info for me, and I’m ok with taking a little time warming up to this project so I can learn about what I’m getting into.
So long term fix is I look for a Stromberg, and short term I’ll still try to get the 500 cfm to do better than it is currently because I miss driving the truck! And it’s mostly gonna sit until I get at least an improvement in this area.. couple other things/projects have jumped in front of her but I’ll get into it soon.

Thanks again,

David Cox
Portland, OR


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[bigblockv6]

It runs pretty good as is but is running real rich. Was thinking I needed to tune the carburetor but I think I’ve got the wrong carburetor to start with.
Called Holley today for help id’ing which carb is in my truck. The numbers show I’ve got a 500 cfm model 4412.
Asked what he would recommend and he said a 350 cfm.

Thanks for any advice,
David Cox
Portland, OR[/QUOTE]
Actually there is no advantage using the 350 cfm carb because it does nothing to increase performance and rather has no more to offer than the stock ww 2bbl carb. Yes you may have issues with the 500cfm carb running rich. Everyone here has given you the right advice on how to counteract the issue, also leaner jets would help. When I ran the 500cfm in my 68's 305E I had the timing and advanced over stock settings , also running the GM HEI distributor and had no issues of it running rich.

[jagarra]

The nice thing about the Holley is that you can get jets for it easily and tune it for your application. When I converted I used a aftermarket air filter set up from Summit, it is tall so it brings in a lot of air, way more than the stock set up. Found that my mileage decreased when I went down one size in the jets from what the carburetor came with.