6066 (1960-1966) GMC Truck Club - New Thread! Replacing the Carb on a 351e V6?

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- - New Thread! Replacing the Carb on a 351e V6? (https://6066gmcclub.com/showthread.php?t=47949)

Re: New Thread! Replacing the Carb on a 351e V6?

Quote:

Originally Posted by bigblockv6 (Post 51626)

The Mr. Gasket #1937 adapter won't work with the trapezoid base 351E Magnum manifold, A few years back I machined up 20 or so adapters for the trapezoid base manifold and sold them off to the members of this site. A few have switched over to 4bbl carbs so someone may have an extra adapter. Another alternative is convert your existing manifold to a 4bbl, it's a relatively easy procedure that does not require welding.

I have no problem switching to a 4bbl carb. What is the procedure to convert my manifold? Buy a new one?

Re: New Thread! Replacing the Carb on a 351e V6?

yeah, the holley 500 cfm carb will work on your 351. i just put one on mine and even ordered the electric choke kit for it too. much better than my old stromberg and manual choke. good luck

Re: New Thread! Replacing the Carb on a 351e V6?

Quote:

Originally Posted by GMCv6inND (Post 51621)

yeah, the holley 500 cfm carb will work on your 351. i just put one on mine and even ordered the electric choke kit for it too. much better than my old stromberg and manual choke. good luck

Ok I went to Trans-Dapt (Hedman Hedders) and ordered the adapter plate for the 2bbl Holley carb. After looking at Jollys Post, it looks pretty easy just to drill and counter-sink a few holes in the 2bbl adapt. plate.

The Holley carb I want is the 4412, but I noticed there's a 4412S, 4412C, and 4412CT. I assume I want the 4412C

Re: New Thread! Replacing the Carb on a 351e V6?

TransDapt used to make the correct adapter at one time, part number:2140, in fact I still have the original package from 1989. According to them it has been discontinued. If you're using an adapter for the 305 application and are attempting to drill it out you will definitely have problems with interference from the other mounting holes. A blank spacer plate will be a better basis for this.

Re: New Thread! Replacing the Carb on a 351e V6?

If you search Jeg's for the Mr. Gasket 1937, a TransDapt adaptor will show up as an alternate. If you look in the catalog you'll see TransDapt's logo, but Mr G's p/n-1937. The TransDapt listed online has a different p/n than Mr. G's and it's about a dollar more as well. Since Mr. G's #1937 was what was referenced here, that's what I chose.

Here is the difference in the carbs:

4412-S has a silver finish (what I picked- I like silver!)

4412-C has a gold finish, chromate based, I think

4412-CT is the circle track (hence CT) racing version.

Make sure you check eBay for these. Holley Performance will offer remanufactured 4412's there from time to time. A 4412-C was listed early last week for $199, I bought a 4412-S last night for $229. That's a savings of $100-$200 wherever you buy it. I have no idea on the price difference- as new the -S sells for less than the -C. Go figure. These carbs are warranty return and a search of some of the performance boards gave them overall very high marks. Some who claimed to know said the units are NOT defective or damaged. Holley tosses the junk. What they reman are those that been setup incorrectly by "smart" owners (i.e. incorrectly re-jetted or adjusted) or have some minor part like an arm that was bent or broken when installed. So Holley takes these back to honor the warranty. They will have little- and likely no- use on them. You'll also get a 90-day warranty. Just make sure the seller is Holley Performance.

Re: New Thread! Replacing the Carb on a 351e V6?

let me know when you get the parts if the mr gasket adapter worked for you because it didnt for me...i had to return it and make one up myself...

Re: New Thread! Replacing the Carb on a 351e V6?

Quote:

Originally Posted by BarryGMC (Post 51603)

Most of the time this is caused by a lean condition. Some crud in the carb or an accelerator pump problem. But I see a lot of soot in the top area of the carb. So I think you have an intake valve that is adjusted to tight and is leaking hot gas back into the intake and ignighting the incoming air fuel mix. This is always more pronounced at low vacuum at WOT. The valve lash hot is .012 intake .018 exhaust .

Not to highjack(more to offer thanks to Barry and encouragement to the o.p), but I just adjusted my valves and it made a pretty noticeable improvement. All but 2 where tight and none were loose. A couple were pretty dang tight. It seems much happier at hwy speed:thumbsup:

Re: New Thread! Replacing the Carb on a 351e V6?

Yep, mine had an issue with the valves being too tight as well. Now it runs great and with the new Holley carb, it starts perfectly, even on a cold morning.