305E Intake mod.

[bigblockv6]

Yes it will bolt up but use the 305 intake gaskets.

[TJ's GMC]

Originally Posted by bigblockv6

Yes it will bolt up but use the 305 intake gaskets.

Good to know!

[Chuck78]

Originally Posted by bigblockv6

If you got a Magnum manifold there won't be any need to do any welding, It's all about milling the top surface flat, cutting out a square bore pattern then fitting a carburetor spacer plate and drilling & tapping it. I've built two already and right now I'm building a third one, I'll post some pics.

Do you happen to have any spare magnum manifolds for sale, original or converted for Holley 2bbl use?

I wonder if it's possible to mill one of these down and convert to a 4 bbl setup? Holley Street Avenger, Rochester Quadrajet, or Carter AFB???

[bigblockv6]

Here's some pics of two 4bbl manifolds I built, one uses a spread bore adapter so Quadrajet can be used and the other just uses a square bore spacer, both manifolds were milled down and the bases were opened up. The Magnum manifold already has 4bbl plenum in it because GMC actually did offer a dealer installed 4bbl option so the 2bbl version of the manifold was just cast with a different top base4bbl manifold for GMC V6.jpg

top view V6 manifold (2).jpg

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[TJ's GMC]

Originally Posted by bigblockv6

Here's some pics of two 4bbl manifolds I built, one uses a spread bore adapter so Quadrajet can be used and the other just uses a square bore spacer, both manifolds were milled down and the bases were opened up. The Magnum manifold already has 4bbl plenum in it because GMC actually did offer a dealer installed 4bbl option so the 2bbl version of the manifold was just cast with a different top base

Didn't know GM offered a 4 barrel option! Anyone ever use it that your aware of? That'd be one heck of a rarity!

[bigblockv6]

Originally Posted by bigblockv6

Here's some pics of two 4bbl manifolds I built, one uses a spread bore adapter so Quadrajet can be used and the other just uses a square bore spacer, both manifolds were milled down and the bases were opened up. The Magnum manifold already has 4bbl plenum in it because GMC actually did offer a dealer installed 4bbl option so the 2bbl version of the manifold was just cast with a different top baseAttachment 4647

Attachment 4648

Attachment 4649

Attachment 4650

I don't have any extra manifolds.

[TJ's GMC]

Well it's all bolted up and the motor is running like a Champ! Drinks the gas with No issues and pulls darn well. Really happy with how it turned out. Super easy to start compared to before to.

[bigblockv6]

Originally Posted by TJ's GMC

Didn't know GM offered a 4 barrel option! Anyone ever use it that your aware of? That'd be one heck of a rarity!

There was a wrecking yard in Southern California that specialized in GMC V6's and they had 1 factory 4bbl manifold for sale back around 15 years ago, unfortunately the wrecking yard caught on fire and is gone. There was also a 66 pickup with a 351E running around Santa Rosa California just next to the town I live in ,hat had a factory 4bbl intake. Not many are out there because hardly anyone knew about the option, GMC should have publicized on that more. Most engine overhaul gasket sets would come with the 4bbl base gasket and air cleaner gaskets for Magnum V6 engines.

[TJ's GMC]

Originally Posted by bigblockv6

There was a wrecking yard in Southern California that specialized in GMC V6's and they had 1 factory 4bbl manifold for sale back around 15 years ago, unfortunately the wrecking yard caught on fire and is gone. There was also a 66 pickup with a 351E running around Santa Rosa California just next to the town I live in ,hat had a factory 4bbl intake. Not many are out there because hardly anyone knew about the option, GMC should have publicized on that more. Most engine overhaul gasket sets would come with the 4bbl base gasket and air cleaner gaskets for Magnum V6 engines.

Now that is neat. Hopefully one of these days I'll run across one. Be a Neat option to have.

[kchampagne]

Originally Posted by TJ's GMC

Well it's all bolted up and the motor is running like a Champ! Drinks the gas with No issues and pulls darn well. Really happy with how it turned out. Super easy to start compared to before to.

Wow, that looks fantastic! I want to do that now! Great work!