LS manifold for Buick 300?

[Airwreckc]

Hi guys,

Has anyone looked into what it might take to modify one of the fabricated low profile LS manifolds to work with a Buick 300?  I am looking into using one of the EFI (such as Sniper) and the idea of a low profile, high flow manifold is very appealing--and these manifolds are fairly inexpensive.  I know the bore spacing is off, but I'm thinking that cutting and rewelding the runners might be possible and not too difficult.  Thoughts?

[mgb260]

It would have to be custom, as the port arrangement is different with both center ports side by side. A guy on V8Buick made one. I'll link it to here.  https://www.v8buick.com/index.php?threads/sbb-sheetmetal-intake-and-more.244911/  

Pic of homemade tunnel ram

[Airwreckc]

Thanks Jim.  I guess this confirms that if you imagine it, someone has already done it.  I'll check it out.

[Airwreckc]

Hi Jim,

I'm not sure how I missed it before, but I see that lots of people have used the Rover EFI  with the upper and lower plenums.  Since I'm planning a Buick 300, are you aware of anyone that has made one of these physically fit the 300?  I was thinking one for the 4.6 might be the closet from a displacement (assuming I used the 4.6's ECU) and block size perspective, but it's only a wild guess on my part.  I have read Curtis' excellent writeup on the Rover EFI, especially about the need to modify the height of the plenum and intake horns, but he doesn't mention anything about the 300.  These sure seem attractive from a price perspective:  https://www.ebay.com/itm/186218614558?var=0&mkevt=1&mkcid=1&mkrid=711-53200-19255-0&campid=5338590836&toolid=10044&customid=7d26c92797781b66e675ac9070acbde8

Thanks as always.

[BlownMGB-V8]

To fit the Rover intake you need a lifter valley cover and adapter side plates to close the gap. A better choice is probably to get in on the first order of the new 300 single plane with injector bungs coming from Australia. Do a search on the MGExperience forum.

Jim

[Roverbeam]

Funny, since I (now) have a 300 in my shed again, without an intake, the other day I took a Rover intake and plopped it on to see how it would look. I've never liked that side-intake plenum, and I'm a better composites guy than an aluminum welder, so I'd be making something different for that - but the lower manifold could be made to work without too much trouble.

The spacers you would need correspond to the difference in deck heights - Buick 300 @ 9.543 deck height, versus Rover's 8.960, so .583" of spacer. I'd buy some 1/2" G10 and trace the intake gasket pattern on it and go to town jig-sawing and filing it to suit. Adding a 2nd gasket would come "close enough" to the .583 you're after. Tell yourself the longer intake runner length is adding torque. Or cut the trumpets shorter. The valley cover could be some 1/8" aluminum plate like the Wildcat design.

[Airwreckc]

Jim B, thanks.  I have looked at that new manifold and the only reason I'm thinking about the Rover EFI plenum is the new manifold appears *much* taller, but I don't really have any specific numbers (not having access to either one).  Do you have any insight into that?  I would really like to fit something under the stock hood without a hood scoop or similar.

[Airwreckc]

Chad thanks--yes one of the things I like about the Rover EFI system is that you can supposedly easily modify the height of it.  As I mentioned to Jim B., I'm really trying to stay under the stock hood.

[7sand8s]

Manifold height info:
https://www.mgexp.com/forum/mg-engine-swaps-forum.40/interest-for-the-willpower-intake.4339676/page-5
Entry #63

[MGBV8]

From Dennis' link above:

Today I went and did an exact measurement using a digital slide caliper and a straight edge setup to measure from the top of the carb flange to the block valley edge. Take in to consideration that the Buick 300 carb is actually beveled with the rear of the carb flange being higher than the front. I took the measurement from the rear of the Buick 300 manifold using a level to make sure I had the exact edge point.

Willpower intake height (with valley plate installed) is 4.00"
Buick 300 original intake is 4.03" tall in the rear.

[Airwreckc]

Carl and Dennis, thanks.  Extremely helpful.  Appreciate it.