Machining a Rover V8 Inlet Manifold for a Holley 390

jonny m · Post by **jonny m** » Sat Oct 05, 2013 9:03 pm

I know it has been done, and I have a machine shop in work who will do for a box of Stella... but which one is best to machine down.

Guessing one is Range Rover, the dirty one is from an SD1

From the limited info on the internet, one of these is trickier due to waterways, but which is which ?!

The dirty one looks like it'd suit machining, but figured it would be worth checking with anyone in the know ?!

Anyone ???

Jon

http://www.flickr.com/photos/79083994@N06/10105965846/

http://www.flickr.com/photos/79083994@N06/10106006703/

ChrisJC · Post by **ChrisJC** » Sun Oct 06, 2013 12:03 pm

Interesting - I never knew that!

I wonder if the distance between carb & head is greater on one that the other?

Chris.

stevieturbo · Post by **stevieturbo** » Sun Oct 06, 2013 3:11 pm

Certainly looks like the taller cleaner one has much bigger waterways right down the middle where you would be machining

unstable load · Post by **unstable load** » Sun Oct 06, 2013 4:21 pm

Didn't the P6 ones (the dirty one) get machined down for the MGB's? Maybe that will be the better option, but I couldn't say one way or the other.

harvey · Post by **harvey** » Sun Oct 06, 2013 4:43 pm

jonny m wrote:I know it has been done, and I have a machine shop in work who will do for a box of Stella... but which one is best to machine down.

Guessing one is Range Rover, the dirty one is from an SD1

From the limited info on the internet, one of these is trickier due to waterways, but which is which ?!

The dirty one looks like it'd suit machining, but figured it would be worth checking with anyone in the know ?!

Anyone ???

Jon

http://www.flickr.com/photos/79083994@N06/10105965846/

http://www.flickr.com/photos/79083994@N06/10106006703/

I think your right about the dirty one being SD1, but the other one is early P5B/P6B (HS6 carbs) because it has the blanking plug on the front of the tower which is where the AED was fitted.

jonny m · Post by **jonny m** » Sun Oct 06, 2013 8:25 pm

Dirty grey one on the right is SD1 - I dismantled the whole engine. Not sure where the silver one came from.

Still not sure which one to chop - hopefully someone has done before and can lead me in the right direction ???

jonny m · Post by **jonny m** » Tue Oct 08, 2013 8:08 am

If anyone follows this in future; getting some advice from the hot rodders here;

http://www.rodsnsods.co.uk/forum/tech-d ... 0-a-122345

kiwicar · Post by **kiwicar** » Tue Oct 08, 2013 11:06 am

Hi
Can I ask why, the twin SU set up on that manifold works very well, so why put a 4 barrel on that manifold? you wont gain anything, the manifold was designed originally or a 2 barrel carb machining it for a 4 barrel won't flow any better than the 2 barrel on a manifold with a plenum designed for the smaller carb then you won't gain a thing. The SU offers more acurate metering and better atomisation, if you want more flow add a pair of 2"Sus and do a bit of work around where the carbs bolt on.
Otherwise put the cost of the case of stella toward a decent manifold designed for a 4 barrel carb from the outset that will get the best out of the carb.
Best regards
Mike

jonny m · Post by **jonny m** » Tue Oct 08, 2013 11:51 am

That's very a good point, and may go some way to explain why people fit a Weber 38DGAS as that is also 2 barrel

My understanding is opening / cutting the top off gives an "open plane" for the fuel to distribute from a 4-barrel carb ?

I'm parts missing from the SU set up, hence going the Holley route with the belief it will work as good (or may be better?)

Jon

Pic of what I think I am going to end up with here;

http://www.rodsnsods.co.uk/forum/tech-d ... ost1110225

kiwicar · Post by **kiwicar** » Tue Oct 08, 2013 12:19 pm

I think the webber 38GAS would be better if you want a down draught, it is a 4 circute cab and for a fixed venturi carb that is a better arrangment than a 2 barrel 3 circute carb, really it is better than a 4 barrel mechanical secondary for the road aswell.
I have seen these manifolds opened out for use with 4 barrels and they are by default "converted" to open plenum (otherwise the barrels are parcially shrouded, but to get them to work as an open plenum carb you end up sticking a big carb spacer on top of the machined manifold, this is fine if you have plenty of under bonnet clearance , but if you do have that clearance there much better true dual plane manifolds that are tall enough to outflow this set up.
How many bits are you missing from the linkages? how mauch is a case of stella? (genuine queston I don't drink) just I bet you could repair replace the linkages for less than the case of stella.
Well set and in good condition SUs are very good carbs, they can be made to flow 10-15% extra and give even more stable metering for about 3 hours work on the pair and the manifold can be made to give a bit more flow quite easily. . . true they don't look very cool.
Best regards
Mike

unstable load · Post by **unstable load** » Thu Oct 10, 2013 5:51 am

Jon, at the bottom of that page is another modified manifold to fit a Weber twin choke that could be a good one if the advice of the more knowledgeable ones on here are right.

jonny m · Post by **jonny m** » Fri Oct 11, 2013 7:13 am

Mike, you've probably hit the nail on the head - I like the look of the 4-barrel for this project

It's going to be a automatic cruiser, so for now I need to scrimp on spend;

http://www.rodsnsods.co.uk/forum/garage ... 3660/page5

Some great advice though; I've got my eye on some off cut phenolic to make a decent 1" spacer

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Machining a Rover V8 Inlet Manifold for a Holley 390

Machining a Rover V8 Inlet Manifold for a Holley 390

Re: Machining a Rover V8 Inlet Manifold for a Holley 390