Rover V8 Injection inlet maniofold miss alignment

SuperV8 · Post by **SuperV8** » Wed Dec 16, 2009 1:49 pm

I have had the heads re-faced/ possably on min now, and the bolck has been re-faced after top hat liners were fitted.

I have just set the cam follower pre load to the min tolerance easily enough needing two shims for each pedistool. I think the thickest and thinnest from the real steel shim kit.

Just about to fit my injection inlet manifold to find the the bolt holes don't line up too well.

Does any one know how to work out how much I need to skim off the manifold to have it line up? or how to check how much out of alignment it is?

Thanks

Tom.

kiwicar · Post by **kiwicar** » Wed Dec 16, 2009 2:04 pm

that is an easy one, same amount as the total skimmed off the heads and the block. ie 10 thou off the heads and 15 thou off the block, total 25 thou, then skim 25 thou off the manifold faces.
Mike

ChrisJC · Post by **ChrisJC** » Wed Dec 16, 2009 4:44 pm

Chris.

SuperV8 · Post by **SuperV8** » Wed Dec 16, 2009 5:08 pm

Super,

Cheers guys

Tom.

Boosted LS1 · Post by **Boosted LS1** » Wed Dec 16, 2009 6:13 pm

And iirc it's not a 90 degree angle just in case they need to know for mounting purposes.

ChrisJC · Post by **ChrisJC** » Thu Dec 17, 2009 8:01 am

Boosted LS1 wrote:And iirc it's not a 90 degree angle just in case they need to know for mounting purposes.

Yes it is, unless I'm very much mistaken?

Chris.

russell_ram · Post by **russell_ram** » Thu Dec 17, 2009 8:27 am

The faces on the inlet manifold are definitely at 90 deg to each other, no question.

Bit late now but, of course, you'd have been better machining the manifold mounting faces on the heads when they were off. Once you do the manifold, you'll have a manifold that won't fit back onto an engine with standard heads should you ever need to change yours back. If you'd have done the head (fire face and manifold face) then your manifold would've fitted and wouldn't have been 'unique' to your current engine set-up.

And the calc in the first reply is correct.

Russ

Boosted LS1 · Post by **Boosted LS1** » Thu Dec 17, 2009 10:40 am

ChrisJC wrote:
Boosted LS1 wrote:And iirc it's not a 90 degree angle just in case they need to know for mounting purposes.
Yes it is, unless I'm very much mistaken?

Chris.

Ok, it just had to be checked. On some 90 degree engines the inlet faces aren't at 90 degrees. I've had a few manifolds skimmed in my time and assumptions can be wrong. I could have sworn that the last rover manifold I had done wasn't at 90 degrees. Still, that was some time ago and I've had a beer or two since then.

SuperV8 · Post by **SuperV8** » Thu Dec 17, 2009 12:41 pm

Cheers for all the usefull info.

Does any one have a technique for checking inlet manifold port to cylinder head overlap/ alingment?

I don't know how much the heads/ block have been skimmed. The engine history is blured! I have had both the heads and block lightly re-faced and It has definatley had a block/ head skim in the past but I don't know how much was talken off?

If I can measure the overlap/ out of alignment of the ports then would this number be the ammount to take off the inlet manifold?

spend · Post by **spend** » Thu Dec 17, 2009 2:33 pm

If you want to open up the inlet ports the manifold generally wants to sit a little higher in the vee to get the most out of the available casting. Thats when moving the bolt holes comes into the equation IMHO.

Generally I'd also rather do the port matching and bolt holes exercise than skim, which may be what Mike is driving at.

I use card the same thickness as the valley gasket and anally blue each side to work out which face (head or manifold) should / can be opened. I make alignment marks all round the flanges and last of all open up the bolt holes. Its really painstaking work - but quite enjoyable really. I honestly don't think you get to understand the shapes the air has to flow without getting into this kind of detail studying the ports at a very detailed level ? Last of all port match the valley gasket to your heads and everything will line up - just make sure any (small) step faces the head rather than the plenum (all depends what detail you want to go to and if you want to incorporate some anti-reversion?)