Thread info - inlet/exhaust manifold

Thread info - inlet/exhaust manifold

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Discussion

Cooper1999

Original Poster:

323 posts

206 months

Saturday 6th March 2021
quotequote all
Hoping someone can help here.

I'm building a Mini Marcos kit car (11 years now and counting) using an MPi engine. I've rebuilt the engine and am fitting a Specialist Components injection system to control the emissions. This comes with a minispares inlet manifold.
Now I've never had a carb mini that I've swapped the inlet manifold on, but the MPi comes with inlet/exhaust manifold nuts that has a sort of built in, rotating washer. Trying to get these located on the inner studs is proving a little problematic, needing to be fitted from underneath and I think the 'washer' element of the MPi nuts are too large in diameter to really fit.
Can anyone advise what the thread is for the inlet/exhaust studs are? I'll look to get normal nuts and fit a smaller, separate washer.

One other thing - the minispares inlet manifold flange thickness is a good millimetre or two thinner than the flange thickness of my Specialist Components stainless exhaust manifold. Has anyone come across this problem before? Have you come up with a good spacer solution to take up the slack on the inlet manifold?

Many thanks,

Grumbly

307 posts

155 months

Saturday 6th March 2021
quotequote all
Carb minis use 5/16 unf studs, I can't think they would have changed the for the MPI but don't know for certain. Brass nuts are best for this application.

stevieturbo

17,525 posts

254 months

Saturday 6th March 2021
quotequote all
For the washers, get a good thick washer, then grind down one half to account for the thickness difference and ensure the stud remains straight when clamping the two items.

But yes it is common as often the inlet and exhaust flanges are different thicknesses. Or weld a couple of half washers or spacers onto the exhaust flange so it becomes same height as the inlet.

Cooper1999

Original Poster:

323 posts

206 months

Saturday 6th March 2021
quotequote all
Thanks for the quick replies.
Just ordered some brass nuts from minispares and some thick washers from ebay. Hopefully here by next weekend and then full steam ahead!
Cheers,

timelord

318 posts

290 months

Sunday 7th March 2021
quotequote all
A dab of weld on the thick washer will add enough to pull the manifold tight