iggy Posted December 21, 2015 Share Posted December 21, 2015 does the 2500s head and an early 2500pi stamped 516816 casting no 308351 head have the same size threads on the studs for the inlet and exhaust manifolds? ive found some nuts that fit my spare pi head but dont no the size, what size and type of thread are they? as i need to buy some brass nuts to fit the studs il be fitting the 2500s inlet manifold to my pi engine as its currently fitted with a 2000cc manifold thanks Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted December 21, 2015 Share Posted December 21, 2015 Yes. 3/8" UNF.Nick Quote Link to comment Share on other sites More sharing options...
iggy Posted December 22, 2015 Author Share Posted December 22, 2015 thanks Nick Quote Link to comment Share on other sites More sharing options...
thescrapman Posted December 22, 2015 Share Posted December 22, 2015 Don't forget it isn't brass nuts to hold the manifolds to the head, just the front pipe to the manifold.Buy ones for a Volvo, they are cheaper ISTR. the studs are the same as well, I bought a bag of them to refurb my manifolds. Quote Link to comment Share on other sites More sharing options...
iggy Posted December 22, 2015 Author Share Posted December 22, 2015 0k thanks Colin il get the nuts from volvo, the spare pi head i have has 10 large studs which i think are 3/8 unf and three smaller studs which i think are 1/4 unf didnt notice the smaller studs the first time i looked, am i right with the thread sizes? hows your tr6 going? its got the quietest triumph engine ive ever herd, is your new garage workshop finished yet? Quote Link to comment Share on other sites More sharing options...
Richard B Posted December 24, 2015 Share Posted December 24, 2015 Quoted from thescrapman Don't forget it isn't brass nuts to hold the manifolds to the head, just the front pipe to the manifold. It isn't OE but I use brass (3/8" UNF nuts) for the exhaust manifold to head studs. Much easier to take off when installed. Quote Link to comment Share on other sites More sharing options...
Jonny-Jimbo Posted December 24, 2015 Share Posted December 24, 2015 Yup, the brass ones don't rust on!The three small holes are for location dowels I think? Not 100% on that though. Quote Link to comment Share on other sites More sharing options...
DJB_Harvey Posted December 24, 2015 Share Posted December 24, 2015 Small studs are 5/16 UNF ... Quote Link to comment Share on other sites More sharing options...
iggy Posted December 24, 2015 Author Share Posted December 24, 2015 thanks lads il get some brass ones as well 🙂 Quote Link to comment Share on other sites More sharing options...
Richard B Posted December 24, 2015 Share Posted December 24, 2015 Suppliers vary, but some do the manifold nuts deeper than the normal steel nuts. About 1/2" or 5/8" long (deep).As they are brass this;a) lessens the load on the threads (and risk of stripping)b) protects the whole stud thread from corrosion Quote Link to comment Share on other sites More sharing options...
iggy Posted December 24, 2015 Author Share Posted December 24, 2015 that makes sense Richard il get il get the longer brass nuts Quote Link to comment Share on other sites More sharing options...
JohnD Posted December 24, 2015 Share Posted December 24, 2015 Ideal, are bronze. But expensive and difficult to find Quote Link to comment Share on other sites More sharing options...
Jonny-Jimbo Posted December 26, 2015 Share Posted December 26, 2015 Ideal if you have some hex and a lathe to knock your own out. Sadly, that's not the case for me... Quote Link to comment Share on other sites More sharing options...
piman Posted December 28, 2015 Share Posted December 28, 2015 Hrllo all,steel nuts and copperslip have served me well for years.Alec Quote Link to comment Share on other sites More sharing options...
TedTaylor Posted December 28, 2015 Share Posted December 28, 2015 Where appropriate I use stainless nuts,MUT Quote Link to comment Share on other sites More sharing options...
iggy Posted December 28, 2015 Author Share Posted December 28, 2015 yep when i dismantle any steel bolts or nuts i re fit with copper slip, Quote Link to comment Share on other sites More sharing options...
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