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Author Topic: Cylinder head studs  (Read 279 times)
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mangocrazy
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« on: March 18, 2021, 12:25:02 PM »

At some point in the not too distant future I hope to be able to fix the inlet and exhaust manifods to the Beta 2000 engine I am rebuilding. However the cylinder head has been de-studded and I am having difficulty in finding suitable replacements. Does anyone have a reliable source? Would GC (now run by Gloria) be likely to have stocks and would she be able to advise?

I've measured the thread depth on inlet and exhaust using vernier calipers and it does seem to vary widely.Depth of the inlet threads varies between 25mm and 40mm, and those of the exhaust between 25mm and 35mm. Surely one doesn't need to have studs which engage to the full thread depth in the head? What depth of thread engagement is reasonable?

The other variable is the depth of the GC manifold; this also varies between 10mm on the two upper fixing points and 23mm on the four lower fixing points.
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capriblu
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« Reply #1 on: March 18, 2021, 02:01:38 PM »

I think they will just be M8 x 1.25 threads and any standard exhaust studding of suitable length will suffice - 1 " should be ample.  (FWIW personally I wouldn't even think about stainless - risk of seizure/galling).

Loads of choice online for exhaust studs with countless variations of thread lengths, plain centre diameter length etc.    I recently had to fit some new studs to the flange face of my exhaust manifold
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peteracs
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« Reply #2 on: March 18, 2021, 04:30:46 PM »

Hi Graham

I agree, given the likely modest torque setting for the nuts, I cannot see any big issue using standard exhaust/inlet studs with a reasonable length into the head. I would keep them all the same. If you want me to 'destud' a spare head I have for OE measurements, let me know.

Peter
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WestonE
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« Reply #3 on: March 18, 2021, 04:51:34 PM »

Hi Graham

GCs studs came from Wurth and are nice high quality plated items. The engineering answer is 1.5 x the thread diameter in the hole. This assumes the threads are not damaged of course. Do check and helicoil or threadsert any damage ones. Also use thread sealant on the top 2 exhaust side or expect oil dripping onto the exhaust later.

I think Gloria will need to know how long and how many. There was stock when I was up in Lincoln and I expect that has moved to Bedford.

Eric 
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mangocrazy
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« Reply #4 on: March 18, 2021, 06:58:39 PM »

Thanks everyone. I won't trouble you to de-stud a head, Peter. I'll just do as Eric suggests and assume a length of 12mm into the head and then calculate outwards from that. I'd prefer at least 8.8 plated steel and ideally with an insert for an allen key to drive the studs home easily and without resorting to the two-nut trick. I'll see if I can find a Wurth catalogue online and get part numbers and dimensions.
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1980 Lancia Beta Spider 2000 (S2FL)
2002 VW Transporter T4
2017 KTM Duke 690R
2008 Aprilia SL1000 Falco
1992 Ducati 888 SP3
1988 Honda VFR750F
1980 Yamaha RD350LC
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