Su Carb nut sizes

spartanv8 · Post by **spartanv8** » Thu Mar 05, 2009 8:19 pm

Hi
I'm sprucing up my engine bay and want to replace the nuts that hold the SU carbs to the inlet manifold with stainless ones. Can anyone tell me what size they are please?
Thanks
Fil

harvey · Post by **harvey** » Thu Mar 05, 2009 8:41 pm

5/16" UNF

spartanv8 · Post by **spartanv8** » Thu Mar 05, 2009 8:46 pm

Thank you, that's great.
Fil

spartanv8 · Post by **spartanv8** » Tue Mar 17, 2009 8:33 pm

Hi

As I said I'm changing my carbs and manifold and so will be fitting a new thermostat. I want to put stainless bolts in the thermostat housing but don't know what size bolts they are. Can anybody help?

Thanks

Fil

harvey · Post by **harvey** » Tue Mar 17, 2009 9:07 pm

5/16" UNC (About 1" long.)

spartanv8 · Post by **spartanv8** » Tue Mar 17, 2009 10:02 pm

Thank you very much, sorry to be such a pain.

Fil

harvey · Post by **harvey** » Wed Mar 18, 2009 4:43 pm

No problem. The thermostat housing bolts are normally set bolts BTW. (Threaded all the way up to the head.)

spartanv8 · Post by **spartanv8** » Sat Mar 21, 2009 7:38 pm

Hi Harvey

Is this because of the reaction between steel and ali, so that they can be unscewed if they corrode together? Would that matter if the bolts are stainless and copper slicked? I was thinking of using these:

http://cgi.ebay.co.uk/5-16-x-1-UNC-Stai ... 240%3A1318

Fil

harvey · Post by **harvey** » Sat Mar 21, 2009 9:18 pm

You need to make sure that the unthreded part of that is less than the thickness of the thermostat housing otherwise it won't tighten up. Personally I've always used the standard bolts and never had problems, you can always paint the heads after they are fitted. If you're worried about corrosion between the steel ansd ally use the proper sealant.

spartanv8 · Post by **spartanv8** » Sat Mar 21, 2009 10:45 pm

I only wanted to use cap head bolts as I 've used these with the inlet and exhaust manifolds so it's not important. But these are the only 5/16 s/s unc bolts on Ebay!

ged · Post by **ged** » Sat Mar 21, 2009 11:44 pm

Hi spartanv8,

Stainless bolts, capscrews or setscrews in aluminium are fine & yes use copperslip but sparingly. coat the threads lightly with a small brush as too much can cause hydraulicing.

spartanv8 · Post by **spartanv8** » Sun Mar 22, 2009 7:18 am

Hi
What is hydraulicing?

RoverP6B · Post by **RoverP6B** » Sun Mar 22, 2009 9:08 am

Hydraulicing by my understanding means an exessive pressure caused by an excess of grease of lubricant when applied to a thread or spline, typically into a blind hole.

If too much grease or lubricant is applied, then it essentially forms a solid mass at the base of the hole, preventing the bolt from being fully tightened or splined shaft from achieving the full range of movement.

Ron.

ged · Post by **ged** » Sun Mar 22, 2009 9:08 am

Hi spartanv8,

Right it's a bit early in the morning for this ( had a wee bit too much wine last night).

Hydraulicing is when you try to compress a fluid in a blind hole. This can lead to parts failure because of the pressure build up. For an example if your removing a bush from a blind hole pack the hole with grease, insert the correct sized shaft, hit shaft with hammer & hey presto bush will come out because of the hydraulicing effect of compressing the grease.

Basicaly what I'm trying to say is use the copper grease sparingly, Don't just dip the bolt in the pot before you use it.

Hope this helps.

Ged

ged · Post by **ged** » Sun Mar 22, 2009 9:12 am

Hi Ron,

If I'd known you were answering I could have saved myself a headache.

The V8 Owners Forum -

Su Carb nut sizes

Su Carb nut sizes

Thermostat housing bolt size