Carburetor bolts replacement

Rhodora

Hi there! The previous owner bodged fit a Holley single pump (350cfm) on the straight six of my 1949 super six (needs only 170cfm).

I bought a WGD but I am missing the bolts to install the carburetor on the intake manifold. Can anyone tell me what thread pattern and size the bolts should be? I live in Europe so I don’t have gauges to my disposal to measure it. We do have imperial bolts for sale at tractor shops. 

29sptphaeton

Paul Schuster has the gaskets required 3 or 4 then the heat shield and 3 or 4 more gaskets. Paul has the gaskets, the heat shield and I think he has the long studs required.

Rhodora

Thanks for your reply. I have already ordered 5 gaskets and a heat shield at Wild Rick. 

Shipping costs and taxes are insane so for me it would be wisest to buy the studs (or bolts) here. I’m not going for factory spec per se as long as the solution can safely and securely attach the carburetor to the manifold

Geoff

3/8" studs.  Originally U.N.C. on one end and U.N.F.  on the other, but it doesn't matter if both ends are U.N.C. 

Rhodora

Thanks, Geoff. My plan is to simply use bolts and washers instead of studs. So 3/8 UNC should do the trick

Old Fogey UK

Geoff said:

3/8" studs.  Originally U.N.C. on one end and U.N.F.  on the other, but it doesn't matter if both ends are U.N.C. 

Geoff, I've often wondered why studs were used on the manifold rather than bolts.
Any idea why ?

Rhodora

If I may be so bold to speculate: I guess it is because it is easier to gently/precisely torque UNF.

I will use bolts but very carefully torque them.

Geoff

Its actually easier to install using studs, so I assume that has something to do with it.  I h have not tired it, but getting a bolt down through the  hole past the linkages could be tricky.

Rhodora

How can I get in contact with Paul? I don’t know why but now that I am changing so many parts to stock I am contemplating about the studs too.

Next I will probably look for an air filter  

Rhodora

3/8” was way too big. Also I found out the previous owner probably tapped or forced 8mm bolts into the manifold so the answer was way closer to home than I imagined.

BigSky

Can I ask how you came up with only needing 170cfm?  Are you assuming a very low volumetric efficiency in the calculation?  I ask because I was looking at the equation the other day to try and determine what CFM my 212 might be able to handle.  

BigSky

I was assuming for my 212 a volumetric efficiency of 80% in this calculation.  However it’s just a guess.

Rhodora

I can’t remember how I calculated it. I used the same site but can’t remember which max RPM and VE I used and if it was exactly 170. Probably not. I just wanted to check if 350cfm made any sense and it did not.

I think I assumed lower VE (maybe even 65%) because of the flathead design and putting a moist finger up in the air.

BigSky

Your probably more accurate using 65% for volumetric efficiency.  It would be interesting to know what some of our engines were doing on efficiency.

I have my stock 2bl carb on the engine & it seems to do ok.  However I’d like to try something a little bigger to see what effect it makes.  

charles4d

You could  find the bolts that fit cut the heads off put 2 nuts on to put the bolts in take the nuts off and do the install
My 2 cents

Rhodora

So I’m getting further and further but also run into all kinds of small things.

One of those is that I am missing fittings for the fuel and the vacuum on the carb foot and on the dizzy. I am guessing the vacuum on the dizzy should connect up to the vacuum on the carb foot. 

Which fittings would I be needing for all three? It’s not a stock item over here.

Rhodora

I don’t know how to edit or erase a message. Please forget the last one, I will start another topic for my technical Q’s about hooking it up.