fuel rail to manifold bolt size?

adamnreeves · Post by **adamnreeves** » Sun Apr 13, 2008 1:35 am

RV8 fuel rail to flapper manifold.

adamnreeves · Post by **adamnreeves** » Sun Apr 13, 2008 8:37 pm

I am guessing this must be 1/4 unf? Thats the only bolt size I do not have!

ChrisJC · Post by **ChrisJC** » Mon Apr 14, 2008 7:45 am

I'll see if I can remember to check tonight. If the bolt head is 7/16ths then it will be 1/4 UNC or UNF.

Chris.

adamnreeves · Post by **adamnreeves** » Mon Apr 14, 2008 4:27 pm

I do not have the original bolts that my problem. an M6 goes in but stops after the first thread! Looking at the thread in the manifold looks very fine.

ChrisJC wrote:I'll see if I can remember to check tonight. If the bolt head is 7/16ths then it will be 1/4 UNC or UNF.

Chris.

ChrisJC · Post by **ChrisJC** » Mon Apr 14, 2008 9:03 pm

B*gger, forgot!. will try to remember tomorrow!

Chris.

adamnreeves · Post by **adamnreeves** » Wed Apr 16, 2008 5:42 pm

Please someone answer my question. I ordered 1/4 UNF bolts on a hope and they do not fit. Is there a fine M6?

ChrisJC · Post by **ChrisJC** » Wed Apr 16, 2008 7:59 pm

Remembered to check. I couldn't see any bolts holding the fuel rail to the manifold - the injector pipes were holding it.

I confess to not looking too hard though, maybe I missed some.

The bolts won't be M6, they will be UNC or UNF. If they are finer than M6 then they are UNF, if coarser then UNC.

Chris.

adamnreeves · Post by **adamnreeves** » Wed Apr 16, 2008 8:15 pm

erm, the fuel rail has four legs which bolt down to the inlet manifold for flapper and hotwire. Why do you think it might not be metric, the plenum chamber to the inlet manifold bolts are M8 I believe.

ChrisJC wrote:Remembered to check. I couldn't see any bolts holding the fuel rail to the manifold - the injector pipes were holding it.

I confess to not looking too hard though, maybe I missed some.

The bolts won't be M6, they will be UNC or UNF. If they are finer than M6 then they are UNF, if coarser then UNC.

Chris.

ChrisJC · Post by **ChrisJC** » Wed Apr 16, 2008 9:05 pm

Just nipped out to the garage (incurring the wrath of 'er indoors!)

My fuel rail is secured to the manifold by two 1/4 UNC bolts. One holds the fuel pressure regulator directly, the other is a small tab fixed to the fuel rail at the rear of the plenum a few inches before the rail finishes on the fuel inlet side.

1/4 UNC is the same as the rocker cover bolts, and also the bolts securing the injectors to the manifold (those funny plate things).

Chris.

adamnreeves · Post by **adamnreeves** » Wed Apr 16, 2008 11:12 pm

Thanks for that Chris. The threads weren't the best and I wanted to be certain. I have re-tapped them and that sorted it out. Cheers.

ChrisJC wrote:Just nipped out to the garage (incurring the wrath of 'er indoors!)

My fuel rail is secured to the manifold by two 1/4 UNC bolts. One holds the fuel pressure regulator directly, the other is a small tab fixed to the fuel rail at the rear of the plenum a few inches before the rail finishes on the fuel inlet side.

1/4 UNC is the same as the rocker cover bolts, and also the bolts securing the injectors to the manifold (those funny plate things).

Chris.