Showing posts with label torque wrench. Show all posts
Showing posts with label torque wrench. Show all posts

Monday, 28 July 2025

FH - still on the bench, but looking good!

 It's been a while, or it feels like it. It's actually almost a week since I did anything to the FH - I've done a couple of railway turns and the weather has been a bit wet.

The head bolts are torqued to 32 lbs ft or so. I tightened them down using a 1/2" square ratchet (as per the manual, as tight as I could get them), then checked them with a torque wrench set to 32 lbs.ft. - so they may be tighter than that. The 32 lbs.ft seems to be bandied around a lot in connection with iron-head A10s.

This is the drive side cylinder - 140 psi or so. this was showing 75 psi on the last test, and is the cylinder that weeps oil.

This is the timing side cylinder, which showed 95 psi in the last test.


Now, obviously these numbers are a lot higher than we saw before, but don't be fooled, this is partly because I had the throttle open during the test - it was closed previously. The big win here is not the high numbers, but the fact that the two cylinders are no longer 20 psi, or around 25% different.

I bought a couple of sets of rocker box gaskets on eBay - they are identical to BSA A10 rocker box gaskets, though the tappet cover gaskets are different. I fitted these with Wellseal last time, and destroyed them lifting the rocker box. This time, I'm going to use Threebond 1215 on one side with grease on the other.

I'll have to find a moment to put it on.

Tuesday, 21 November 2023

FH - Finishing the crankshaft

In our last post, we determined that the big end clearances were good. At the same time, I checked the new gudgeon pins in the small ends and found those to be good too, so with the sludge trap cleaned and assembled some time ago we can commit to closing up the big ends with the proper big end nuts. These are £3 each, and can only be used once.

We torque them up to 22 lbf.ft, or about 29 Nm using the Draper 3/8" torque wrench.


I took the chance to clean the crankshaft down again with some brake & clutch cleaner and dropped it into the drive side crankcase half which I had laid out over the hole in my bench:


Here's another view, showing the new 356 camshaft as fitted to BSA A10 Road Rockets and early Super Rockets.


Tomorrow, I'll use some Threebond 1215 to seal the crankcase halves. Meanwhile, I need to sort out the bolts to hold the cases together. I have this lovely box of studs from Acme Stainless:


This sketch, from Draganfly's 'List 15' (a very useful document) shows where the studs go: