Seized jackshaft allen key bolts

[cleverusername]

This shouldn't even be a question, I mean how hard can the two allen key bolts that hold in the jackshaft retaining plate be to shift? The answer is very.

I have put a bar on an allen key, and nearly snapped it in two trying to move them. Tried an allen key socket and it did snap in two. Tried heating them up with a blow torch, still siezed.

Only thing I can think of, short of drilling them, is an allen key impact socket. Does anyone know the size of these bolts so I can get one?

Oh if anyone has any ideas how to shift them in the mean time?

[Mad Mart]

Yes they can sometimes be very difficult to remove, usually you end up rounding the hex hole. If that happens I usually get a small chisel and tap them around. Done this many times.

[Carledo]

You can get a tool called an "Impact Driver" they usually come with screwdriver fittings but the base will be a 1/2" square drive so will take a normal socket (in this case an Allen key socket) Doesn't require air as you hit it with a big hammer! Which adds pressure, a turning moment and shock to free seized fittings. See ebay item number 231568318419 for what I mean!

I use mine all the time for removing things like countersunk torx bolts securing discs to hubs and similar hard to shift fittings.

Another trick that has worked for me in the past on cheese head Allen bolts is to get a good quality Mole grip round the head whilst using an Allen key, simultaneously applying pressure to both. Puts double the effort in!

Steve

[cleverusername]

Got them out, bought some better quality metric 1/2" driver allen key sockets and hammered a slightly oversized one into the bolts. Then put all my might on a long breaker bar and they eventually moved.

Bit surprised that the jackshaft from my old block looks to be in better knick than the one from bored out 1850 block. Can you switch the shafts from different blocks or is it a better idea to stick with one that matches the block?

Only thing left to removed from the old block is the water pump. Though I am tempted to replace it, it feels properly knackered and my experience at rebuilding it hasn't been that successful. Only thing that makes me hesitate is I have heard stories of new pumps not having hardened shafts and teeth. is that still a problem?

I have an impact driver, handy tool but the mistake we made was to get one off Amazon. Driver is fine, the cheap bits are made of cheese and didn't survive much use.

[new to this]

If your original water pump gears look okay, i would get a rebuild kit and repair your own pump

Dave

[xvivalve]

Switching shafts is fine, but do check there is no play of the shaft in the front block bearing. The late Brian Kitley used to advocate keeping pump (and distributor) skew gears matched to the shaft where possible so long as there's no perceptible wear on either (a slight visual register on the contact faces is fine and expected).

A rebuilt pump is as good as a new one, so long as the skew gears are OK and the contact surface on the underside of the impeller has been machined flat.

I thought I'd removed the pump...but if not, how did you remove the jackshaft with it in place???

[cleverusername]

Switching shafts is fine, but do check there is no play of the shaft in the front block bearing. The late Brian Kitley used to advocate keeping pump (and distributor) skew gears matched to the shaft where possible so long as there's no perceptible wear on either (a slight visual register on the contact faces is fine and expected).

A rebuilt pump is as good as a new one, so long as the skew gears are OK and the contact surface on the underside of the impeller has been machined flat.

I thought I'd removed the pump...but if not, how did you remove the jackshaft with it in place???

You did but my old block still has has the pump in it. I just wiggled the jackshaft till it went past, it didn't seem to cause an issue.

[Mad Mart]

Does anyone know the size of these bolts so I can get one?

Better late than never...

Thread is 5/16" UNF
Length is 3/4"
3/16" hex