Short Barrel(s)

[dollydog]

agree jab, that's how i file the outer edges, trap the plate between 2 slabs of wood. in the vice and a pair of mole grips each end. bit heath robinson, but never buggered one up yet.
cheers, dd.
ps, thanks alan

[alanr]

wondering how you got on with the barrell fix?

[joolstacho]

but why would you use brass plate on aluminium barrels? surely it's common sense to use the same material? heat co-efficient and all that, brass holding heat a lot longer than ali? why brass? 3 times the price and a damned sight harder to work. anybody can make anything out of any material with the right tools. we're talking blokes in a shed with the basics. and PLEASE don't slag people off that are just trying to help somebody out. maybe it's no biggie to you, but to me it's job satisfaction and the 4mm aluminium lifter plates i cut out myself using the above method [not having access to fancy tools] and fitted to my gt350 work perfectly oh, and even though they were done by hand, they look good as well

All I can say is to quote:
"A little knowledge is a dangerous thing" and "Common sense isn't so common"!
Don't accuse me of slagging people off. All I did is to suggest a better way of doing the job... IN-MY-HUMBLE-OPINION !
I'd guarantee race-shop engineers would agree 100% with me. Having worked on race engines, and getting advice from very distinguished race mechanics, there's no argument.
If you have the choice, brass plate is the superior material to use in this application.

Brass sheet gives a VERY STABLE cylinder base, and is much less likely to be damaged or distorted. And in manufacture it is much more precise in thickness.

The real problem is that thin aluminium is soft and EASILY DISTORTED. - Just what you DON'T need at the critical cylinder base.
Co-efficient of expansion doesn't come into it at all. If your objection is that it's harder to work? -well, tough!
Do it your way.

[daxman]

wondering how you got on with the barrell fix?

I bought a decent thread file and i think I've recovered the original barrel threads sufficiently to give them a try.
I also drilled out the old (snapped at base) m6 'collar holding tab screw' so I can use that mechanism again - hopefully.
so short barrels are back on the shelf atm
Lots going on at once with this particular 'box of shocks'.

[Alan H]

All I can say is to quote:
"A little knowledge is a dangerous thing" and "Common sense isn't so common"!
Don't accuse me of slagging people off. All I did is to suggest a better way of doing the job... IN-MY-HUMBLE-OPINION !
I'd guarantee race-shop engineers would agree 100% with me. Having worked on race engines, and getting advice from very distinguished race mechanics, there's no argument.
If you have the choice, brass plate is the superior material to use in this application.

Brass sheet gives a VERY STABLE cylinder base, and is much less likely to be damaged or distorted. And in manufacture it is much more precise in thickness.

The real problem is that thin aluminium is soft and EASILY DISTORTED. - Just what you DON'T need at the critical cylinder base.
Co-efficient of expansion doesn't come into it at all. If your objection is that it's harder to work? -well, tough!
Do it your way.

You seem to have missed some points.
Aluminium is easier to work in a 'nornal' shed/workship that most of us have, we aren't race mechanics with unlimited budget and tools, and it isn't a race engine.
One of the beauties of aluminium is that being soft, any distortion after working is easily put back to 'normal'. Distortion between barrels and cases shouldn't matter as the surfaces will close any bumps or anomalies anyway. A thin smear of relevant gasket 'goo' or paper gaskets either side will sort that out if necessary. I've seen Ade's workshop and it's cramped, 'busy' and like most of ours, full of 'stuff' that is always useful sometime. He does some top class work with what he has to work with and has a damned sight more patience than most of us on here.
Better way? Perhaps.
Practical way? Carry on being practical, Ade. It works.

[dollydog]

thanks alan now i've left the house after my bowl of gruel, i'll carry on in my non insulated, freezing cold shed, doing what i do best - doing it my way. a couple of points though. 4mm aluminium is hardly thin, which is what i used on the gt350 barrels, and as you know, it starts easy and runs perfectly another point was dressing worn exhaust threads with a needle file. there's absolutely no point, because the o.d has diminished, therefor the threaded exhaust nut will always be loose. usually til it gets right up the top end. the only way round that without resorting to new metal is [something i tried and it worked, but just as a stop-gap measure] get some solid copper washers, anneal them and then tighten the exhaust nut onto them. being a lot thinner than normal gaskets, the nut will tighten further up - hopefully where the threads are good. then tighten the silencer nuts. that should stop the exhausts leaking at the manifold. one idea i've got in the pipeline for replacing threads is common or garden aluminium scaffold tube. 48mm o.d and about 5mm wall. should be able to thread them easily, and go from there replacing the exhaust stubs is not easy - but it's do-able, even in my hovel of a shed
cheers, dd.