Twin cam shims

[Shaun II]

I'm after 3 shims in the 4.55 region for my new cam in the volumex, any about, any ideas? Sando did let me look after the club tools/shims but most are around the v.low 4.X. In my collection of heads the shims all seem to be about the same, 3.95 - 4.25. I hope cam carrier machining is not the option.

[Martin K]

Funnily enough we were re-shimming the inlet cam on our twink yesterday.

With re-profiled cams, or new cams with high lift and a smaller than standard base circle diameter, there can be a problem finding shims thick enough.

We had run without a gasket under the inlet cam box as this is about 0.77-0.84 thick. Not fitting one reduces the thickness of shims required by the same amount. However we were unable to completely seal an oil leak from the high pressure feed to the No. 3 cam bearing (close to cylinder 4) so we had to revert to using a gasket. This gave us the same problem you are having finding shims thick enough.

John has a full set of shims and the largest 'standard issue' in the box is 4.20.

On the twin cam there is a washer of hardened steel, 1 mm thick, which fits under the valve springs to prevent the spring wearing into the alloy head. The solution we adopted is to use one of these washers under each shim. If you follow the same strategy you will require shims of 3.55. I am not sure of the smallest shims available (I can ask John) but they certainly go lower than 3.55 so you should be able to find standard shims to suit.

Good luck!

Martin

[maseratighibli]

I have a box of twin cam shims in the shed, will have a look 2moro for you.

Gareth

[Shaun II]

Thanks for the input, the cam I used came from a standard injection head and is not reprofiled, that could well be the next project but I thought to keep things simple for the start. The camcarriers are not interchangeable without machining and I think there were two shims of 4,70 in the SEC collection - way too much.

[BETANUT]

The IE cam (I found) doesn't offer enough extra "ooooomph" in the VX to make it a worthwhile exercise IMHO..... sorry to be posting this now :o (unless you've gone for a meaningful carb change?).
If you can get your hands on a FIAT 130TC inlet cam, now we're talking serious gains - and you can keep the standard exhaust cam :D 130 inlet cam turns the VX from a bit of a plodder to something much much more interesting :eek:
But you probably know all this already ;)
Odd that it should require so much shimming though - don't recall those issues with my VX engine and assorted cams.

[maseratighibli]

Shaun, measure up and tell me exactly what size shims you require as some are marked and others I have are not so I will need to mic them.

Gareth

[Shaun II]

3x 4.55 or 3.55 would be perfect(ish)

Hamish, I did buy a 130tc complete engine that turned out to be a 125tc but with a volumex head. The cam swap was a good intro to twincams, I've only played with pintos before. The difference in shimming is a bit worrying, theres a gremlin lurking.....

Todays jobs were inner door handles, I can get out the car now.

[BETANUT]

Hamish, I did buy a 130tc complete engine that turned out to be a 125tc but with a volumex head.
Pisser :( But a VX head is always a useful thing, even without those lovely 130 cams ;)

The cam swap was a good intro to twincams, I've only played with pintos before. The difference in shimming is a bit worrying, theres a gremlin lurking......
Aye - you and me both. There really shouldn't be the need for that much major shimming. It's unusual :confused:
How you finding the twink after the Pinto :eek:

[maseratighibli]

Okay, will have a measure up 2moro.

Gareth

[Shaun II]

Thanks.

After the pinto - just seems expensive.

[maseratighibli]

I have a fair selection of shims between 4.50 and 4.57 so not a problem,email me to arrange delivery.
Gareth
07779740950
gk@gkautobody.freeserve.co.uk