Distributer

[GDPR]

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I think shifting a head to do an inlet manifold is overkill and daft - I would never countenance doing such a thing.

Obviously an idea invented by someone wanting to make extra cash by removing a head.....

If you don't need to remove the head - don't. A simple compression test will tell you all you need to know about your valves.

Russ

[Arbman Al]

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Hi all,
Thanks for all the replies.
Can a compression test be done without the carbs on?
If so I will do that first then decide whether the heads stay on or come off.

Best get back up that tree now and earn some more stag repair funds!

[NickA]

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arbman101 wrote:

Can a compression test be done without the carbs on?

Short answer is Yes.

[Arbman Al]

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NickA wrote:

arbman101 wrote:

Can a compression test be done without the carbs on?

Short answer is Yes.

What sort of pressure should I be expecting from the compression test?

[stustag]

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The ROM states to check each cylinder noting each reading and that all cylinders should have a pressure within 10 ib/in (0.70 KG/cm) differential.

It doesn't however tell you what is a good or bad reading!:?

Having never done a compression test on my Stag I don't know, maybe the King of Green can help us out here!

Stuart

[redstag]

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Mine were around 165 - 170which I think is ok.

Don't forget to have the throttle fully open - not a problem if you don't have the carbs fitted of course.

Pete

[NickA]

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arbman101 wrote:

NickA wrote:

arbman101 wrote:

Can a compression test be done without the carbs on?

Short answer is Yes.

What sort of pressure should I be expecting from the compression test?

Last one I did on a rebuilt bottom end but with the existing heads was between 165 and 175psi per cylinder

[GDPR]

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Sorry for delay in replying but been in Bluewater for the day emptying my pockets.

Minimum 120psi - be nice to see above 150psi, (170 or more could mean an over-skimmed head with less combustion chamber volume) with a max rise of 20 psi after 3 squirts of engine oil down the plug 'ole with a squirty oil can - a rise of more than 20 psi tends to denote a ring problem. As was previously mentioned there should be less than 10 psi difference between cylinders. If two adjacent cylinders are low, put the plug back into the one not being tested, and if it goes up, the HG is blown between the cyls.

In Al's case as the engine hasn't run for some years just having the minimum 120 should be enough to get it going, and it will normally improve after it's got up to temp a couple of times.

[Arbman Al]

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Thanks for all your replies.

I will post my readings on here when I have done them (probably tomorrow).

Russ - hope you still have some Stag funds left!:?

Al.

[redstag]

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Should have mentioned my readings of 165-170 were on a brand new head and rebuilt block.

Pete

[GDPR]

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arbman101 wrote:

Thanks for all your replies.

I will post my readings on here when I have done them (probably tomorrow).

Russ - hope you still have some Stag funds left!:?

Al.

The Stag funds are ring-fenced with barbed wire, hungry Dobermenand sentry posts.... but thanks for asking