> The trouble i have got is far worse.My S has a just rebuilt motor,a sports
> cam,
> { PI } and a PI head.The S starts very good but when you open throtle the
> engine revs up but then dies back with a very different exhaust sound,very
> flat and dead.
Is the problem worse under load ? Sounds like a classic fuel delivery
problem, I'd start by checking the fuel pressure at the carbs when the
problem is happening. Most vacuum test gauges will also read fuel pump
pressure. Tee it in at one of the carbs, then lead the hose out from under
the bonnet and prop it under a wiper blade, so you can see it while you
drive.
> To cut a long story short i have had the carbs off 3
> times,did find by pouring petrol over the carb flange a change in engine
> revs.Put on a vacum gauge and got 15 at idle.Tonight i changed the inlet
> manifold,more new gaskets and this S will still not rev over 3000
> revs.
Vacuum leaks are always more obvious at idle ... if it will idle then a
manifold vacuum leak is probably not the "3000 rpm" problem.
> My next step is to checked the compressions,
Same thing applies to compression.
> With the changed inlet manifold i am getting small back
> fires this is new so iam wondering if i have more than one problem.
I'd say you definitely have multiple problems.
> What i am
> wondering is, does the sealed jet tube fail?
I'm not sure what you are referring to here. If you're talking about the
tube from the float bowl to the jet on a HS6 SU, then yes, they definitely
can fail. If the failure is being crushed accidentally, they could cause
the problem you are seeing, too.
HTH
Randall
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