Hi my Tiger has slow speed running issues since it started. It will start and run at 3000 and up. Once it gets near 2000 it stops. It is a fully rebuilt 289 with alloy heads and a 4 barrel holley. I took it to a mechanic and he even changed the carby to try to fix the problem. I now have the Tiger back and still have the problem. He said it has a vacumn leak most probably between the inlet manifold and the heads, Is this a common occurance with new parts? If so I will have to lift the inlet manifold and have the gaps checked.
Vacumn leak
- Thread starter steven
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ABSunbeams
Gold forum user
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Manifold leak?
Had the same issue using a F4B manifold, leaked between the carb and the manifold. Did not change with a different carb. Ended up using a 1/8" heat plate between the two, sprayed the surfaces with adhesive put a gasket on each side. Could adjust the air mixture screws after that.
Old trick my mechanic used was to squirt lacquer thinner around the base, manifold and listen for an RPM change to find leaks. Just keep a fire extinguisher handy.
Had the same issue using a F4B manifold, leaked between the carb and the manifold. Did not change with a different carb. Ended up using a 1/8" heat plate between the two, sprayed the surfaces with adhesive put a gasket on each side. Could adjust the air mixture screws after that.
Old trick my mechanic used was to squirt lacquer thinner around the base, manifold and listen for an RPM change to find leaks. Just keep a fire extinguisher handy.
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Them gaskets
Some gaskets are better than others. Outsourcing has produced a variety of quality/inequality products. Check for simple things like wavy surfaces and/or dimensions that just don't match the ports. The bean counters don't get their hands dirty . . . . . .
Some gaskets are better than others. Outsourcing has produced a variety of quality/inequality products. Check for simple things like wavy surfaces and/or dimensions that just don't match the ports. The bean counters don't get their hands dirty . . . . . .
Another Way to Find the Vacuum Leak
Another way to find the vacuum leak is to use aerosol shaving cream. But this works only with a cold engine. Just spread the shaving cream over the areas you suspect might be leaking and then have someone crank the engine while you watch for any disappearing shaving cream. This is a lot safer than some other methods, but can be messy. But it works only for leaks that are available to you, such as between the heads and top of intake, but not between the heads and bottom of intake (or lifter area).
Good luck finding your vacuum leak!
Another way to find the vacuum leak is to use aerosol shaving cream. But this works only with a cold engine. Just spread the shaving cream over the areas you suspect might be leaking and then have someone crank the engine while you watch for any disappearing shaving cream. This is a lot safer than some other methods, but can be messy. But it works only for leaks that are available to you, such as between the heads and top of intake, but not between the heads and bottom of intake (or lifter area).
Good luck finding your vacuum leak!
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It has been a while however I finally found the problem. This is after a workshop told me it was a vacumm problem and charged me $1,000 for the advise.
Changed the new distributor for a MSD I had on the shelf. Started and ran. Final timing and carby idle and I have a fully working motor. Very Happy.
Happy New Year to all
Changed the new distributor for a MSD I had on the shelf. Started and ran. Final timing and carby idle and I have a fully working motor. Very Happy.
Happy New Year to all