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I have ski boat with a black 308 (from a VK). It has very low vacuum and low power under load - but will rev to 5000 rpm in neutral. It wont idle (I think becuse of the vacuum problem). I have just got the boat and the guy that sold it to me said it had a rebuild about 15 hours before. I have had it to a mechanic and he tells me the vacuum problem is due to the cam being too lumpy. Today I pull of the timing case and it looks like the camshaft has been installed 180 deg out. I double checked that I was on Comp TDC but the camshaft is nowhere near the 9 links it should be (it sits at about 9 oclock as you look at it and shouuld be at about 3 oclock according to my Holden book). Is it possible for a 308 to have the camshaft 180 out? would this explain my problems?
Is is just a matter of removing the chain and setting it up correctly on TDC? Thanks
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silly question? it does not have a vn style cam in it? of the top of my head i cant remeber the pushrod rod to port location.
did you have a timing light one it????? check the balancer has not slipped also.
bring number one cylinder up to tdc compressio
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When the cylinder is on the compression stroke the inlet will be closing then both valves need to be closed before the piston is at the top of the bore. Crank the motor with the plug out on no 1 cylinder, put your finger over the hole and watch the bal Edited by user Saturday, 3 January 2009 10:14:05 AM(UTC)
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You only have to be in front at the end of the race. |
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Thanks James. Yes it is 180 out. Actually I think a better way to look at it is that the crank is 360 deg out. I think this means that the engine will run the same - as the only thing that decides TDC on compression is the valve position. eg if the cam ch
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Thanks for the advice guys. I have just put it back together and still have the same issue - low vacuum...I wonder if the cam is that wild - with a big overlap and thats the issue...vacuum is very low - around 5" (should about 20") and wont idle at anythi
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cam cant be 180 out think about it if it,s at tdc you take the chain off providing there is enough piston to valve clearance, turn the crank 360 degress refit fit chain you are back where you started.
it,s two crankshaft turn,s to one camshaft turn.
th
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I 100% agree petaus. I dont know any details on the cam...just thats its not std. I have been doing some more research and most people seem to be saying that an aftermarket cam will give low vacuum and cause carby and idle problems...especially on 253s an
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the numbers are usally on back of the cam if you could get the cam plug out?
what sort of carby are you running? if it,s a rochester it may need the mixture curcuits drilled out.
if it,s a huge cam it may need to idle at around 1000 rpm anyway.
rochest
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