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Low vacuum/rough idle issues


Beaver

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Then all you need is a big motor.

A15 is a big block, Rog.

Interested to hear what this turns out being, does sound like a silly annoying vac leak but nothing doing in that scenario so it's gotta be something else.

Sure it not a split hose somewhere?

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Righto. Fingers crossed someone may have managed to fit three quarters of a race cam onto a quarter of a stock one. Or alternatively, the timing it out or.. a combination of the two, the timing it out because someone put another cam in.

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have u checked the vacuum advance hose

had one that had a serious of small pin holes  not picked up by eye

motor had similar problems

 

I will tripple check/replace it and see if it makes a difference

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Are the tappets set properly? they can be kind of a difficult if you're not used to them.

 

IM reasonably confident Im doing it right haha, have done a few cars which didnt turn to custard so Im pretty sure they are sweet.

 

But I will triple check

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are valves all opening a similar amount ? maybe worn a cam lobe ?

 

I have no diea haha, not sure how one would check that? Measure how much each intake valve spring compresses as the cam cycles through?

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my engine that has a leak in the booster when you press the brakes does exactly what yours does. but as stated you have no booster and very little in the way of vacuum systems to go wrong so im not really too sure.

 

it does sound like a vac issue though since taking out a bung has little effect. and at idle my engine with a mild cam and bike carbs pulls more than 10inhg 

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Let me know if you need to try or buy any parts, I have a full stripped A15. Also if you need to try out any parts as I have a good running a15 in my sunny.

Also by any chance do you still have the 4 speed out of your car?

 

Legend, thanks man, Ill keep that in mind. Nah Ive sold the 4 speed and a12 engine a while back.

 

I also have a vanette with an a15 so can try parts from that as well haha, but im running out of things to swap out.

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I made a vacuum tester for my daily driver by putting some paper into a bottle and some vacuum lines coming out then lighting the paper and blow blow blow.

Found the leak and replaced the line. Maybe that'll help you

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I have no diea haha, not sure how one would check that? Measure how much each intake valve spring compresses as the cam cycles through?

yeah , that would give you a pretty good idea (dial guage would be better) remember intake and exhaust may be different , another thing to look at is how much difference there is in tappet adjusters if one is heaps further in/out it may be a clue , also when you set tappets are you batch setting or pairs ? opposing pairs (rocking on 1 set on 4 etc) is better for acuracy . good luck !

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Rule of 9 Beaver.

If you look at the engine page in your Haynes manual, (All datto peeps need one of those) the numbers add up to 9.

it's important that you adjust the tappet with the follower on the back of the lobe.

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