Can CAM and crank timing be off a tooth or so and still run but rough?

63LONGBED

MEMBER
1963 CHEVROLET
6,000 MILES

I have a 305 chevy small block timing mark 12 oclock, but the guy that rebuilt it put a chrome timing chain cover on it wit timing tab in 2 oclock position. After I checked compresion 130 each cylinder, found tdc and set timing on distributor, change intake and carb gaskets, adjusted valves it runs better but low vacuum 6 inches and hard power brake pedel at idel, it in a 63 chevy pickup and the old 305 ran with plenty of vacuum and sooper smooth idel. Can the cam and crank timing be off let, s
say 1 thooth and still run but rough idel in drive and low vacuum?

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5 Replies

ASEMASTER6371

MECHANIC
52,797 POSTS

130 lbs compression is good. Doubt timing is off.

6 inches is way too low. Where are they taking the vacuum source from?

Roy

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Sunday, September 30th, 2012 AT 3:14 AM

63LONGBED

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3 POSTS

Carb vacuum for distributor, is it posable to have the cam and crank out of sink and still run

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Sunday, September 30th, 2012 AT 4:41 AM

ASEMASTER6371

MECHANIC
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Not really.

Is it ported manifold vacuum or ported vacuum?

Roy

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Sunday, September 30th, 2012 AT 4:43 AM

63LONGBED

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My vacuum guage was hook to the drivers side adjustable tube on my edelbrock 1405 . I replaced the intake manifold and gaskets, adjusted the valves, set #1 to piston stop marked balancer. And turnde crank back to piston stop and marked balancer and found tdc in between marks. I think the guy that rebuilt the engine went by the timing mark on the after maket timing chain cover 2 oclock instead of 12 oclock as the original marking tab would have been at. Once again is it possable to have set the crank at the wrong position timing mark and the cam at another and have the engine run as 1 tooth in or out

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Sunday, September 30th, 2012 AT 4:59 AM

ASEMASTER6371

MECHANIC
52,797 POSTS

Is it possible, yes. How does it run above idle?

The chrome timing cover may have the wrong pointer on it as they arew generic to make the motor look good.

To be sure, you will have to remove the cover to verify the marks. The crank mark at 12 o clock and the cam mark at the same.

I keep asking about the vacuum source to verify you have it in the correct location to get the proper vacuum to the booster. Nothing else can be on that line, as the pcv as it is a regulated vacuum leak.

Roy