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Ernie Woodburn

Buick 455 Engine Rebuild

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Hi all.  I just finished a complete rebuild and have the motor installed.  It runs terrible.  Sputters and shakes like crazy.  It will only idle.  New carb (edelbrock 650).  Fuel pump is working.  Tried reinstalling distributor many times.  I've actually ordered a new one.

 

Question, when I installed crank and cam, I lined up the dots but can the crank be out 180 degrees?  TDC compression shows timing slot right on zero.  Also, using a timing light, the spark is intermittent.

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Bloo    48

No

 

The crank is out 180 degrees EVERY OTHER rotation, because it turns twice as fast as the cam. It's completely normal.

 

It IS, however, possible for the distributor to be out 180 degrees with relation to the cam, because it turns the same speed as the cam. This is NOT your problem. If it were simply 180 degrees out, it could not run at all. Its impossible.

 

I would double check the ignition timing again, and the firing order. Could the wires be put on the distributor incorrectly? See which way the distributor turns, put on #1, then follow the firing order around the distributor in the direction the rotor turns.

 

To be clear, when you put the #1 wire on, the engine should be on top dead center of the COMPRESSION STROKE for cylinder #1. Remember this only happens EVERY OTHER turn of the crank. Put #1 on the post the rotor is pointing at.

 

You may need to advance the timing a little bit to get it to start. To advance, turn the distributor SLIGHTLY in the OPPOSITE direction the rotor turns. If its kicking back while trying to start use less advance.

 

If that doesn't help go back to the basics, and do a compression test and a leakdown test.

 

Good luck!

 

 

Edited by Bloo (see edit history)

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Sorry for my delay.  Larry, I'm in London ON.  Fell into this 72 Riviera that was purchased in 1973 and parked in the barn in 1977.  Frank, new points.  Everything original except for 1 sleeve I had to install.

 

My issue is resolved.  I hooked up a timing light and found the flash was intermittent (new cap rotor points plugs and wires).  Yanked distributor and got a new one.  Runs awesome now.  Housing was likely worn...loose cap and spark was jumping around.

IMG_0378.JPG

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Frank DuVal    48

I bet the points plate was the culprit. The part of the plate that moves by the vacuum advance looses ground in the pivot pin. A wire added between this moveable plate and the housing will confirm if this is the problem. Extremely common on the GM six cylinder distributors 62 -73. I have rebuilt many of these, as OEM 6 cylinder points plates went discontinued years ago.

 

72, would have been 8.5:1 factory. Only 1970 had the 10:1 pistons.

Edited by Frank DuVal (see edit history)

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Update.  thought it was fixed but wasn't.  Ran great at idle but ran awful when in gear.  Turns out, the PCV valve (in the intake???)  ran to the front of the old carb.  I disconnected that on my edelbrock and plugged it.  Now it runs awesome.

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JACK M    421

From the intake to the front of the carb?

Seems like it wouldn't do any ventilating but must have caused a vacuum leak somewhere.

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Frank DuVal    48

The connection to the air breather (I guess you mean the air cleaner) I have seen are on closed PCV systems. On these there is a little filter on the side of the air cleaner that attaches by a large hose (maybe 1" ID) to the rocker cover or other engine crankcase inlet port. This filters the air going into the crankcase. It also means that fumes flowing the wrong way are still within the intake system, unlike the old filter on the oil fill pipe (or rocker cover), where fumes just go out into the atmosphere.

 

The PCV valve in the rocker cover or pushrod valley needs to connect to a source of engine vacuum to suck crankcase fumes out of the crankcase, through the PCV valve and into the intake of the engine. This source is usually a 3/8" port on or below the carburetor (including the intake manifold).

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