blue thunder

I'd like to know if you have tried to make it run right by rotating the distributor and timing it by ear. I may be a simplton, but I have inadvertently bumped the advance knob on my fancy timing light more than once (before setting timing) and been alarmed at the result, before relizing what happened. I was ready to tear the motor down one time before the "your a dumb ass" light came on.

BT

jaf302

make sure no mouse house in the exhaust, pesky critters!could be in far enough to hold a exhaust valve open. I always had to plug my flat bottom every year with plumbers test plugs. Just a thought Paul

kaamacat

Ok here is the latest. (And Jaf302, long time ago had something similar on a car, the cat converter broke apart hosing up the exhaust)......but back to my story.

Today pulled off the timing cover and all. With the marks inwards, (and they are aligned perfectly, no slack at all) the harmonic IS AT TDC 0*. BUT, the distributor is at about #6. So, does this just sound like the gear has just twisted on the distributor shaft. (pin broke or something like that).

Right?.........Imbarrased to confirm this but. With both marks facing inwards and the HB at TDC, I should be firing #1 (correct)?

jaf302

with the marks aligned I think #6 is fireing and #1 is in overlap If the valve cover is off rock the crank back and forth with a breaker bar and #1 valves should move. the exhaust when you turn clockwise and the intake counter clockwise

rjcardinal

If you stab the distributor and put it on the number one cylinder with both timing marks aligned inward as close as they can get together you will be 180 degrees out.

Dont ask how I know this.

Rotate the engine 360 degrees from where it is now and you should be on # 1 cylinder. Both timing marks will be at the top of their gears. If it lines up on number one you havent jumped timing.

Good luck,

Ron

kaamacat

Guess I should have confirmed this first. Its a 1986 BBC. (the typical high perf GM that KAAMA used).

What are the positions for the timing marks? (cam/top crank/top, cam/down crank up)..? My older auto manuals had them as closest which would have been cam/down and crank/up).


Bob

Tinkerer

With the BBC the dots should be aligned between the center of both gears.( next to each other ) With the harmonic balancer at 0 degrees the two marks should line up and the rotor in the distributer should be pointing directly at #1 wire post. Was the dist. loose? Is there any chance it got turned? If no to both of these questions than pull the dist. and check the gear for badly worn or missing teeth. GOOD LUCK

kaamacat

Tinkerboater. Going to re-check the distributor this morning. But, as the engine sits now, it is exactly as you had said. Camshaft is down, Crank is up making them closest to each other, Balancer (if I just place it on) is at TDC, but the distributor is at #6.

.........thanks for all the help.........(so far )

rjcardinal

Be careful. I believe your timing is correct with the distributor pointing at # 6 with the marks aligned. I timed an engine like Tinker says and it was 180 off. To be sure you need to rotate the crank 360 degrees untill both timing marks are at the top of the gears to get the distributor to point to number one.

Think about it. If what Tinker says is correct your engine is 180 degrees off on distributor timing. I doubt your engine is 180 degrees off like it sits now because you said it will run somewhat. At 180 degrees off it will do nothing but backfire ocasionally while cranking.

Ron

blue thunder

If the roll pin on the dist gear let go, it wouldn't run and you wouldn't get oil pressure. Stupid question... but did you make sure the rotor isn't broke and spinning on the dist. shaft? Also make sure it is clean. A greasy hand spinning the rotor around to get the dist to drop will result in your symtoms.
If it isn't the rotor, and the dist gear checks out ok, I would try re-timing the engine and firing it up to see what you get.
From my memory, when the marks on the gears are aligned you are at tdc on the #1 cylinder, starting the power stroke.

BT