kaamacat

Will find out tomorrow. Wanted to pull the plugs today so I didnt stress the starter. (and that in-itself is a project). I also want to watch the total valve train when the engine is moving.

After thinking about it again. The balancer would only reach the 0* mark two times overall. Once for #1 and the other for #6. If I am aligned with both marks inward (cam @ 0600 and crank @ 1200) #1 would be on the compression stroke and ready to fire. The next time the crank its turned 360*, #6 would be at the compression stroke and ready to fire, but I would expect the cam gear mark to be @ 12:00 and the crank @r 12:00.

My distributor is @ #6ish.

I hope I get a good laugh out of this when its over. Its almost comical. (unless i'm still at it a month from now).

Tinkerer

YOU GUYS NEED TO READ THE BOOK -- I stand by my earlier post. I have two engines running just fine with the set up I said.

rjcardinal

There, you just figured it out for yourself. The engine appears to be timed correctly. I have built several engines and on the first few I installed the cam with both marks closest together then stabbed the distributor aligned to # 1. It never failed the timing was 180 degrees off. Solved the problem by rewiring the distributor once. Restabbed a couple of other times. Finally I would check for compression. Thats when I realised what was happening. Since then I still install the cam with the marks aligned closest together but then rotate the crank 360 degrees to get #1 on the compression stroke. When this is done the marks are both at 12 o'clock. Never have any timing issues anymore.

Another clue that the timing is not 180 degrees out is the fact that the engine runs at all. I can tell you from experience that at 180 degrees out the engine will not run at all.

I hate to say it but if you have ruled out any electronic or mechanical timing advance malfunction I would look at the cam lobes and lifters. I had a 454 that did the same thing once and it was a cam lobe. This was a high milage engine in a Chevelle.

Good luck and keep us posted.

Ron

rjcardinal

Tinker,

Just checked the Mercruiser service manual. It says to install the cam with the marks closest together. It makes no mention that this should give you #1 cylinder at TDC compression stroke. In another section about installing the distributor it makes no mention of where the timing marks on the gears should be. It just says to check for #1 to be at TDC and on compression stroke by rocking the rockers to be sure that both valves are closed and the lifter is on the base circle.

GM designed this so it would be easier to install the cam without being one tooth off. But this is about valve timing not ignition timing.

If your theory is correct then Kamma's engine has jumped time by 180 degrees. He has already stated that the engine runs somewhat and even claims to just have a mis at 2000 rpm. This would hardly be possible with an engine miss timed by 180 degrees.

Respectfully,

Ron

GregP

Dare I jump into the fray ??

Put your finger in the #1 plug hole and crank over the engine. When it pushes your finder out the #1 piston is on compression going up to TDC. Continue turning slightly until balancer is at TDC and the crank is on the "correct" revolution for compression/firing.

At this time the BBC timing marks should be directly across from each other at their closest point of approach, give or take 2-4 degrees in case your cam wasn't installed "straight up".

Align the distributor rotor a few degrees CCW of the #1 plug wire, to account for the fact that the rotor will turn a little when you slip in in from the "twist" in the gear, and drop it intp place.

It should actually start at 0 degrees advance (as long as it's out of gear so there is no load) and then allow you to set timing. If not you can twist the distributor "around" 10 degrees in the opposite direction of the rotor rotation and then lock it down.

Now to the miss. Also check that all the valves are actually moving as it cranks over. I've wiped off a cam lobe before, and the motor would run but had a very difficult to trace miss in it.

Good Luck - Greg


I guess I'll add that the BBC will actually run with about 15-20 degrees of timing error, as when I broke my crank in two it still ran, without any miss, even though I could turn the front two cylinders about 20 degrees before the back two would start to move.

excaleagle42

kcat,
after your engine is running again by the method which greg p. explained, and you set your timing with a light ; if you still have a miss, you can pull one wire at a time from the distributor cap while running and missing and when you find the culprit, it will stop missing if its a stuck valve, bad valve, worn lobe.(unless there is more than one)
just to add to the turmoil, some cams are ground with advance in them, the comp cams i use have 4*ground in them even when they are dot to dot.
down where your springs are under the rotor there are stop posts that limit the mechanical advance in some distibutors. i've seen them break off and over advance.
one last bit of trivia, i know of a small block that ran 180* out for a few minutes. then the air cleaner blew off from a backfire and hit my friend in the head causing him to get stiches.

kaamacat

Thanks. I may get up to it tonight, and watch the valve train and the distributor while cranking.

This (again) is almost stupid. Im thinking how many times I've rebuilt a motor, and you just do this stuff without looking, put in the distributor....and sha-zam, "ITS ALIVE"..........then one day comes and you forget your name.

But would you guys agree (and not even checking for compression strike with plug removed, or watching the valves). If the marks are inwards at 6pm/12am, AND the balancer is facing TDC, the engine "can" ONLY be at the #1 position, and the distibutor "should" also be in #1-land.

Bob "My-Brain-Hurts" KAAMACAT

Tinkerer

You can install the distributer in any position that you want. All that matters is that the rotor is pointed at the post that you intend to use as #1 plug wire. With the cam marks both pointed up you will have to point the rotor at #6 because that will be the first one to fire in your rotation order. You made #6 into #1.

blue thunder

Yes... I agree with that. 6 oclock on both dots will give you 180 degrees off number 1 firing. 6 oclock and 12 oclock will give you TDC on number 1, starting power stroke. Did you clean the greasy hand print off the rotor yet?

BT

rjcardinal

Let us know how it comes out. I am interested to know. I will stand by my statements.

For the record I believe that your engine is timed correctly as it sits now if you have not changed anything. That is being with timing marks aligned at the 6 oclock (cam) and 12 oclock (crank) and the distributor pointing at # 6 wire post. If you were to rotate the crank 360 degrees the timing marks will both be at 12 oclock and the distributor will be at the #1 wire post. I believe this to be correct timing on a BBC.

I have been wrong before but I just went through this last January.

Good luck and post what you find.

Ron