Having some problems tuning my L-72 427. Motor runs great but cannot get the timing mark into the timing tab.Motor runs best with the balancer mark(flash) at 12 o'clock instead of on the tab at 2 o'clock and thus cannot get a acurate time on the motor. If I try and moive the mark onto the tab the motor runs like crap!!ANyone know what I skrewed up?!!HELP!! Thanks

ALbert

Stupid question. Do you have the timing light on #1 wire?

Stupid question. Do you have the timing light on #1 wire?
yes..firing order is correct as well

Possibly a tooth off when dropping in the distributor?

this might be a stupid question but did you check to see if the mark on the balancer is on 0 with the #1 spark plug out check to see if the piston is at T.D.C.. i put together an engine once and after starting it up and running it. the balancer moved!! everytime i checked the timming i would start to adjust timming and it would run like crap. i bought a new balancer and i was able to time with the light no problem. the rubber gasket in the old balancer was old and cracked so the center hub moved after running the engine

Not sure about the one tooth off could be..would that move the mark back into range??

checked the balancer..keyway and mark are lined up.

keep them coming there is something I missed!!.

ALbert

Could be a slipped balancer putting your timing mark off. I'd start by locating true tdc. If the mark on the balancer doesn't agree you'll need a new balancer. If the mark does match tdc, set total and let initial be whatever it will be until you recurve the distributor.

I believe the balancer keyway and mark are NOT supposed to line up. I think this is where the problem is.

Does the distributor seem to be in an odd position where it does run good, compared to your other BBC? If so I'm guessing one tooth off. If I understand correctly, as long as the rotor points to number 1 on the cap (not 180 off though) you could turn the distributor all the way around and get it to run correctly. I'm no expert, but have had my share of problems!!!

The distributor being 1 tooth, or ten teeth off, would not make the tiiming mark wrong. If the engine is running good, then the distributor is in right. Sounds like something is wrong with the damper, timing tab, or possibly your timing light. Is it a dial back type light ? If so and you are using it with an MSD system, chances are that is the problem.

Pull the number one plug, stick a long screwdriver in the cylinder and turn the engine over by hand until it is as close to TDC as you can get it. See where your timing mark is.

Albert, did you install the cam and crank sprocket with both marks or 0s pointing toward each other?
Jody

Also is your vacuum advance hose still hooked up?
Jody

i went out to the garage and looked at my generation VI 454 and the timming mark and the keyway line up perfectly. and it has a brand new balancer on it (never been run yet) so the keyway the timming mark and the timming tab all line up on it. the only motors i can think of that don't line up like that are some of those long water pump engine's that have the timming tab up in the middle behind the water pump. if your balancer came from an engine like that and you put a timming tab on it off to the side you would have this kind of problem

You are correct, I was wrong, the big block is 0 to the crank key. The SMALL block is 10 off of the key. I had these backwards. Sorry for the confusion.

Yeah, hopefully you have the vaccum can hooked up. Else the light could be wrong. If the can wasn't hooked up, use a piston stop and roll the motor back and forth to get true TDC. Mark TDC. Therein may lie the error.

Distributor being a "tooth" off does nothing but physically locate the distributor base dfferently.It has no bearing on #1 timing.

If it all checks out and it still runs best way advanced, then I would use UDHarold's quick and dirty cam timing check and see where the heck the cam is installed.

Yeah, hopefully you have the vaccum can hooked up. Else the light could be wrong. If the can wasn't hooked up, use a piston stop and roll the motor back and forth to get true TDC. Mark TDC. Therein may lie the error.

Distributor being a "tooth" off does nothing but physically locate the distributor base dfferently.It has no bearing on #1 timing.

If it all checks out and it still runs best way advanced, then I would use UDHarold's quick and dirty cam timing check and see where the heck the cam is installed.
Ahhh, Makes sense, the timing mark will not change:clonk: Just where the disributor sits. I'll sit back and read now!!!:waving: Good luck Albert

It will only change where the #1 hole on the cap sticks up, or where the vacuum can locates, if that makes sense.

Yeah, hopefully you have the vaccum can hooked up. Else the light could be wrong. If the can wasn't hooked up, use a piston stop and roll the motor back and forth to get true TDC. Mark TDC. Therein may lie the error.

Distributor being a "tooth" off does nothing but physically locate the distributor base dfferently.It has no bearing on #1 timing.

If it all checks out and it still runs best way advanced, then I would use UDHarold's quick and dirty cam timing check and see where the heck the cam is installed.

OK Gene I suck at the search feature clue me in:D..at TDC mark is in the center of the balancer..just the way it was when we assembled the motor. Timing was checked with the vacumn pod disconnected..trying to set base timing of 4 degrees. I have a dialback light although it is a inexpensive one, but works on my other motor very well. Here are the cam specs if that may have any bearing on this mess:Solid roller

Lift .575 intake .597 exhaust
Advertised duration 296 In 300 Exh
Duration @.050 256 intake 264 exhaust
LSA 112
Cam was intalled straight up

how about dwell?..Points?..any bearing on timing there??Distributor was redone by Jerry Macniesh..curevd as well for a L-78 motor almost the same as a L-72 but different..maybe?? Also, very little vacumn at idle until throttle plates are opened a little..Normal?? Holley 4346 carb.
All in all the motor runs pretty good but without any marks to time it I have no idea of where the timing really is. Thanks for all your replies.

ALbert

Do you mean at the top of the balancer, like straight up. It sounds like you may have a later model balancer to me.

Dwell changes the timing, but timing doesn't change the dwell. That is why you set the dwell and then check the timing.

Your gonna need around 20° base and maybe 38° total to run correctly with that big a camshaft maybe more if you run a automatic trans.

The way you have it set now the total timing is going to be way high.
speak to your distributor guy about this.