385sbc timing question
 

i've got a 385sbc its all forged with eagle bottom end dart heads lunati voo doo cam installed straight up.the top end consists of an edelbrock air gap intake 770 street avenger carb and msd hei billet distributor. my question is this when i go to time the car it doesnt want to idle under about50 degrees and when i do back the timing down to around 34-36 (with the vacumm advance unhooked) it starts to run poorly and backfires through the carb wehn you hit the throttle.any ideas on what it could be.the motor has a aftermarket fluid balancer and cloyes timing chain cover with aftermarket pointer.think the timing marks could be off? could i be one terminal too far clockwise on the distributor cap with my #1 plug wire?is there any easy way to double check to make sure the timing marks on the balancer are right?
thanks for any help!!!!!

Verify TDC on the Balancer and timing tab are actually located at TDC first.

i took the valve cover off and made sure that both valves were closed on number one cylinder when the timing tab and harmonic balancer registered zero.i dont think thats a real accurate way to tell tough is it?is there any other way to do a more accurate job on locating exact tdc?

It is a little more in depth. I recommend removal of all spark plugs for making it easier to turn over by hand. But, you have to take out #1 spark plug and create a stop of some sort, just so the engine will not rotate completely. I have used a Philips screwdriver before stuck through the spark plug hole. This must remain at the same location and depth for both marks. Do not use the starter. Gently rotate clockwise by hand until it stops against your stop. Now make a mark on the balancer at the pointer. You can place masking tape on the balancer and mark on this instead. Next, you must rotate it counter clockwise until it stops against your stop. This will be almost 1 complete revolution. Now, you will make an additional mark on the balancer. TDC is the point halfway between the two marks. Verify that this lines up with the machined mark on the balancer. Remove your stop before doing anything else, so that you don't forget.

Bill M

without taking off the head and placing a dial indicator on it with a degree wheel... ..this is the only way to get close other than what Bill said above.
continue as you did by taking off valve cover and getting both valves closed...check your piston in #1 spark plug hole and make sure the piston is up..its possible to have both valves closed and the piston NOT be at the top...this is called the OVER LAP....
Once you verify this and the harmonic balancer is on "o" degrees drop in the distributer with the rotor cap off. make sure the rotor button clip is pointed toward the #1 piston......lock down your cap ...then contiue to roll your harmonic balancer around to what ever degree you want the final timing mark set on ..examle: 36 degrees.


if your harmonic balancer was installed properly at "TDC"..This process will be dead on target and fire up No problems...


note: if this is a high performance motor there will be some issues on installing the cam on the marks straight up and down..normal low performance street motors this is a ok method..

Good luck.

Brian

i've got the distibutor pointing at #1 when the balancer reads tdc.so if i rotate the balancer to36 degrees and lock down the distributor that should work? i'll give it a try i've worked on quite a few sbc and this is the first time i've run into this sort of problem.
as for the cam its got a 4 degree advance ground into it and it stated in the instructions to install it straight up.this an 11.1 street motor will this hurt my hp numbers?
thaks seth

Just an FYI I have a " dead stop " I made from using a " non fouler " spark plug adapter and taping it for a 3/8 - 16 thread and then using a corresponding bolt in it

Yes you can actually static time your engine by setting the harmonic to the degree you want to fire, you can confirm this with a VOM thru your pickup.
we had a similar problem with idle on a ford we were working on, seems the springs on vac advance were a bit loose and when hooked up the timing would jump one cylinder, it seems you have the same problem but in reverse.

ok just make sure you take off the valve cover and make sure both valves are closed and the piston is at the top....just shine a flashlight in there and you can see yher piston at the top of you can get down there to it..if not a coat hanger or anything like that will do........make sure the distributer is dropped in pointing toward #1...then roll harmonic on around to your desired degree mark.. hit the igintion...you should be able to lock the distributer down right where you dropped it in.....


by reading your 1st post it sounded to me that you propbaly did aLL THAT I mentioned but you did not roll the balancer on around to the timing desired..WHICH WOULD RESULT IN LOW TIMING...WHICH WILL ACXT JUST LIKE YOU WERE DESCRIBING IT WOULD....
OR YOU COULD HAVE HAD BOTH VALVES CLOSED BUT THE PISTON BE AT THE BOTTOM OF CYLINDER...( A COMMON MISTAKE)..

if you do this properly it will work 100% guaranteed...

if you have any problems setting up the timing..give me a call and i will walk you thru it..864-607-6511.....if i do not answwer leave a message and i will call you back, when i am in the shop my cell phone doesn't pick up incoming calls..

BRIAN


let us know how it turned out.


Brian

YOU SHOULD BE OK BEING A STREET MOTOR...
I DID IT THAT WAY OVER 25 YEARS AGO WHEN I WAS REPLACING HYDRAULIC CAMS IN MY 70 CAMARO I DROVE TO HIGH SCHOOL..


BRIAN

chev78 wrote: I have used the method described about setting the distributor for start up. I set the balancer to 20 degrees and then set the distributor in and then after it is running adjust the timing with the light. But I have verified where TDC is at with a dial indicator before the head was installed.
From the post above, it sounds like he was using a light and couldn't get it to run correctly at 36 degrees, so if you manually set it at 20-35 degrees it would still run poorly unless it is a bad timing light. It could be the timing light (I would try a different light), not on #1 plug wire (not likely), TDC marks are incorrect for the balancer and pointer (I always verify this), and the camshaft timing to be incorrect (I have found the 0 mark on the crank gear to be stamped incorrectly and the dowel pin hole to be off. A guy had installed his cam "straight up", but it would not run the ET's expected. He had me degree his camshaft, and I found that it was 12 degrees advanced. The timing set was in error)
As bjuice stated if the timing set is correct, setting the cam in straight up in a street car you will not tell much of a difference in hp. In degreeing the camshaft, most of the time you are verifying that the pieces weren't built on a "hang over" Monday or on a "get out of here" Friday.
Other things that can cause the rought idle and popping through the carburator could be valves adjusted too tight or the carburator itself. I have found so many carburator problems corrected themselves by just verifying the timing, plugs, and wires.
It sounds like it is sluggish from the timing.

Just some information from my misfortunes,
Bill M

i'll give it a try and let you all know.
thanks for all the advice!!!!

thanks for all the advice guys this site is second to none when it comes to technical advice.i got the car timed (36) degrees and running smooth.i really have no explanation why it was reading in the 50 and 60,s before.the only thing i changed was isolating the 1 wire from the rest when i attached the pickup for the light it might have been picking up some pulses from the number 3 wire even though i'm running taylor 8.8mm wires.i also had the leads that go to the battery for the light hooked to my dodge diesel battery which runs dual 12 volts because the battery for my nova is in the trunk.do you think the dual batteries affected the light i wouldnt think it would cause its still 12 volts.when i timed it tonight i ran the positive lead down to the starter and the ground to the frame and it worked fine.anyways it sounds great i cant wait to get it on the road and strip!!!!

thanks again to all who responded you guys are all a bunch of stand up guys!!!!

Glad that you got it running and timed.

I think that what happened is that the timing light was not grounded to the car that you were timing. That caused a differential voltage on the light.


Bill