timing problems
Thread Starter
Racer
Joined: Jul 2002
Posts: 250
Likes: 0
From: Victoria BC
timing problems
Ive been trying to sort out the poor performance issues on a carborated 84. Running a holley 4150(600cfm), MSD pro billet dist.(blue stop sushing, one light/one heavy silver advance springs), crane hi-6, new wires,cap, rotor and plugs. Just rebuilt the carb to slight improvement. heads slightly polished.
Heres the problem: when i set the initial timing to 40degrees it idles just nice and smooth, when i draw it back to 10degrees it runs poorly, hesitates on acceleration(big hesitation at 3000rpm, then the wheels spinn) this engine also is cammed out with a ~268H profile. Any one know the vacum it should run at?
I drilled a hole in the old cap at the #1 spot and it seems to align just right. kinda hard but i can see the whiteout painted rotor when its spinning.
Has the timing chain slipped? I'd rather try and figure that one out before taking the cover off the front.
thanks
Heres the problem: when i set the initial timing to 40degrees it idles just nice and smooth, when i draw it back to 10degrees it runs poorly, hesitates on acceleration(big hesitation at 3000rpm, then the wheels spinn) this engine also is cammed out with a ~268H profile. Any one know the vacum it should run at?
I drilled a hole in the old cap at the #1 spot and it seems to align just right. kinda hard but i can see the whiteout painted rotor when its spinning.
Has the timing chain slipped? I'd rather try and figure that one out before taking the cover off the front.
thanks
Drifting
Joined: Sep 2003
Posts: 1,325
Likes: 6
From: FRANKLIN GA
More likley the outer ring on the harmonic balancer has slipped and it's giving you a false reading. Check your TDC against the mark on your balancer to see if they are both the same. I had a ring slip on mine and almost pulled my hair out trying to figure it out. Almost the same symptoms your having.
Safety Car
Joined: Feb 1999
Posts: 3,630
Likes: 14
From: Fountain Hills AZ
I agree with Eddie. Either your balancer has slipped or perhaps you aren't getting accurate readings for some other reason. You are taking them with the vacuum advance disconected and the idle set as low as possible, right? The blue bushing allows 21º centrifugal so 15º-17º initial should get you where you need to be. IMO, the best and easiest method is to just set total timing. If you want more or less initial, change springs and/or bushings to get you there.
Thread Starter
Racer
Joined: Jul 2002
Posts: 250
Likes: 0
From: Victoria BC
Ok the vacum advance was not in effect as this model of distributer doesnt use it.
To set total advance should i just bring it up to say 2500 rpm and set it at 15/17+21 for 36-38degrees total?
Ive been leary of setting it high ,where it idles high and smooth, as im not sure if could start breaking things. Could it?
To set total advance should i just bring it up to say 2500 rpm and set it at 15/17+21 for 36-38degrees total?
Ive been leary of setting it high ,where it idles high and smooth, as im not sure if could start breaking things. Could it?
Safety Car
Joined: Feb 1999
Posts: 3,630
Likes: 14
From: Fountain Hills AZ
Originally Posted by shane99
To set total advance should i just bring it up to say 2500 rpm and set it at 15/17+21 for 36-38degrees total?
Thread Starter
Racer
Joined: Jul 2002
Posts: 250
Likes: 0
From: Victoria BC
Thanks vetteroddder Ill give that a try.
Eddie, Im pretty sure its ligned up on #1 to give accurate TDC as the hole in dist. showed that its ligning up alright. Ill double check it though.
PS What would i check to see if the balancer ring has spun?
Eddie, Im pretty sure its ligned up on #1 to give accurate TDC as the hole in dist. showed that its ligning up alright. Ill double check it though.
PS What would i check to see if the balancer ring has spun?
Last edited by shane99; Jan 3, 2005 at 11:06 AM.
