Timing question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Army_Dude · 01-26-2006, 09:01 PM

85 Silverado, 305 stock...

When I first bought it I noticed it dieseled on the first trip of the morning. it also had a pop every now and again coming from the right tailpipe. That's the best way to describe it. Not really a backfire. Just a pop. Well today it dieseled twice (after the usual first time in the morning).

I went out to check the timing tonight and it was way off. My sticker says 4 degrees BTDC and it was set on about 8 degrees BTDC. I disconnected the vacumn line, plugged it, and checked it. Then I set it where it should be . I rechecked it and unplugged and reconnected the vacumn hose.

The thing is now, it just seems to run weird. At idle if I rev the engine, it pops and rumbles (unlike before). It is very possible that it is now normal and I just never knew cause it had been set so far off since I owned it. I'm gonna drive it tomorrow like it is and see how it goes. What do you guys think?

82c10 · 01-26-2006, 09:06 PM

in my truck with the old motor it was a 350 told it was a 305, i had to replace the distributor cap, and didnt have a timing light handy so i drive it with the timing at like 16 degrees initial, and it would flat out haul, then i set it at specs and it didn't run as good, i say set it around 8-10 degrees

Army_Dude · 01-27-2006, 08:47 AM

C'mon, all you guys running stock 305's and noone has any experience/suggestions/wisdom on the timing?

87 STEPPER · 01-27-2006, 09:08 AM

I cant tell ya anything about your timing issue but its a pretty simple system.

If the cap/rotor ign. module wires & plugs are in good condition then theres not much else in the sys that it could be.

Set the base timing to what the under hood placard states and see how it runs. if its still doing funny things check the mechanical timing ie bring #1 up to TDC compression stroke and ck the balancer with the timing pointer if its good.

Then.......................

The poping could be from your EGR valve being off schedule check everything in that system ie vaccum lines and wiring and connector to the solenoid ck the mount bolts on the valve do a suction ck to see if the diaphram has a leak and it moves.

It may be a good idea to ck all vaccum lines on the eng.

Good luck

01-26-2006, 09:06 PM	#2
82c10 needin' money Join Date: May 2005 Location: Chickasha, Oklahoma Posts: 1,106	Re: Timing question in my truck with the old motor it was a 350 told it was a 305, i had to replace the distributor cap, and didnt have a timing light handy so i drive it with the timing at like 16 degrees initial, and it would flat out haul, then i set it at specs and it didn't run as good, i say set it around 8-10 degrees __________________ *SWB Stands for Short Wide Bed*

01-27-2006, 08:47 AM	#3
Army_Dude Registered User Join Date: Dec 2005 Location: Fayetteville, NC Posts: 187	Re: Timing question C'mon, all you guys running stock 305's and noone has any experience/suggestions/wisdom on the timing?

01-27-2006, 09:08 AM	#4
87 STEPPER STILL PLAYS WITH TRUX Join Date: Nov 2002 Location: Melbourne, Fla. Posts: 2,764	Re: Timing question I cant tell ya anything about your timing issue but its a pretty simple system. If the cap/rotor ign. module wires & plugs are in good condition then theres not much else in the sys that it could be. Set the base timing to what the under hood placard states and see how it runs. if its still doing funny things check the mechanical timing ie bring #1 up to TDC compression stroke and ck the balancer with the timing pointer if its good. Then....................... The poping could be from your EGR valve being off schedule check everything in that system ie vaccum lines and wiring and connector to the solenoid ck the mount bolts on the valve do a suction ck to see if the diaphram has a leak and it moves. It may be a good idea to ck all vaccum lines on the eng. Good luck __________________ ~~Bruce~~ MY 87 STEPPER MY 99 2D/WD TAHOE

01-26-2006, 09:01 PM	#1
Army_Dude Registered User Join Date: Dec 2005 Location: Fayetteville, NC Posts: 187	Timing question 85 Silverado, 305 stock... When I first bought it I noticed it dieseled on the first trip of the morning. it also had a pop every now and again coming from the right tailpipe. That's the best way to describe it. Not really a backfire. Just a pop. Well today it dieseled twice (after the usual first time in the morning). I went out to check the timing tonight and it was way off. My sticker says 4 degrees BTDC and it was set on about 8 degrees BTDC. I disconnected the vacumn line, plugged it, and checked it. Then I set it where it should be . I rechecked it and unplugged and reconnected the vacumn hose. The thing is now, it just seems to run weird. At idle if I rev the engine, it pops and rumbles (unlike before). It is very possible that it is now normal and I just never knew cause it had been set so far off since I owned it. I'm gonna drive it tomorrow like it is and see how it goes. What do you guys think?



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