Timing ? on TPI to Carb swap....
Timing ? on TPI to Carb swap....
I just finished converting my 85 TPI camaro and replaced it with new intake and carb. Now I'm trying to set timing but I dont see any marking on the balancer or timing tab, is that normal on TPI's?
Joined: Mar 2000
Posts: 43,187
Likes: 42
From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Re: Timing ? on TPI to Carb swap....
First, you need to replace the distributor as well. The TPI system advances the ignition timing electronically via the computer, while a non-computer carb needs a vacuum/mechanical advance distributor to do the job.
The timing tab should be at 12 o'clock, behind and below the water pump. When you bring the #1 cylinder up to top dead center, the timing mark on the damper will be at 12 o'clock.
When you get the proper distributor and find the timing mark/tab, set the initial timing (at idle, vacuum advance disconnected) between 8-12 degrees before top dead center. That should give you proper idle and power after rehooking up the vacuum advance.
The timing tab should be at 12 o'clock, behind and below the water pump. When you bring the #1 cylinder up to top dead center, the timing mark on the damper will be at 12 o'clock.
When you get the proper distributor and find the timing mark/tab, set the initial timing (at idle, vacuum advance disconnected) between 8-12 degrees before top dead center. That should give you proper idle and power after rehooking up the vacuum advance.
Re: Timing ? on TPI to Carb swap....
Thanks, I already replaced the dist. with non comp HEI, I just could really set my timing didnt know where the timing tab was. So is there timing marks labeled on the balance to get me to 8-12 degree TDC?
Joined: Mar 2000
Posts: 43,187
Likes: 42
From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Well, you didn't mention changing the distributor.
The damper just has a line (slot) on the edge. The timing tab has the degree markings. If you do a
, you'll see what the timing tab looks like.
What I would typically do is find the timing mark, clean it, then fill it with white-out (or paint it white). That makes it easier to see with the timing light.
The damper just has a line (slot) on the edge. The timing tab has the degree markings. If you do a
, you'll see what the timing tab looks like.What I would typically do is find the timing mark, clean it, then fill it with white-out (or paint it white). That makes it easier to see with the timing light.
Member

Joined: Oct 2002
Posts: 162
Likes: 3
From: MA
Car: 1994 firebird
Engine: 427ci lsx bowtie block
Transmission: tremec t56 micro edged gears
Axle/Gears: Strange dana 60 with racing spool
Re: Timing ? on TPI to Carb swap....
I did this swap because the previous owner of the car hacked up the harness and sold the tpi, i had a tpi motor but no harness, ecm etc. So i finished converting the car to carb by removing the efi harness and swapping in a mechanical fuel pump and fuel sending unit out of an 84 camaro. Now i set my initial timing to 10 degrees like suggested in this thread. I read in other forums that you want a total advance timing of 36 degrees at over 3k rpm some say 3500rpm for iron l98 "slow burn" heads and 32 degrees for fast burn vortec type heads. I have the stock l98 heads. So I have a timing light that can be set to 36 degrees and then line up the timing mark on the balancer to 0 on the timing notch. The car seems to run awesome no lag off idel and have loads of power but timing at idle is off the timing notches so it must be 14 to 16 degrees btdc. Did I do this wrong? Yes I did this with the vacuum advance hose off and plugged. I put the hose back on AFTER setting full advance timing AND checking timing at idle.
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