Thread: 88 350/383 TBI/HEI timing issues, Help please.

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I put together a 383 from a 1988 Chevy 1 ton truck and reinstalled the engine. Here is the problem I am seeing, I looked at the emmissions sticker on the rad support and it says to set timing at 0°.

I did this and I used my dial-back timing light to see what the exact timing is and it seems that the distrib is only giving about 8-9° of advance. This can not be correct, the sticker at 0 can not be planning the total advance to be only 8 degrees.

This is a TBI engine, and there are no sensors hooked up anymore on the block or heads. There is an old knock senser in the block that keeps the water from coming out. There is also the vacuum hoses, I have them all run aside from the one that at one time went to a air pump, we have never seen this air pump.

The wiring harness has been basterdized long before this truck came into our hands, and I never looked at the timing before to see what it was at. I also bumped the initial timing to 10 and revved the engine and it went to about 18 total. Im wondering 2 things, is the computer looking for a knock sensor, and without it...maybe the CPU refuses to give any advance? 2nd thought on the issue is, what if I toss an old 70's HEI in this thing and set the timing as usual on an older 350? I have a wiring diagram, so tomorow I may go looking for the wire that belonged on the knock sensor. Could this dizzy be just to dang old and worn to work properly? Im considering just setting it at 15 degrees so it has 23 total...a sort of compromise.

Oh, I did find this description online, not sure if this will make any sense to you:

1. Install timing light on no.1 spark plug wire. Disconnect 1-wire (tan with black stripe) timing bypass connector at distributor.

2. Place automatic tranny in park and manual in "N". Check and adjust ignition timming with engine at normal operating temperature. Reconnect by-pass connector. Clear trouble code by removing ECM power fuse for 10 seconds.

TBI Engines: 5.0 / 5.7 Liter Engines, TDC (0) @Idle - Auto/Manual
7.4 Liter Engines 4 Degrees @ Idle - Auto/Manual

So, is there something that this timming by-pass is doing, and what is it bypassing? Is ther something that will not let me see the full advance without the engine being loaded? Maybe it only adds advance if the truck is in gear and pulling a load? Maybe the knock sensor should have had something to do with this stuff and the CPU is running in a fail-safe mode?

Never mind, I found it. As it appears, this wire is not to be disconnected at the dizzy, rather it is just outside of the fuse block, in the engine compartment. You find the tan/black wire just under the fuse block, ihere is a nice disconnect there. I did this, put a new fuel injector in, put guages in to show mw whats up, and Im happy. I set timing at 0 with the tan/black wire unpluged, removed the fuse for the ECM, and pluged the tan/black wire in, waited over 30 seconds to put the ECM fuse in and now its great. I have 25 lb hot idle for oil pressure, and 185 water temperature. All things in life are good. Oh, 55 lbs oil pressure at cruise RPM's.