Distributor installation problem

[deadbeat]

Make sure if you do get it where you can turn it, that after turning it you rev the engine to over 1k rpms to reload the reading.

 

[454cid]

How are you determining TDC?

 

[homeslice]

Make sure if you do get it where you can turn it, that after turning it you rev the engine to over 1k rpms to reload the reading.

Yep, I know about the rpm needing to be about 1200.

 

[homeslice]

How are you determining TDC?

pulling #1 spark plug, turning engine over until I feel air blowing out the spark plug hole. This should tell me I'm on compression stroke. I then roll the harmonic balancer over until the TDC scribed line matches up with the timing pointer on the timing cover.

 

[454cid]

pulling #1 spark plug, turning engine over until I feel air blowing out the spark plug hole. This should tell me I'm on compression stroke. I then roll the harmonic balancer over until the TDC scribed line matches up with the timing pointer on the timing cover.

Maybe the outer ring has slipped on the inner ring... assuming that's how it's made. I've hear that suggested a lot, for older engines.

 

[east302]

Just in case something got missed, here’s the GM procedure...

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[delta_p]

out of curiosity what does your truck do at -4 or -26? Mines shows -9deg (or maybe it was -5) last i looked with the scanner, but it ran good and got good mileage so i just left it. My truck is a '96 scsb though.

 

[homeslice]

Just in case something got missed, here’s the GM procedure...

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Thank you. I will try this and report results.

 

[homeslice]

out of curiosity what does your truck do at -4 or -26? Mines shows -9deg (or maybe it was -5) last i looked with the scanner, but it ran good and got good mileage so i just left it. My truck is a '96 scsb though.

Mine is a 96 scsb as well. Its ran fine, as I was not aware of camshaft offset retard until I did the 0411 swap and BB tune. Once I logged data and sent back to BB, they told me all looks good; but distributor is not installed correctly. I then data logged camshaft offset using EFI Live thru the Autocal; which showed it at -26 degrees offset. I was able to adjust that down to -4 degrees.

Since then (a few weeks ago), I've been on a mission to get it to 0 degrees offset.

Edit - I would add that I did have the new summit dist cap crap out within 6 months and leave truck stranded. From the time I first put the new engine in the truck, it had this weird thing it did on some startups. Its like it would prematurely fire off, which would cause the engine to jolt on startup. Hard to explain I guess, but since I learned about the camshaft offset; I've wondered if the wrong dist setting caused the dist cap to go out.

 

[delta_p]

ok, thanks for reply.

BTW i have always wondered about this for the stock PCM setup since the 96 service manual lists typical range for cam retard in the Engine 3 Scantool Data list engine at operating temp, idling in closed loop as 0, +/-20 degs. Those are the Tech 2 data lists 1 through 3.

Since I have a set of service manual for 3 yrs, 96-98 I looked and the '98 is the only one that list the tight range in the scantool data list, and is also the only one that mentions setting at 0, and there is a the test procedure for determining intermittent setting of P1345. Quoted " When the engine speed is raised to 2000 RPM the camshaft retard offset should not vary more than two degrees." "if the distributor is one tooth off in either the advanced or retard positions the vehicle may run but 0 degrees camshaft retard offset will not be obtained." If 0 degrees cannot be obtained during this procedure refer to diagnostic aids."

None of that complexity in the 96 or 97 service manual but I think lot of extra sensors, tightening up emissions ect. added to the OBDII in '98 that i can tell from the service manuals.