I’ve got this thing built, new valve seals, springs, pushrods, 1.6 roller tip rockers, first tpi intake, long tube headers, amped cooling system (also all new), brand new sparkplugs wires and distributor (the whole thing)

My question is right now the mechanical timing is at 10 degrees, somewhere in there, but adjusting it would be an absolute massive pain cause there’s 0 space with the new intake and I didn’t upgrade to a small cap like a dummy. Engine is running like a super powered dream, never heard an engine sound this mean in person and it revs great, I haven’t tested WOT but I’ve reved it up with no pinging. I’ve yet to drive it cause I’m rebuilding the suspension so this is all neutral running. What do I risk with mechanical advance being that high?

 

12' or higher i thought was pushing it; 10' should be ok? imo

 

yeah I had to confirm it was at 10, but okay sweet cause every post I saw said like 8 max and even that small of adjustment would be a ton of work

 

I'm sorry but I'm having trouble understanding why you can't set the timing at 6-8 degrees? You're saying that the position of the distributor won't allow you to rotate it so that you can get closer than 10 degrees, and there's some mechanical interference with the distributor cap caused by the shape of the cap and connectors, limiting rotation?

You know you can move that cap and distributor body relative to the TPI intake, and as along as you mark where your rotor position is relative to the body itself, you can lift and change the position of the rotor to match the new rotated position of the distributor body right? To do this, just set the engine rotation on the damper to the TDC 0 degree mark, then mark the position of the rotor on the outer edge of the metal distributor body beneath it. Lift the distributor up out of the manifold, rotate it to where the cap clears well, then just place the distributor back in making sure to align that mark on the rotor and the body. Now your distributor is same 0 degrees as it was when you had the interference position, but it should be free to move with more clearance... Then set base timing at 6-8 degrees like you want. The #1 plug wire is wherever you put it in the new position rotated a bit away from normal.

You'll have to rotate the oil pump drive when the distributor is out of the engine so that the distributor shaft engages with the oil pump drive correctly on reinstall, but you normally have to do that a bit anyway every time you reinstall the distributor.

Will that not work for you?

 

in short the 10° I got is after doing pretty much that exact thing, which is why I asked if it was good enough. With enough fiddling I’m sure I could probably get it to 8 or even 6 but it’s going to be a ton of extra work that if unnecessary I rather avoid

 

Roughly how many degrees of rotation can you get with the distributor between interference points on each end?

 

Maybe post a photo also if you want.

 

roughly 1-2 clockwise only

 

 

I run mine at 12. No problem. Others will correct me if I'm wrong but the ignition controller will max at 36 degrees and the knock sensor will retard the timing if you get knocks.

 

You wouldn't be able to rotate that distributor 180 degrees from there? The wires that would have to reach are the tach and the battery lead, but the 4-wire is from the base itself so no problem there.... Just a thought.

 

thats exactly what I needed to hear, thank you, I just wanted to make sure I wasn’t gonna break my engine.

 

where it’s at is from a lot of experimenting and that’s the best spot I could get it in, the main interference is actually at the base of the intake which I can’t picture

 

Pinging should not occur while revving the engine. Pinging or detonation is much more common under loads.

Checking the Knock sensor is easy, simply tap a wrench or something metal against the cylinder head or block. Don't bang the block but a good tap should make the idle change a bit as it retards the timing a bit. If nothing happens then you might have a bad Knock sensor. I had a bad knock sensor and it is like loosing four cylinders out of the eight you started with. It really hurt the performance as it kept the timing pulled back.

 

On an L98, knock retard is disabled below 2 mph and below 650 rpm (auto trans) or 850 rpm (manual trans), so knock sensor/knock retard functionality cannot be tested in this manner (at idle rpm while stationary). If you're able to accomplish this with the car in motion, and detect an rpm drop or verify any timing change with a timing light, more power to you.

4 degrees of global spark advance offset may be tolerable, but not all spark advance curves are created equal. There can be significant spark advance variation year to year. Later cars tend to have more advance. What year is the car? What is the memcal's broadcast code or scan id?

If tuning, the initial advance can be set anywhere it is desired, presuming you compensate for it in the tune. In my own car, I have the initial advance set to 0 degrees, since that is where my distributor sits squarely. Easy to see if the distributor has slipped and easy to set the timing visually without a timing light. Note: my distributor gear dot is aligned with the rotor tip. If the distributor gear dot is aligned opposite to the tip, it will be rotated by 1/2 a tooth, so ymmv.

Set the distributor however you want it, or however it will fit best, check the timing, and correct the initial advance in the tune to fit the actual mechanical advance. Living with an offset or being forced to run 6 degrees advance is so primitive.

 

I data logged mine at like 14 when it was stock and had no retard issues. Car seemed to like anything between 8 and 12 though. Now that it is tuned base is at 8 in the bin however.

 

its 1988, I don’t have a tuner but it is chipped (heck if I know what the chip is tuned like though, it’s some random hypertek). Also that’s really useful info thanks a lot

 

Yeah I’m still on the original knock sensor, I need to redrain the block anyway so I’ll order a new one just in case for that. Running 100% water while I do leak testing and such