I need someone to check me here. This is my first time, so be gentle.

Starting with Lars' timing paper, I took off the cap and rotor and replaced the springs with shiny new gold ones. Put everything back together, hooked up my handy Snap-on timing light and disconnected and plugged the vacuum advance. I set the light to 36, ran the engine up to around 2500 and adjusted the distributor until the timing mark zeroed out. At 36 degrees, I had some dieseling when I killed the motor, so I backed it off to 33 and everything seems to run well.

I haven't driven the car yet, but everything sounds pretty good. I'm sure my mixture screws aren't dialed in. I set them pretty close and have around 15-16 inches of vacuum. Idle is around 950 in park, 750 or so in gear. It's a Holley rebuilt Q-jet that's never been tuned (and given what I've heard about them, I'm not even sure it CAN be properly) but as far as I know, none of this should affect timing.

The only thing I don't understand is it was my understanding that initial timing should be something like 12-16? At idle, I'm not seeing a lot of difference than total. It's a little lower and more erratic, but nothing close to what I was expecting. Am I doing or setting something wrong? Or am I just using the light incorrectly? It's a digital Snap-On light, and as I said, it's my first time using it, so anythings possible.

Any-hoo, good, bad or ugly?

EDIT: I was doing all this without any help, so I couldn't check the timing while it was in gear, if that makes any difference.

EDIT2: Whoops! I'm using a non-computer HEI and carb.

 

Try lowering your idle, and set the timing to 36 total with vacuum plugged. The deseling is your idle too high.

 

I really don't like dropping the idle much lower than about 700 when it's in gear. Much lower than that and it runs a lot lopier than I like. I may play with it and try bumping the timing to 34 or 35 and see if it'll run without dieseling. I've had this problem in the past and fixed it by bumping the timing back down. This is just the first time I've actually had a light to stick on it (also the first time I actually had any idea of what I was really doing, but we're not gonna go there. The jury's still out on that one.)

Looks like my passenger valve cover is dropping oil straight onto the exhaust, so there's something else to tear apart this weekend.

 

let us know what you do

 

A couple of thoughts:

First, your "dieseling," or run-on, is caused by idle speed too high. When you advance your timing, the idle speed will also increase. Drop your idle speed to the lowest reliable idle speed.

Second, a used HEI is notorious for having a sticky advance system. Check the advance system out and make sure it's operating smoothly and freely with no binding or stickiness. If the weights are moving freely, the advance system has to be working, and you will get at least a 20-degree difference between initial and total timing, providing your springs aren't so soft that the total timing is coming in at idle. If it is, you need to run some stiffer springs.

Lars

 

You indicated that you SET the rpm at 2500 and then adjusted for 36 degrees advance. You first should have found MAX timing by raising rpm until it maxed out. THEN set your timing at 36 degrees (vacuum advance disconnected). I'm thinking you never reached max advance before you reset it. If your max number comes in after 3000 rpm, you need to put softer springs on the flyweights.

 

If I am understanding what you did, you installed the springs and then set the timing at 2500. Timing was not all in by then. Lars, you recommend setting the timing without any springs right?? That way you can easily set the all-in timing to 36, then when you put the springs in you can goose it to 3500 or 3600 and make sure everything is coming in by that point.


So... thinking this through... if you were at 36 @ 2500, and the timing didn't back off a whole lot at idle, then you probably had way too much advance dialed in to start. If you had run it up to 3500 rpm... maybe you would have had 40+ total?

 

I set it at around 2500 because that's was my understanding from Lars's paper:

Admittedly, I didn't rev it up much higher than that, so that could be a problem.

As for removing the springs, I thought it said to only do that on a points style distributor, nothing about HEI. I replaced the stock springs with the gold springs from a Mr. Gasket 928 kit.

You'll have to forgive me. Last night was my first time so much as removing the cap and I'm scared to death of breaking something I can't fix. How do I go about checking the advance system?

 

Lars paper indicates 36 degrees when advance is "all in", meaning maxed out. So, with vacuum line pulled from the dist. [and plugged off] you rev the engine while watching the timing mark with your light. When the mark quits advancing (becomes steady), you have reached your maximum advance point. Record engine RPM's at this point, and if your distibutor is loosened enough for adjustment, move it to set 36 degrees. You have now set your "all in" timing and you can lock down your distributor. If the engine RPM's at that max point were around 2500-2700, it's probably fine there. If higher than 2700, you need to put on weaker springs to bring in the max advance sooner; if lower than 2500, you need to put on stronger springs to bring in the max advance later. Once that is set, put your vacuum advance line back on and check to make sure that is working correctly (smoothly changes as you "jack" the throttle and total at idle reads around 50 degrees + or -).

 

Lars paper indicates 36 degrees when advance is "all in", meaning maxed out. So, with vacuum line pulled from the dist. [and plugged off] you rev the engine while watching the timing mark with your light. When the mark quits advancing (becomes steady), you have reached your maximum advance point. Record engine RPM's at this point, and if your distibutor is loosened enough for adjustment, move it to set 36 degrees. You have now set your "all in" timing and you can lock down your distributor. If the engine RPM's at that max point were around 2500-2700, it's probably fine there. If higher than 2700, you need to put on weaker springs to bring in the max advance sooner; if lower than 2500, you need to put on stronger springs to bring in the max advance later. Once that is set, put your vacuum advance line back on and check to make sure that is working correctly (smoothly changes as you "jack" the throttle).

 

[QUOTE=PRNDL;1559616686Lars, you recommend setting the timing without any springs right?? That way you can easily set the all-in timing to 36, then when you put the springs in you can goose it to 3500 or 3600 and make sure everything is coming in by that point.


NOT on an HEI distributor, which he said in the first post he is using. Leave the springs in if it is HEI!!!

 

BTW, while I'm at it does red dust under the rotor mean anything?

 

Check the fit of the weights to the pins. It's usually just surface rust from the weights thrown off. Clean it up.(Under the rotor).

 

For a novice it would be better if you go slow. Set the initial advance at 12 to 16 degrees BTDC with the vacuum advance unpluged. Set the idle speed at about 850 RPM with the transmission in neutral or park. This is an initial setting not the final one. This will get the engine to settle down and be nice while you continue your tuning.

Now that you have the initial set it is time to make a map of the mechanicial advance. Map the advance up to 3000 RPM. If it is under 36 degrees BTDC it is too slow and not enough. If you have a spring kit and have checked the advance mechanism for porper function, install the medium springs in place of the stock springs. Now run the test again.

At 3000 RPM you should have more advance. If you get to 3000 RPM and still don't have 36 degrees TOTAL advance there could be a couple reasons. One is that the springs could still be too stiff. You can try one (1) light spring in place of one of the medium springs. Yes, you can mix and match the springs. Run the test again and see what happens.

The other possibility is that the mechanicial advance mechanism may not give enough advance to get to 36 degrees TOTAL advance. Remember, initial + mechanicial + TOTAL. If the mechanicial advance mechanism will only give you 18 degrees advance you will need to go outside the 12 to 16 degree initial setting to reach 36 degrees TOTAL. You will have to set the initial at 18 degrees. This is one good reason to make sure the mechanicial advance mechanism is operating porperly. It may be robbing you of advance.

Now that you have the total timing set up you can connect the vacuum advance. You can use manifold or ported, whatever your engine likes best. Lars likes to run manifold but some engines like ported more. It depends on the level of engine modifications. The last thing you do is reset the idle speed at the carburetor.

Someone who knows their way around this kind of stuff would probably skip some of this, but it may help some of the beginers to understand it a little better.

BigBlockk

Later.....

 

Lars.....and any others that may know. I set up my 72 smallblock according to the method described above. Best running stock SB I have ever had........ I am about finished with a total rebuild with a Comp 268H camshaft in my 74 Big Block.

Does this timing method work with the 454 ?

 

Yes

 

How do I check the total timing....also on the timing light I picked up it shows hooking the clamps to the battery terminals n since I can't where do I connect them.....Thanx...Jerrylee///

 

You can hook it to the hot wire coming out of the back of the alternator.

BigBlockk

Later.....

 

You check total timeing after you hook up the vacum line, base + mech adv + vac adv dont go past 52 on total. if you get it set to 36 and hook up vacume line and it goes past 52 then change the vacum can to one that provides 16 degrees advance.

the (ar 23) vacume can will provide 16 degrees

 

Were does the second clamp hook up to....Thanx.....Jerrylee///