Hot Rod Forum : Hotrodders Bulletin Board

Hot Rod Forum : Hotrodders Bulletin Board (http://www.hotrodders.com/forum/)
-   Engine (http://www.hotrodders.com/forum/engine/)
-   -   Setting Ignition Timing? (http://www.hotrodders.com/forum/setting-ignition-timing-189105.html)

StockR 12-14-2010 02:43 PM

Setting Ignition Timing?
 
Hey guys, this is my first post so cut me a little slack. :)

I recently just got a 1969 El Camino with a SB 350 and a 3 speed automatic.


I am new to the car world and was just wondering how to set the ignition timing with a timing light???

The 350 has headers, high rise intake manifold, Holley 600 and mild cam. Not sure the exact size of the cam though.

I'm also sorry if this question has been asked 100 times before, but why not start a fresh one right?

[IMG]http://i284.photobucket.com/albums/l...ino007/350.jpg[/IMG]

andythedrummer 12-14-2010 04:10 PM

engine timing
 
Hi, The best hay to set your timing is,#1 put your lite back in your toolbox,grab your vacume gage connect it to manifold for main vac.with your engine up to temp,ajust your dist,to try and get 18 inch of vac, this is the only way I know if you dont have any specs for the cam. If it sounds like its pinging back it off just a little

bubbahotep 12-14-2010 09:35 PM

I have to disagree with the vacuum gage use, some cams wont get 18hg at idle so I dont see how that can be used as a means to set timing

There are hundreds of posts so just search but in general you just need to get the #1 piston (drivers side front) to TDC and mark your balancer or crank pulley for 0' TDC.

If the engine is already in use you might already have timing marks. Connect the light to the #1 spark wire and point the light at the crank pulley. You might see timing marks already there and somewhat accurate

kc8oye 12-15-2010 01:17 AM

step one. .get a bottle of white out, or other bright colored paint.

step two, find the mark on the dampner ring.

step three.. fill the groove with the marking compound.. wipe off excess.. this makes seeing the timing mark so much easier.

step 4, disconnect vacuum advance and plug.

5) clean the timing tab off.. figure out which mark is the ZERO mark. .makes life easier.

6) start the engine.. point the gun at the balancer and timing tab.. look for the line.

look at the timing mark that the line lines up with..

the strobing effect of the flashing timing gun will make the mark appear to sit still, even tho it's spinning on the crank.

set your 'base' timing for about 10 degrees.. this is a good safe place to start.

then test drive.. if it doesn't ping.. add more timing.. repeat until it starts pinging under heavy throttle.. once you reach that point.. back it off a couple of degrees and lock it down.


if you have an 'advance' gun that you can dial in the timing, then you can set your timing by 'total' timing which tends to be more accurate..
figure out your timing you want.. say.. 38 degrees.. set the gun for 38 degrees...

have a parter rev the engine to 3000 or higher.. whatever it takes for the timing to stop advancing.. 3000 is usually enough.
adjust the timing so that the mark on the damper aligns with the 'zero' mark on the tab (since the gun is already set for 38)

454C10 12-15-2010 07:12 AM

and read this.

http://www.corvette-restoration.com/.../Timing101.pdf

has some good timing numbers to go by.

Frisco 12-15-2010 07:32 AM

The 1969 El Camino had points ignition originally.

If you still have the points ignition you need to set the point gap first. After starting the engine and getting it to 'normal' operating temps, you will need to check and set the dwell with a dwell meter. The adjustment is made using a small allen wrench thru the sliding window in the distributor cap. I don't recall the specs for the dwell. You will have to get the specs for the dwell. Check the automotive section in the library.

After setting the point gap and the dwell, hook up the timing light and set the timing as posted above. Should be in the 10-12 degree range at idle in NEUTRAL for the stock engine.

If you have a non-computer controlled GM HEI, setting the timing will be the same except there are no points to adjust and no dwell to adjust.

Always check/adjust the timing with the vacuum advance dis-connected and plugged. Re-connect AFTER checking/setting the timing. This will be the same with points or HEI ignition. Use full manifold vacuum for the advance canister. When re-connecting the vacuum advance hose the idle will increase. Re-adjust the idle after re-connecting the vacuum hose. The idle should be about 650-750 RPM in DRIVE if an automatic and in NEUTRAL if a standard shift.

Frisco 12-15-2010 08:40 AM

I just checked my manual. The point gap is .019 and the dwell is 28-32 degrees. Spark plug gap is .035. The original factory specs for the timing varies with the engine used. Stock 1969 Chevy El Camino with the 350 runs from 4 degrees BTDC to 8 degrees BTDC. This was slightly lower for California cars with the smog pumps.

My experience was that running 10-12 degrees BTDC gave the best overall performance for the stock 1969 350 cu in Chevy smallblock with a four barrel carb and a 4 speed trans.

StockR 12-16-2010 02:43 PM

Hei
 
Thanks guys for the help, I forgot to add that the distributor is a HEI (non-points) distributor.

So the timing gun that I have is an Actron Digital CP7529.

There are several options...

1. Measuring Engine RPM

2. Setting Initial Timing

3. Checking & Measuring Centrifugal Advance

4. Measuring Vacuum Advance.

So what is the purpose and difference for those`?

Appreciate the help, guys.

Custom10 12-16-2010 04:51 PM

The digital device you have allows what some may consider a simplified way to calculate the 3 different aspects of setting up your timing. The up down arrows on the gun are there to allow you to zero the timing tab marker in relation to the damper 0 mark when setting/checking for base, mechanical adv and vacuum advance values.

These are the three amigo's of engine timing in your case.

Essentially there is no difference in what the gun display is telling you that you could not figure out with a simple inductive light without a dial back pot other than you don't need a timing tape that reads up to 60 deg BTDC with a dial back or in this case your digital dial back unit.

Before you go to far it is a real good idea to check that your timing tab/marker aligns with the balancer/damper tab at TDC, as bubba stated I also would highly recommend that you do this first and foremost:

http://www.crankshaftcoalition.com/w...op_dead_center

Did i mention I love El Camino's? :thumbup:

1ownerT 12-16-2010 04:57 PM

Are you sure it is an HEI?
It sure looks like there is a coil wire in addition to the plug wires, HEI will have the coil in the cap.

Custom10 12-16-2010 05:01 PM

Good eye T

kc8oye 12-17-2010 01:25 AM

those are not HEI wires. those are definately points-style. not to say it doesnt have a pertronix or some such in it..

StockR 12-17-2010 04:34 PM

Yeah, you guys were right... it's points. I don't know what I was thinking.

Anyways, Frisco, The block is from a 1980 Chevy truck I believe. So with the specs you listed for the original stock 69 block do those also pertain to the 1980 block as well? I can look for the casting numbers if you want?

Frisco 12-18-2010 07:50 AM

Quote:

Originally Posted by StockR
Yeah, you guys were right... it's points. I don't know what I was thinking.

Anyways, Frisco, The block is from a 1980 Chevy truck I believe. So with the specs you listed for the original stock 69 block do those also pertain to the 1980 block as well?

Yes, the factory specs would still apply. Check my post #7 above. Setting the timing somewhat higher (within a reasonable amount) than the factory specs for a stock small block Chevy engine will help overall performance.

SDLuck 12-18-2010 03:04 PM

What timing cover and balancer do you have? They are different for different years abd miss matching them is a common problem.Did you mak sure tdc is correct?


All times are GMT -6. The time now is 06:31 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.