timing/ignition question

speedracer · April 03, 2006, 01:55:25 AM

Hey guys, I just installed a MSD box 6A (4 wire module dist module) the engine starts fine but misses alittle and sounds like its coughing up thru the carb, any advice?? I know the shop set the timing different because of the proformance stuff done to the engine and they also have the vacuum advice plugged, said because of the cam that they installed, just wondering when I installed the MSD box do I need to adjust the timing again? Or anything else??
Thanks, johnny

Dirk35 · April 03, 2006, 04:05:04 PM

I used the same MSD box on my 35.

It depends on what configuration you used to set it up.

I used the MSD Coil, and the MSD Distributor also, and on my set-up:

The Ignition only supplies spark when the distributor tells it to (the contacts on the purple to green wire are broken), It really does nothing to do but send power to your coil as I understand it.

What kind of Distrubutor are you running, and is it mechanical or vacuum advance?

EMSjunkie · April 03, 2006, 04:50:01 PM

I still am having trouble with the "plugged" vacuum advance. :? :?

unless you plan on running WOT all the time, IMO, you need vacuum advance. cut and dried. doesn't matter what kinda "goodies" the shop put in the motor, once again, IMO, you need vacuum advance to make it streetable. when you don't have vacuum advance, the motor is gonna run hot. at least that has been my experience.

http://www.chevytalk.org/threads/showflat.php?Cat=0&Board=UBB64&Number=1105501&Searchpage=1&Main=1105264&Words=%26quot%3Bcamaros.net%26quot%3B&topic=&Search=true#Post1105501

read this article, hopefully it will help clear things up.

Vance

unklian · April 03, 2006, 05:01:29 PM

If the vacuum advance is hooked up correctly,
it will help a street motor,no question.

speedracer · April 03, 2006, 05:55:45 PM

Quote from: "Dirk35"I used the same MSD box on my 35.

It depends on what configuration you used to set it up.

I used the MSD Coil, and the MSD Distributor also, and on my set-up:

The Ignition only supplies spark when the distributor tells it to (the contacts on the purple to green wire are broken), It really does nothing to do but send power to your coil as I understand it.

What kind of Distrubutor are you running, and is it mechanical or vacuum advance?

Yea I installed the MSD proformance kit (coil, rotor etc.) inside the hei GM distributor, I didn't know ya don't need the module inside so that was a waste. So I hooked up the 2 wires inside the dist and followed the diagram in the MSD box instructions. Everything same to hook up easy enough but it still has a miss in the engine. I called tech support this afternoon and they said I probably need to adjust my 750 holley (vac adv) to give it more fuel. Said with the box its going to have alot more spark requiring more fuel. So did that and still has a miss in it and coughs back thru the carb under a load. Then he said to check the ground and make sure no wires at all are close to the hot wire from the MSD box. So I'll do that later this evening and maybe in the dark to check for any archs. And the distributor is a vacuum advance but its plugged off. I asked the MSD tech guy that and he said its OK to do that because of the high lift cam that was installed and also because theres not enough vacuum made by the engine to hook up a vacuum line to it. I've asked different people about the pro and cons of plugging that thing off and I get a hundred different reasons why to and to why not. This car is a daily driver but I plan on racing it sometime soon. I'm installing a 4 core aluminum radiator Friday hopefully that'll cool her down alittle, right now in town she runs around 200 degrees and I'm scared of cracking those expensive aluminum heads

speedracer · April 03, 2006, 05:58:38 PM

Quote from: "EMSjunkie"I still am having trouble with the "plugged" vacuum advance. :? :?

unless you plan on running WOT all the time, IMO, you need vacuum advance. cut and dried. doesn't matter what kinda "goodies" the shop put in the motor, once again, IMO, you need vacuum advance to make it streetable. when you don't have vacuum advance, the motor is gonna run hot. at least that has been my experience.

http://www.chevytalk.org/threads/showflat.php?Cat=0&Board=UBB64&Number=1105501&Searchpage=1&Main=1105264&Words=%26quot%3Bcamaros.net%26quot%3B&topic=&Search=true#Post1105501

read this article, hopefully it will help clear things up.

Vance

Vance read above what I told the guy before you. Thanks!

enjenjo · April 03, 2006, 07:56:28 PM

Don't want to sound like a broken record, but the reason it's running 200 degrees, is you don't have a vacuum advance.

unklian · April 03, 2006, 08:15:53 PM

200 isn't hot enough to do any damage.
With a decent rad cap you can run 240 without boiling over.

Go back to ground zero.

Check the firing order.
Check that all the spark plugs are tight.
Check the initail advance with a timing light,
then the centrifugal advance,then the vacuum advance.

The vacuum advance helps with idle quality,
and drivability during part throttle cruise.Also
improves gas milage at low speeds.

speedracer · April 03, 2006, 08:51:45 PM

Quote from: "unklian"200 isn't hot enough to do any damage.
With a decent rad cap you can run 240 without boiling over.

Go back to ground zero.

Check the firing order.
Check that all the spark plugs are tight.
Check the initail advance with a timing light,
then the centrifugal advance,then the vacuum advance.

The vacuum advance helps with idle quality,
and drivability during part throttle cruise.Also
improves gas milage at low speeds.

ROGER

kb426 · April 03, 2006, 09:06:04 PM

Check the total advance at 2000, 3000, 4000 and above. Maybe you're getting 40 degrees when you need 32. I agree with UNKLIAN, check everything from the beginning. Without beer and with a young guy with good eyesite.

unklian · April 03, 2006, 10:22:27 PM

Then make sure there are no vacuum leaks,
the carb is bolted tight to the manifold,

and double check you are getting full throttle
when the pedal is on the floor.(never hurts to check)

Any idea on exactly what cam they installed ?

EMSjunkie · April 04, 2006, 12:09:59 AM

I ran a 327 with 194/150 heads and a Q-jet carb, that had a .513 lift 312* duration cam,on the street, with vacuum advance, and never had a lick of trouble. had enough vacuum to run the advance just fine.

I am a firm believer in the K.I.S.S. principal................keep it simple stuipd :!:

just tryin' to help Johnny. :?

Vance

speedracer · April 04, 2006, 02:30:48 AM

Quote from: "EMSjunkie"I ran a 327 with 194/150 heads and a Q-jet carb, that had a .513 lift 312* duration cam,on the street, with vacuum advance, and never had a lick of trouble. had enough vacuum to run the advance just fine.

I am a firm believer in the K.I.S.S. principal................keep it simple stuipd :!:

just tryin' to help Johnny. :?

Vance

Oh hey I appreciate all yalls help and input and ya know I'm going to hook up the vacuum advance hopefully tomorrow, I know he has the timing advanced big time so I'll use a lite a check and set it maybe 5 degrees advance or so and see how she runs. I agree totally on having a vacuum line hooked up on the distributor its just that he's the mechanic and I'm no where near him in that field but I think to satisfy myself I'll do some experimenting with it, I don't think I could screw something up by doing it?? Right?
Anyway yall keep me informed on input and I'll do the same. I'll see if I can find the spec's on the cam. Thanks again, johnny

speedracer · April 04, 2006, 02:31:05 AM

Quote from: "EMSjunkie"I ran a 327 with 194/150 heads and a Q-jet carb, that had a .513 lift 312* duration cam,on the street, with vacuum advance, and never had a lick of trouble. had enough vacuum to run the advance just fine.

I am a firm believer in the K.I.S.S. principal................keep it simple stuipd :!:

just tryin' to help Johnny. :?

Vance

Oh hey I appreciate all yalls help and input and ya know I'm going to hook up the vacuum advance hopefully tomorrow, I know he has the timing advanced big time so I'll use a lite a check and set it maybe 5 degrees advance or so and see how she runs. I agree totally on having a vacuum line hooked up on the distributor its just that he's the mechanic and I'm no where near him in that field but I think to satisfy myself I'll do some experimenting with it, I don't think I could screw something up by doing it?? Right?
Anyway yall keep me informed on input and I'll do the same. I'll see if I can find the spec's on the cam. Thanks again, johnny

EMSjunkie · April 04, 2006, 10:07:54 AM

good luck Johnny, ya can't screw up too much, whats the worst that could happen?....................melt a piston, throw a rod,.... make it run better.

I would venture to guess that by hooking up the vacuum advance,it will make a world of difference.

if it doesn't.................I'll buy the first 2 rounds. :b-d: :b-d:

please keep us posted.

Vance