Max Timing for L69 with Bolt on Mods & Comp Cam

oldsmobile joe

Royal Smart Person
Nov 12, 2015
1,544
113
mpls
Question, what does it mean when it says "throttle is on the high step of the idle cam" .. do I have to rev the engine to a certain rpm? If so what is it?
This is referring to the fast idle cam and is used to set cold idle. It is located on right side of th we carb and is interwoven with the choke. Begin with a warmed up engine. Turn off the engine. Open the throttle fully while closing the choke blade. With the choke blade closed, release the throttle. This will put you on the high step of the cam. Start the engine, leave it in park. Yes the engine will be high. Now you can set your fast(cold) idle speed. Using a long skinny screwdriver, you can turn the adjuster till your speed is 2200 rpm. Access to this screw is from the front of the carb. Clockwise to increase, counterclockwise to decrease. Hope this helps.
 

pontiac guy

Master Mechanic
Oct 28, 2016
465
93
Royse City, TX
I used to run my 84 TA with the LG4 at 10 degrees base timing. The 305 never really woke up that well TBH until I stroked it. I always felt the factory computer was the bottle neck. There used to be a PROM you could get. That should help. My max timing never got passed 28 degrees. You need a looser converter with a high flow cat and a gear. 3.42 minimum. I was 3.23 and it just wasn't enough.

I will be doing the 3.42 when I put it back together. You could go to 3.73 if you have tall tires but beyond that just isn't comfy on the street IMO
 

Neill

Not-quite-so-new-guy
Supporting Member
Mar 7, 2014
114
28
Roanoke ,VA.
Hello Everyone, so I finally got the G Body running but I must say I was REALLY DISAPPOINTED on the performance before and after the bolt on parts as I have read the difference is night and day, & yes I know its a 305 but it just seems like the is some lag off the line & lacks any sort of pep, I feel like i' driving a 4 cyl 1.5 Civic.

So I am thinking maybe I did not set the timing right or it needs more timing?

Currently, the timing is set to 6 degrees BTDC which is what the Haynes book says the OE timing is.

How I set the timing, basically plugged every vacuum line & turned on the car. I set the timing to zero using the timing gun and moving the distributor, then I set the timing gun to 6 degrees and moves the distributor until it read zero on the harmonic balancer & called it good.

Currently, the car idles at about 500 RPM after it warms up but it struggles to stay on at idle, it seems like its a little happier at 650 - 700ish RPM. When I bought the car and before any of the bolt-ons the idle screw was set all the way back as in zero idle adjustment was needed, but i dont remember the rpm's it idled at.

I thought about moving the idle screw in to get the RPM's happier at idle but again my gut tells me it needs more timing or i didn't set the timing correctly.

So my question is, was my timing procedure correct, if not where did I go wrong? Whats the right procedure?

Second, should I put more timing into it (10 12 degrees BTDC) or is there something else going on that is hindering performance?

Spec's:

305 L69, with all the Smog Components.

I believe previous owner rebuilt it in the late 90's & bored it out like .020" over.
Hardland Sharp Rockers (was not able to tell the ratio as they are not marked but i think they are 1.5)
I am sure he upgraded the springs as well but not sure.

My mods:
Edelbrock TES Headers (w/ Y pipe) , Stock Exhaust System
Edelbrock 3701 Intake
Comp Cam & Lifters Xtreme Energy 262H (Lift .462/.469, Duration 262/270, P/N CL12-238-2)
Comp Cam Double Roller Timing Chain (Set at zero)
NGK UR4 Plugs with 8mm Taylor Wires
 

Neill

Not-quite-so-new-guy
Supporting Member
Mar 7, 2014
114
28
Roanoke ,VA.
Hello Everyone, so I finally got the G Body running but I must say I was REALLY DISAPPOINTED on the performance before and after the bolt on parts as I have read the difference is night and day, & yes I know its a 305 but it just seems like the is some lag off the line & lacks any sort of pep, I feel like i' driving a 4 cyl 1.5 Civic.

So I am thinking maybe I did not set the timing right or it needs more timing?

Currently, the timing is set to 6 degrees BTDC which is what the Haynes book says the OE timing is.

How I set the timing, basically plugged every vacuum line & turned on the car. I set the timing to zero using the timing gun and moving the distributor, then I set the timing gun to 6 degrees and moves the distributor until it read zero on the harmonic balancer & called it good.

Currently, the car idles at about 500 RPM after it warms up but it struggles to stay on at idle, it seems like its a little happier at 650 - 700ish RPM. When I bought the car and before any of the bolt-ons the idle screw was set all the way back as in zero idle adjustment was needed, but i dont remember the rpm's it idled at.

I thought about moving the idle screw in to get the RPM's happier at idle but again my gut tells me it needs more timing or i didn't set the timing correctly.

So my question is, was my timing procedure correct, if not where did I go wrong? Whats the right procedure?

Second, should I put more timing into it (10 12 degrees BTDC) or is there something else going on that is hindering performance?

Spec's:

305 L69, with all the Smog Components.

I believe previous owner rebuilt it in the late 90's & bored it out like .020" over.
Hardland Sharp Rockers (was not able to tell the ratio as they are not marked but i think they are 1.5)
I am sure he upgraded the springs as well but not sure.

My mods:
Edelbrock TES Headers (w/ Y pipe) , Stock Exhaust System
Edelbrock 3701 Intake
Comp Cam & Lifters Xtreme Energy 262H (Lift .462/.469, Duration 262/270, P/N CL12-238-2)
Comp Cam Double Roller Timing Chain (Set at zero)
NGK UR4 Plugs with 8mm Taylor Wires
Don't use a timing light, just a vacuum gauge at idle. Adjust the distributor for highest reading, , and back it down if you notice pinging under load. The only time I use a timing light is to check the advance weight's rate of advance in the distributor. Sounds like your timing may be retarded, so using the vacuum gauge might wake your engine up.
 
Last edited:

1983calais

Master Mechanic
Feb 26, 2015
275
63
Tiffin, OH
Because that cam is a pig off idle in a 350 at 9:1. So lower compression and less cubes won't be an improvement. Especially with a stock converter.
We will agree to disagree. Like I said, I have used This exact cam and it had power everywhere. Have you used one? I actually plan on getting another one of these cams because it worked so great. actually comp cams recommended this cam for low and mid power.
 

Supa.Slo.SS

Not-quite-so-new-guy
Thread starter
Aug 7, 2020
21
3
CA
3.42 should be enough for that 305 and that cam. Definitely sounds like timing. Are you running cats too?
Yes, I am running a CAT. OEM exhaust which is a Y pipe from the headers into the CAT then splits down the line with 2 muffler & exit pipes.
 
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