Max Timing for L69 with Bolt on Mods & Comp Cam

Supa.Slo.SS

Not-quite-so-new-guy
Aug 7, 2020
20
3
CA
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
 

oldsmobile joe

Royal Smart Person
Nov 12, 2015
1,585
113
mpls
Are you running the factory computer? If so, there is a specific procedure for setting timing which involves disconnecting a wire which puts the timing to base timing. If not done correctly, your timing will actually be retarded, causing poor performance.
 
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Supa.Slo.SS

Not-quite-so-new-guy
Thread starter
Aug 7, 2020
20
3
CA
What is your your max timing currently? If you rev the motor what is the highest timing you see with the timing light?

I would get a vacuum gauge. Adjust your idle timing for highest vacuum and then check your max timing.

My best performance timing is currently startup at 10 degrees BTDC and then it's locked in at 40 degrees from idle to the rev limiter, Hooker Competition headers and true 2.5" dual exhaust, no smog, or computer.

I started at 36 degrees max and worked my way up to 40 making sure I had no detonation.

I've got a L69 bored 30 over, Edelbrock performer cam, heads have been ported and shaved

Timing makes all the difference!

I have no clue what my max timing is. I will see if I can check it tonight. At what RPM would I hold to check?

I am unfamiliar with vacuums. Would I set the gauge at a specific line or at each line? This stock motor has a crazy amount of vacuum lines.
 

Supa.Slo.SS

Not-quite-so-new-guy
Thread starter
Aug 7, 2020
20
3
CA
Are you running the factory computer? If so, there is a specific procedure for setting timing which involves disconnecting a wire which puts the timing to base timing. If not done correctly, your timing will actually be retarded, causing poor performance.
Yes, factory computer. I was told the same thing, something about unplugging one of the plugs from the distributor but 1) I could never find the proper procedure and 2) If I remember correctly, I have 3 plugs that go to the distributor one of which is the tach so I tried unplugging the other 2 separately but then the car wouldn’t start, so figured that wasn’t the right procedure. Unless I have to start the car then unplug while it’s running?
 

oldsmobile joe

Royal Smart Person
Nov 12, 2015
1,585
113
mpls
I hope someone with this engine responds. I'm going off of memory, its been 32 years since i worked on one. There is a one wire connector that sticks out of the wiring loom on the right rear corner of the engine, behind the egr valve that you disconnect. This keeps the computer from changing it on you. Then you can set your base timing.
Also, your base idle is too low, 600-650 rpms is what your looking for.
If you can find a copy, picture of the emission sticker that was attached the the fan shroud, it will have your timing and idle specs you need as well as the order in which you are to perform them.
 
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Clone TIE Pilot

Comic Book Super Hero
Aug 14, 2011
2,540
113
Galaxy far far away
Stock idle speed in closed loop is 600 rpm in drive, 700 with A/C on, and 2,200 cold with choke closed. The idle speed must be set in drive. You can bump the base timing to 8 to 10 degrees. The plug you disconnect to disable timing advance is the big 4 wire plug by the side of the distributor.
 

Supa.Slo.SS

Not-quite-so-new-guy
Thread starter
Aug 7, 2020
20
3
CA
Stock idle speed in closed loop is 600 rpm in drive, 700 with A/C on, and 2,200 cold with choke closed. The idle speed must be set in drive. You can bump the base timing to 8 to 10 degrees. The plug you disconnect to disable timing advance is the big 4 wire plug by the side of the distributor.
So is the car suppose to be on then disconnect? Because I remember now that’s the plug they told me to disconnect but when I did the car would not start unless it was plugged in. To verify, this 4 wire plug is the one that come out of the bottom portion of the distributor and connects to itself basically up on top with all the other plugs. Am I doing something wrong?
 
Oct 14, 2008
6,926
113
Melville,Saskatchewan
Hopefully the sbc Comp timing set is more accurate than the Olds version.
As said the tan wire needs to be disconnected to set the timing.
 

Supa.Slo.SS

Not-quite-so-new-guy
Thread starter
Aug 7, 2020
20
3
CA
UPDATE:

So for those following with the same issues/question, a member from a different forum pointed out if you still have your OEM Emissions Sticker it actually gives you the procedure. If you don't have it, go to OPGI.com and search decal emissions for your car & you can see the procedure.

I realized my mistake, the plug(s) I was disconnecting and messing with were the wrong ones. I should have paid more attention but on the driver side of the distributor NONE of those wires that plug into the distributor on that side are 4 wires, they are 3 wire or less.

The wires/plug I needed to disconnect was more on the passenger side of the distributor. As many had said, its a 4 wire plug that comes out of the bottom portion of the distributor with a black plug (maybe 2.5" long) that that has all 4 pins in a straight row & that plugs into the wiring harness.

Below is the picture and the stated process.

Can't say I understand the verbiage entirely, so if someone can translate those 4 steps in lamest terms that would help.

Thank you all!

decal-84-monte-carlo-emissions-305-corrected-l220281.jpg
 

64nailhead

Goat Herder
Supporting Member
Dec 1, 2014
2,481
113
Upstate NY
That cam is going to be a pig off idle, but should wake it up once the rpm's get over 3500.

Regarding the timing settings - no idea how to do it, but if you have 34-36 degrees of all in timing and it's not detonating/pinging, then it should be good.
 
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