What is all this talk I hear about base timing and total timing and all that? How do I set the base and how do I know the total? I thought to test the timing you dissconnect the plug, start the car and set it to your level, then shut off and plug back in. I have been getting rather poor milage after someone at a shop played with my timing and I think he screwed it up not setting it right. I reset it using the method above to about 10 degrees, but how do I figure out this base and total stuff? Thanks.

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87 GTA 350 L98
K&N filter, beefed up TH-700r4, Accel Manifold, Ported Plenum and Runners, Fuel Press. Regulator 49.5psi, air foil, modified MAF, SLP cold air box, Hypertech Thermomaster chip w/160 thermostat, MSD 6AL and Blaster 3, B&M shift kit & megashifter, Moser Ford 9in Rear with Richmond 3.50 and locker, Edlebrock TES headers and Cat Back,Gutted cat, removed emissions, Hotchkis setup in rear, Poly suspension and Koni in the front, relocated MAT, bypassed TB coolant, 300 lbs lighter

Fastest ET's
Stock-0-60 6.8, 1/4 15.0 @ 94
Best-0-60 4.7, 1/4 12.8 @ 112
Norm-0-60 5.2, 1/4 13.2 @ 108

 

Base timing is what you set it at. Total timing is dependent on the total advance of the distributor and the base timing. Meaning, if you set the base timing to 10 and you have a total advanc of 30, your total timing will be 40. (I believe that's how that works.)

To set the base timing, you have to make sure that the car's not going to try to advance the timing any. In the older vaccuum advance distributors, this was done by disconnecting the vaccuum line. In the computer controlled cars, it was done by bypassing the EST by opening the tan wire with a black stripe that was sticking out of the main engine wiring harness on the passenger side of the car near the wheel well. (at least, that's where it's at in my car.)

Then you set the timing with the car on, turn it off, hook everything back up, and be on your merry way. 10* base timing might be too much. Emphasis on the word might. I think the base timing for your engine from the factory is 6 degrees, but every engine is different.

Timing's a tricky thing. Getting it just right takes a lot of trial-and-error really, but if you ever hear knock then you're way off. heh.

As far as total timing is concerned, I'm sure there's some publication somewhere about your distributor's total advance.

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89 iroc-z 305 tbi
k&n filtercharger, open element air filter. nuffin' else

 

Yea, I hear that a lot about adjusting base, but your really pushing your total timing up that’s where you feel the difference.
Lets say I have my total set to 36 degrees, and I want to move my base timing up say 2 degrees for a better idle. Well I can't just drop in two degrees without worrying about detonation above 3000RPM's. So I would have to change my springs, or better yet put a couple of turns on my vacuum advance, if I want to turn the distributor a couple of degrees. Let me see if this works ? If you want the power on the top end, you adjust your total, if you want a better idle you adjust the base. If you want the best power from idle to the top end, it's all in the curve.
'Enkil' is right - it takes a lot of trail and error, in fact a lot of publications say you should advance your timing per every thousand or so RPM's to where it detonates, and back it off two degrees. From this you have the timing curve for your car, hand that sheet to the distributor specialist, and your set. I don't know it this applies to your car, without burning a new chip. Hell they probably already do that on those aftermarket chips, but not for you combo.

Ron



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'82 Trans Am
'81 Camaro Z-28
'94 Vette LT1 Coupe

 

So how exactly would I set the timing.

I have an eratic idle. -> When idling the car shakes a bit and the engine changes speeds (it revs below 1000 and fluctuates a lot) Would timing have anything to do with this??

Or what else could that be??

I borrowed a timing light from one of my dad's friends, it's a basic one. No switches on it or anything, just a trigger. and a positive and negative clip comming off it as well as some other clip that attaches to the cylinder, or spark plug?????

I never asked him how to use it, and i never have used one before.. In fact, I have never done timing before? Should I take it to a mechanic or will it be not too hard if i try to figure it out myself.


I would REALLY appreciate help.

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'86 Camaro
2.8 MPFI

AC Delco RapidFire SparkPlugs
Premium Gold Distributor Cap & Rotor

 

As quoted from.. Me.

Setting the timing on the car is very easy to do. First buy a timing light and an offset timing wrench. (The bolt on the distributor is placed inconveniently if you don't have one. heh) That'll run you probably no more than 40 bucks.
To bypass the computer, look for a tan wire with a black stripe on it on the passenger side of the car. There should be a bundle of wires helt together with some black plastic tubing, and sticking out of that will be the wire. It's got a plug on the wire, just disconnect that. (Do this with your car off.)

To hook up the timing light...

Put the inductive pickup on the #1 spark plug wire. It's the wire closest to the front of the car on the driver's side of the distributor. Then hook the positive cable to the positive terminal, then the ground to any good ground you can find. Turn the car on, and after a few seconds the check engine light should come on. (Also be careful not to let the wires of the timing light get anywhere near the belts or the fan.) With the car warmed up and at idle, point the timing light down to the marks. As you've seen, the marks are made up of a bunch of triangle shaped wedges. The widest "valley," towards the drivers side, is TDC. Then, the peaks, heading towards passenger's side, are 4*BTDC and then, I believe, 8*BTDC.

Loosen up the bolt on the distributor, and slowly turn it either way to adjust the timing: Counterclockwise to advance, clockwise to retard. Don't jerk the distributor as it doesn't take much to adjust the timing. Also, when adjusting the timing the engine's RPM's will vary, so don't let that throw you off. After you get the timing set, tighten down the distributor and check the timing again to make sure it didn't move. Then turn the car off, disconnect the timing light and plug back in the EST.

Now, the erratic idle might not be the timing. It could be a vacuum leak, or it could be a poorly adjusted IAC/TPS, or maybe dirty IAC passageways. I'm sure there's things I'm leaving out here but I think those are the most common.

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89 iroc-z 305 tbi
k&n filtercharger, open element air filter. nuffin' else

 

You can reach the distributor bolt with a 14mm crow foot wrench (about $7 at Sears)...assuming you have a 3/8 drive ratchet w/extension

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92 Camaro RS, LO3, 5-spd, T-tops

Performance:
K&N Open Air Filter, Edelbrock performer TBI intake, Fastchip Prom, Timing +4 degrees, Centerforce clutch, Xact 8mm wires, SLP 1 3/4" Headers (coated), Flowmaster Catback Exhaust, Z28 Grille w/aftmkt fog lamps
Electronics:
Alpine 8030 Alarm System, Valentine One Radar Detector (How did I ever drive without one?), Pioneer DEH 7450 Head Unit w/6-pack CD changer, Pioneer DEQ 7600 Sound Processor, 2 Kenwood KAC-846 Amps powering 2 12" Pro Red subs, 2 Pioneer 6x9 and 2 MTX 4x6 speakers.
NEXT UP: TBI mods, 3.42 gears w/Torsen posi

 

I got a distributor wrench from AutoZone that works PERFECT on my car. It was only $4.99 too!

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission
Borg Warner 7.75" 9 Bolt Rear End with 2.77:1 Gears.

Current Mods: LT4 HOT Cam, Comp Cams 1.52:1 Roller Rocker Arms, Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET (w/o LT4 cam): 14.32 @ 97.7mph
(corrected for elevation)

Soon to Come: 7.625" 10 Bolt with 3.42s and Accel TPI Intake Base

 

OKay, i need a wrench...


But where the heck is the distributor hold down bolt???

does anyone have a picture??

Also............ The inductive pick up on the timing light,... The thing that connects to the spark plug wire, where does it connect? On the end of the spark plug? On one end of the wire? or to the distributor cap???

Does the wire need to be attached to the spark plug and/or distributor cap?

This is all probably really simple if you've done it before, but i haven't.. so i'm still confused, sorry for all the questions but i am learning A LOT!!! Thanks guys!