The Stovebolt Site Forums The Shop Area Engine Shop Timing on a 70 chevy

Today, I'm trying to check- adjust the timing on my 70 chevy (307). Like everything else I've done on this truck, I've never done it and have a question.

1) My manual says to sheck the Vehicle Emission Control label under the hood for the proper timing setting. This information is no longer under the hood and I can't locate it anywhere. The guy at the parts store said 4degrees above center should be right, but I wanted direction from someone who knows.

2) I just put in a new point and condenser kit. The manual said if I didn't have a gauge that I should warm the engine up, turn the spacer bolt on the distributer (points) until the engine starts to misfire. Then turn it back 1/2 turn. Is this acceptable.

3) Once I can check the timing. The manual says to loosen the distributer bolt and turn the distributer as necessary to adjust timing. Can anyone give me a bit more detail or explain how this affects the timing.

Thanks in advance. Everyone's advice so far, has been invaluable and right on the money. I figure i've saved $1,505,000.00 so far. And all I've done is put in new spark plugs and an oil filter. :

Scott,
If this is not a new engine the timing chain is stretched to the poing where the timing mark on the damper and pointer on the block is all but useless. In that case use the following procedure: If that is true and you do not have a timing lite and the engine will start cold and hot you are close. Next - loosen the dist bolt a little - go in from the pass side to loosen. Might be a good time to get a dist wrench, will be handy in the coming years. After you have loosened up the bolt. Set the idle up to around 2100 rpm, put a vaccuum guage on the carb in place of the dist vac and turn the dist til you recv the highest vac reading on the guage. Bolt down the dist, return the rpm to normal and rehook up the vac line to the carb. The engine should be hot now. Shut off and try to restart. If it cranks easiely and fires up you are ok. IF not loosen the dist and retard a little. Bolt back down and try again. Setting up the idle a little when timing will allow optimum timing in high gear and better gas mileage. If you have a timing lite. Same procedure except set timing at idle, with vac pluged to carb. Loosen dist bolt turn to where the pointer on block and line on vib damper are at 6 degrees or 8 degrees. Verify the timing with the vac guage. You will quickly notice the vac guage will be your better guide if the timing chain is stretched (high mileage). Good luck we are here for you.
Tim

4 degrees sounds right per the book, but you can set it to 8 if it doesn't ping on acceleration.

Loosening the distributor clamp bolt allows you to rotate the body, which changes when the points close, allowing you to advance or retard the timing.

Scott,
Forgot the most imp information. Normal vac is 20-22 inches steady readings are the goal. Some guages it will be steady vac in the green area. The guage can also be used to set your carb air fuel mixture screws. Highes vac reading on each screw is desired.
T

I cut my teeth learning to tune my '69 Camaro with a 307, back in the day.

I can tell you this... if you put the timing at the "by the book" setting, the engine won't fall out of a tree. Bump it up to about 8 degrees before TDC and see the difference in power and mileage!

The book setting is for optimal smog idling compliance, not actual driving. And smog performance on an engine that old is a laugh anyway.

Be sure to unhook the vacuum advance line at the distributor and plug it before setting the timing.

If I recall properly, each short mark on the timing cover corresponds to 2 degrees.

It also wouldn't hurt to pull the distributor (if you are comfortable about how to retime it) and make sure the centrifugal and vacuum advance mechanisms are working properly.

But first, borrow or buy a dwell meter (they aren't expensive) and get the points set properly. 28 to 32 degrees is OK. I used to set mine about 30.

Check yard sales, flea markets and even eBay for a inexpensive dwell meter. If you are going to mess with old cars, it is well worth the outlay.

--> Bill

Timing on '70 307 with standard transmission is 2º, with automatic is 8º according to Motor's Auto Repair Manual.