Hello, I have two questions.

1) I have the points installed on the 72 vette and the dwell set at 30. The total timing is 34 at 2500 rpm. The engine is original 454 bone stock. Is this a good timing?

2) my camaro (1970 350,30 over 11 to 1 pistons , 486 lift cam, vacume canister, over 400hp) was at 49 at 2500 rpm total timing and now i set it at 36 degrees. It sounds a little rough. In the timing post it says don't exceed 52. Will 49 get detonation?

Thanks Eric

 

At wide open throttle you should be at around 36 BTDC (initial + mechanical). The 52 degree figure is for part throttle cruise (60 MPH high vacuum).

DO NOT SET THE TIMING AT 49 DEGREES AT WIDE OPEN THROTTLE!!! You will only do this once.

Have you checked the balancer for slippage?

BigBlockk

Later.....

 

There does not appear to be any slipage on the balancer. The timing marker is in the right location. I took it for a ride around the block last night (36 btdc @ 2500 with vacume canister and advance hooked up ). It ran so bad i got half way down the street and slowly drove it back. It had no power. I am going to put it back up higher tonight or tomorrow. I think i am going to use it the old way without the dial back and the the vacume advance pluged at idle. Then it is roughly an inch and a half past the end of the timing marker 16.

Thanks Eric

 

Im no expert here but the 36 deg all in is with vaccuum advance disconnected and plugged....

 

You can not just look at the balancer and tell if it has slipped. You must measure for this. Get a piston stop and do it right.

BigBlockk

Later.....

 

I looked up a piston stop tool (first time i have seen one). What do you measure after you have it at tdc?

Thankyou. I will check the timing tomorrow night with the vacume advance plugged and see what the number is and adjust it.
Thanks Eric

 

Did you shim the distributor yet?

Don't do this until you shim dist.
36 degrees at 2500 to 2900 and higher RPM. Once that is set you come around 13 to 16 degrees at idle. Again vacuum is disconnected from advance and plugged. Then hook up vacuum advance and if car denotates when you shut it off, bump up timing 2 degrees.


Good Luck

 

Years ago i bought an accell blueprint hei distributor, msd 6al, accell super coil and installed them. Then i put the timing and inch and a half past 16 ( the end of the timing marker ) and drove it like this for years. That was the extent of my timing knowledge. I never shimmed a distributor before. I didn't know you could shim a distributor. How do you shim a distributor? Now that i bought this dial back pro light #5568 i thought i would fine tune the timing.

 

http://forums.corvetteforum.com/show...ght=spedaleden

Check out this thread

Setting shaft end play to .005 - .007" for cast iron units and .010 - .015" for aluminum housings

 

Thankyou

I timed the car tonight. With the vacume advance pluged i put it at 36 btdc. Then when i connected the vacume advance back up it went up 14 degrees to 50 total timing at 2,500-3,000 rpm. The car sounds good now. I will take it for a test drive tomorrow. I checked it at 0 also and thats about were i used to have it with the non dial back feature. If the timing is at 50 degrees at 2,500rpm with the vacume advance hooked up ,would it still be 50 at 6,000?

Eric

 

At 6000 RPM under load you will be at WOT. There is no vacuum advance at WOT.

BigBlockk

Later.....

 

My timing is still off. I pretty sure the harmonic balancer is slipping. I went to autozone today and the manager told me they didn't sell any. He also said he thinks that would be inacurate beacuse of the angle. I told him this is how i was going to do it.

I told him this and he said that was wrong. He said to take the #1 plug out put your finger on the hole turn the engine with a breaker bar until your finger get pushed out with air. Then look for the piston to go all the way up and stop then go down a slight bit. That is tdc 0 or very close to it.

I guess you can do both ways.

Eric

 

Eric,

Just curious, why do you say your timing is off?

Paul

 

Paul, I went to drive lat night with the timing at 50 total. I started it up it sounded a little rough. I went half way down the street and relized it had hardly any power. I pulled it back in the driveway and the timing was still 50. I timed it by ear till it sounded normal. I put the timing light back on it and it read 70 total (with vac hooked up). %2 is supposed to be the max. The car at 70 timing @ 2500rpm sounds good.

Eric

 

To find top dead center on an engine that has the heads on it.

1) Remove all spark plugs.

2) Remove the drivers side valve cover.

3) Clean the timing tab and highlight the "0" mark. Clean the balancer ring and wrap it with 1" masking tape. This is to give you a clean surface to mark on so you will be able to see the marks well.

4) Rotate the crankshaft clockwise (standing at the front of the car looking at the front of the engine) until the intake valve for #1 cylinder closes. Use a ratchet on the balancer bolt or, using a helper, a ring gear wrench on the flex plate/fly wheel.

5) The #1 piston is now coming up on its compression stroke. Install the piston stop in #1 spark plug hole.

6) Continue rotating the crankshaft clockwise until #1 piston contacts the stop. DO NOT USE FORCE! All you want is to touch the stop.

7) Find the "0" on the timing tab and mark the balancer at this point.

8) Rotate the crankshaft counter-clockwise until the piston contacts the stop. Mark the balancer at the "0" on the timing tab.

You should now have two (2) marks on the masking tape. If the marks are too far apart for you to see both of them at the same time back the piston stop off about a turn or two and repeat steps 3 through 8.

Once you have marks that you can see, measure the distance between them. TRUE TOP DEAD CENTER IS EXACTLY HALF WAY BETWEEN THEM.

Now, clean up the balancer and starting at your new TDC mark, paint it with white paint in the clockwise direction for 3 1/2" or so. Allow this to dry. Now you can mark off degrees using a fine tip Sharpie marker. This will allow you to get the timing set correctly.

If the "new" TDC mark and "old" TDC mark are not in EXACTLY the same place, start looking for a new balancer.

BigBlockk

Later.....