Ignition Timing

[bosco]

I have a 73 with a Crane Ignition and Weber 32/36. Engine (1969) is fairly newly rebuilt.....so timing chain is (hopefully) not too stretched. My question is.......should I be advancing the timing, say 5 degrees or so, or should I be setting it right on the pointer. I realize if I advance it too far I will experience pinging but I was wondering what the other pros and cons are on advancing vs. not advancing. I think right now it is advanced about 5 degrees but since the weather has cooled down I find that its very "grumpy" in the morning until it really gets well warmed up. I have a sprint exhaust on it so I realize it will take longer to warm up the intake but I wondered if the timing could also have an effect on this.

Any thoughts appreciated.

[tekenaar]

Originally Posted by bosco I have a 73 with a Crane Ignition and Weber 32/36. Engine (1969) is fairly newly rebuilt.....so timing chain is (hopefully) not too stretched. My question is.......should I be advancing the timing, say 5 degrees or so, or should I be setting it right on the pointer. I realize if I advance it too far I will experience pinging but I was wondering what the other pros and cons are on advancing vs. not advancing. I think right now it is advanced about 5 degrees but since the weather has cooled down I find that its very "grumpy" in the morning until it really gets well warmed up. I have a sprint exhaust on it so I realize it will take longer to warm up the intake but I wondered if the timing could also have an effect on this. Any thoughts appreciated.

Just curious, electric or hot water choke?

If the car was running fine in warm weather, leave timing alone . . . it's not your "grumpy in the morning" (ie. when cold) problem. Yes, the sprint manifold affects your "warm-up" time when it's colder outside, but not entirely how you think. "Stove" heating of the intake plenum helps vaporize the fuel when engine is cold, but is somewhat detrimental to engine operation once it reaches operating temperature (most of the time).

I would loosen the 3 "adjustment" screws on the carb's choke cover and turn the choke cover 1 or 2 "notches" CW (1/8" - 1/4"), tensioning the choke plates a bit more for your "cold weather" setting and then back it off again during the summer months. Small price to pay for the benefits of the sprint manifold!

[baz]

had a thought on this and have to ask
has anyone put a thermocouple on a stove header/inlet plenum to see how quick it warms up ?
i think it will take the heat as long to effect the inlet temp as it dose to warm the engine to the point where the choke is comming off
this would put the stove in the emmisions park not the speedy warmup/economy park
as i say just a thought

[bosco]

It's an electric choke and I'll try putting a bit more tension on the butterflies to see if that helps. Thanks for the tip, much appreciated.
Mike

[bosco]

I was just thinking that maybe I didn't explain my problem too well above. The engine actually starts and (fast) idles very well when cold......it's when you first hit touch the throttle and the fast idle clicks off.......THEN it's "grumpy". driveability-wise. It wants to cut out starting from a stop for several miles. Once all is totally warmed up it runs very smoothly. My son drives it to school (2-3 miles away) and he says it spits and sputters the whole way there even if he warms it up for 10 minutes before he leaves. Would this be even slightly alleviated by moving the choke housing or would that just help for cold start-up?

[madhatterpdc]

Ironically enough, the added detail of your son driving 2-3 miles to school rung a certain bell in my head. When I was in high school, I drove a '78 Jeep pickup, about 2-3 miles, and it behaved *exactly* as you have just described. Turns out the carb was running rich. Checked the floats and it behaved much better (I say better because there were many other issues with that truck). The best way for you to check out your own carb is to simply check a plug or twoo. Black, rich, etc. I am sure you know the drill. If the plugs have been in for a while, swap them out, the only real way to "read" plugs is if they are fresh. Plus, I have seen fresh plugs hide all sorts of problems... until they are no longer fresh anyways.

[GTJIM]

Originally Posted by bosco I have a 73 with a Crane Ignition and Weber 32/36. Engine (1969) is fairly newly rebuilt.....so timing chain is (hopefully) not too stretched. My question is.......should I be advancing the timing, say 5 degrees or so, or should I be setting it right on the pointer. I realize if I advance it too far I will experience pinging but I was wondering what the other pros and cons are on advancing vs. not advancing. I think right now it is advanced about 5 degrees but since the weather has cooled down I find that its very "grumpy" in the morning until it really gets well warmed up. I have a sprint exhaust on it so I realize it will take longer to warm up the intake but I wondered if the timing could also have an effect on this. Any thoughts appreciated.

Most Opel distributors are set up for "0" degrees initial advance and have 35-37 degrees of mechanical advance in them to get the required maximum advance above 3,000 rpm. When the initial advance is increased this also "moves" the maximum advance by the same amount - unless the distributor is modified to reduce the mechanical advance in the distributor.
So just dialing in some more initial advance means that the maximum advance becomes too great as CIH Opel motors are reputed to give best power with a maximum advance of 34 to 36 degrees. That is why a '75 FI distributor is often recommended as it has 25 degrees of mechanical advance and so can be used with up to 10 degrees of initial advance before going too far in maximum advance.

Just a wee note to explain why just increasing initial advance is only part of the story!

[bosco]

Back in the 70's I had a supposedly Opel trained mechanic who operated an Opel garage in Mesa, AZ tell me that I should set my timing by advancing it until the engine started to ping under acceleration then back it off a tad. That would put the total advance, including mechanical advance, up to somewhere in the 45 to 50 degree range!!