1970 GTX 440 Timing

[Tony 70GTX]

I just installed a Edelbrook 750 CFM. I feel I need to advance the timing to get more out of the carb. The secondary doesn’t kick in as soon as I would like. The Carter AVS had a better feel. I know how to advance the timing but wanted to ask the group has anyone experience this and if so how far did you advance the timing?

 

[R413]

Why did you change the carb if the Carter felt better?

Was the timing right prior to this? Don't change it.

The secondaries are adjustable on the AVS, so adjust them first.

The carb was the only change, so just change that new carb not the other settings.

 

[Crackedback]

Advancing timing in most situations is fine to get better idle quality and throttle response. The book numbers are garbage in most cases as they weren't optimized to performance, a crutch to meet emissions.

You have to be careful advancing idle timing as it moves you total timing number up the same amount, Stay away from pinging. It may require some distributor surgery to limit mechanical to obtain a good overall timing package

Timing won't likely change when the secondary door opens, that's a carb adjustment. Not sure but, IIRC, 750 Ede's had a bad rep for OOTB tune up/settings. Don't know if they fixed them.

 

[turbine68rt]

What are your current timing settings?

 

[Bird 426]

Adjust the secondary spring. Loosen the lock screw and count the turns until the secondary blade opens, then back until it just closes. Now, many turns was that? If your engine isn't boging, the spring is a little too tight, back it off until you are happy with it. If it bogs, the spring needs to be tighter. This is how I always did it. My Dart back in the day had a factory setting of 1 3/4 turns, but it bogged, it liked 2 1,/2.

 

[Tony 70GTX]

Why did you change the carb if the Carter felt better?

Was the timing right prior to this? Don't change it.

The secondaries are adjustable on the AVS, so adjust them first.

The carb was the only change, so just change that new carb not the other settings.

Why did you change the carb if the Carter felt better?

Was the timing right prior to this? Don't change it.

The secondaries are adjustable on the AVS, so adjust them first.

The carb was the only change, so just change that new carb not the other settings.

The Carter was rebuilt several times. It was time for it to be replaced.

 

[BSB67]

The Carter was rebuilt several times. It was time for it to be replaced.

Strange.

 

[Geoff 2]

Edel do not make a 750 AVS.....

 

[Tony 70GTX]

Edel do not make a 750 AVS.....

https://www.edelbrock.com/marine-series-750-cfm-carburetor-with-electric-choke-non-egr-1410.html

 

[BSB67]

https://www.edelbrock.com/marine-series-750-cfm-carburetor-with-electric-choke-non-egr-1410.html

750 yes. AVS, no.

 

[Tony 70GTX]

750 yes. AVS, no.

Yeah, had a senior moment ‍. It’s a Edelbrock 750 CFM. Thanks for catching that.