This engine has Dart Iron eagles, erson roller cam 228/236 @0.5, .540 lift on both intake/exhaust 110 LSA, proproducts air gap with 770 holley street avenger. I am still learing about this engine and was wondering what the timing should be at idle? When it was dynoed, the dyno sheet showed 38 degrees - would that be at peak horesepower (dynoed 435hp @ 5500rpm).

The 38 on the dyno was at WOT so it would be the total advance set by the dyno folks. That may or may not work for you on the street. Did the dist come with the engine? What does the engie builder recommend?

Disconnect the vacuum advance and plug the source, check your total to verify what it is, then check the initial and report back.

I'll ask the engine builder tomorrow. My uncle backed off the timing because it "bogged" a little bit. Right now it reads 10 degrees advanced at idle. Runs a little rough. THanks for the input.

10 is not enough. Try 16-18 (with vac advance disconnected) be sure to double check your total timing too.

Dennis, the engine builder said that the timing at idle should be between 18 & 22 degrees (Jim, you were right on the nose). Thanks for both of your replies.

Dennis, the engine builder said that the timing at idle should be between 18 & 22 degrees (Jim, you were right on the nose). Thanks for both of your replies.


I'm also following this post since I have a similar 383 and have it currently set at 14 at idle with 36 total. It runs great (no bogs, hesitations, etc.) but maybe I can get more out of it. So now that your going somewhere between 18 - 22 at idle what will you or what do you guys recommend setting the total timing to be at full advance???

Bill - do the math 36 total minus your 14 initial gives you 22 degrees in your mechanical curve. Set your initial to 22 and your total will be 44, set your initial to 10 and your total is 32. The typical 383 likes less timing than a 350, I'm running 34 total on 91 oct. I need better gas if I want to run more total. 22 in the dist is not a bad start, just tune for the most total you can safely run and tune the carb's idle and transfer (accl pump) to work with the initial you end up with. You can also use vacuum advance to supplement your initial by connecting it to a manifold source.

Cool - I'll try to up the timing at the balancer and reduce in the distributor to total around 34. Are you aware of how high altitude may factor into this equation?? I'm at over 6,000ft above sea level (which really make it more difficult to make the hp).

Also - I do have MSD Dist. w/Vaccumm advance connected. Does that change your recomendations???

Thanks!

Hi Bill - you lost me with "up the timing at the balancer and reduce in the distributor"

You never set timing with the vacuum advance hooked up, disconnect it and plug the source. Set timing then hook vacuum back up.

As far as altitude just pick a starting point and adjust up or down 2 degs at a time based on road tests (listening for pinging)... I would think air fuel mixture would be more effected than timing but then the engine will respond different to timing based on if it's running rich or lean.

Hi Bill - you lost me with "up the timing at the balancer and reduce in the distributor"

You never set timing with the vacuum advance hooked up, disconnect it and plug the source. Set timing then hook vacuum back up.

As far as altitude just pick a starting point and adjust up or down 2 degs at a time based on road tests (listening for pinging)... I would think air fuel mixture would be more effected than timing but then the engine will respond different to timing based on if it's running rich or lean.


To Clarify what I'm saying: As I'm understanding from the previous comments is that 34 - 36 total timing is a good place to be on a 383 however, that at least 18 of it should be seen on the harmonic balancer at idle and the rest of it kicks in at full advance (assuming around 3200 rpm). So I currently have about 14 on the balancer at idle (780rpm) with the vac can disconnected and plugged. When I take reading at 3200rpm, I have a total of 36. Basically what I'm trying to gather is that maybe the 14 on the dist is too low and should I set at more like 18 and bring down the advance in the dist. (by changing the stop bushings) so still totals at around 34 at 3200 rpm with cannister plugged. Does this make sense and sound like what I should be shooting for to start with?

Thanks

I run 14 to start at 800 rpm and had the 36 total set up to come in at 2500 rpm as the torque is in by 2500. I have the dist. locked out now but I'm adding the vac. adv. this week end to improve timing for some long distance drives coming up. I have never seen a motor for the street started at 18-22 at idle. Seems like it would be hard to start when hot.....What have I been missing?

I run 14 to start at 800 rpm and had the 36 total set up to come in at 2500 rpm as the torque is in by 2500. I have the dist. locked out now but I'm adding the vac. adv. this week end to improve timing for some long distance drives coming up. I have never seen a motor for the street started at 18-22 at idle. Seems like it would be hard to start when hot.....What have I been missing?


That's exactly what I'm talking about bluecamaro. 18-22 just seems too high so I'm trying to understand what the deal is or if maybe I've been setting mine too low. I'm not expert so trying to understand and found this discussion interesting so trying to follow.

To Clarify what I'm saying: As I'm understanding from the previous comments is that 34 - 36 total timing is a good place to be on a 383 however, that at least 18 of it should be seen on the harmonic balancer at idle and the rest of it kicks in at full advance (assuming around 3200 rpm). So I currently have about 14 on the balancer at idle (780rpm) with the vac can disconnected and plugged. When I take reading at 3200rpm, I have a total of 36. Basically what I'm trying to gather is that maybe the 14 on the dist is too low and should I set at more like 18 and bring down the advance in the dist. (by changing the stop bushings) so still totals at around 34 at 3200 rpm with cannister plugged. Does this make sense and sound like what I should be shooting for to start with?

Thanks

OK I see now you are talking about limiting the mechanical in the dist so you can run more initial without changing the total.

I personally don't put as much emphases on initial unless you have a real radical cam that just won't idle without a lot of advance. Especially since you can augument the initial with vacuum advance by running a manifold source to the vacuum can...

That said, I'd run your dist with 22 mechanical and set the total to where the car runs the best without detonation. Then if you can't make it idle with what ever initial you end up with put the vacuum advance on a manifold source (now the vacuum advance will be added to the initial) and see how that does. If that doesn't do it for you then limit the mechanical some so you can run more initial without raising the total...

I'ts my understanding that the vacuum advance will take the timing beyond the initial and the dist's mech. total up into the 40's for better fuel economy..is this correct??

I'ts my understanding that the vacuum advance will take the timing beyond the initial and the dist's mech. total up into the 40's for better fuel economy..is this correct??

Yes, think of the vacuum advance as on demand advance. It augments the mechanical based on what is going on in the engine. Vacuum increases - advance increases, vacuum decreases - advance decreases.

I'ts my understanding that the vacuum advance will take the timing beyond the initial and the dist's mech. total up into the 40's for better fuel economy..is this correct??

I'm not qualified enough to answer about the 40s degree part of your question but can provide this feedback:
I have the MSD Dist., 6AL, etc and was orignally not going to not run with the cannister, however, a guy at my local speed shop convinced me to use it if I'm not strictly racing the car and primarily driving on the street. He said that it does benfit MPG in this type of driving and also keeps engine in more ideal range in situations when your stepping in and out of the gas vs. simply flooring it down the track. That was enough for me to put the vac assist on and as I recall couldn't really feel the difference in the seat of the pants but is hopefully helping.

I have heard the same arguement 68rs/ss and have been running my dist. locked out now for 8 years at 36 total, I installed a new vac. adv. unit last night so we'll see how it runs or if mileage is different.

Are you aware of how high altitude may factor into this equation?? I'm at over 6,000ft above sea level (which really make it more difficult to make the hp).

This is what I read on the internet:

"The 36-degree 2500 rpm advance curve is optimum for performance, but may require premium fuel. Lug the car around, and punch the throttle at low rpm while listening for detonation (engine knock). If you’re getting any audible knock, you MUST retard the timing. Retard the timing in 2-degree increments until engine knock stops. Engine knock will seriously damage engine components if not corrected. If you get no knock, you may see slightly improved performance at 38 degrees total timing. This is particularly true if you’re running at high altitude."

This is what I read on the internet:

"The 36-degree 2500 rpm advance curve is optimum for performance, but may require premium fuel. Lug the car around, and punch the throttle at low rpm while listening for detonation (engine knock). If you’re getting any audible knock, you MUST retard the timing. Retard the timing in 2-degree increments until engine knock stops. Engine knock will seriously damage engine components if not corrected. If you get no knock, you may see slightly improved performance at 38 degrees total timing. This is particularly true if you’re running at high altitude."


Intersting! Why thank you very much for posting that info pertaining to high altitude (you guys at sea level are lucky - almost makes me want to move from my beautiful state of NM only to get more hp) I'm currently running the 36 total all in at approx. 2800rpm and not pinging so sounds like would be worth a shot to try out the 38 and see what happens. Now does anyone know if this would be better accomplished by raising the timing at the harmonic balancer at idle (currently at 14)or should I change the stop bushing in the MSD Distributor to achieve a total of 38 degrees?