HEI Limiting Mechanical Advance to 10? - Page 4 - Chevelle Tech
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post #46 of 99 (permalink) Old Sep 11th, 19, 2:24 PM
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Re: HEI Limiting Mechanical Advance to 10?

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Originally Posted by Droptop72 View Post
I'm not going to judge one way or another, but I was always taught that in all but the most radical street engines, if it runs better without vacuum advance, you were just crutching some other issue. Take it for what you paid for it.
Some high HP/TQ builds that have over 10:1 compression with very high cylinder pressures might not tolerate that extra 10-15* of timing at part throttle. Not worth the gamble. No crutch there.
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post #47 of 99 (permalink) Old Sep 11th, 19, 2:35 PM
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Re: HEI Limiting Mechanical Advance to 10?

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Originally Posted by mr 4 speed View Post
Some high HP/TQ builds that have over 10:1 compression with very high cylinder pressures might not tolerate that extra 10-15* of timing at part throttle. Not worth the gamble. No crutch there.
There are vac advance cans that drop away timing at the drop of a hat (well, slightest throttle opening). Sounds like that one is a better application in that situation

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post #48 of 99 (permalink) Old Sep 11th, 19, 2:51 PM
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Re: HEI Limiting Mechanical Advance to 10?

As far as having "expertise" in mechanical systems, I work on flyball-governor controlled steam turbines. The mechanical control system is simply amazing in that it does everything a modern digital electronic system does, but it controls with changes in oil pressure from the flyball governor.

Vince's simple "stop bolt" that is ground with an oval shape makes it simple to set your total centrifugal advance. Then you pick the correct spring to control the speed of the advance.

"KISS" comes to mind. It works, and it does it with simplicity.
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post #49 of 99 (permalink) Old Sep 11th, 19, 3:50 PM Thread Starter
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Re: HEI Limiting Mechanical Advance to 10?

I did the same think as Vince did and it works perfectly. I have 12 degrees mechanical that's all in by 2600.. I run22 initial.. With low compression, a 160 thermostat and hi test it runs like a charm.. I love how powerful it is right off idle while going up and down the hilly back roads.
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post #50 of 99 (permalink) Old Sep 11th, 19, 4:33 PM
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Re: HEI Limiting Mechanical Advance to 10?

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Originally Posted by hydro462 View Post
I did the same think as Vince did and it works perfectly. I have 12 degrees mechanical that's all in by 2600.. I run22 initial.. With low compression, a 160 thermostat and hi test it runs like a charm.. I love how powerful it is right off idle while going up and down the hilly back roads.
Especially since you don't have high-compression, I think you are giving up about 3-4 mpg by not adding 10-14 degrees of vacuum advance.

Engines like about 45-52 degrees advance at light load cruising.

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post #51 of 99 (permalink) Old Sep 11th, 19, 8:08 PM
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Re: HEI Limiting Mechanical Advance to 10?

Quote:
Originally Posted by Dave Ray View Post
Lets see, almost every after market large HEI manufacturer has adopted the 41/375 set as their default curve parts, NOT their specific curve kits, but what they put in the distributors they sell. I guess it is too hard to contact one and ask if they are available separately.

Decades ago, I developed bushings that fit over the pins in those distributors, so they could be set up for start/limit points, NOBODY wanted them. And, a plate that went between the reluctor and top of the shaft, with a screw set on each side, to allow easy adjustment, but, NOBODY wanted it, either.

So, instead, because it was "easier", we got welding, brazing, jam a screw in place, rip, tear, hack, and not much good of it.

Is setting the curve and start/limit points easy on the coil in cap HEI, HECK NO, doing it right requires the correct combo of parts, not hacking it all up.
Your kidding me right? You berate everybody for modifying or "hacking" their curves for something better, yet YOU "jam" bushings and/or some kind of hacked-up plate to make things adjustable and that's OK?????

I'm done.
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post #52 of 99 (permalink) Old Sep 12th, 19, 7:41 AM Thread Starter
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Lightbulb Re: HEI Limiting Mechanical Advance to 10?

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Originally Posted by 69-CHVL View Post
Your kidding me right? You berate everybody for modifying or "hacking" their curves for something better, yet YOU "jam" bushings and/or some kind of hacked-up plate to make things adjustable and that's OK?????

I'm done.
Vince, here's what I did.. Use this forums version of Preparation H..

1-Hit the User CP tab at the top of the page.

2-Hit the edit Ignore list tab, its the 10th one down on the left side.

3- Put the name in there and they disappear.

4- Enjoy having fun with your car again. Some people are not into this for fun like we are...
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post #53 of 99 (permalink) Old Sep 12th, 19, 1:49 PM
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Re: HEI Limiting Mechanical Advance to 10?

What a crock of BS from a couple of you. I developed two different stop setups for large HEI, NOBODY WANTED THEM. You get on my case for saying it, and continue to flame away at me.

lets remember one thing about the coil in cap HEI, IT WAS NEVER DESIGNED TO BE A PERFORMANCE IGNITION, IT WAS DESIGNED TO BE A FULLY SELF CONTAINED EMISSIONS IGNITION.

Too bad some of you refuse to realize that is just what they are, there are much better performance, and even stock type ignitions than a large cap HEI.
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post #54 of 99 (permalink) Old Sep 12th, 19, 2:17 PM
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Re: HEI Limiting Mechanical Advance to 10?

Quote:
Originally Posted by Dave Ray View Post
What a crock of BS from a couple of you. I developed two different stop setups for large HEI, NOBODY WANTED THEM. You get on my case for saying it, and continue to flame away at me.
Perhaps if you'd explain what made your stop set-up work different than a simple screw stop, we'd understand a little better. If nobody knew what made it different than a screw as shown above, that could be why nobody wanted them.
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post #55 of 99 (permalink) Old Sep 12th, 19, 2:21 PM
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Re: HEI Limiting Mechanical Advance to 10?

Quote:
Originally Posted by Dave Ray View Post
What a crock of BS from a couple of you. I developed two different stop setups for large HEI, NOBODY WANTED THEM. You get on my case for saying it, and continue to flame away at me.

lets remember one thing about the coil in cap HEI, IT WAS NEVER DESIGNED TO BE A PERFORMANCE IGNITION, IT WAS DESIGNED TO BE A FULLY SELF CONTAINED EMISSIONS IGNITION.

Too bad some of you refuse to realize that is just what they are, there are much better performance, and even stock type ignitions than a large cap HEI.


Man,you need to check that attitude...
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post #56 of 99 (permalink) Old Sep 12th, 19, 3:02 PM
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Re: HEI Limiting Mechanical Advance to 10?

Quote:
Originally Posted by Dave Ray View Post
What a crock of BS from a couple of you. I developed two different stop setups for large HEI, NOBODY WANTED THEM. You get on my case for saying it, and continue to flame away at me.

lets remember one thing about the coil in cap HEI, IT WAS NEVER DESIGNED TO BE A PERFORMANCE IGNITION, IT WAS DESIGNED TO BE A FULLY SELF CONTAINED EMISSIONS IGNITION.

Too bad some of you refuse to realize that is just what they are, there are much better performance, and even stock type ignitions than a large cap HEI.
What's your definition of a performance ignition? Be specific!
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post #57 of 99 (permalink) Old Sep 12th, 19, 3:14 PM
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Re: HEI Limiting Mechanical Advance to 10?

Quote:
Originally Posted by mr 4 speed View Post
Some high HP/TQ builds that have over 10:1 compression with very high cylinder pressures might not tolerate that extra 10-15* of timing at part throttle. Not worth the gamble. No crutch there.

Every internal combustion engine has a combustion burn rate that is dependent upon the cylinder pressure/VE. Any engine timing curve that does not modify the spark advance over the range of cylinder pressures is putting the LPP at inefficient crank angles, and just pissing away fuel mileage, cooling efficiency, and throttle response.

My engine is over 10:1 CR, and with how much time and money it cost me to build it, I don't gamble with its performance and longevity. It gets the expensive oil and a proper timing curve, which includes a vacuum advance canister to reduce exhaust valve temperatures at light loads.
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post #58 of 99 (permalink) Old Sep 12th, 19, 3:35 PM
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Re: HEI Limiting Mechanical Advance to 10?

Some of you are discovering what I found several months ago: A person can claim to know all the stuff that won't work, which leads you to ask that person what DOES work. You then find that said person won't simply answer the question. For example, let's suppose the person in question told you about a category of coils that are failure prone. One might be tempted (indeed, I was) to ask that person what coils are NOT failure prone. No answer is forthcoming. I did a bit of looking around and discovered that I was not the first person to ask that basic and obvious question to no avail, nor have I been the last. I don't know WHY the person won't answer that question, only THAT they won't. Hence, my earlier remark of "it is what it is and they do what they do". You won't likely get anything helpful on specifics of coils that are good, only which ones aren't. There's something peculiar psychologically going on there, but I'll be damned if I know what it is.

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post #59 of 99 (permalink) Old Sep 12th, 19, 3:47 PM
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Re: HEI Limiting Mechanical Advance to 10?

I developed two different stop setups for large HEI, NOBODY WANTED THEM

Based on the comments here, there would be some kind of market for them.
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post #60 of 99 (permalink) Old Sep 12th, 19, 4:11 PM
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Re: HEI Limiting Mechanical Advance to 10?

Quote:
Originally Posted by Dave Ray View Post
Decades ago, I developed bushings that fit over the pins in those distributors, so they could be set up for start/limit points, NOBODY wanted them. And, a plate that went between the reluctor and top of the shaft, with a screw set on each side, to allow easy adjustment, but, NOBODY wanted it, either.

.

I do. This would be very beneficial when I want to go drag racing and lock out advance.
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