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Old 02-10-2019, 03:21 AM
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Just an FYI I think your engine is making more power than you give it credit for. Look at Caster1 build he did just a few weeks ago and look at his numbers. You should be up around there. I too am gonna run the holley sniper and wonder what my timing curve needs to look like. I am concerned about doing damage to the engine trying to get my timing set perfectly so before I really start driving it I am gonna take it to a chassis Dyno. Hopefully that step will get me my most return on investment. I have a lot of money in this build and plan on driving it about 8000 miles a year so I can’t afford to make errors

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Old 02-10-2019, 05:16 AM
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This is from FiTech tech responses:
Quote:
"This is typically performed on a dynamometer – creep up on timing until performance stops increasing – for a starting point, use expert opinions – more is not better with timing. Cranking at “Distr Base Timing” is often OK at about 10 degrees and cannot be changed unless the distributor is also moved to re-sychronize. Idle can often be pretty good at 15-25 degrees (depends on the cam). 1100 and 45kPa can often be similar to the idle timing. Most engines need only ~15 at 1100 RPM WOT, and 29-36 degrees at WOT 3000 RPM. Cruising 45kPa will easily like more than that – 40+ degrees at 3000 RPM is common – but watch out that you’re not too far from the “Distr Base Timing” or there will be arcing under the distributor cap, which can sometimes cause surging if it misfires. The 6000 RPM settings can often just be the same or a little more than the 3000 RPM settings."
I can attest to these numbers as a good basic starting point. Start conservative, especially with the WOT numbers, and don't get too aggressive on the timing tune until you know your AFR's are in a safe place. Too much timing during a lean condition can be harmful. I run 14 base degrees, 14 cranking degrees, 29 at idle, 34 degrees WOT 3k and 6k, and maybe 45 degrees for high vacuum 3k (cruise). Off idle is somewhere around 20 degrees. I have more tuning to do, but it runs pretty nice. I can't see ever going back to non-EFI.

Changing the timing from the handheld is awesome! It sure beats smacking your head under the hood trying to tweak a distributor.

I still want to map out the timing for the 5.3 in my GMC truck using my OBDII interface and Android app. I just haven't got around to it yet. I'm gonna bet there are some super smart engineering dudes who got paid a lot of money to figure this out.

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Old 02-10-2019, 12:41 PM
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Originally Posted by 64speed View Post
Just an FYI I think your engine is making more power than you give it credit for. Look at Caster1 build he did just a few weeks ago and look at his numbers. You should be up around there. I too am gonna run the holley sniper and wonder what my timing curve needs to look like. I am concerned about doing damage to the engine trying to get my timing set perfectly so before I really start driving it I am gonna take it to a chassis Dyno. Hopefully that step will get me my most return on investment. I have a lot of money in this build and plan on driving it about 8000 miles a year so I can’t afford to make errors
When I finished the engine and took it back to the engine guy that did my machine work to run the engine and break it in we were going to dyno it but his dyno was down. For now I can only go off of what the DeskTop Dyno program estimates the power at. My intention was to get the carburetor running the best I could then I was going to take the car back to him to have him fine tune it on his chassis dyno. When I started thinking of the Sniper swap I decided not to waste the money on the dyno until I decided to either keep the carburetor setup or upgrade to the Sniper EFI. I think having the engine ran on a dyno once I have it set up the way I want would be a good investment and insurance policy that I don't tear up my engine. I know just enough about engine tuning to be dangerous. I can get a car to run good, but not great. And I definitely am no good at fine tuning a carburetor.

Thanks for the response,
Dale

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  #24  
Old 02-10-2019, 12:59 PM
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Originally Posted by Squidward View Post
This is from FiTech tech responses:


I can attest to these numbers as a good basic starting point. Start conservative, especially with the WOT numbers, and don't get too aggressive on the timing tune until you know your AFR's are in a safe place. Too much timing during a lean condition can be harmful. I run 14 base degrees, 14 cranking degrees, 29 at idle, 34 degrees WOT 3k and 6k, and maybe 45 degrees for high vacuum 3k (cruise). Off idle is somewhere around 20 degrees. I have more tuning to do, but it runs pretty nice. I can't see ever going back to non-EFI.

Changing the timing from the handheld is awesome! It sure beats smacking your head under the hood trying to tweak a distributor.

I still want to map out the timing for the 5.3 in my GMC truck using my OBDII interface and Android app. I just haven't got around to it yet. I'm gonna bet there are some super smart engineering dudes who got paid a lot of money to figure this out.
Thanks for the information. All of this information makes a really good starting place. If I decide to do this I think I will get it installed and running. Then I will have my son come visit for the weekend and help get it tuned in better. He actually went to college for this stuff so he knows a lot more than I do. After he gets it dialed in the best he can then I will decide whether or not to take it to the chassis dyno to ensure it is setup properly and see what the engine is actually producing. I know the numbers from a chassis dyno will be different than those from a stand dyno but it will be good enough to let me know what the engine is actually doing. Now I just need to decide if I want to spend the money and time to convert the car to EFI or leave the Q-Jet on it.

What engine are you running with those timing numbers and how is your engine setup?

Dale

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Old 02-12-2019, 11:12 PM
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I'd start with about 8 degrees cranking, 15 degrees idle, 38 degrees WOT, and 44 cruise with your setup. Increase the cruise in 2 degree increments up to 48, after it self tunes the fuel a bit (if you get pinging under light throttle, back it off to the previous setting where it didn't ping).

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  #26  
Old 02-13-2019, 09:43 AM
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Originally Posted by amcmike View Post
I'd start with about 8 degrees cranking, 15 degrees idle, 38 degrees WOT, and 44 cruise with your setup. Increase the cruise in 2 degree increments up to 48, after it self tunes the fuel a bit (if you get pinging under light throttle, back it off to the previous setting where it didn't ping).
Thanks for the advice. I noticed the Sniper is preset to a cranking timing of 15 degrees. What would the 8 degrees cranking timing do for the car? Also, right now the mechanical timing on the Unilite distributor is all in around 2500-2600. I have noticed a lot of people use 3000-3200. What would the benefit be of the 2500 versus the 3000, my rear end gear is 3.36?

Dale

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  #27  
Old 02-13-2019, 07:41 PM
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Originally Posted by highrisk View Post
Thanks for the advice. I noticed the Sniper is preset to a cranking timing of 15 degrees. What would the 8 degrees cranking timing do for the car? Also, right now the mechanical timing on the Unilite distributor is all in around 2500-2600. I have noticed a lot of people use 3000-3200. What would the benefit be of the 2500 versus the 3000, my rear end gear is 3.36?

Dale

Shouldn't need that much crank timing as long as you have the proper amount at idle. That much timing can put a lot of unnecessary load on the starter, which will wear it out quicker. And it may even make the vehicle hard to crank over when hot, or the battery is really cold.

Regarding your question about when to to have the mechanical all in: On a conventional distributor, if you bring the mechanical in too fast, you might end up having to limit the total you can put in @ WOT.

For example, lets say the engine can only handle 35 degrees at 2500, but prefers 40 at 3000rpm, and your advance comes all in @ 2500rpm: If you set it to 40 degrees total, you'll have too much between 2500-3000rpm, which @ minimum means lost power, and worst case damage the engine. If you only set it to 35 degrees, then you've given up power from 2500 to max rpm.

That's the beauty of a fully programmable system; you can create a load/rpm map that optimizes the advance at various points (with interpolation in between) for max power (and fuel economy) across the entire speed/load range. Holley's system appears to be a simplified version, letting you put in key points, and then it estimates the map from that. Not as accurate as creating a map from scratch by running an MBT sweep with a dyno, but probably a step above a conventional distributor.

BTW, I'd start with the 38degrees max WOT, until the fuel learns. Then like the part throttle timing, if you want you can try adding more (I'd do 1 degree at a time). However, not all detonation is audible (especially when driving), and sometimes too much timing can still cause power loss without detonation. So best if you can do tune that portion on a dyno, where you can watch for power loss as well as listen for knock.

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Last edited by amcmike; 02-13-2019 at 07:49 PM.
  #28  
Old 02-13-2019, 07:44 PM
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Originally Posted by amcmike View Post
Shouldn't need that much crank timing as long as you have the proper amount at idle. That much timing can put a lot of unnecessary load on the starter, which will wear it out quicker. And it may even make the vehicle hard to crank over when hot, or the battery is really cold.



Regarding your question about when to to have the mechanical all in: On a conventional distributor, if you bring the mechanical in too fast, you might end up having to limit the total you can put in @ WOT.



For example, lets say the engine can only handle 35 degrees at 2500, but prefers 40 at 3000rpm, and your advance comes all in @ 2500rpm: If you set it to 40 degrees total, you'll have too much between 2500-3000rpm, which @ minimum means lost power, and worst case damage the engine. If you only set it to 35 degrees, then you've given up power from 2500 to max rpm.


That's the beauty of a fully programmable system; you can create a load/rpm map that optimizes the advance at various points (with interpolation in between) for max power (and fuel economy) across the entire speed/load range. Holley's system appears to be a simplified version, letting you put in key points, and then it estimates the map from that. Not as accurate as creating a map from scratch by running an MBT sweep with a dyno, but probably a step above a conventional distributor.
Thanks, I appreciate the additional information.
Dale

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Old 01-22-2020, 05:39 PM
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Just wanted to update this thread. I finally decided to put the Holley Sniper on my car. I used their Muscle Car sending unit and in tank pump so I did not have to run a return line and got their Hyperspark distributor for Pontiacs. Delaying a year was a smart idea because they now offer a Pontiac Hyperspark. I kept my Mallory 6AL ignition box and Mallory Coil. I also set it up where the EFI controls the timing. I ended up replicating the timing curve that was set up for the engine years ago. I am using 8 degrees cranking, 12 degrees idle, 36 degrees WOT, and 42 degrees cruise. I tried other settings but the car does best at these numbers. I am still fine tuning it a little to get rid of a rich condition during warm up, but WOW, now the engine responds and has the power that I thought it should have. I can be at 2000 RPM in second or third gear and mash it to the floor and my expensive sticky tires will instantly break and the car will start fishtailing. Very happy with the switch and adding the EFI. The Muscle Car sending unit module really made the install a lot easier. It is actually a fairly simple install, just requires a lot of preplanning and rewiring.

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Old 01-22-2020, 06:52 PM
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Good work. Welcome to modern tuning. I enjoyed the education I got when I switched.

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  #31  
Old 01-22-2020, 07:46 PM
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Good work. Welcome to modern tuning. I enjoyed the education I got when I switched.
Once it is installed and running it is amazing how easy it is to make changes. You want to change the Air/Fuel Ratio, it takes only a couple of seconds with the handheld screen. Same thing with trying different timing settings and idle speeds. No more having to shut off the engine, get the tools out, loosen this or that, make the changes, then try it again. And then if you want to make some serious changes you save your tune to the SD card, take it into your computer and open up the EFI software, and do some serious changes. If you have a laptop you can actually plug straight into the ECU of the unit and make the changes there. Really has simplified the entire process. Plus you don't have to be an expert, the unit does a lot of the tuning itself. I am no carburetor tuner so I could never get the full potential out of my engine. A little reading and a few adjustments and the car is now a beast.

Dale

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  #32  
Old 01-22-2020, 11:46 PM
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Once it is installed and running it is amazing how easy it is to make changes. You want to change the Air/Fuel Ratio, it takes only a couple of seconds with the handheld screen. Same thing with trying different timing settings and idle speeds. No more having to shut off the engine, get the tools out, loosen this or that, make the changes, then try it again. And then if you want to make some serious changes you save your tune to the SD card, take it into your computer and open up the EFI software, and do some serious changes. If you have a laptop you can actually plug straight into the ECU of the unit and make the changes there. Really has simplified the entire process. Plus you don't have to be an expert, the unit does a lot of the tuning itself. I am no carburetor tuner so I could never get the full potential out of my engine. A little reading and a few adjustments and the car is now a beast.

Dale
Welcome to modern day engine management. You'll never go back!

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  #33  
Old 01-28-2020, 08:01 PM
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Welcome to modern day engine management. You'll never go back!
It is amazing how much more responsive the engine is. In my case it untapped a lot of power that I wasn't getting with the carburetor. I know if the carburetor was tuned properly it would perform the same but I am not that good with carburetors. But it is amazing that with the same knowledge I was able to get the EFI running very well and now the engine is a beast..
Dale

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  #34  
Old 01-28-2020, 08:59 PM
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I know if the carburetor was tuned properly it would perform the same but I am not that good with carburetors.
I totally disagree with that statement as a whole because a carburettor is what I would call a dumb or a slave device, it only does what it's told to do. It will not compensate for changes other than throttle angle. Whereas when you're sampling air temperature and manifold pressure along with a bias for coolant temperature at varying RPM, which calculates air density (and some systems will factor in barometric pressure) then you have what's called a smart device. This is what OEMs do and good aftermarket systems do which makes the car perform under as many conditions as possible and be efficient.

Another thing to remember with a good engine management system is it doesn't control JUST fuel. Timing is as, if not more, important to control.

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