Total Timing Recommendations?
06-10-2016 | 08:12 PM
#3
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Joined: Feb 2009
Posts: 8,356
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From: NW Michigan
I'd have to agree with griff. You can always bump a deg or two after you get some time on it. Just an FYI you can find used snap on bore inspection cameras for under 150.00 on eBay. Might be a good investment and good to have in your tool box anyway. Spark plugs tell a lot but don't always show aluminum specs.
06-13-2016 | 05:00 PM
#5
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Joined: Jul 2004
Posts: 11,332
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From: chicago
I'd be more concerned with the timing curve, than the actual total number.
There are many factors in determining the proper time to light the combustible fuel/air mixture. One of the main factors, is RPM (piston speed). Then there is the octane, camshaft design, charge density, chamber design, piston design, charge temperature, bore size, and so on.
I think alot of supercharged engines, get hurt from bringing the timing in too quickly, as well as being too lean. I once believed locked timing was the way to go, until I did some testing on the dyno. When I pulled 8-9 degrees of timing in the midrange, and saw a increase in power, and decrease in EGT, I learned something new. If an engine likes 34 degrees at 6000, and 26 degrees at 4000, i see it running 34 degrees at 4000, no different than running 42 degrees at 6000. When you are firing a plug so early, that it actually causes a loss in power, you have way too much timing. Flip side, if you have too little timing at max rpm, you will see high EGT temperatures, and a loss of power.
With that being said, I ran 34* locked on my 9:1 supercharged 468's making 6lbs boost for years, and never tuliped a valve, damaged a piston, or anything like that. I ran them cold water temp wise, and on the rich side for fuel. Without a dyno, its very hard to tell what the engine will like for timing. Sure you can read the ground strap on the plug and look for the heat marks, but then the variable can also be, the spark plug style, heat range, etc.
There are many factors in determining the proper time to light the combustible fuel/air mixture. One of the main factors, is RPM (piston speed). Then there is the octane, camshaft design, charge density, chamber design, piston design, charge temperature, bore size, and so on.
I think alot of supercharged engines, get hurt from bringing the timing in too quickly, as well as being too lean. I once believed locked timing was the way to go, until I did some testing on the dyno. When I pulled 8-9 degrees of timing in the midrange, and saw a increase in power, and decrease in EGT, I learned something new. If an engine likes 34 degrees at 6000, and 26 degrees at 4000, i see it running 34 degrees at 4000, no different than running 42 degrees at 6000. When you are firing a plug so early, that it actually causes a loss in power, you have way too much timing. Flip side, if you have too little timing at max rpm, you will see high EGT temperatures, and a loss of power.
With that being said, I ran 34* locked on my 9:1 supercharged 468's making 6lbs boost for years, and never tuliped a valve, damaged a piston, or anything like that. I ran them cold water temp wise, and on the rich side for fuel. Without a dyno, its very hard to tell what the engine will like for timing. Sure you can read the ground strap on the plug and look for the heat marks, but then the variable can also be, the spark plug style, heat range, etc.
Last edited by MILD THUNDER; 06-13-2016 at 05:06 PM.
06-13-2016 | 07:19 PM
#7
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Joined: Feb 2009
Posts: 8,356
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From: NW Michigan
I'd be more concerned with the timing curve, than the actual total number.
There are many factors in determining the proper time to light the combustible fuel/air mixture. One of the main factors, is RPM (piston speed). Then there is the octane, camshaft design, charge density, chamber design, piston design, charge temperature, bore size, and so on.
I think alot of supercharged engines, get hurt from bringing the timing in too quickly, as well as being too lean. I once believed locked timing was the way to go, until I did some testing on the dyno. When I pulled 8-9 degrees of timing in the midrange, and saw a increase in power, and decrease in EGT, I learned something new. If an engine likes 34 degrees at 6000, and 26 degrees at 4000, i see it running 34 degrees at 4000, no different than running 42 degrees at 6000. When you are firing a plug so early, that it actually causes a loss in power, you have way too much timing. Flip side, if you have too little timing at max rpm, you will see high EGT temperatures, and a loss of power.
With that being said, I ran 34* locked on my 9:1 supercharged 468's making 6lbs boost for years, and never tuliped a valve, damaged a piston, or anything like that. I ran them cold water temp wise, and on the rich side for fuel. Without a dyno, its very hard to tell what the engine will like for timing. Sure you can read the ground strap on the plug and look for the heat marks, but then the variable can also be, the spark plug style, heat range, etc.
There are many factors in determining the proper time to light the combustible fuel/air mixture. One of the main factors, is RPM (piston speed). Then there is the octane, camshaft design, charge density, chamber design, piston design, charge temperature, bore size, and so on.
I think alot of supercharged engines, get hurt from bringing the timing in too quickly, as well as being too lean. I once believed locked timing was the way to go, until I did some testing on the dyno. When I pulled 8-9 degrees of timing in the midrange, and saw a increase in power, and decrease in EGT, I learned something new. If an engine likes 34 degrees at 6000, and 26 degrees at 4000, i see it running 34 degrees at 4000, no different than running 42 degrees at 6000. When you are firing a plug so early, that it actually causes a loss in power, you have way too much timing. Flip side, if you have too little timing at max rpm, you will see high EGT temperatures, and a loss of power.
With that being said, I ran 34* locked on my 9:1 supercharged 468's making 6lbs boost for years, and never tuliped a valve, damaged a piston, or anything like that. I ran them cold water temp wise, and on the rich side for fuel. Without a dyno, its very hard to tell what the engine will like for timing. Sure you can read the ground strap on the plug and look for the heat marks, but then the variable can also be, the spark plug style, heat range, etc.
06-13-2016 | 07:20 PM
#8
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From: chicago
06-13-2016 | 09:50 PM
#9
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Joined: Feb 2009
Posts: 8,356
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From: NW Michigan
Much better route but must say I'm surprised how many I see and or hear that are locked in btwn 30-34 and never have issues. I would imagine awareness and knowing has to help. Some who may drive with complete different style etc could have issues as mentioned.
