How much timing on a racing gen 3

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RockinRobin

RockinRobin

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I have had my new build out to the track twice now and have made 7 passes with it to get the EFI fuel tuning close to being right, now the focus will be timing. Timing is being controlled by a MSD 6-Hemi box. Advance is controlled by RPM only in my situation. I have had it ramping up to 30 degrees total advance at 7000 rpm which has produced okay results and the plugs look fine. I talked to someone who builds racing gen 3's and he told me they usually do best at around 25 degrees on the engine dyno with the same cam as mine, so I will be retarding things 2 degrees at a time and will see how it affects ET. I don't know how much timing these motors will take, except that I've already done 30 degrees with no problems.
 
When my 426 was dynoed, the best pulls were at 28. I also have heard and have experienced with other gen 3 builds, that they do no require " normal" timing. Usually around the 25 or less. Obviously, real world and dyno conditions vary.
 
408 swinger said:
When my 426 was dynoed, the best pulls were at 28. I also have heard and have experienced with other gen 3 builds, that they do no require " normal" timing. Usually around the 25 or less. Obviously, real world and dyno conditions vary.
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Is your 426 a gen 3 or a gen 2?
Going to make 1st pass at 30 for reference, then try 28 and see what happens. Then 26.
Thinking about finding a chassis dyno in the area. Problem is most of them aren't familiar with Mopar, just late model Ford, Chevy and ricers.
 
Look up the engine masters episode discussing this very topic on two different gen 3 Hemis. I’ll see if I can find it.
 
Also engine masters episode 79 in season 5 they speak about timing also on a modified gen 3 making around 500hp. Brule found that 26-28 degrees is where it was happiest.
 
Just put a timing light on it and screw the distributor around! HAH!
See you tomorrow night.
 
RockinRobin said:
Is your 426 a gen 3 or a gen 2?
Going to make 1st pass at 30 for reference, then try 28 and see what happens. Then 26.
Thinking about finding a chassis dyno in the area. Problem is most of them aren't familiar with Mopar, just late model Ford, Chevy and ricers.
Click to expand...
Gen 3. 6.1 based 426.
 
Report: I made passes at 30, 28 & 26 total timing. It seemed to like 26 best. Will probably leave it there and tweak fuel tuning, then lock everything in and go racing.
 
TT5.9mag said:
What did it run?
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6.55 @105mph D.A. was 3300. We'll see how it does when the weather is cooler.

Also it has straight 30 weight break in oil in it right now. changing to 10w40 this week. Don't know if that will make a difference.
 
RockinRobin said:
6.55 @105mph D.A. was 3300. We'll see how it does when the weather is cooler.

Also it has straight 30 weight break in oil in it right now. changing to 10w40 this week. Don't know if that will make a difference.
Click to expand...
Nice can you tell us how the runs differed between the different timing numbers? Like how sensitive was the engine to timing adjustment.
 
TT5.9mag said:
Nice can you tell us how the runs differed between the different timing numbers? Like how sensitive was the engine to timing adjustment.
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It seems to be more sensitive to the DA than the timing adjustment.
@ 30 degrees 6.64 102mph DA 3450
@ 28 Degrees 6.57 104mph DA 3350
@ 26 degrees 6.55 105 mph DA 3300
Had a 2nd pass @ 26 degrees where it spun and had a bad 60 Ft. but still ran a 6.57 105mph DA 2900. Prob. would have been around 6.52 if it hooked.
Last week it did have a 6.55 pass with 30 degrees of timing but the DA was down to 2850.
60 Ft. is consistent around 1.46 I think it has more in it if I tweak fuel tuning some more and maybe try 24 and 25 degrees timing. It used to 60 ft. around 1.42 on carburetor years ago.
 
Now that the fuel tune has stabilized, I have too much power to keep it from spinning at some tracks. In 88 degree weather (2600 DA) when it hooks it pulls a 1.43 60', a 4.12 330' and a 6.50 8th mile@106mph. I've had it to 2 tracks. At one it hooks reliably (better track prep) and at the other it spins 50% of the time. I am trying to chassis tune/shock adjust/tire pressure that issue. We are getting into some weather in the 60's and 70's soon down here and I'm looking forward to some mid to low 6.40's if I can can get it to stay on the tire.
 
We are having a double header at I30 Sunday if you are bored….
 
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