Retard Timing In High Gear

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Retard Timing In High Gear

Postby cps57 » Thu Aug 30, 2007 8:10 pm

Question for any of you that have tried this. On a nitrous big block chevy with 2 kits equaling 500-600 shot if you start retarding timing in the upper rpms of high gear will it pull harder, run faster, mph faster? Or should one just tune your kits like normal and only pull the set amount of timing out? I was told that if you could reach the distributer as you were going down the track and turn it by hand (retarding it) that it would make it pull harder. Well we can do just that now with these digital boxes. So is it faster or not? Hoping someone has tried this and could give some pointers on how much timing to pull and what rpm to start it at, IF ANY?


Posts: 495
Joined: Sun Oct 30, 2005 1:25 am
Location: Phoenix AZ area

Postby Stevespeed » Fri Aug 31, 2007 12:19 am

Think about what's going on as you go through the gears going down the track. This is the biggest thing people have a hard time grasping when they take their engine off the dyno and want to run the exact same tuneup at the track. The dyno can apply load but the typical sweep test only lasts a few seconds. Compare the heat build in the chamber between a few second pull with plenty of water capacity on the dyno against limited water capacity and stretching the run time going down the strip or making laps. Far different. Try pulling some timing in high gear. No magical number as finding one amount fits all. Depends on how edgy your tuneup is to begin with.

Hendrens Racing Engines
Posts: 400
Joined: Tue May 29, 2007 5:43 pm
Location: Rutherfordton N.C.

Postby Hendrens Racing Engines » Fri Aug 31, 2007 8:46 am

We found some interesting things on our turbo SB2.2 engine that was having detonation problems at high boost [36 lbs]. first eliminated the electric water pump and installed a Stewart stage three pump,made up pulleys to run the pump 10% faster than crank speed. installed -12 lines from pump to bottom center of the block with a restrictor behind the pump with a 7/16 hole,forcing most of the water to the bottom center of the block.installed restrictors at the 4 outlets of the cyl heads where water enters the manifold.
All of this increased the pressure and scrubbing action behind the combustion chamber walls and prevented the water from flashing to steam.we also installed a Schraeder valve in the radiator and using a 28 lb radiator cap pump the radiator up with air until you hit the 28 lbs. this raises the boiling point of the water way up. the combination of all this cured the problems completely and the same modifications would probably help you N20 guys as well.Bill
Hendrens Racing Engines
1310 U.S.Hwy 221 North
Rutherfordton North Carolina 28139


Postby cps57 » Fri Aug 31, 2007 2:38 pm

I think we'll try that .
Thinks for all the great help!!! lol

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