timing question

can anyone tell me what timing is safe when using NOS plate setup. I run a 557bbf, 14.5-1com. this engine has the best parts and pistons are made for NOS incase I want to use. timing set on motor is 30-32 advance. I will need timing info for 100 shot, 150shot and 175 shot, may go to 210shot but not likely. thanks Bob

rd,

post some more details if you dont mind ..... heads , cam, what ignition system, which nos plate , etc..... the more details the better....then we can get you some baseline to start from

bruno wrote:rd,

post some more details if you dont mind ..... heads , cam, what ignition system, which nos plate , etc..... the more details the better....then we can get you some baseline to start from

x2 even with good parts that thing should be making good power on its own, then one bad tune up and boom, sounds like a good combo

thanks for the feedback guys, lets see now, about my engine. like i said it's a 557, full race ported A460 new style heads (flow around 450+), matching intake, (single 1150carb worked by Tony Wilson out of Memphis) comp cam .800 lift roller with HS 1.73 rockers, 1.35 intake valves, 1.88 ex. msd 7al-2 box, msd fixed distributer, elec. water pump, BTE powerglide with 1.80 stright cut, 10cluch drum, etc. etc, best of everything, 9"proheavy big barring chuck with moser 35 spline. any thing else you all need?

is the motor zero deck? how thick are the gaskets what type are they? what type of Rings? what is the gap on the rings? who made the pistons are they dome or flat top? how far down is the top ring on the pistons? what is the cylinder to wall clearance? What type of N20? plate, fogger Diffuser. who is it made by what company? what is the lobe seperation on the cam? duration on intake and exhaust?

0.007-0.009 deck, pistons are from JE and set for NOS/BLOWER rings are made for that setup also. gap is .007/bore inch, sheet calls for that when got rings. can't remember duration but is around 292/289. dome pistons, gasket will come from Charlie Evens, with thickness not deturmand yet, I am re-building this and thought I would try the NOS which I had not before. I am working with several guys that are on this and another 460 site to make sure it runs at it's best, on motor with 3300lb car/me it ran 5.62 and didn't hook good, only a 1.45 60 ft. it is an NOS plate

is it a cheater plate or big shot, with what you have you should be 60 better than that, on my 532 on motor i can do a 1.42 on the spray some 1.32 with stock suspension and 28x10.5 tires and i have not scaled the car or set the limiters, your tune up with a dome piston and almost zero deck is going to be critical. the compression will not hurt it most of the guys that i run with try to get .063-100 quench more the better with nos exact opposite of a NA motor.

I'm not really understanding what you mean by ".063-100 quench", and that 60ft time I gave you was wrong, looked at my time slips and the times were between 1.19 and 1.21 on motor.

I do not know the official way of describing, but here is my layman's definition. the quench is the area between the pistons and valves the air has to move/travel in the combustion area most NA motors have a zero deck or tight quench area they try to get the piston even with the block and close to the head as possible with minimal valve clearance. this makes the air/fuel charge compress tightly as in enters and exits the combustion chamber effectively making more power by mixing the fuel/air charge tightly resulting in a cleaner/more faster burning mixture. On a N20 motor "most" builders try to loosen this process so it is not as violent entering and exiting the chamber by either leaving the piston in the hole/ thicker head gaskets or more cc heads. this allow the delivery system plate/ fogger/ whatever to mix the fuel mixture and allows a softer hit in the combustion chamber as some times the combustion process with a zero deck and tight quench area can ignite the process early/late due to heat in this area by allowing more quench you have a little larger tuning window.

hope this helps and does not confuse you even more

the one piece of advice i can give you from experience is gap the rings a little looser than what is called for it is better to have a little blow by then have the rings touch. if the motor is zero deck if you are going to rely on the spray on race day put am .80 thick cometic or fel pro mls gasket on it. It sounds like you are fast already, how fast are you trying to go?

ok, that's what I thouht, the car is fast but if a person builds a car like I have and expectations are flawed because of some mistakes on my part then it isn't that I want it to go faster I just want it to run like it should and was built to. the head gasket thing makes sinse to me, i was running a .40 head gasket and was tapping to heads and flatning out the plugs. all that has been fixed and everything looks good, i don't plan on hitting more than 175 shot and most likely just a 150 shot. I am wanting to run in a 5.50 index class that we have down here, they also run a 6.00 class which i have to de-tune to slow down on motor, I just want to have the juice incase I am short of the 5.50 mark. the .80 head gasket sounds like it will fix most of the problems I was having. thanks so much guys for the advise and if you all have more, let me know. thanks again Bob