I'm sure it's been posted before, but how much duration can be gotten away with in a big inch motor (400) and GM ecm (#7165)? speed density.

or, 305 duration, 350 duration, then can be guesstimated from there.......

hydraulic roller cam
im looking at a 112 lsa, with 230 / 238 duration, to keep the idle smooth enough with a 406 to keep the ecm happy....

heads and everything else will be BIG.
40 lb injectors / .210 intake valves, etc.

(time to go make r1ce pudding!)

chris400

 

I'm using 230-236 with MAF with no problems, and a friend is using 240-240 with SD in a 383.

Other are using 240-250 solid rollers with SD with no problems.

 

thanks for the heads up!
keep them coming......
do ya think a solid roller is going to make much difference on the computer?

I would think the duration issues would pop up, regardless, on the knock sensor.

that actually is by biggest concern with duration.

any tricks / tips better knock sensors out there anyone has heard of?

Thanks People!
Chris400

 

You can de-sensitize the knock sensor using the prom or a resistor in the white wire going to the knock sensor. You will have to know the difference between false knock and real knock though. The duration and the computer isn't a problem. You might need a vacuum resevoir for the brakes though.

 

thanks again for the heads up, 88gta383.

I think i'll be alright on the vac for the brakes, was just unfamiliar with being able to desensitize the knock sensor.

what value resistor will work, any ideas? or is it just as easy to program in on the speed density cars?

nice car, sucks about the old motor letting go!

chris400