is there any way to change the rev limit on the 420a and what is better to do, long rods with 8.6:1 pistons or eagle h-beam standard length rods if i am going to run a turbo

My rev limiter was negated when I installed my programmable MSD DIS-2. I set it my rev limiter to 8500rpm. You definitely want to upgrade your valve train though, and make sure it's even necessary that you up your rev limiter.

Originally posted by devvin
My rev limiter was negated when I installed my programmable MSD DIS-2. I set it my rev limiter to 8500rpm. You definitely want to upgrade your valve train though, and make sure it's even necessary that you up your rev limiter.

Impossible. You'll still fuel cut at 7200 RPM, unless you have something else providing fuel, and you'll still spark cut at 7800RPM unless you have something else providing spark trigger signals. Those RPM are hardcoded into the factory ECU.

Originally posted by DarkOne

Originally posted by devvin My rev limiter was negated when I installed my programmable MSD DIS-2. I set it my rev limiter to 8500rpm. You definitely want to upgrade your valve train though, and make sure it's even necessary that you up your rev limiter.

Impossible. You'll still fuel cut at 7200 RPM, unless you have something else providing fuel, and you'll still spark cut at 7800RPM unless you have something else providing spark trigger signals. Those RPM are hardcoded into the factory ECU.

Yes, I control spark with my programmable DIS-2 and I control fuel with my split second r4 program.

Originally posted by devvin
Yes, I control spark with my programmable DIS-2 and I control fuel with my split second r4 program.

No, your factory ECU is still sending the spark trigger signals to the DIS. You'll still cut at 7800 RPM, regardless of what you think.... and the stock injecotrs, if you're doing an 8-injector setup, will still shut down at 7200RPM. if the R4 is a standalone fuel controller like a MS, then you'll be fine to 7800RPM, and no more.

I must have hooked it up incorrectly somehow because I have hit just under 9000rpm before. I know you know what you're talking about, but I can promise you that I'm telling the truth about my particular setup. I was actually suprised when it happened the first time because in the instructions for the MSD it stated that the unit would not override my factory Rev-limiter, and yet it did. It freaked me out. I can't explain why my car revs that high without cutting spark. I'm happy it does though.

Originally posted by devvin
I must have hooked it up incorrectly somehow because I have hit just under 9000rpm before. I know you know what you're talking about, but I can promise you that I'm telling the truth about my particular setup. I was actually suprised when it happened the first time because in the instructions for the MSD it stated that the unit would not override my factory Rev-limiter, and yet it did. It freaked me out. I can't explain why my car revs that high without cutting spark. I'm happy it does though.

Your tach is wrong. :)

Your tach is wrong. :)

how could my tach be wrong? It sits right under 1k at idle and seems right in relation to my speedometer as far as needle position while on the highway. Could it be wrong only at high rpm??? I don't understand how my tach could be fine with a functioning rev-limit at 7200rpm and then I install an MSD dis-2 and the NEXT day the car revs out to almost 9000rpm with no rev-limit so then my tach is wrong?. That makes no sense. Please explain. Thanks Dino.

Originally posted by rykki
long rods with 8.6:1 pistons or eagle h-beam standard length rods

I'd go with the long-rod kit, as it does two main things:

1) provides longer dwell time at TDC and can increase torque
2) provides better rod length to stroke ratio, which changes the angle at which pressure is applied to the rod during compression and power strokes. This allows you to turn higher RPMs (if you can support it) and applies less stress to the rod.

Originally posted by rykki
is there any way to change the rev limit on the 420a

MSnS? AEM? Gotta have a standalone or a piggyback that will alter spark and fuel (wait I thought I just read that somewhere?)

Unless you have a 97 then you can go with the AFX/ECU and but you are restricted to their settings.

MB

i have a 97 gs, but i am looking for the best parts because i am building up for a turbo......

how much is MSnS?

all help appreciated....

MSnS is very affordable but I suggest you do a search on these forums to see what is involved and where to get one before jumping for it. the unit can be had preassembled for $300-$400 then you need relays wiring and some GM sensors.

-Kevin

price not bad, but how har is this to install, and what do i benefit from it???

Originally posted by rykki
price not bad, but how har is this to install, and what do i benefit from it???

If you look up at the top of this forum, there is a Tuning section. Inside are all kinds of threads about people setting up MSnS on their cars. Basically, it's like a stand alone for your car. You still use the stock ECU, but the MSnS can control all your fuel and spark. This allows you to move the rev limter wherever you like and make sure you have the fuel and spark to handle it.

Spend some time reading around in there. MSnS is the least expensive way to get near stand alone tunability for your car. And it's barely more than the SAFC.