I haven't done ANY research yet so I figure I'd ask here first since this board contains the best car guys in the world...yes take a bow folks.

Ever since day 1 I found my 305 TPI IROC-Z has had a rev limit right at 5600 RPM. It wasn't a problem with the TPI but now that I'm carbed I want to surpass that. So far I've gone to a non-computer controlled distributor, stock fuel pump, etc and last week I actually took the computer out all together and gave to it a buddy for his car(ended up solving his problem actually in the process!). Rev limit is still there sadly and the car still runs flawless.

Is this fuel related or spark related? Is there a seperate module that does this to the engine?

Don't tell me it's in the chip hehe

Thanks in advance!

 

I dont have alot of experience with manuals and rev-limiters. However I do have many hours of experience in browsing through Summit catalogs. And revlimiters always come up as an extra you can buy with ignitions. So maybe this one you speak of is built into your stock ignition, and you would have to switch it. Just a thought

 

Might be that your engine is at its limits and will not rev any higher. If the ECM is gone, there is no rev limiter.

 

Denny, there is a built in speed limiter in the ECM's code and I have seen guys who have turned it into a rev limiter, BUT I have never heard of a 5600 rpm limit... My car goes up to 6000 rpm easy and its an 89 Iroc like yours.

Sounds like ignition limits... are we talking in 3rd gear here or what?

 

Possibly severe valve float. The world will never know

Anyone else got an idea?

 

Don't trust me eh Denny? I am the one who wired the damn thing, you don't have a rev limiter. How high of an RPM do you expect to hit with those small stock heads and tiny cam? That's as fast as she'll spin buddy!

 

My experience..... ever since I installed the new gears into my 87 IROC (305 TPI), it will bounce off of the rev. limit from First>second shift (automatic). The engine actually stutters 2-3 times before it shifts right at 5500 RPM's. On my '85 Z-28 305 TPI, it also would hit a rev. limit about 5800 RPM's. Both cars are completely stock with factory chips. I never intentionally hkt the rev. limit, but its very noticable when the tranny laggs to shift gears.

 

these cars dont have rev limiters its either
valve float
ignition
or
fuel delivery

 

Fine! Fine! That's Fine!

I'll just live with it fellas. I'll find a better way to get this 305 into the 10's on a 300 shot All while at or below 5500 rpm.

 

Stevem is right. There is no rev limiter. There is a provision for it in the PROM code, but GM never used it.

 

I also vote for valve float. Sometimes valve float is obvious, but sometimes the engine will just not rev past a certain point. My nephew had a 454 Chevelle that wouldn't go over 5,200. I told him to pop in some Comp Cams springs. The engine suddenly could rev to the desired 6,000 shift point, but was also much stronger above 4,500. A lot of times with weak springs, you start to lose hp even before you get to the valve float rpm.