When it rains it POURS!!!

[USAFPILOT]

i think the most likely situation is the tach is a little off. I've read numerous times that the tach will read high.

[RedRiderZR1]

Tach is off in my car. Logged it once and realized 7k actual is 8k on my tach. So I know its time to shift when the car tachs out. Thought it was odd I never hit the rev limiter at 7200. Not sure how to fix that. Heard something once about a "tach filter". Not sure what that is or if the car has one of those. But all I know is 7k is 8k on the tach.

[C4Fanatic]

Originally Posted by Kevin

i can't imagine why someone would do that

Me neither, hope I'm wrong and that, as others have said, the tach is reading low at the top end.

[C4Fanatic]

Originally Posted by cvette98pacecar

Dave, Sorry to hear the bad news. Guess you have to get another ZR-1 until you can get the car to Mark or Corey, Dont forget about Aaron (SGC). That is a beautiful car, Are you thinking 385 or 415?

Right now all I want to do is get it fixed and get it back on the road. Another beautiful, sunny 60* day here and the car is sitting in the garage again.

[Paul Workman]

Calibrating the tach is pretty straight forward, and can be done by anyone with average mechanical and some soldering skills. PM me for details.

P.

[rhipsher]

Dave mine is the same way. No limiter. After the top end porting I hit 8k so fast in first but it's only for a split second then its in 2nd gear. Two bit's of advice. Get an impact driver. If you have the original button head cam cover bolts you will have some that you will strip the torx pattern out of. They feel soft. The impact driver is like the Honey Badger. 'IT DON'T GIVE A CRAP." Those screws will come out no problem. Stripped head or not. And if you decide to go the brake booster removal rout, It takes a 13mm socket to remove the 4 bolts that hold the booster to the fire wall. You can remove three of them with a 3/8 drive extension and swivel. But that fourth one that is a pain can be easily removed using a 1/4 drive 13mm socket and extension with a swivel. 1/4 extension is the only one that will fit in between the wiring harnesses the steering column and that sheet metal piece. Done that job three times already

[tomtom72]

Okay, I'm no mechanic so this is fwiw.....from the dummy gallery!

Valves, springs, and cam is the only moving parts under a cam cover on our cars, right? Oh, forgot the cam drive gear and by extension the primary chain set up. My point is you make no mention of a dead miss? How about checking the P/S pump for bearing damage? Or even the W/P or any of the other driven accessories? My reasoning is that in the owner's manual our ECM's shut off the A/C compressor at 4k rpms automatically so no damage can happen due to over reving the compressor.

Remember when they put A/C in the old 72 LT-1 cars? GM had a rule back then, before electronics, no solid lifter motors could get factory A/C because two things would happen. Over reving = compressor damage & the belts were too long and at 6k they jumped off the pulley, unless you used 8 thousand series belts. I had one of those LT-1's and the owner's manual cautioned not to engage the A/C after 3500 rpms and / or not to use the A/C if sustained expected engine speed would exceed 3k rpms for any length of time. To prevent all that they used the tach face from an L48 motor to stop you going to 6.5k to shift!
Peace!

Tom

[Torchred96]

Having reduced all the harmonics (harmonies?) of injectors, ignition, flywheel, timing chain, etc., after I got done with my plenum pull, I was surprised to hear a soloist toward the front of my engine singing a capella. Turns out mine was a water pump.

To eliminate all the accessories as a culprit, with the engine running, I put a 1/2 in drive socket wrench (VERY CAREFULLY) into the serpentine belt tensioner and released tension on the belt until all the accessories stopped spinning, engine got very quiet.....soooo nice to hear the LT5 with no noise.
Anyway, Hope yours turns out well. Learning how to change a lifter (and while I'm in there timing chains) on my LT5 is nice to know, but I'd rather wait until I HAVE to know to learn about it.

Good luck with it.

[Kevin]

Originally Posted by rhipsher

Dave mine is the same way. No limiter.

you may want to get the car retuned to fix that. who did the tune on your car?

[rhipsher]

Originally Posted by Kevin

you may want to get the car retuned to fix that. who did the tune on your car?

I've had the car 5 years and never had it tuned. Who ever owned it before me had the 1-4 shift disabled. I never have to press the clutch down to start the car amongst other things. I know that the tac needs to be recalibrated because the first time I took the car to top speed to where it had no more to give in 5th gear my tac was sitting at 7100-7200 rpms. After top end porting I ran the car top speed all out again to 181 and the tac was at 8000. But both times the tac was always at 950 rpms at idle. But im getting ready to have corey do headers and all so he with tune the car where everything should be.