I hve a 90 camaro RS. I just recently did a engine swap. i took the origonal 305 TBI motor out and put in a 350 TBI motor in. Everything seems to run great except one thing, my tach reads twice the RPM's of what it really is. Ex: if my engine is running at a idle of 680 rpms the tach will read about 1360 rpms. Anyone know how to solve this problem or why its doing this? Thanks Gregg

 

I've had this problem as well... There was a post about wiring a V6 tach with a new capacitor to make it work with a V8 so I did it, will let you know if it solved my problem when I get the damn thing to start (Thursday)!

 

I greatly appreciate it. Please let me know how it goes. Thanks Gregg

 

any word on if your trick worked?

 

When you swaped engines did you uses the same distributer/ignition system, or did you upgrade anything?

 

I used the same Ignition system

 

Was thinking maybe if you had installed an MSD ir something the multiple spark may be screwing with the tach signal, but is not the case here obviously.

 

thanks for the help!

 

Sorry for not replying, had a couple of hurricanes to deal with... I'll be finished cleaning Thursday, then we are bugging-out over Ivan... Not staying around for this one!!!

 

Well, I got her running and drove it around... Tach still reading off by a huge amount even with the new diode. My problem has to be in the tach-filter which is located inline with one of the white wires coming out of the coil plug. The correct one (mine has 2 white wires) will have a diagnostic connector about 4" from the coil that comes out of the loom cover. I still haven't traced mine all the way to the filter yet as I have 8.8mm wires, a strut tower brace, and other crap that make access very tight behind the engine. Right now I have to get her ready for a trip to Atlanta tonight. Hopefully, I'll have a home to come back too!!