Tach too fast

[Steve V.]

Just cranked up my 1960 230 hp engine after sitting for a year of so. The car did not come with a tach drive distributor and I added one recently. The tach reads way to fast. It goes all the way straight down at 30-40 mph. What could be the problem/

Steve

[Roger W.]

Re: Tach too fast

The distributor driven tach is different than the generator driven tach. You will need a tach that is specific for distributor drive.

[Steven B.]

Re: Tach too fast

Just cranked up my 1960 230 hp engine after sitting for a year of so. The car did not come with a tach drive distributor and I added one recently. The tach reads way to fast. It goes all the way straight down at 30-40 mph. What could be the problem/

Steve

Steve, your engine used a generator driven tach, which drives at a different speed than the distributor drive. You should have the generator drive. Steve

[Steve V.]

Re: Tach too fast

OK guys, sorry for not proofreading my post. I installed a tach drive GENERATOR not distributor. Tach reads to fast with the generator drive.

Steve

[Bruce B.]

Re: Tach too fast

Steve,
The generator driven tach runs twice as fast as a distributor driven tach.
So your tach sounds like it needs to be distributor driven which is 1/2 the speed of the generator drive.
I might have a generator tach if you need one.
Bruce B

[Joe R.]

Re: Tach too fast

Steve,

This problem is solved by re-calibrating the tach. ANY, well nearly ANY of the advertisers for instrument restoration in the "Driveline" can supply this service.

JR

[Steve V.]

Re: Tach too fast

Interesting Bruce, Why would a 230 HP car have a distributor driven tach? Is there any way to tell externally if the tach was designed for a distributor drive. Is the redline different? This one redlines at 5500. The car came with a non tach drive generator and a HEI distributor when I got it. What's involved it removing the tach? I have had the cluster out and replaced all the wiring but have not removed any gauges as they all work OK.

Steve

[Steven B.]

Re: Tach too fast

Interesting Bruce, Why would a 230 HP car have a distributor driven tach? Is there any way to tell externally if the tach was designed for a distributor drive. Is the redline different? This one redlines at 5500. The car came with a non tach drive generator and a HEI distributor when I got it. What's involved it removing the tach? I have had the cluster out and replaced all the wiring but have not removed any gauges as they all work OK.

Steve

Steve, from the factory the 230 HP had a generator driven tach. The redlines are different for hydraulic vs. mechanical lifter engines: 230, 245, and 250 HP have hydraulic and 270 and 290 HP have mechanical. Your generator drive was likely removed. Check the tag to determine which part number your generator is. You can purchase generators and tach drives. Your 5500 tach is correct for the 230 HP engine. You just need the generator and generator drive unit. An easy install. Bruce is correct about the gearing. (Bruce is a sharp guy and his advice is always good.) I have a couple of AC 8000 RPM tachs and converted one for generator driven use. Bruce's gearing is correct as mentioned. Steve

[Steve V.]

Re: Tach too fast

Did any of the carburetor engines have a distributor driven tach?
Steve

[Ray K.]

Re: Tach too fast

Steve,

The 1962 Corvette was the first to use a distributor driven tachometer for carburetor engines.

Ray