Im chaning over from the old points to a new HEI unit and have a question. Do I need to install a resistor between my factory Tach and the new HEI. thanks 67 small block.

I didn't have to, on my 68.
Dale

I'm curious about this also as I got a tach from Classic Industries for my '67. In their downloadable catalog it says it's not compatible with HEI, but on the website it says it is HEI tested.

I recently converted my 327 to HEI, but haven't gotten around to installing the tach yet and would be curious if anyone has used that same tach.

http://www.classicindustries.com/controller.cfm?type=product&action=productDetail&keyword=tach&productYearId=1&startRow=1&sortBy=1&sortOrder=1&resultsPerPage=10&currentPage=1&productId=61315&productSearchCatalogId=1

I did the switch on my 69, plugged in the wires, and the tach sprung to life. No problems at all.

I'm curious about this also as I got a tach from Classic Industries for my '67. In their downloadable catalog it says it's not compatible with HEI, but on the website it says it is HEI tested.

I recently converted my 327 to HEI, but haven't gotten around to installing the tach yet and would be curious if anyone has used that same tach.

http://www.classicindustries.com/controller.cfm?type=product&action=productDetail&keyword=tach&productYearId=1&startRow=1&sortBy=1&sortOrder=1&resultsPerPage=10&currentPage=1&productId=61315&productSearchCatalogId=1

I got the same info from Classic Industries, but now everyone tells me I can just plug the tach into the HEI.

If you search for this topic you'll find a wide range of experiences using electronic ignitions with factory tachs. Some plug and play while others fry and die. Tachs are somewhat tuned to the ignition they were made for, so changing ignitions will often change how they work (or don't work). There is a lot of variation in the performance of tachs and ignition systems.

My recommendation is to search for "tach filter" in this forum and you'll find a little DIY kit with an adjustable resistor on it that you can build for less than $10. It kind of acts like a volume control for the tach signal, except it's actually filtering some of the higher frequencies out. Turn it up until it works and it'll work a long time without risking damage to the tach. Stay away from a popular manufacturer's (name omitted) "tach adapter". I'm not sure what it is, but its not the same thing as the tach filter, it's much more expensive, and I know a few tachs that have been fried with them. The tach filter project is passive, it's safe, simple, cheap, and good insurance IMHO.

My factory tach hooked straight up and has worked ever since for the last 15 odd yrs and 100,000 odd miles.