I know this has been covered but I can't find anything using the search.

I will be buying a hood tach for my 69 and wonder what others have to say about who to buy from. I have had my best luck with Ames but at $209 their tach is the cheapest and may be of lesser quality than some others.

Also I need one that works with a GM HEI.

I would appreciate any advice from others who have been down this road. Any insallation tips would be welcome, is the 3.75" hole standard for any "stock looking" hood tach I buy? Thanks

I bought mine from The Parts Place. Their better quality one that is screwed together not glued with silicone. It does require a little larger hole. I think it was 4-1/4" but can't say for sure without finding the paperwork from it. I does work fine so far on my HEI.

I'm not sure if the diameter of the hole is important, but the location of the hole is.

One of the PO's of my convertible installed a hood tach. When they did, they used the template for the GTO. So my tach is in the wrong location. Not only the sheet metal was cut, so was the under structure.

So do the research to find the correct size and location.

I have a template for the hole location I will scan for everyone. I'll bring it to work tomorrow1