Good news is, my big bad Buick is back on the road after a couple of weeks of engine and tranny work. The car seems to be running great The problem I have chosen to chase first is a hood tach that doesn't want to work for me. I bought one of Postons reproduction tachs, had it painted and bolted it on. When we first got the hood back on and hooked it up it was dead. The needle will jump for a second when the car fires up and then just sits at almost zero. What I mean by that is that when you shut it down the needle drops an 1/8th inch. This morning I fired it up from cold (electric choke is sooo much nicer than no choke!) it looked like is was going to work. The needle was pretty jumpy and it wasn't registering correctly. After a quick stop for gas it was back to yesterdays act. I have an HEI on the car which has an MSD module in it. I do not have the full 6AL box or anything, just MSD internals and coil, cap, rotor, wires. Is this the problem? I hate to have to call Postons as the technical advice there so far has been kind of weak IMO. I am hoping you guys might know whats up with it.
Just a thought here. SOme years back I ran into a replacement hood tack that did not work, Actually it did work, but only at night. What they had done is run the 12 volt source wire for the tach and the light wire for the tach to the same point, so unless the headlights were on, there was no 12 volt source for the tach to work. Could be waht's going on with yours. Jim Burek P.A.E. ENTERPRIESES
Thanks for the hint. I just tried it with the lights on and no go. I had already checked the wiring to the tach, before and after the connector. Power is there and grounding the tach signal kills the engine. I must have a bad tach. I also called MSD's tech line. They told me that no tach adapter is needed with their super HEI kit. It should be running off of the standard tach port.
I've run into similiar problems with Year Ones hood tach. They are probably made by the same company. I find that when the car is sitting in the sun and the hood gets hot, it won't work. If you had it painted and the body shop baked it, that may screwed it up. There was a sticker on mine that said the unit should not get over 170 or so degrees. Whatever you do, do not spray anything in the tach to try and get it to work, that will destroy the silkscreening on the numbers and it will be messed up. If you get another one, ask the body shop to let it air dry. also, try tapping it to see if it frees up. It may take a while to free itself if it is a little tight. good luck.
year one tach Hey Guys I have the same problem with my tach you have to tap it every1 out of five times.They all have the same problem. the word REPRO means junk.Your not alone. steve
Mine had a sticker about the temp too. I called the paint shop and they air dried it. I had taken apart my old one because it didn't work either. There isn't anything in there that needs to loosen up. It is electronic and when turned upside down the needle flops about. I called Postons and they claimed they haven't had any problems with them. What bugs me is that I had a tach mounted temporarily on the floor and it was working fine with my old HEI. I put the new dist with the "Ultimate HEI" kit from MSD and now neither one works right. I am going to try swapping to a stock module to see if MSD was wrong and it is their kit causing the problem. My fairly new, but admittedly cheap, floor mounted tach doesn't register above 2000 rpm. The hood tach seems to do the same thing when it is working. I will also rewire the whole thing tonight.
I wouldn't say the problem is in the tach itself, but the fact that it is mounted on the hood which gets hot and above the hot engine. Mine needs a tap when the car is sitting in the sun for a long period. then it works fine. Obviously the hood tach is a looks thing and not necessarily a well thought out design.
hot tach's Has anyone thought about installing some thin mica under the tach to buffer the heating effect? my $.02
I HAD ASKED THAT SAME QUESTION ABOUT THE TACH ABOUT 2 MONTHS AGO AND GOT A VERY ENLIGHTENING REPLY FROM LARRY70GS. IF YOU ARE TRIGGERING THE BOX WITH A MAGNETIC PICKUP, YOU NEED MSD PART #8920. IF YOU ARE USING POINTS AND THE WHITE WIRE, YOU NEED PART #8910. I THEN SPOKE WITH MIKE T AT YEAR ONE (ALSO A MEMBER), HE GAVE ME MSD'S NUMBER - 915-857-5200 AND I SPOKE WITH A TECH. LARRY70GS WAS RIGHT ON THE MONEY, I ORDERED WHAT I NEEDED FROM MIKE T, ABOUT #50.00. I HAVE NOT HOOKED IT UP YET BUT WILL THE WEEKEND OF THE 19th. GOOD LUCK, CHRIS
I took a few minutes last night and rewired it USING THE THE SUPPLIED HARNESS, duh!, and it worked perfectly. Thanks for the tips anyway.
Easy first test: Any time you get a tach that doesn't work with an HEI and you suspect the HEI to be the problem, disconnect the tach in the car. Next, connect a common tach-dwell meter to the TACH termial and check the HEI. WTach-dwell meter works, problem is in the tach or its wiring, doesn't, HEI problem.
