Need a tach

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Old February 18th, 2013 | 10:11 AM
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jjokrm's Avatar
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Need a tach

Hey everyone. I'm looking to put a tach in my 68' cutlass convertible rocket 350 so I can monitor what this thing is turning. I want something on the cheaper end for now, either 2-5/8" or 3-3/8" in diameter (nothing huge). Does anyone have any suggestions? I know Autozone has the Sunpro gauges, but wasn't sure if these are ok to go with.

Also, with the distributor, is this considered a breaker-point type ignition system? I want to make sure I get the right gauge.
Old February 18th, 2013 | 10:42 AM
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If you are still running the stock distributor yes, that is a breaker point distributor. HEI would be a larger distributor housing with the coil on the distributor cap.

I would say Sunpro is a decent brand. Be advised many auto parts stores usually carry the "low end" of the brand.
Old February 18th, 2013 | 10:45 AM
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Previous owner of my '69 put an Autometer tach in the dash in place of the clock blank. Not stock for the purist but looks pretty good in a driver. Stock distributor was replaced years ago with GM HEI so the tach simply connects to the tach spade terminal on the distributor.
Old February 18th, 2013 | 11:23 AM
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I use a cheapy sunpro. Works fine.
Old February 19th, 2013 | 10:43 AM
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Thanks guys. Much appreciated!!
Old February 19th, 2013 | 10:44 AM
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So what's the difference and pro's or cons to replacing the stock distibutor with an HEI type distributor?

Originally Posted by hookem horns
Previous owner of my '69 put an Autometer tach in the dash in place of the clock blank. Not stock for the purist but looks pretty good in a driver. Stock distributor was replaced years ago with GM HEI so the tach simply connects to the tach spade terminal on the distributor.
Old February 19th, 2013 | 10:50 AM
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replacing with a non computer HEI will result in eliminating the points. Be advised the larger distributor housing will require modification to your air cleaner housing or a smaller diameter housing.
Wiring the HEI requires using a heavy gage wire direct to the fuse box (a switched tang)so the key will kill the engine. (not a continuous on all the time circut). Also will have to wrap up the old coil wire or do away with it.

Others may chime in with anything I forgot. I made the conversion on my 71 and it is nice not to mess with points.
Old February 19th, 2013 | 10:51 AM
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Performance wise, not a lot. Just don't have mess with points anymore if you don't like that sort of thing.
Old February 19th, 2013 | 02:42 PM
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HEI has less mechanical advance bult in, as a result you need to run more intial advance.

the air cleaner initerference is true for a stock type air cleaner, if you run a non drop base open element there is no issue
Old February 19th, 2013 | 04:39 PM
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Awesome. Thanks again guys.
Old February 19th, 2013 | 09:48 PM
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I use electronic points 70 bucks from napa no points but the same cap and rotor as the points. 70 cutlass 350
Old February 20th, 2013 | 04:53 AM
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Originally Posted by fourtwenty
I use electronic points 70 bucks from napa no points but the same cap and rotor as the points. 70 cutlass 350
What's involved with switching to the electric points? Just curious.
Old February 20th, 2013 | 07:51 AM
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Same as a Petronix type set up. Take out points and condenser replace w E pickup ensure 12V and run it. It works good and keeps the stock dist. They can and do fail, but are generally as reliable as HEI
Old February 20th, 2013 | 08:02 AM
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Originally Posted by RetroRanger
Same as a Petronix type set up. Take out points and condenser replace w E pickup ensure 12V and run it. It works good and keeps the stock dist. They can and do fail, but are generally as reliable as HEI
I'll give this a look. Is it easy to hook up a tach to these? Also, since it would no longer be breaker-point type ignition, would it be electronic ignition (so I know what type of tach to buy)?

Thanks.
Old February 20th, 2013 | 08:05 AM
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Yes the tach will hook to the coil the same way.
Old February 20th, 2013 | 08:14 AM
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Originally Posted by oldcutlass
Yes the tach will hook to the coil the same way.

Good deal. Thanks!!
Old February 21st, 2013 | 06:21 PM
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I spotted a pic of a small, (3" ?) Autometer tach stuffed into the clock hole on a '67. Looked great like a perfect fit. Probably a full dash tear down required but I might give it a go. Looked cleaner then a column lump growth.
Old February 21st, 2013 | 08:51 PM
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Originally Posted by oldcutlass
I use a cheapy sunpro. Works fine.
Yep. They do just fine.
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