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Tachometer Gear

J

JOE BYRNE

Guest
Hey Guys,

I have learned so much since I have joined the Action Center. I now have a tachometer problem on my 73 that I need your help on. About a month ago it stopped working so I bought a new tach gear for it (cheapest fix). I installed it and it worked for about an hour. When I took off the cable it looked just like the one I had taken out. It has two teeth that have been damaged. Is the problem the gear shaft in the distributor? If so how big of a job is it?????

Thanks,

Joe
 

Jack

Well-known member
Joined
Dec 27, 2000
Messages
1,825
Location
Florence, SC (Timmonsville SC)
Corvette
71 War Bonnet Yellow VERT 71 BH Blue CPE (SOLD)
Joe: The teeth on the mainshaft are probably bad ... you'll need another new crossgear and new mainshaft. Good chance the distributor body has wear in mainshaft bore ... that bore may need to be bushed and reamed to fit. Too much slop in bore-to-mainshaft can cause crossgear-to-mainshaft gear misalignment and can result in failure of either or both tach gears

Remove distributor. You'll have to drift out the distributor drive gear's roll pin and pull distributor gear from bottom of mainshaft ... the mainshaft comes out the top ... then you'll have to press off the breaker point cam from old mainshaft and press it onto new mainshaft ... slide mainshaft back into housing and press the distributor gear onto and its roll pin into mainshaft. If you don't have the proper tooling & skills for this (or know a shop/someone who does) you might wanna consider a factory-rebuilt distributor.

If originality is not required, a later HEI distributor (75 up) works great but requires OE Mechanical tach to be replaced with OE Electronic tach from 75 thru 79 vette ... IMHO the end result is superior to the 68 thru 74 setup ... but swapping tachs is an aggravating tight squeeze. G'Luck.
JACK:gap
 
J

JOE BYRNE

Guest
Jack,

Thanks for the info. Sounds like electronic is the way to go. I appreciate the help.

Joe
 

GTR1999

Well-known member
Joined
Sep 4, 2003
Messages
1,146
Location
New Haven CT
Corvette
1969,1972,1975
Chances are correct the main shaft was bad too. also the replacement gears are not as good as the original cross gears. I've had bad ones that were brand new,same with the replacement main shaft. The distributors are rebuildable and will work fine once rebuilt for years. If you decide to keep it you can talk to Hitech in FL they make gears and rebuild them.
 
G

George Black

Guest
Joe: Jack and Coupeman have some excellent comments and advice.

Do not competely rule out rebuilding your existing distributor. There are several excellent rebuild shops; cost is normally very reasonable for the work. I can provide a few good rebuild shop names.
I have always attempted to avoid having to remove the driver's side dash panal. It can be a major job due to steering column, switches, gauges, etc. etc. Everyone that I have known that has done it says it is a time consuming project. Rebuilding the distributor would avoid the new electronic tach/panal removal issue. Just something to think about.
---Patricki
 

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