C3 HEI Distributor Conversion
Thread Starter
Intermediate
Joined: Oct 2018
Posts: 39
Likes: 0
From: Jacksonville, FL
C3 HEI Distributor Conversion
My 1973 Corvette is at the shop and my mechanic says it's running poorly and they want to replace/upgrade the distributor to an HEI set-up with vacuum advance. They're also saying that HEI does not allow for a mechanical tachometer. I'm out of my depth here but, am reluctant to make a change that would require an electronic tach added to the dash and the stock one being disabled.
Is HEI really necessary or do I need a better mechanic? Does anyone know of one in Jacksonville, FL?
Thanks!
Is HEI really necessary or do I need a better mechanic? Does anyone know of one in Jacksonville, FL?
Thanks!
Race Director
Joined: May 2006
Posts: 18,736
Likes: 2,582
What exactly is wrong with the original distributor that it requires replacing?
If you really want to go that route, here is a mechanical tach drive HEI distributor https://www.summitracing.com/parts/s...model/corvette
You may need a mechanic who is familiar with older cars and specifically Corvettes.
If you really want to go that route, here is a mechanical tach drive HEI distributor https://www.summitracing.com/parts/s...model/corvette
You may need a mechanic who is familiar with older cars and specifically Corvettes.
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
Get your car and take it home. Do not let those folks work on it. They messed up huge for two reasons:
1) A points distributor is a rock solid setup that, when set up proper, will run smooth and responsive....I am big on MSD and electronic conversions but not big on HEI.....they are huge in size and difficult to curve without the right parts. If they cannot make your original distributor work, they do not deserve to work on your Vette IMHO. Red flag
2) There are HEI units that are available with tach drive on them....they are available from multiple vendors, the fact that they don't know this and did not take the time to research it, is a huge red flag.
They may be a good shop.....but they do not need to work on this car.
Your distributor can be made to function VERY well. They ran good in 73' and will run good now. Look up Lars Griswald and e-mail him for his distributor papers v8fastcars@msn.com. I still keep a dwell tach in my garage for all original cars.....it is the only "special tool" you need to set one up. Basically new points, condenser, curve kit and springs, vacuum cannister.......set dwell and timing and good to go!
Jebby
1) A points distributor is a rock solid setup that, when set up proper, will run smooth and responsive....I am big on MSD and electronic conversions but not big on HEI.....they are huge in size and difficult to curve without the right parts. If they cannot make your original distributor work, they do not deserve to work on your Vette IMHO. Red flag
2) There are HEI units that are available with tach drive on them....they are available from multiple vendors, the fact that they don't know this and did not take the time to research it, is a huge red flag.
They may be a good shop.....but they do not need to work on this car.
Your distributor can be made to function VERY well. They ran good in 73' and will run good now. Look up Lars Griswald and e-mail him for his distributor papers v8fastcars@msn.com. I still keep a dwell tach in my garage for all original cars.....it is the only "special tool" you need to set one up. Basically new points, condenser, curve kit and springs, vacuum cannister.......set dwell and timing and good to go!
Jebby
Last edited by Jebbysan; Sep 11, 2019 at 09:44 AM.
Thread Starter
Intermediate
Joined: Oct 2018
Posts: 39
Likes: 0
From: Jacksonville, FL
I'm not clear on the specific problem with the current set-up. It started when the Corvette was idling at a stop light . When I put it into gear it bucked like I was a first time manual driver. I got it to the side of the road and it wouldn't start again.
The mechanic said the carb was too large for the engine (750 carb) and he swapped it down to 650 (I think). Now they're saying it starts again but, does not run well. The carb size makes some sense. My Dad was the owner before me and said the car was difficult to tune and ran rich so, I think the smaller carb makes sense.
I agree about needing a good mechanic. This is the third one I'm trying and haven't been impressed with any, yet.
Finally, thanks very much for the part url!
The mechanic said the carb was too large for the engine (750 carb) and he swapped it down to 650 (I think). Now they're saying it starts again but, does not run well. The carb size makes some sense. My Dad was the owner before me and said the car was difficult to tune and ran rich so, I think the smaller carb makes sense.
I agree about needing a good mechanic. This is the third one I'm trying and haven't been impressed with any, yet.
Finally, thanks very much for the part url!
Burning Brakes
Joined: May 2013
Posts: 789
Likes: 129
From: Los Banos CA
The mechanic said the carb was too large for the engine (750 carb) and he swapped it down to 650 (I think). Now they're saying it starts again but, does not run well. The carb size makes some sense. My Dad was the owner before me and said the car was difficult to tune and ran rich so, I think the smaller carb makes sense.
BTW - the previous owner of my 69 was getting all of his service at a GM dealership. They did nothing but mess up the car there also...
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
It sucks because myself and many others on here specialize in this type of work.....even the most saavy modern techs are lost on a points system.....
You need to find a guy that works on and specializes on older cars....this is an unfortunate fact nowadays....
I am 48 years old and I was two when this car was produced....that would put the average owner of one at about 68 now if he/she had one in the 70’s.
There are no 68 year old techs at a Chevrolet dealer....very few in the private industry....I was fortunate that my late Father showed me as a kid....and he would be 68 now!!!!
I tune about two or three points cars a year.....and the people that own them are always amazed that the stock stuff works.....
Too many stories like yours of “techs” throwing parts at cars made me appreciate what I know now even more....and as the years go on, knowledge like this will be in even more in demand as the Baby Boomers gracefully pass on.
Good luck sir...let us know what you do.
Jebby
You need to find a guy that works on and specializes on older cars....this is an unfortunate fact nowadays....
I am 48 years old and I was two when this car was produced....that would put the average owner of one at about 68 now if he/she had one in the 70’s.
There are no 68 year old techs at a Chevrolet dealer....very few in the private industry....I was fortunate that my late Father showed me as a kid....and he would be 68 now!!!!
I tune about two or three points cars a year.....and the people that own them are always amazed that the stock stuff works.....
Too many stories like yours of “techs” throwing parts at cars made me appreciate what I know now even more....and as the years go on, knowledge like this will be in even more in demand as the Baby Boomers gracefully pass on.
Good luck sir...let us know what you do.
Jebby
Race Director
Joined: Oct 2008
Posts: 19,224
Likes: 1,672
From: Long Island
Points cars run fine and don't need a conversion unless you want to get rid of the points.
There are numerous conversion kits for a points distributor that will convert your dissy to electronic / no points setup. Summit and Jegs both have them .
I would pull the car out and get another mechanic for sure...
You can put the points conversion in your self , it's simple. But you will have to set the timing with a light.
https://www.google.com/url?sa=t&rct=...hUjl5zlwEhu9Cz
There are numerous conversion kits for a points distributor that will convert your dissy to electronic / no points setup. Summit and Jegs both have them .
I would pull the car out and get another mechanic for sure...
You can put the points conversion in your self , it's simple. But you will have to set the timing with a light.
https://www.google.com/url?sa=t&rct=...hUjl5zlwEhu9Cz
Last edited by BLUE1972; Sep 11, 2019 at 10:40 AM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,390
From: At my Bar drinking and wrenching in Lafayette Colorado
What Jebby states above in his posts is completely correct. The stock, points-type tach drive distributor is a great setup that is easily tune-able for outstanding performance. Anything that is wrong with it can be easily repaired. See this thread and scroll down to my post#7. Any distributor can be set up to run as well as any other on a mild street car, and most stock points-distributors, set up right, will actually outperform any out-of-the-box new aftermarket HEI:
https://www.corvetteforum.com/forums...or-choice.html
Fix what you have to make it run well.
The 750 carb was not the problem. The stock carb on your Vette is a 750 Q-Jet. A 750 Holley will run just great. If there was a problem with it, it could have been easily fixed. Unfortunately, you are dealing with incompetent "mechanics," who do not know how to correctly troubleshoot your problem, nor how to repair the parts - they are simply replacing parts that they don't know how to fix or troubleshoot. This is a very common problem, and the best advise is to find someone who knows how to work on old cars. Get away from the guy you currently have doing the work - he doesn't have any idea what he's doing...
Lars
https://www.corvetteforum.com/forums...or-choice.html
Fix what you have to make it run well.
The 750 carb was not the problem. The stock carb on your Vette is a 750 Q-Jet. A 750 Holley will run just great. If there was a problem with it, it could have been easily fixed. Unfortunately, you are dealing with incompetent "mechanics," who do not know how to correctly troubleshoot your problem, nor how to repair the parts - they are simply replacing parts that they don't know how to fix or troubleshoot. This is a very common problem, and the best advise is to find someone who knows how to work on old cars. Get away from the guy you currently have doing the work - he doesn't have any idea what he's doing...
Lars
Pro
Joined: Mar 2014
Posts: 529
Likes: 113
From: Texas
Find a local Corvette club or Camaro club for that matter, They will know the right shop and/or person to take your car to.