HEI Distributor Conversion
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Interesting thread, think the answer I seek lies within, but to verify: I have a 73 454, it has a Delco Remy 9591 HEI distributor, no mechanical tach allowance (I have a line on a 77 gauge). My question is, is the HEI preferable performance wise to a new MDS points distributor + Petronix coil? I am new to corvettes obviously. I put a Petronix system on my first mechanical resto experience, a 78 Scout with 345 V8, and the Petronix was a nice upgrade, but I'm guessing leaving the HEI (not original to car, 75 maybe) is better left alone. That ring true?
Instructor
Joined: Jun 2014
Posts: 100
Likes: 0
Thanks Mike. What about the 'stronger spark', 'wider plug gap'... All that.... I read a thread here earlier that suggested the best Performance ignition wise would be achieved by buying the cheap AC plugs and changing them out every couple months as opposed to ignition fancy plugs and wires. That ring true?
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
Thanks Mike. What about the 'stronger spark', 'wider plug gap'... All that.... I read a thread here earlier that suggested the best Performance ignition wise would be achieved by buying the cheap AC plugs and changing them out every couple months as opposed to ignition fancy plugs and wires. That ring true?
Instructor
Joined: Feb 2009
Posts: 159
Likes: 0
From: asheville nc
I saw a test done on a dynometer between the two distributors on the internet...the points actually out performed the HEI at a couple of high rpm points...my 327-350hp spins very quickly with the orig points distributor and I know at one time 8,000 rpm was showing with no cut out...and if things don't work...its a very easy fix...its either the points or condensor. My 327 was balanced by the old Nascar race team of Banjo Matthews and this makes the distributor really turn more quickly than stock.
You cannot get performance with Made in China points...buy the top line points from NAPA...Echlin brand. You will get all the rpm you want unless you are racing your vette...my last set of points was in the car from 1993 to this year...21 years with NO problems...just an adjustment to points a time or two.
I even tried both distributors in my 49 chevy with 283...ran the HEI first...switched to points and I am happier.
You cannot get performance with Made in China points...buy the top line points from NAPA...Echlin brand. You will get all the rpm you want unless you are racing your vette...my last set of points was in the car from 1993 to this year...21 years with NO problems...just an adjustment to points a time or two.
I even tried both distributors in my 49 chevy with 283...ran the HEI first...switched to points and I am happier.
Instructor
Joined: Feb 2009
Posts: 159
Likes: 0
From: asheville nc
Here is a link to my vette....BEFORE rebuilding the carb due to no power valve feeding gas and still running points and plugs installed in 1993.
Last edited by 68L79; Jul 21, 2014 at 01:47 PM.
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Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
I met one of the GM engineers that worked with the HEI, decades ago, and so he is correct by my observations also....in that the only thing MSD can do better than HEI, is fire a over rich idle mix and so engine runs better/smoother it idle.....and over the years, I have proven that many times to myself......
the HEI should fit just fine in any shark.....got one in my '72.....
that mechanical tach crap is just that, modern 'tronics' is better there, so get one from a 75-77 vette.....
the HEI should fit just fine in any shark.....got one in my '72.....
that mechanical tach crap is just that, modern 'tronics' is better there, so get one from a 75-77 vette.....
Instructor
Joined: Feb 2009
Posts: 159
Likes: 0
From: asheville nc
Its been bored 60 over and has micky thompson 11:15 to 1 pistons...and with the engine being balanced and a more aggresive cam....I would say its very close to or over 400 HP now. Not many stock big blocks 71 and later am I afraid of...ford, chrysler or chevy in a 1/4 mile.
Last edited by 68L79; Jul 21, 2014 at 03:03 PM.
Instructor
Joined: Jun 2014
Posts: 100
Likes: 0
Just to confirm, as wow there is a lot of conflicting info out there.... On BBCs with an HEI, plugs should be gapped to 0.045?
Checked mine last night,gapped at 0.035, and they were a bit crusted and dirty, NGK YR5s. As they look like they could use a change I thought I would clean them up and gap them to 0.045 first to get an idea if that is going to smooth things out. Car runs ok, a bit rough... Does anyone any experience that might save me from a wasted couple hours?
Thanks
S
Checked mine last night,gapped at 0.035, and they were a bit crusted and dirty, NGK YR5s. As they look like they could use a change I thought I would clean them up and gap them to 0.045 first to get an idea if that is going to smooth things out. Car runs ok, a bit rough... Does anyone any experience that might save me from a wasted couple hours?
Thanks
S
1973, c3, conversion, corvette, distributor, distributres, dragon, drive, fire, hei, ignition, installing, pic, pics, pictures, tach, wiring
