So, I purchased a new distributor a while back. I've done everything I can think of doing to this Taiwanese hunk of junk. but the best I can get out of it, .... base timing, (With vacuum advance disconnected), 18 degrees, starts advancing at about 1,050 , smoothly advances (Progressively with RPM) to 30 degrees at 2,500. then to get the last 5 degrees out of it you have to rev the snot out of it. doesn't move above 30 degrees untill 4,500.
Just isn't good enough.
So, is there a HEI distributor available that has 18 degrees of mechanical advance that advances smoothly?
I've tryed different footballs, several different sets of weights. tryed modifying weights. I'm over it.
I've seen a couple distributors recommended on this forum.
However I have never seen total advance in crank degrees listed. So, for a mildly modified 350, with a fair bit of cam. that needs about 18 to 20 initial timing. is there a distributor that one can buy. bolt in, time up and be done?

 

Dumb question but you did buy and try the different springs right? Thats what I had to change on my PCE tach drive hei unit to get it to advance smoothly. It ran great till I just swapped cams but the consensus there is I may have assembled a tooth off.

 

I work on them for a living and you are finding out why I woln't touch them. It would take too much space here to go into the details, but by the time you get enough spring on one of those to keep some of the timing out at idle speed they fail on the other end of the curve. The problems range from "soft" internals to too much leverage and poorly designed advance curve mechanism.

Far better to get a decent stock unmolested unit from a swap meet, Ebay or a poor soul who bought some sort of aftermarket bug zapping "upgrade" and sidelined his OEM unit, then spend your efforts there instead. About all a good factory HEI needs is a positive stop welded in for the advance (you set how much it adds at the same time) and maybe one slightly lighter spring on one side, or opening up the "eyes" of the springs to bring everything in just a tad sooner.

This trend to have the timing "all-in" by 1500-2000 rpms never worked from the day I got into the this hobby and even worse on a well though out engine build. We've found over the years that efficient engines put together with optimum compression and well chosen cams require LESS timing and fuel at every RPM to make best power and most efficient for "normal" driving......FWIW......Cliff

 

i run about 17 initial, seems your readings may not be far off if you look at the 3 / 4 point curve and ramp up? im all in 1800 -19 (but i do not like having that fan inline with my head and timing light so..) even though it says 2000..was it Taiwan or chinesium?

 

Have Davis DUI build you one.......
I hate curving HEI's....it is a crap shoot. And it seems there are several different flavors of Chinesium out there too......
18-20 initial is pretty high with vacuum advance......shoot for 15-16.

Jebby

 

running 10 degrees vacuum advance. took a bit to get the right can for my low Vacuum. 18 plus 10 is giving me 28 at idle. and it likes it. my problem is getting the curve right above 30 degrees. 2,500 RPM.

 

I understand.
If it likes 18+10 then cool......the problem is that just about ALL HEI's pull 21-22 degrees mechanical......so 18 will give you 40.....which is kinda high for total.....some old 327's like 40, closed chamber BBC likes 40 in some cases......but later stuff all wants 36.
At any rate.....it is worth it to have Davis build you one, or just go small cap MSD.....that is my other gripe about HEI is the damn thing is big. The MSD has exact curves in the box to adjust.....
MSD does make an excellent HEI (Not the China Street Fire) that you can set exact curves too....but they are in love with that thing.

Jebby

 

Buy a brand new GM Performance Parts 93440806 From Summit for $178. It has 18 degrees in the centrifugal mechanism. Curve starting at 900 RPM and finishing at 2900 RPM. Has a vacuum advance that is all in by 6.5" for 18 degrees extra. You might want to change the can or just limit the travel.

What else would you need?

 

This is a good option......but why do they show this curve on it? I don't remember this curve......but it says it pulls the same 22 degrees as stock....it says it pulls a ton of vacuum advance too.
This was pulled from Pace Performance.....


Jebby

 

You could go to your local junkyard and pickup an HEI cheap. They are a very reliable unit so a junkyard HEI should be a good bet. You can the put in an MSD HEI upgrade kit. Finally, read this: https://www.crankshaftcoalition.com/...EI_distributor. Before I went with a programmable MSD box, which is the way to go these days, I followed their method which is simple and it worked great for dialing in a curve. Cliff R noted this in his post above regarding limiting the mechanical advance. Its so simple to do but some guys are just too lazy to read and spend too much money and time dicking around with buying new distr's with custom curves when it can be easily done in your garage with some trial and error. But it works!

 

Is this Cliff Riggles.....of Quadrajet fame from Ohio?

 

Yes, Cliff Ruggles.

I've been working on distributors over 4 decades at this point and nothing from the aftermarket in terms of the cheap Chinesium HEI clones that have shown up here are worth two squirts of duck poop.

Some actually just continue to add advance like the OEM units will IF you put light springs on them. Without a positive stop added to a factory HEI they stop advancing when the "flats" on the weights roll around onto the flats of the center cam, but up at high RPM's the lighter springs folks put on them all the weights to "roll out" onto the cam and add a butt-load of timing. This is covered in my book on page 50 if you have access to one. It's ALWAYS been like that, folks just don't see it because they don't follow the timing with a light to really high RPM's.

To prevent that issue and fine tune the amount of mechanical advance added at the same time I MIG weld a positive stop into every one I build here, done deal and good to go.

These aftermarket pieces of bovine excrement folks buy for around $100 bucks or so are HORRIBLE. I've had them sent here, and tossed them aside and built the customer a unit that works like it's suppose to from a good used core instead. I wasted enough of mine time trying to tune that junk, and have actually found issues with them, poor quality control, and "soft" castings where the screws holding down the VA already stripped out to just avoid them completely........Cliff

 

*Ruggles

 

Cliff,

Thanks for contributing to the C3 forum. There are lots of folks here that have problems with Quadrajets, and you could be of great help. Lars Grimsrud is the forums Quadrajet guy, but fact is, he is not the only person on the planet who can do a great job fixing them. I expect you are on the list, as well as others. Not to take away from Lars, as I had him rebuild mine, and it worked great. I have your book too.

As for distributors, I know very little. I spent the big bucks to buy the over $400 MSD Pro Billet......primarily because I did not want to buy cheap Chinese options. It does have a changeable advance stop, with extra stops for different settings. It also comes with mutliple springs and charts to help select the one for your engine. Its a very high quality unit.......but you pay for it. I will reserve my judgement of this HEI distributor until I have some time on it. But......I believe a factory unit can work just as well with mods like you suggest.

So,....glad you are here. Please keep contributing.

 

The specs are from Big2Bird. He bought one and ran it on his bench. I would trust him over the specs that were published online.

 

"So, two Pontiac guys wander into a Corvette forum. One goes up to the bartender, and says,...."

Nice to run into you, Cliff!

 

I run the MSD 8360 small cap which has a nice curve and is well documented in the instructions on how to set it up.

 

Thanks, and nice to be here, hope I can help out some.

For sure I'm not specifically a "Pontiac guy", although I currently own/drive one and have extensive experience with them. I've actually owned and raced more Chevy powered cars than Pontiac's, and a nice 1970 440 powered Roadrunner for quite a few years.

I don't wonder around much on the Forums but retired first of April so have a little more time these days for posting. I still work on carbs and distributors daily and will continue the parts business for a few more years. The focus however is parts, and most of the carbs I'm working on have been done elsewhere and not working as intended. So nice clean/restored units for the most part that just need some help in a few places.

Another BIG issue I've seen with these offshore distributors is gear wear. Not sure what car bumpers they melted down to make the last one that was in here from but it was chewed to a "knife" edge in less than 200 miles. It was an Olds HEI bought from one of the big Speed Shops, no names mentioned.......

 

I’m now wondering about the distributor in the blueprint 396 sbc in my ‘69 Corvette. It is a tach driver, wide cap HEI. The only source for these I can find is China. I adjusted the timing curve using Lars paper and it seemed to be fine, but it is connected to the ported vacuum source on the EFI throttle body (FAST EZ EFI). Thoughts?

 

Yes, Davis DUI does it. They custom curve them all. Mine has 20° initial timing, 36° total, all in at 2500 rpm. No one makes a HEI recurve kit that can do that. Some "old school" guys with a Sun machine could do it, but my local guy retired.