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HEI Distributor Rebuild

40K views 84 replies 20 participants last post by  sanweaver 
#1 · (Edited)
Hello all,

I'm currently in the middle of a full-on HEI rebuild with the goal in mind to maximize timing performance to achieve the best possible fuel economy. We're not talking your basic cap and rotor type rebuild, but a full disassembly and cleaning, checking the advance mechanism, re-curving of advance weights and an adjustable vacuum advance. I will document everything here visually for those that are interested, but first I have a question:

What is an ideal shimmed clearance between the distributor housing and the gear? I have a Moroso shim kit for such an adjustment, but there is no indication as to what I'm shooting for. Currently, I have about .058" (via feeler gauges) endplay. You can physically lift the rotor shaft up when installed, which has a distinct effect on the timing, retarding it quite a bit.


Shaft endplay - shaft at its bottom of travel




Shaft endplay - when the shaft lifts, as it would under acceleration, timing retard significantly



Anyone have a spec to I should try to achieve for clearance? Thanks!
 
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#27 · (Edited)
Okay, I've made a decision:

I'm going to pull the distributor again and remove the adjustable vacuum can and the GOLD springs. Why? I'm trying to process too many variables. I have no idea what is effecting what. I'd like to scientifically test to see what each additional change gives me. So I'll start with the first fundamental change.

First test: Shimming
How does performance/economy change when the erratic bouncing timing is tamed? I will run the OEM advance springs and vacuum can and do city & highway mileage tests.

Second test: Springs
How does performance/economy improve with the new springs? I will test both GOLD and SILVER springs from the kit.

While these tests are underway, I will bench test the adjustable vacuum advance can. I had done an initial bench test and found that it took 16" Hg vacuum to actuate it all the way. That seems excessive to me and it tells me that my last highway test I was running without at least some of the vacuum advance I used to have. Bench testing will allow me to understand what turning the setting does. Which way gives advance at lower vacuums. I will also test my OEM can to see what vacuum level I should be shooting for, so I have a super clear idea if this can will work for me.

Third test: Adjustable Vaccum Advance
Depending what my bench tests show, I may or may not re-install the adjustable vacuum can. We'll see.

To many this may seem like a set back. To me it is the way I should have approached the problem initially, just that I was too impatient. The saga continues...
 
#29 · (Edited)
@bonos40,

First of all read the top section of this:

Tech Paper from performacedistributors.com

There are distributor housing to manifold shims available. They are nylon and come in a set of three with sizes: .030", .060" & .100". I'm assuming you can use all three (with a gasket on the intake of course) for a total .190", but I would think you should only raise it as much as you absolutely need to. The article above explains how. And yes, it will effect the wear pattern of the cam/distributor gears. They should be mating in the middle.

I hope this helps.
 
#31 ·
bonos40,

Absotively! Glad I could help! Keep an eye out, results may be slow coming, but I will definitely post them here for all. Cheers! :beer:
 
#32 ·
Scientific update #1

I have removed the adjustable vacuum advance can and replaced the OEM vac can. I have also reinstalled the OEM springs. Reinstalled dizzy, set timing to 12° and took for a spin.

Initial thoughts:
The new found power is still there. This 229 V6 has more command presence now than it ever had prior to doing any work on the distributor. I can unequivocally state that my new found power and consistency is due solely to the properly shimmed and timed HEI distributor. It was BAD before. So bad. I'm not lying when I say that my lower RPM power band now has some authority. Previously, I would never try to launch and out accelerate someone else at a light. Today I did it and won!

So, lessoned learned: when trying to achieve performance or cure dead spots, look to a properly operating stock distributor FIRST before falling into the chasm of re-jetting, new carb, headers, new dizzy, blah blah blah. If your timing isn't tamed first, than you're just wasting money.

Also...

Adjustable Vacuum Advance inspection

Now that it is on my bench again, I've turned my attention to the adjustable can to learn what it does and how. I first tested my OEM can to find that it takes 7" Hg vacuum to fully actuate the advance.

I set to test the adjustable can it to the "all the way in" setting to find that it 16" Hg to fully actuate the can. Same thing for "all the way out". The only difference between the two settings is the amount of throw. So, I can say for certain that I wasted my money on the adjustable can... I can't use it.

More to come...
 
#33 ·
Scientific update #2:

Test #1 - Shimmed Distributor, Stock Advance Springs, Stock Vac Advance Can

Driving conditions
So I had a chance to do another 70 miles on a fresh tank of gas. The dizzy was set back to almost stock (shimmed of course) and timing set to 12°, the stock setting according to my emissions decal on radiator shroud. Of those 70 miles, 20 or so where city-ish stop and go to light city-ish with small amounts of short cruising at 35mph. The other 50 miles were extended highway cruising at 55 to 60mph, steady, even-footed driving.


Fill up proceedure
When I filled up, I tried to use the same station and pump as before. I couldn't get the same pump, though. I let it fill hands free until the nozzle clicked off. Then, I continued to fill again with my hand on the nozzle lever, just barely actuating it, so that I could get as much in my tank as possible, which is my method when doing mileage tests. It went through two hand-held clicks, which at the time made me think I was as full as before.

Results
I traveled 70 miles (based on trip meter). I put in 2 gallons of gas (actually 1.99). That gives me an economy of 35mpg!!!!! While I'm jumping up and down excited at the possibility of that, I'm not entirely convinced. I'm thinking that looking back at the filling procedure, I not absolutely sure I was full full full, like I was before. The nozzle I was using could be overly sensitive and kicking off way too soon. But let's crunch some numbers, shall we?

2 gallons = 35mpg
2.5 gallons = 28mpg
2.75 gallons = 25.45mpg
3 gallons = 23.33mpg

All are impressive numbers. Especially considering that these are based on the actual readings of my gauges. From previous tests, I know that my gauges are off by .92:1 (meaning If my gauges say I've gone 1 mile, I've actually gone 1.085 miles. I'm running some BIG FAT tires that are not compensated for at the tranny speedo gear.) My previous average for highway mileage, as actually read by gauges, is around 18mpg~19mpg, which I've extrapolated in my head to the CORRECTED number of 19.5~20.5mpg. The numbers I portray above wildly exceed that that... and they are UNCORRECTED.

Corrected Mileage Range
2 gallons = 37.97mpg
2.5 gallons = 30.38mpg
2.75 gallons = 27.61mpg
3 gallons = 25.31mpg

STUNNING. All are simply stunning numbers. Especially considering that I now have acceleration and performance like I have never experienced before with this engine, essentially untouched with the exception of shimming the dizzy. There are potential errors and we'll look at them more in the future, but I cannot believe the HUGE impact a $5 shim kit has had.

I can't wait to see what the improvement to city-driving only will be. And this is only Test #1!!! I'm thinking that future tests with new springs will not have much effect on extended highway economy, as running on the highway is basically an all-in condition for total advance. I'm looking for the springs to help me out with city economy. But we need a Test #1 baseline for that condition first.

More soon...
 
#34 ·
229 timing.

I believe as your testing progresses, you'll find that the pretty much all the power tricks that work on a regular small block will work on the 229. All they are is a baby small block. If there where no emissions testing, induction and exhaust work will really wake it up. :nanawrench:
 
#35 ·
This thread is not dead either...

Hey all,

It would seem I have a lot projects simmering on a lot of back burners these days. I just wanted to give you an update as to where my mileage test results were at. As stated previously, my rear wheels are oversized and so my ACTUAL results are better than these numbers, which are based entirely on what my odometer says. Let's get started:

Tests all start with tank full full full. Nearly to the fuel cap full.

65.9 miles driven, filled with 4.27 gallons
15.43 uncorrected MPG of mixed city and highway driving (mostly city.)

36.2 miles driven, filled with 2.95 gallons
12.27 uncorrected MPG of city only driving. Hmm... not as good as I was hoping.

33.3 miles driven, filled with 5.154 gallons (WHAT?)
6.66 uncorrected MPG of city only driving. CRAP! What happened?

This last fill up was a shocker. I'm not at all sure what happened. I have noticed puffs of smoke at initial engine fireup after sitting overnight, but quickly clears up. My research/experience is pointing to valve seals, but lately that smoke has been continuing while idling for warm up. I double checked my timing and I'm still at 12° at warm idle. I have to pull spark plugs to see what I have there.

Also, I'm not sure if my drop from 15.43 to 12.27 MPG reading was the beginning signs of what ever issue I'm currently dealing with. I certainly need to look into what going on more before I can even begin to ask questions or for advice.

:dontknow:
 
#42 ·
new carb/rebuild?
When the Camino first came to me, I rebuilt the carb on the 50k miles spare V6 and simply swapped carbs then tuned on the engine. It hasn't been very long and the Camino gets regular use. When I reinstalled the shimmed distributor to start my scientific experiments, I made sure to check/tweak idle mixture and idle speed, along with my timing, to be sure I was as dead on to specs as I could be. That way, when I make a change I can always double check my initial settings so that future tests can be compared to past tests on an apples to apples basis.

So, long reply boring... carb was rebuilt a couple years ago. Maybe an issue, maybe not. We'll see...
 
#41 ·
...You know whats really interising is?? where it says;" Max. Module Continuous Operating temp to be 125c at the base plate". And a R.F.I sheild...
Yeah, that is intersting. All the more reason for the heat-sink compound to help wick away heat from module.

RFI shield? I'm not seeing that on the blueprint. Where is it located??? I haven't seen anything I'd say is a shield in the guts I've sifted through.

Where did you come across that blueprint?
 
#38 ·
Interesting thread Michael, and very informative.
In regard to the adjustable vac cannister, I have one on my Caddy engine in the Elco project. The Caddy guys like to run 16 to 18 degrees initial timing, with the cannsiter tweeked for a curve of some sort. Then there is a timing advance limiter to limit vacuum advance, to keep from going past the total timing number. In other words, raising the initial timing above the so-called stock timing, can make full advance too much, so the limiter lets the initial be set higher. Those folks us 35 or 36 degrees total timing.
The limiter plates I have are a Crane Cams p/n 99619-1, for point or HEi distributors.
Jacking the initial timing ahead brings the power in quicker it seems.
The limiter is a little cam-lobe shaped disc, with notches to set the advance limit, and it gets mounted on one of the cannister mounting screws.
 
#39 ·
Hey guys,

The smoke is light blue, like an oil smoke, and up until very recently I was thinking it's just valve seals. I have wanted to do a compression test since I got this Camino, but the schraeder valve on the tester leaks and so the gauge doesn't hold pressure. It doesn't take a standard valve (tried that.) Up until now it has not been a pressing matter, but now I'm really needing answers.

Even if the rings are shot and the engine needs to be pulled, the good news is that this Camino came with an identical spare V6 and TH200C (total price paid for Camino and spares $1200.) The spares are purported to have been pulled from an 80 Malibu with 50k on the clock, so I have a practically FREE course of action.

Another possibility that occurs to me is that one of my thermo/vac switches has gone south. This would of course account for the mileage drop and not the smoke issue, but that is simply a WAG at this point and the correct course of action is to diagnose the engine.

So, a new compression tester is in my future. I will also perform a vacuum test, which I've previously done in lieu of a compression test and looked fine.
 
#40 · (Edited)
Concerning Adjustable Vac Cans

Bill,

80v6 and I have discussed this a bit in the past. I had purchased a Moroso adjustable vac can that I've determined I cannot use. I was super eager early on to slap everything into the build and see what happens, and what did happen was a reduced economy on the highway. Bench testing the adjustable and OEM units showed that the adjustable vac can operates on significantly more vacuum than OEM, so I was never seeing full vacuum advance. Ever. Also, I do remember a vacuum restrictor connecting inline to the distributor, as indicated on my emissions/vac hose routing decal. With all the thermo vac switches (TVS) in place for emissions, there is probably a reason for that. I'm not ditching my emissions set up so I'll keep everything as stock as can be, so no adjustable vac can.

The adjustable can was a nice idea, but I'm really not at that stage yet. I've changed so many things that I need to go slow and investigate what benefits/drawbacks each modification has, hence reinstalling the distributor basically unchanged (OEM weights, springs, and vac can) so that I can see what difference *just* the shimming brings. Then I'll play with springs and test the gold and silver (heaviest and medium from the rebuild kit) to see where those net me out on economy and performance (seat of the pants dyno only.) That very may very well be the end of it for this engine. If I try to go further and really "wake up" the baby 229 then that's another story, but it's not one that's going to be told anytime soon.
 
#44 ·
Blue smoke.

Your lucky to have a spare engine. At any rate, this will be a good test bed for the spare and parts are transferable before installation. Lot of options available. There are ways to detect where the engine is leaking. If just the heads need work maybe the spare heads can be used after checking them instead of a whole engine install. If neither engine is useable, Rock Auto has both heads and short blocks for a quick replacement instead of waiting for machine work etc. Good luck. :idea:
 
#45 ·
Eureka?

I may have an answer!

I haven't been able to compression/vacuum test the engine. But I did have an errand to run this morning. I noticed a weird brake pedal feel. The pedal felt a slight bit mushy, but on a hard stop (at a stop sign or red light) I could feel the brake pedal creeping towards the floorboards. Go home and check brake fluids... very low. I had *just* checked that and topped off. Hmmmmmm. After a fluid top off I continue on my way.

During my trip I can hear a constant squeak that is absolutely coming from me and changes in pitch with speed. And then it dawns on me like lightening. My brake master cylinder is about to go south. An that is the source of my troubles!

My severe drop in economy is easy to explain. With fluid slipping past the master cylinder piston the brakes are still applied after braking due to simple hydraulics (piston can't return because fluid behind it can't be compressed and has to leak down to return.) This means that every time I apply my brakes, they continue to be applied for a short while and while I'm in motion, under acceleration and load.

The blue smoke at idle is also easy to explain. The master cylinder leaks fluid past its main seal into the brake booster. Said fluid is then picked up by vacuum and taken into the engine to create the smoke I've been describing at idle.

I can tell you all that I know for a fact that I have brake issues to deal with. I very highly suspect that said issues are also the culprit of my reduced economy.

So I have to replace my master cylinder... more to come....
 
#49 ·
My replacement Bendix booster and MC arrived today. My work for tomorrow has been decided!
 
#50 · (Edited)
This thread is still not dead. Though it has taken an unforeseen turn. I haven't been able to get outside to work much, but here is what has happened so far:

I've not been able to see any evidence of brake fluid leak, so I was pretty sure that I was looking at a bad MC and Booster. Those got replaced plus a full four corner bleed/fluid flush, but pedal feel and slow sink has not changed.

While bleeding I had noticed that a rear slave cylinder look awfully dirty with a caked-on mud appearance, so I was thinking that may be my leak. Replaced both rear wheel cylinders (GOD I HATE THOSE RETAINER CLIPS!!!!) and brake shoes as one side was looking thin, and bleed again. Still no effect on pedal, and this time I completely lost my brakes (while rolling out of my driveway towards a new Caddy SUV parked in front of me!) E-braked and threw it into Park, to avert disaster. After some pedal pumping, I got some pedal feel back, but with an even quicker sink to the floor. Park it again.

I look towards my driveway and see puddles of brake fluid. Hop back in the Camino to pump the pedal and I can confirm that my passenger side front hose IS LEAKING by the puddle of fresh fluid on the ground and the wet hose, near the hardline connector!!!!!

New hoses ordered and major catastrophe averted (don't want to think about a hose bursting in traffic!) Whew! More to come...
 
#53 ·
Thanks for the replies guys!



You and me both! I have good relations with my neighbors. Broadsiding their visitor's Caddy is really not a situation I'd like to explore. Ever.

Limped it home after and replaced both rear cylinders. That was a scary day!
No kidding! WOW! So so so SOOOOOOO glad this happened under (somewhat) controlled circumstances. A totally unrelated motorcycling experience comes to my mind after your cement truck story:

I learned to ride in the NYC metro area. I used to commute for work everyday into Manhattan. For what ever reason, I had the notion that I should know what it's like to stop on a dime. Not your typical, nice slow stops, but FULL ON PANIC, I gotta stop NOW, kind of braking. And so, for a couple of months, every stop I did was as if my life depended on it, because someday it might. I got used to the feeling. Was even able to feel the front wheel lock, be able to let it go and then get back on it.

Then one day, I'm in Fort Lee, NJ and I'm accelerating on a downhill on-ramp for US Route 46. To my right side, is a solid wall of concrete, to my left are cement jersey barriers, at the bottom of the ramp there is an entrance to a gas station on the right side. As I'm approaching, a tractor trailer crosses me from traffic on my left to slowly enter the gas station on my right...completely cutting me off from any and ALL avenues of escape! I had no where to go. So I jumped on the binders for all I was worth. I grabbed hard, then harder, seeing the trailer's huge double rear wheels getting closer and closer, EVEN HARDER STILL. I had been really accelerating, because traffic whips by on US46 and I was riding a meager 500cc 1984 V30 Magna, which needs a runway to get up to speed.

I stopped with inches to spare! Less than a foot! I was right on top of those huge wheels and sat SHAKING as they slowly lumbered past, IMMEDIATELY in front of me. I had to keep going on the bike, because I knew that if I tried to get off and stand up, my legs would give out, I was so shaken. I didn't realize it at that moment, but it later dawned on me, that the previous months of panic braking practice just saved me from a world of hurt and maybe my life.

Long story short, good brakes are our ally, your friend!
 
#52 ·
Yeah, it's bad news when they go on the road! Years ago I was coming to a 5 way stop, down a hill, my mother and brother in the cruck with me, and a cement truck pulling out from another stop. and my rear cylinder doesn't just leak, the seal pops off into the drum! Bad news! I have to toss it into park while pumping the breaks like crazy, managed to stop (halfway in the intersection... just not the half with the cement truck!)

Limped it home after and replaced both rear cylinders. That was a scary day!

Jeri~
 
#55 · (Edited)
I hear you, Bill. The Chevelle can certainly GO, and I've not been a hooligan in public in a very long time, because she's got a lot mass and I'd rather not TEST her binders for no good reason. As far as I know, they've not been altered for anything other than pads/shoes. Might be a good, for my own peace of mind project over the winter.

What really amazes me is that, here-to-fore, I never gave a second thought to brakes. They're there and they "have been" working fine. No noises, no issues. Now I can't stop thinking about them. In the past, I've built my own stainless steel braid teflon lines to replace older rubber lines on my motorcycles. The improvement of brake feel is drastic. To replace the Camino's lines I simply went with DuraStop/Delco rubber replacements. Anyone have any experience on this upgrade for their Caminos? It seems like a no-brainer (other than cost) replacement.
 
#56 ·
I was coming up to a stop sign at a T intersection about 35 mph. (on snow and ice):dontknow:

Brakes "were" working fine. I tried to stop and the main steel line for the front brakes split wide open.

What to do, what to do.

A cop was coming to my left so going through the intersection and hitting the snowbank was not an option.

I shoved it in reverse punched it and cranked the wheel.

Hit a fire hydrant dead center, wasted the bumper, grille, frame horns and both fenders got tweeked. But I missed the cop, he stopped, no ticket.

81 chevy pk w/5.7L diesel so no great loss.:dontknow:
 
#57 ·
Living in the Northern states where road salt is used, is always a recipe for rusted brake & fuel lines. I keep a bunch of fittings & lengths of lines around handy to keep the vehicles from drizzling gas & brake fluid.
I haven't used any stainless steel lines yet, but it's looking like a good idea....Summit Racing has coils of the stuff & the fittings.
 
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