Restoring Rusty

[Gregski]

Originally Posted by 68Timber

Are the bushings on in that pic?

Yes, tiny little black plastic thingies under the outside studs of the little springs, hard to see

[rich weyand]

The setup that worked best for me is 16 base, 20 centrifugal, giving 36 total, and 15 vacuum.

[Gregski]

Originally Posted by rich weyand

The setup that worked best for me is 16 base, 20 centrifugal, giving 36 total, and 15 vacuum.

Thanks Rich, so what was your what I would call All In Timining, that would be your Base + Centrifugal + Vacuum?

I ask because before I messed with anything I had a similar setup

16 + 23 centrifugal, giving me 32 total somehow (maybe reading error on my part)

But my All In Timing was 55*, which I never understood since there should be little to no Vacuum advance at 3500 RPM so how could 10 Initial plus 23 Mechanical add up to 55, that leaves me with 15 vacuum at WOT, made no sense, so I started messing with it

I think for starters I need to get a timing tape put on my harmonic balancer so I don't rely on my digital Snap On timing light to get the Total Timing numbers, as that's tricky to do with one light

[Gregski]

a buddy of mine gave me this CRANE CAMS Adjustable Vacuum Advance Kit part number 99600-1 it comes with a set of springs

[Gregski]

so what did I do? I went out and bought my own, ha ha, what do you do after you buy a cheap distributor and one cheap kit for it? well naturally you go out and buy another cheap kit for it, a Financial Wizard I'm not!

Yup, another Made in Taiwan Proform kit part number 66952C. Now hear me out, I really couldn't tell if the canister on my distributor was adjustable or not, who ever said well just look inside that tinny vacuum hole and you will be able to tell, has never done it themselves or has Superman vision, cause I couldn't tell even with the distributor off the truck outside with the sun shinning and me using a flashlight to see whats in there, so I have no idea how they can see in there with the unit still in the truck, IMPOSSIBLE I tell ya

anyway plus I wanted to have a Proform unit to go with the Proform distributor, I am just built that way is all I am sayin', possibly some of you may relate

[Gregski]

using the provided little alan wrench I was able to confirm that indeed my old vacuum canister is NOT adjustable

so then I decided to see how much adjustability is in that new canister

first Pic is where we started turning from we'll say 1:00 o'clock

second Pic is where we ended up after 4 counter clockwise turns (to the left) we ended up somewhere around 8:00 o'clock

so it has about 4 1/2 turns of adjustability

[Gregski]

then it was time to remove my non adjustable vacuum canister

it is only held on with two philip head bolts made out of very soft metal I found out (surprise)

I don't think you have to remove the springs and weights first but I did to improve visibility plus as I said before, I wanted those cheap(er) parts off anyway

[Gregski]

I am not sure if one can tell a non adjustable canister (left) from an adjustable unit (right) simply by their outside physical appearance, but here they are side by side, the adjustable one does have that hex section on the canister where the other one doesn't

[Gregski]

and soon enuff we had the new canister in place on the distributor

this is an easy job, especially with the unit off the truck and on a workbench

[Gregski]

and the original weights and springs back on the distributor

it is a task I would recommend everyone attempt at least once, yes even if you don't need an adjustable vacuum canister or different weights and springs, I say that to make you appreciate the newer distributor less systems, ha ha

its sort of like learning long hand math first before the teacher allows you to use the calculator, (well shoot I know what you is thinking, you want that than "treat" yourself to a points distributor, I get it - but lets be reasonable here, we are not Barbarians, LOL)

... well I would love to test this thing, but we got a gaping hole in our transmission where the speedo drive used to be, remember we is still waiting on the new 43T driven gear and some seals to stop that fluid leak

[enaberif]

Just as refresher for the Gregski ..

16* is your base timing

You will have mechanical timing which is the weights and springs which you need to add up to 32*. So your distributor weights/spring combo should yield 32* at 2500-3000rpm

After that you then have your vacuum advance timing which should yield around 55* of timing when your driving. If you are within these realms the truck should run pretty good.

Last note how much up and down play does that distributor have? If you buy a shim kit you can reduce this for a more stable distributor.

[Gregski]

Originally Posted by enaberif

Just as refresher for the Gregski ..

16* is your base timing

You will have mechanical timing which is the weights and springs which you need to add up to 32*. So your distributor weights/spring combo should yield 32* at 2500-3000rpm

After that you then have your vacuum advance timing which should yield around 55* of timing when your driving. If you are within these realms the truck should run pretty good.

Last note how much up and down play does that distributor have? If you buy a shim kit you can reduce this for a more stable distributor.

Thank you for that, however let me share with you an interesting observation, one that I have validated with a number of tests. The point that I will be making is that it is not that clear cut, Base Timing + Mechanical Timing, or in other words so far I have not seen such a thing as pure Base Timing, allow me to explain

It appears that Initial Timing (what you call Base Timing) always includes some Mechanical Timining aka advance. In my case my original Mechanical Advance Curve starts at around 800 RPM, so if my idle RPM is 850 I am already relying on mechanical advance in the initial 16*. This could explain why in my original configuration 16 Initial plus 24 Mechanical = 32* instead of 40* (that's because the initial 16 already has some of the 24 mechanical in it) hope I didn't just confuse the hiebie jibies out of somebody

If you look at the curve for the new weights, (pic above in the thread) it starts even earlier at 600 RPM, so for sure at 850 RPM idle we are using the mechanical advance. Now what muddies the waters a bit is crappy aftermarket inaccurate parts. Which I blame for 10 initial plus 8 mechanical = 18 (which really shows that their curve does not start at 600 RPM, lol)

Now looking at the GM HEI distributor part number 93440806 which I will be purchasing tomorrow (aka Pay Day) it's Mechanical Advance curve don't start till 1600 RPM - so we shall see how that all adds up

[enaberif]

Originally Posted by Gregski

Thank you for that, however let me share with you an interesting observation, one that I have validated with a number of tests. The point that I will be making is that it is not that clear cut, Base Timing + Mechanical Timing, or in other words so far I have not seen such a thing as pure Base Timing, allow me to explain

It appears that Initial Timing (what you call Base Timing) always includes some Mechanical Timining aka advance. In my case my original Mechanical Advance Curve starts at around 800 RPM, so if my idle RPM is 850 I am already relying on mechanical advance in the initial 16*. This could explain why in my original configuration 16 Initial plus 24 Mechanical = 32* instead of 40* (that's because the initial 16 already has some of the 24 mechanical in it) hope I didn't just confuse the hiebie jibies out of somebody

If you look at the curve for the new weights, (pic above in the thread) it starts even earlier at 600 RPM, so for sure at 850 RPM idle we are using the mechanical advance. Now what muddies the waters a bit is crappy aftermarket inaccurate parts. Which I blame for 10 initial plus 8 mechanical = 18 (which really shows that their curve does not start at 600 RPM, lol)

Now looking at the GM HEI distributor part number 93440806 which I will be purchasing tomorrow (aka Pay Day) it's Mechanical Advance curve don't start till 1600 RPM - so we shall see how that all adds up

The springs you use is what determines your advance at idle. You should have a few different springs from a soft to a stiff spring. The softer the spring the earlier the advance comes in and vice versa with the stiff springs.

Depending on your cam shaft you may want your advance to start early or a bit later so find out your cam profile and where the lowest point of torque is made.

[hatzie]

Advance can be adversely affected by one more setting that's usually ignored...
What's the end play on the distributor gear. http://www.chevytalk.org/fusionbb/showpost.php?post/1257140/Measuring HEI gear end play.
It should be 0.010" +0.004" - 0.000" but most are set up way too loose. Every 0.0128" is 1° of advance as the gear lifts so the closer you can get to 0.010" the better.

It's cheap and easy to fix...

[Gregski]

Originally Posted by hatzie

Advance can be adversely affected by one more setting that's usually ignored...
What's the end play on the distributor gear. http://www.chevytalk.org/fusionbb/showpost.php?post/1257140/Measuring HEI gear end play.
It should be 0.010" +0.004" - 0.000" but most are set up way too loose. Every 0.0128" is 1° of advance as the gear lifts so the closer you can get to 0.010" the better.

It's cheap and easy to fix...

thanks I just checked mine and its at .065 and that's with one shim already in there

I also checked my old original OEM points distributor and it has about the same at .062

keep in mind a gasket will take up some of that space, I think at least half

[hatzie]

Originally Posted by Gregski

thanks I just checked mine and its at .065 and that's with one shim already in there

I also checked my old original OEM points distributor and it has about the same at .062

keep in mind a gasket will take up some of that space, I think at least half

I have no idea why GM would set them up so loose. Maybe that much wear? Yours is new tho.

There's no gasket there just shims and an odd spacer. At .062 you'll need three of the five shims in the Moroso kit... 2x .020 & 1x .010 should get you .012 clearance or even .011... 1° timing float isn't bad at all.
http://www.summitracing.com/parts/mo...FYomhgodmgEDkQ

The gasket or spacers between the intake manifold and the distributor housing will fix the distributor bottoming on the oil pump drive or block if that's an issue.

[rich weyand]

To answer some earlier questions. I am running 16-17 base timing. That is, timing without the vacuum advance hooked up and with the idle slowed to about 600 rpm.

The GM HEI adds 20* mechanical advance, so I am running 36-37 degrees total timing.

The AR23 vacuum advance adds another 15* (spec is 7.5*, which is camshaft degrees), to make 51* all in.

51* is what the advance is at cruise, 2500+ rpm, with the throttle plate mostly closed (not accelerating), so the mechanical and vacuum advance are both in.

I have seen 52* given as an absolute maximum for cruise "all in" timing.

Check this: http://67-72chevytrucks.com/vboard/s...d.php?t=689321

[Gregski]

Originally Posted by rich weyand

To answer some earlier questions. I am running 16-17 base timing. That is, timing without the vacuum advance hooked up and with the idle slowed to about 600 rpm.

The GM HEI adds 20* mechanical advance, so I am running 36-37 degrees total timing.

The AR23 vacuum advance adds another 15* (spec is 7.5*, which is camshaft degrees), to make 51* all in.

51* is what the advance is at cruise, 2500+ rpm, with the throttle plate mostly closed (not accelerating), so the mechanical and vacuum advance are both in.

I have seen 52* given as an absolute maximum for cruise "all in" timing.

Check this: http://67-72chevytrucks.com/vboard/s...d.php?t=689321

thanks my original setup was very similar to yours, now as I am getting more comfortable with this stuff I am just trying to tune it in a bit more precisely, can you tell me at what RPM your mechanical advance starts ie kicks in please

[rich weyand]

Originally Posted by Gregski

thanks my original setup was very similar to yours, now as I am getting more comfortable with this stuff I am just trying to tune it in a bit more precisely, can you tell me at what RPM your mechanical advance starts ie kicks in please

Not sure. I know it was messed with a bit before I got it. I know it is 20* all in, and I also know it doesn't come in below 800 and is all in by about 2500. They had the correct (AR23) vacuum advance can on it, which is not stock, so I assumed they played with the mechanical as well and I just left it alone.

[Gregski]

picked up some MasterPro RAMCOA rubber bushings for my anti sway bar from O'Reillys. They were only $8.00 bucks a pair, and I must say I am rather impressed and excited to give them a go, they are made in the USA and seem pretty nice

not sure why one pair came in a bigger box (dated 2012) than the other pair (dated 2016), they are identical

I have not favored the eurothane bushings everyone seems to talk about in the past, in my opinion rubber bushings are designed to cushion the situation and those polyeurothane things are essentially spacers and just make things rigid, sorta defeats the purpose in my mind

I looked at the MOOG ones but for some odd reason their 1-1/16 ones only came in BLUE green truck and blue bushings, come on man! that would totally cramp my style, how was we going to go fishin' lookin' like that

[Gregski]

a little stare and compare of the old ones and the new

I can't wait to try these, I don't think I ever had an anti sway bar before, it must be good for at least 20 horse power, ha ha

[Gregski]

i gotta tell ya, I paid less ($3.61) for all the 3/8ths Grade 8 nuts and bolts on the left at Blue Collar Supply than I did for the twelve locking washers on the right at ACE Hardware

this is for the anti sway bar, I usually don't like using the gold stuff on my vehicles but since this aint going to live in the engine bay I think it beats cleaning those old bolts

by the way do any of youz know if the cad plated "gold" bolts are better than stainless in terms of rust resistance?

[rich weyand]

Originally Posted by Gregski

by the way do any of youz know if the cad plated "gold" bolts are better than stainless in terms of rust resistance?

Stainless steel is more electropositive than carbon steel. You will get bimetallic corrosion. That is to say, the stainless steel will not rust, but it will promote and accelerate rust in carbon steel to which it is attached, compared to using carbon steel to attach to carbon steel.

Grade 8 hardware has 50% more tensile strength than stainless steel hardware. Grade 5 hardware has 20% more tensile strength than stainless steel hardware. No comparison.

Stainless steel hardware sounds good at first blush, but you probably don't want to go there.

[68post]

Originally Posted by rich weyand

Stainless steel is more electropositive than carbon steel. You will get bimetallic corrosion. That is to say, the stainless steel will not rust, but it will promote and accelerate rust in carbon steel to which it is attached, compared to using carbon steel to attach to carbon steel.

Grade 8 hardware has 50% more tensile strength than stainless steel hardware. Grade 5 hardware has 20% more tensile strength than stainless steel hardware. No comparison.

Stainless steel hardware sounds good at first blush, but you probably don't want to go there.

Good info Rich !

[enaberif]

Originally Posted by rich weyand

Stainless steel is more electropositive than carbon steel. You will get bimetallic corrosion. That is to say, the stainless steel will not rust, but it will promote and accelerate rust in carbon steel to which it is attached, compared to using carbon steel to attach to carbon steel.

Grade 8 hardware has 50% more tensile strength than stainless steel hardware. Grade 5 hardware has 20% more tensile strength than stainless steel hardware. No comparison.

Stainless steel hardware sounds good at first blush, but you probably don't want to go there.

This is why when using stainless hardware in places that isn't stainless you should use a anti-size coating of some sort to prevent seizing or corrosion.