trying to set timing - again

crawdaddy · Nov 5, 2013

thanks everyone for sticking with me. i certainly appreciate it.
as far as original, no I'm sure not many things on this engine are original. It was a replacement engine I got in the early 90's.
I know not to mess with more than one thing at a time but it seems I have to address this vacuum leak. I thought of that and sprayed carb cleaner (almost empty can) and some starting fluid around the carburetor base, intake and vacuum lines. There was no change in idle. I think it must be something in the carburetor. The carburetor is a Edelbrock 1405. The 1405 I from what I read 'factory rich' and I'm not sure what ballpark its in but it does smell rich. I just rebuilt it when I got the car out of storage. I did look down the throat and it seems the primary and secondary blades are fully 'closed' at idle but air has to get in there from somewhere. I hate to muddy the water but the a/f mixture screw on the left side doesn't effect the carb as it should but I figured I would tackle all that next.

Quote:
I plugged the vacuum advance back in and at idle the advance was at 30.
the rpms would have increased.. I assume u dropped the rpms back under 1000?

I expected them to increase but they didn't, not by more than 100 or so.

As for the B1 can, yes it is rated at a max of 16 degrees crank advance. I will get another vacuum can more along the recommended lines. I had a chart with all the cans and their specs but computer crash and I lost my bookmarks.
I will also round up some weights for the distributor and see what I can do. This part might take me a couple days but I will be back. For those following along, if I can't find that vac leak will it be better to continue in this thread or start a new one then pick back up here once that is sorted?

again thanks everyone, see ya' soon

Steptoe · Nov 6, 2013

will it be better to continue in this thread or start a new one then pick back up here once that is sorted?

No...mixtures and timing go hand in hand

I have found the best 'tool' for finding a vac leak is one of those elcheapo chinese LPG pencil torches....
Also check the vaccuum lines to activate the kick panel vent doors etc.

The carburetor is a Edelbrock 1405.

Give me a holley or a vintage British carb, or B&S nps.. the others I have never bothered to familarise myself with.
In saying that.. when u "rebuilt" it did u also rebuild the butterfly shaft bushes and re align the butterflies EXACTLY correct?
Starting with the butterfly bushes.. these wear due to ppl using too heavy return springs... check fore movement / play particularly in the just off hozonal position... they wear oval.
No the butterflies do NOT sit against the bores fully closed....doing so ends up messing the machined surfaces of the bores , and jambing butterflies when sitting for a while which results in bent shafts....all of that results in vaccuum leaks around the butteries.

I just rebuilt it when I got the car out of storage.

That concerns me... no not a dig at u either...one of the biggest and expensive and consistent and headaches causing baldness ... issues with carbs is "rebuilds" and 2nd hand carbs...
Dont even bother.. simply go to holley Elddy, whatever tell them what u have AND what u are going to use the car for 95% of the time and the rpm range u will be using 99% of the time.....they match it up... from there about the onbly thing u have to do is maybe drop the jets size a couple pionts.... Set the accel pump and secondary butterflies.

The ONLY time I rebuild a carb now is because the carb company , and the brand of engine, and car manufacturer have gone out of business 60 or 70 years ago... I even replace IMPCO lpg carbs now.
Other than that its just not worth the time, effort money or headaches.
Personally I prefer hollies for ease of tuning adjustement etc. and once dialed in they dont have to be touched for decades.

PS get original Chev counter weights... do not use after market ones .. they dont fit on the bushes and pins properly

Lawrence454 · Nov 6, 2013

crawdaddy said:
As for the B1 can, yes it is rated at a max of 16 degrees crank advance. I will get another vacuum can more along the recommended lines. I had a chart with all the cans and their specs but computer crash and I lost my bookmarks.

This Accel unit is a little pricey, but should do what you need :

http://www.summitracing.com/parts/acc-31034/overview/

crawdaddy · Nov 6, 2013

I saw that Accel unit and have been trying to find just how adjustable they are but I don't see it listed anywhere. So the Accel should allow me to adjust both the vacuum AND the total amount of advance?
I got out my big boy scoop and have really been digging in threads because alot is said to be covered in old posts. I finally found deeper information on making 'any' vacuum can adjustable for both the vacuum and the amount of advance it provides. I then found pictures and it made more sense. If that Accel unit will 'drop in' and do what I want it will be easier but I am not past making the little brackets to tune my own can. I might do that on my time instead of wasting everyone else's time...that would be another variable. I did find that chart with all the vacuum cans and their values but there are none close to what I need.
Thinking about it....my can starts at 6" and ends at 19". If I were to limit the degrees that would change my 'all in' point which would be at a lower Hg(?) If I stopped my can at the 7 or so crank degrees I could see what Hg my new all in was...steps, you did say shoot for starting at 7" all in at 14" with 7degrees (crank) advance right?
Steps - about the carb....my dad has a 1967 Morgan with the dual SU carbs on it. He doesn't work on anything but was wanting to get rid of them for some aftermarket junk because his guy can't really get them right. I told him his guy just wasn't talking to them right.
When I say I rebuilt my 1405 I guess I should say I took it apart and cleaned it up. I went to the store, got the kit and replaced the old parts. I also added an electric choke. I don't remember what all was in the kit, I replaced a leaking float, accelerator pump thing, needles and maybe seats, and some various other gaskets i think. I don't remember touching the butterfly bushes or any of that. I'll have to find the kit and instructions. This carb probably doesn't have 20000 miles on it but has sat for years. I don't think my return spring is heavy and I have read that about the butterflies sitting against the bores in previous posts. I don't think I have them there but I am trying to get in the weeds of all this (like I am this timing) instead of just scratching the surface to make it run.

Dont even bother.. simply go to holley Elddy, whatever tell them what u have AND what u are going to use the car for 95% of the time and the rpm range u will be using 99% of the time.....they match it up... from there about the onbly thing u have to do is maybe drop the jets size a couple pionts.... Set the accel pump and secondary butterflies.

That is pretty much how I got the 1405 back in the day but I took it out of the box, put it on and drove it......scratched the surface.
That pen torch sounds like a good plan to look for that leak. I had one (harbor freight) that lasted about 25 minutes. I do have a slightly bigger torch though and I think that will work. I did just do alot of work to the climate control system and its vacuum components but pretty sure that is buttoned up except that position where the vacuum is vented. It is turned off right now though. To eliminate all that I might take the hoses off the manifold and plug all that, then the only place it can be is in the carb or on the manifold. I also read to take out the mixture screws, spray some cleaner in there and try again. Can't hurt.
Alright, I'll go play a while and let folks know what I come up with. Thanks again everyone.

crawdaddy · Nov 6, 2013

Ok, here is the late morning update:
Ignition: I started looking at the vacuum advance can on the distributor my buddy gave me to play with. After cleaning it up I found the numbers 626 10 on it. He thinks it was on a C3 corvette. I researched these numbers and found it speced at 0 degrees starting vacuum of 4" Hg with a maximum crank degrees of 10 at 8" Hg. It held vacuum and there would be my 10 degrees of advance so I think this one will work like it is.

Air leak, carburetor: Idle speed screw is all the way out. Fast idle cam not a factor. I unhooked all vacuum hoses and plugged them at the manifold. I started the motor and it idles around 650-750 rpms. There is a little swing in there but I have my tach on low rpm setting. I played with the idle mixture screws figuring if I could turn them all the way in and it still runs then it is not idling on the idle circuit but probably the main circuit, or another, or the leak. I could turn the left mixture screw all the way in. The carburetor wouldn't really react until the screw was seated. Then the idle would drop by about 50 points or so, smooth out just a hair and I could hear a slight whistle. Sounded like coming from inside the carburetor throat, secondaries if I had to guess. I could then turn the right side idle mixture screw in and it would slowly kill the engine. The lowest I could get it to idle was around 500 rpms. While running I could take my propane and slowly move it all around the base of the carb, around the shafts, everywhere I could think to point it...I even put the nozzle down in the secondaries...even the primaries and there was no change at all. I sprayed brake cleaner, carb cleaner and wd 40 all around the carb exterior as well with no change in idle. I took my hands and covered the throat of the carb with a decrease in rpms. I took a rag and covered the secondaries and could kill the motor after a while. I covered the primaries and could kill the motor after a while.
Any thoughts from here?
so.....what do y'all think of the 626 10 vacuum can and where should I go on the idle thing?

Steptoe · Nov 6, 2013

I am not past making the little brackets to tune my own can..... If I were to limit the degrees that would change my 'all in' point which would be at a lower Hg(?) If I stopped my can at the 7 or so crank degrees I could see what Hg my new all in was...steps, you did say shoot for starting at 7" all in at 14" with 7degrees (crank) advance right?

yep I assume u have read my other posts about making stop tags that mount on the VA mounting screws....

.....I researched these numbers and found it speced at 0 degrees starting vacuum of 4" Hg with a maximum crank degrees of 10 at 8" Hg. It held vacuum and there would be my 10 degrees of advance

Yep.. the numbers on the stem of the VAs can vary, 1 number I still have no idea what it reales to.. even part numbers etc... the other number is the degrees in the can.....but still physically...check if those degrees are crank or dizzy degs

For what u want, practically any old working VA off a stock dizzie will work for u , but may require tags if not adjustable internally.
Any basic aftermarket 'adjustable' will do the job u want also as the specs u are looking for basically are over lapped in all the adjustable I have used over the years.

A note: recently I have used Chinese GM HEI adjustable... because needed in a hurry, and 2 out of 3 the diapham gaskets have sucked a kumura (if u dont know what that means... google it lol)... and the metal on the adjustment screw is crap and very easy to strip the screws .. so when adjusting pull a vaccuum on the VA and adjust without spring load on the adjusting screw housing.

crawdaddy · Nov 6, 2013

kumura.....sweet tater.....yes i had to google it

I going to throw that 626 can on there and get some more numbers I was going to try the weights from that distributor as well but they look like crap. the holes are kinda egg shape. My research leads me to believe the 626 is the last 2 numbers of the part number and the 10 is the amount of degrees. There was some question as to if that was crank or distributor degrees. With such a short area of travel for the rod i am guessing crank degrees but i will find out in a second.

I am still pondering the carburetor thing. Thinking out loud here but if I am not mistaken the idle speed screw pushes on the throttle blades. With my idle screw all the way out the carburetor should be operating in the idle circuit only. If I close off both a/f mixture screws it should not start. If I adjust them about 2 turns out it should start, adjust the a/f screws for max vaccum right now then adjust the idle speed with the idle speed screw if it isn't correct. Wouldn't that indicate there is no vacuum leak? That still doesn't explain the left side a/f screw not having much authority until it is seated though.

crawdaddy · Nov 6, 2013

no such luck....the 626 can is a tad longer and wont fit. I could get the hole nearest the canister to line up but the other hole wouldn't line up. Also, with that short throw the breaker plate will not move enough for me to put the screw in anyway. Oh well. I'll just get that crane adjustable I think.
Thanks for the heads up on the stripped screws...that is all i need now.

crawdaddy · Nov 8, 2013

I should have just made a stop for the VA can. So I ordered an Accel model 31034 adjustable vacuum advance kit. The kit was the can and an allen wrench. Unless I can't read directions this thing is a piece of junk. I tested the vacuum and sure enough, it starts around 5 Hg and is all in at 10 Hg. That part is good and fine. It says to turn the wrench inside the chamber and lists how to change total advance by the number of turns. It indicates from 1 turn for somewhere under 5 degrees of advance all the way up to 9 turns for a total of right at 30 degrees.
I took pressure off the unit by holding my finger on the advancing rod and turned the allen wrench. After one turn the allen wrench stripped inside the unit. I have a wide assortment of allen wrenches and found one that will turn whatever is in there but from stop to stop it will only turn 2 full turns. I think the can is pulling about 24 degrees of advance and won't adjust. I might just try to force it more.....its already crap but I am no where further along but out some money. Just to see where I am now, I put the rubber band on my weights (it wasn't pulling any centrifugal at idle but I wanted to be sure) and fired it up. My initial was still at 15ish. I turned my initial down to 10 degrees with the vacuum unplugged. I plugged in the VA and the advance went to 34 degrees at idle so around 24 degrees in that can.
I guess I will get to making that VA stop.

Lawrence454 · Nov 9, 2013

Did they include the instructions ?

http://prestoliteperformance.com/me.../media/instructions/accel/ACCEL_Instructions_vacuum_advance_points_v8_31034.pdf

crawdaddy · Nov 9, 2013

yes, same as in your link however are the instructions not showing 1 turn from fully counter-clockwise as being less than 5 degrees advance, all the way up to 9 turns as being close to 30 degrees advance. This unit will only turn 2 full turns from fully counter-clockwise and is up around 23 degrees advance in the can at fully counter-clockwise.

Steptoe · Nov 9, 2013

After one turn the allen wrench stripped inside the unit.

yeah I mentioned about chinese made cans a few posts back... if u cut the can open u will find it is not the head of the grub screw but the thread in the crap metal plate it goes into that stripped.

crawdaddy · Nov 9, 2013

You did. I remembered as I was turning the thing but it still screwed up. Its ok. The starting Hg is ok and I should have time tomorrow to make the stop

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Steptoe · Nov 9, 2013

Here is a pic.. u can make them to fit both ends... adjusting the start and finish vaccuum specs... and the distance between is the number of degs.

Also , depending on the VA can spec u can file out the slot as the case with this one at one or both ends, but this has limitations as to the distance the diaphragm moves in the can.
The pic is of the very 1st gm points dizzie I was messing around with, figuring out the 'how to' adjustments I talk about, nearly 40 yrs ago.. before internet and magazines started to get it right... well the occasional one even these days.
Most talk about changing the anvail rather than the counter weight tails... its far easier and more accurate to change the tail profile.

crawdaddy · Nov 9, 2013

thanks steps, do you have any pictures of where you recommend to file the weights? the picture of the stop was worth 1000 words.
I haven't gotten around to the stop yet, I have to put my wife's jeep back together so she can go somewhere tomorrow....i'll work on it tonight unless my 2 yr old won't let me.

my metal working skills are infinitesimal but i'll make it work....might not be as pretty but it will work

Steptoe · Nov 10, 2013

Sorry . dont have pics of filled counter weights.....hmmm maybe?
Will have a seach... maybe have an old dizzie with modded weights on in the old garage???? Im preety sure it hasnt got counterweightsa on it... been a few yrs since looked at it.
Will have a look later this morning

Put the counter weight in a vice.....
on the tail edge that contacts the anvil......file off about 1/2 mm deep and back from the tip about 2mm/ 3mm in a sort of rounded elliptical shape.
It is best to do both counterweights in the vice at the same time to get very similar shapes.
Drop in and see how many degree in the cent now.....
Do not over do the filing, doesnt take much.
And u DO have those spare ones from the wrecking yard right?

crawdaddy · Nov 10, 2013

I might save you from a picture, I am going to type this then send another post with a drawing (easier to type on the computer and send photos on the phone)
I'm just making sure my nomenclature is right on where to file. I think so, it makes sense to remove a small amount to enable the weight to swing out a tad more (right?)
I will put both weights in a vice together to make them as 'same' as I can get. I don't have my spares yet but want to be ready when I do. I will hopefully get the VA done today then work on finishing this up this week.

crawdaddy · Nov 10, 2013

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crawdaddy · Nov 11, 2013

I might be able to close this epic thread if folks agree.....
I made my stop last night, installed it this afternoon, fired it up and here is what I have:
idle 700 rpms with VA attached = 18 degrees advance
idle 600 rpms without VA attached, line plugged = 10 degrees advance
at 3000 rpms = 30 degrees advance
at 4200 rpms (all in point) = 34 degrees advance
with VA attached at 4200 rpms = 42 degrees advance

I haven't done anything to the weights and I don't think I'll have to. I will play with the springs to bring the all in down to around 3000 rpms and see how it does....

what does everyone think?
I don't think the carb or I have a vac leak...I do think i might have some crud in the left a/f port and will address that.

without an a/f mixture gauge, data logger, etc, is there much point messing with the carb too much? My plugs have always looked rich but I'd rather be a tad rich than a tad lean. I'll run this for a while with my new advance / curve and see what happens.
Thanks everyone, I appreciate it and will try to pay it back.

Steptoe · Nov 11, 2013

The dizzie didnt have any counterweights in it sry.. but the top pic is spot on....but take 1/3 that off then try.. and if need be take more....doesnt take much for sa lot of degs.

at 3000 rpms = 30 degrees advance
at 4200 rpms (all in point) = 34 degrees advance

that last 4 degs between 3000 and 4200 will NOT be springs... things like pins bending/ loose, pin bushes worn, main shaft / bushes worn will be the culprit there...
@ 4 degs indicates wear that is border line rebuld ( spot weld any loose spring pins... replace counterweight bushes and chances are a new shaft will take up most the play in the shaft/ bushes wear... it is the shaft that wears the most)

without an a/f mixture gauge, data logger, etc, is there much point messing with the carb too much?

No.. so long as u dont have excessive eye burning smells and other obvious issues.
And if the carb is close.....try plugs a heat step hotter, espec the front cnr cyclinders should remove the soot... If not drop the jets a step down.
And if the mixture/ idle speed screws are 1 1/2 turn +/- 1/3 turn u will be not far off at most.

I appreciate it and will try to pay it back.

you have learnt a lot...pay back is passing that onto others...thu often its hard because old wives tales just hand in there.. and as John (who wrote the timing 101) comments somewhere alone the lines that even experienced mechanics who should know better have no real idea about timing , why, how to....or the relationship between mixture loads and timing.

trying to set timing - again

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