Hello,

I had dig the web and the forums, but i have found no answer.

this is my application:
-Vaccum of
-weights locked full out position.
no sideplay on the end of the hei, (lots of up and down play, but that should be normal)
-hei shaft gears are in good condiotion

engine starts with 40 degree advance (weights locked out) as reving up, advance retards to 10 degrees.

When weights are free retarding stops, but advance stays on initial.

changed coil no change, pick up coil measured 0.8Kohms, removed capacitor, no change.

What caqn cause this retarding? camshaft movement? ignition module? pick up module?

oh..did try 3 different strobes and had the same results

I have no clue...please help

Thanks.

Milan

 

oh..did try 3 different strobes and had the same results

 

What camshaft do you have? Is the vacuum advance hooked up? And to where if it is.

 

it's hard for me to believe that it would start with that much advance. Perhaps the timing marks are incorrect. And a locked out mechanical advance? Why?

 

Two things could happen. One, the bolt is too loose on the distributor. The second one is that your timing marks are moving. The harmonic balancer rubber gets old and the outer ring moves. I had the same issue. Timing would move around, and I thought I was going crazy.

 

Dear All,

Thanks for the input, really appriciated.

I have locked the weights out, to exclude them of the phenomena, and so did get the vaccum off as well (when its on its mainfold and does its job well)

the camshaft is a Comp Cams Extreme Energy one, and there are edelbrock perforem rpm heads, and edelbrock torker intake on the block.

it idles nice only above 20 degrees, end still ok on 30. was starting up a bit harsh on 40.

Timing is engraved on the harmonic ballancer, should be ok, TDC was on mark 0 for sure.

The HEI was taken apart end inspected, all screws are ok, and the shaft is not bottoming down on the oil pump.

The harmonic balancer was installed pretty new, the whole engine was rebuild a few year ago, but i will look into that.

here is the engine:
http://hebonline.hu/imageview.php?da...90888de86z.jpg

Thanks,

Milan

 

this is the Harmonic Ballancer, looks like mint, and cant move the outer ring on the shaft at all by hand, is there any way how to test it?

http://www.summitracing.com/int/part...ake/oldsmobile

Thanks,

Milan

 

Completely remove the weights and wire weight the posts to the center posts the advance plate goes on so that it is as tight as possible. It's very possible you are bending the pins weights the attach to which could be your issue. But that is a lot for it to be retarding. At higher rpm a couple degrees is not uncommon and actually beneficial. But not 30* worth.

Watched the video and your not turning a lot of RPM from what it sounds like. Mighty cool way to get them in the air. How much cable is on that spool?

 

hello,

it revs up to 4.5k on the initial climb, than comes back to 3k for the most of the launch.
so we need torque more than rpm...thats why this engine should be great.

problem is, that if i dont use the vaccum, the ignition retards unred initial, and when launcing with the vacuum on it goes pretty well until the 2nd troathopens, and vacuum goes away from the carb, the engine looses power as loosing the advance.

i will try the weight pins, but should not cause this, when i have locekd out i have locjed them out pretty well.

should I try to change the module or the pick up coil? or the cables themselves? this sound stupid but i have gone trough all logical things and found nothing.
It should be a natural retards, as the coil needs fixed time to saturate, but that should be a few degrees, not few tens.

its 1400m cable on the drum. we get out around 450m height in 45 seconds.

its good fun:
all the best,

Milan

 

 

To test the position of the timing mark on the balancer use a piston stop in #1 cylinder and rotate the engine clockwise until it stops and mark the balancer, then rotate the engine counterclockwise until it stops and mark the balancer. The 0 mark should be in the middle of your two marks.

 

You wouldn't be able to move the outer ring by hand unless it was REALLY worn out. Is your vacuum advance hooked up to a port on the manifold or to a port on the carburetor?

 

hello,

the ballancer is at top center, thats ok, i meant testing if the timing marks are rotating with the bellancer outter shell, as waterzap sugggested.

Thanks,

Milan

 

when its hooked up, its on mainfold, and the vaccuum advance works fine. Problemcomes when on high power the vaccum decrases in the carb, and the advance goes back as well.
So i can only use the engine before second throttle opens

 

So I'm no expert on this but it sounds like only the vacuum advance is working and the mechanical advance isn't. When your at WOT you don't have much vacuum so if your mechanical isn't working and your losing vacuum advance your advance will be reducing.
Experts can chime in and correct me if I'm off base.

 

if it keep retarding it self you might want to check the chain . Have had a 389 and 400 pontiac do that to me . Do you know what they used for a chain on it ?

 

1. I am deeply impressed by your mechanical contrivances, and by the fact that you can launch human beings into the atmosphere with that thing.

2. Where are you? The only people I've known named Milan have been Bosnian.

3. If I read this correctly, it sounds as though the mechanical advance doesn't advance when left alone, and as though it actually retards at high RPMs, even when it seems to be "locked" in the fully advanced position.

If this is the case, I would suggest checking the arrangement of your weights and crosspiece. If the arrangement is set up as for a Chevy, it will "advance backwards" (like the Italian army), as the Chevrolet distributor turns clockwise, while the Olds turns counterclockwise.

Also, I am not clear on your vacuum advance problem, but it sounds as though it may be related to parts being reversed as well.

Welcome to ClassicOlds!

- Eric

 

1. Thanks!! you should try it!

2 Hungary!

3 mechanical advance seems work ok...there is a mysterious dissapearng of 30 degrees (could be a books title) the hei is ok. weights and all ok.

maybe? shimming the hei enplay? (its about .08)
maybe? checking cranckshaft end play?

thank you very much for the welcome and the input!

 

Hmmmm.....

it was a double chain set installed...dont know what it is...

some more shots of it:
http://hebonline.hu/tmp/455/

thanks!!

 

When you're reeling that winch in is the engine at WOT? Because the timing retarding itself would make perfect sense. Vacuum drops to near zero and the vacuum canister advance comes out of the equation leaving only initial and mechanical (distributor).

Having 40* at idle makes sense also because now it's the opposite of WOT. The vacuum canister is adding it's 'advance' timing to the equation because engine vacuum is pulling on it. My timing at idle is north of 45* so no big deal there.

Maybe I'm just confused by this thread? Lol I do like the ingenuity though.

 

PROBLEM SOLVED,
thanks for all the replies. Changed the HEI modul and the problem is gone, timing works as it should be,....strange as it is, the hei module was lagging 30 degrees on high rpm, and none on idle...searched the web for weeks on Hei faults but seems like this problem was unique.

THANKS!!

 

Never heard of that before.

Glad you got it fixed.

Keep 'em flying!

- Eric

 

I bought a collection of engines and transmissions dirt cheap from a British gliding club around seven years ago, an Olds 350/th350, a Mopar 383/727 and a Chevy 350/th350(broken). I turned a fair profit on them, the glider club was rationalising to BB chevys and custom built powerglides which had the desired characteristics for the heavier gliders they had acquired and wanted the old units gone quick.
I got lucky, right place, right time, and the cash in my pocket. .


Roger.