Setting Timing with a Vacuum Gauge.

Setting Timing with a Vacuum Gauge.

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By The Master Cylinder - 12 Years Ago

This morning I was working on the ol' Y and decided to check the timing while there. Disconnected the vacuum line and put the light to it. Timing was @ ~20° advanced. w00t

Brought it down to 10° and it almost stalled. Didn't like it at all. Hmmm Checked the damper, it was spot on.

Then I connected my vacuum gauge and timed it using just the readings on the gauge. Runs/starts good. Rechecked with light and it's back up to 16-18° advanced. Didn't notice any detonation or over heating (tho my electric fan did come on while I was leaning over it. 'Bout scared me to death). Smooooth

Runs good so I left it but it's got me puzzled.

Any ideas why it likes the timing so far advanced?

By oldcarmark - 12 Years Ago

[quote]The Master Cylinder (9/16/2013)

This morning I was working on the ol' Y and decided to check the timing while there. Disconnected the vacuum line and put the light to it. Timing was @ ~20° advanced. w00t

Runs good so I left it but it's got me puzzled.

Any ideas why it likes the timing so far advanced?[/quote

The first thing that comes to mind is the damper outer ring has shifted.The only way to check it is remove the rocker cover on passenger side and rotate engine until both valves are closed on #1 cylinder..Should put you very close to TDC.Check the postion on the damper.If its off you have found the problem.Many old timers used to set the timing with a vacuum gauge.If its not pinging or hard to start it should be fine.If it is,back the timing down until it doesn't.

By The Master Cylinder - 12 Years Ago

Hi Mark. Yeah checked the damper with Piston TDC Stop similar to this one. The "0" is right on the money. Has me a little baffled.

http://forums.y-blocksforever.com/Uploads/Images/ebbbcabe-630c-40be-a973-e74f.jpg

By the way I'm probably one of those "old timers that used to set the timing with a vacuum gauge". We used to "Power Time" the engine also, haha

By Talkwrench - 12 Years Ago

Whats the chances that someone has modified the dissy? How many inches of vacuum did you come back?

By The Master Cylinder - 12 Years Ago

Talkwrench (9/17/2013)

Whats the chances that someone has modified the dissy? How many inches of vacuum did you come back?

Background on the distributor; Cardone reman ~1 year ago, Mr. Gasket advance springs, Pertronix III w/Rev limiter set a 5500 rpm.

I advanced the distributor until 20 in/hg, then backed off 2 in. That's where it is now, timing ~16° BTDC at idle. Much lower than that and the engine starts to stumble a little.

By Talkwrench - 12 Years Ago

Mmm somthins a little odd..? 20" is pretty good then 2" off = OK..But what is your max degrees now? With those springs you should be all in well before 2500RPM. Ahh think yourself lucky if all is running well .

By The Master Cylinder - 12 Years Ago

It does seem a little odd. That's what has me puzzled. I don't know what the max advance is now, the damper reads only so far...

By GREENBIRD56 - 12 Years Ago

I would suggest you mark the damper with the full advance you want - 36º/38º and do just what you said earlier............"power time" the engine. Meaning rev the engine to see the maximum mechanical advance and lock it at the 36º/38º by observing the point where she stops gaining advance.

When you release the throttle it should back off according to the slots you used in setting up the mechanical advance - if it doesn't, you'll have to find out why...... Where was it set when you put the lighter springs in?

By The Master Cylinder - 12 Years Ago

Steve, thanks for the suggestion. I'll check it out as soon as I get some timing 'tape' to extend the reading on the damper so I know where it's at at full advance.

When I rev it now with the timing light it does show that it is advancing and returning to ~16° BTDC.

I think the timing was set at 10° when I installed the lighter springs, but that was a while ago (~ 1 year) and lately I have a hard remembering what I had for breakfast.

Do you have any suggestions what 'tape' to use on the damper?

Like I stated earlier it does seem to ping (that I can hear, damn old age) and doesn't over heat like it's out of time.

By The Master Cylinder - 12 Years Ago

GREENBIRD56 (9/17/2013)

do just what you said earlier............"power time" the engine.

Haha, what I meant by "power time" is we would the trans in low, hold the brake and stand on the gas w00t

while advancing the timing until we heard it ping, then back off the timing a little. best to do outside. w00t

Only works on an auto.

By oldcarmark - 12 Years Ago

The Master Cylinder (9/17/2013)

As far as what tape to purchase-they don't make one for the Y-block but there is one made that's real close.They are sold based on diameter of the damper and I think the closest is Small Block Ford or Small Block Brand X.I don't remember which it was that I purchased but maybe someone else here will.

By GREENBIRD56 - 12 Years Ago

I've never had good luck with the tapes - and usually calculate the advance distance (damper diameter times Pi divided by 10 equals 36º).

If for instance you have the distributor's mechanical advance stops set in the slots for 10º (x2) - that would result in a drop back to near 16º initial at idle. Many guys that run "ported" manifold vacuum to the distributor report good results with 16º initial.

By The Master Cylinder - 12 Years Ago

GREENBIRD56 (9/17/2013)

Thanks for that formula ( actually a big DUH! on my part, haha. That's too easy). I'll check it out.

One other question for you guys. Do you think that the Multi-spark of the Pertronix III could be messing up the reading of the timing light? Like when it flashes. Off the wall question but I heard in the past that a MSD can cause a light to give erratic flashes.

By pegleg - 12 Years Ago

Master, No! I have run both and had no problems with spark scatter. If you are seeing this, make sure the cap and rotor are good and connections to & from the coil. I'd also take a look at the dist plates for a bad ground or something loose.

By The Master Cylinder - 12 Years Ago

Thanks Frank. I'll go back and check everything. Gotta be something I missed. Either that or she's just gettin' persnickety on me. w00t

Marked the damper for 36° BTDC per Steve's suggestion but won't have a chance to to look under her skirt for a couple of days now tho.

By pegleg - 12 Years Ago

I should probably add that because I haven't had issues with the Pertronix doesn't mean it can't happen. They did in fact have issues with the first two series, lotsa complaints about them.

By John Mummert - 12 Years Ago

Master cyl, sounds like your engine has an other than stock cam. Y-Blocks just don't seem to run with less than 14° advance once any performance cam is installed. For what its worth, I had nothing but trouble with the basic Pertronix units but everyone I talked to loved them so I generally didn't say much about it.

Enjoying life EAST of PCH

By aussiebill - 12 Years Ago

pegleg (9/18/2013)

I should probably add that because I haven't had issues with the Pertronix doesn't mean it can't happen. They did in fact have issues with the first two series, lotsa complaints about them.

Frank, hard to work out some of the symptoms our friends relate here for us to help, i,ve only heard that the pertronix 1st series could burn out if ignition left on for periods while testing things, i have 3 cars with pertronix 11 and correct coils for years with no problems and nice performance. I often think other nuances cause half the problems. Smile

By smokey - 12 Years Ago

Great Topic,

How much total advance advisable with a Y Block, is 42 to much? How soon should it all be in, 2000 rpm, 2500 rpm? We have a 57 272 with G heads, cam shaft 238 @50, 16 degrees of overlap, .485 on intake and exhaust, 113 sep.

Please don't be afraid to hurt my feelings if the cam is to much for a 272 in a Custom 300 with 3 speed overdrive.

First stop will be to have the 57 distributor evaluated on a machine by a very reputable ignition specialist. Then a 57 autolite 4100 will replace the 600 Holly. The problem is we do not have a great deal of experience with Y block.

Thank you all!

By The Master Cylinder - 12 Years Ago

John Mummert (9/18/2013)

Master cyl, sounds like your engine has an other than stock cam. Y-Blocks just don't seem to run with less than 14° advance once any performance cam is installed.

Eeeep...

That never even crossed my mind. Yes it does have a Clay Smith cam. That explains some things. Thanks for the info. I'm still going to check TOTAL advance to make sure it isn't advancing too far due to the initial timing being at ~ 16° BTDC.

John Mummert (9/18/2013)

For what its worth, I had nothing but trouble with the basic Pertronix units but everyone I talked to loved them so I generally didn't say much about it.

I had a Pert I go out on me be I must admit it was my fault for leaving the key on with the engine S/D for some adjustments. It worked fine before that. I was using it to trigger my MSD 6A. That problem has supposedly been rectified with the II and III.

John Mummert (9/18/2013)

Enjoying life EAST of PCH

Finally someone answered my question about life EAST of PCH... Wow

By pegleg - 12 Years Ago

Pretty hard to be West of the Pacific Coast Hwy without getting wet, or being in a boat!!

By The Master Cylinder - 12 Years Ago

Bahaha. I live west of PCH. I'm not getting wet... not yet anyway!! w00t

By Talkwrench - 12 Years Ago

I live west of the PCH...waaayy west ! I enjoyed the drive once past Santa Barbara and the traffic wasnt so bad, made it as far as Rocky point [?]. Stayed in San Simeon so we could go to Hearst Castle. Did a few stops on the way and back to Garden Grove.. Cambria etc.

Would have been back this year but the old man died , so next year Julyish.. Smile

By The Master Cylinder - 12 Years Ago

Did you see the Giant elephant seals on the beach by San Simeon. Really something to see. I really like it up by Cambria.

By Talkwrench - 12 Years Ago

No , did keep an eye out and called into a few places .. but no fatties on the beach 'cept me and the missus..

By The Master Cylinder - 12 Years Ago

Haha, Not sure you would want to share the beach with them even if you were allowed to. The weigh more than your '56 w00t