Low vacuum/ high timing

[xx88man]

I figured I would start a new thread on this. Tried playing with this again today. Adjusted distributor to get maximum vacuum. Max is steady at 14hg. Picked up a new timing light and it shows my timing at 42 degrees advanced not fluctuating. (Vac advance plugged) I feel like my timing mark is lying to me. Can the harmonic balancer have spun yet still hold a steady reading? Car runs fine but would it even crank if it was advanced that far? Any help is appreciated at this point. Oh ya 1974 with a 360

[Cuda Cody]

Tell us more.  What do you know about the engine specs.  What cam do you have, what compression?

[Solarguy]

Bring it to TDC on the compression stroke and see where marks are. 

[Dakota]

One of several ways to help with the check on TDC during the compression stroke is to use a "piston stop".   I bought one at Summit Racing (about $10).  With it placed in the spark plug hole for the #1 cylinder, you can manually rotate the crank until the piston reaches the stop.  Note where you are on the timing marks, then reverse the rotation direction until the stop is reached again and note that mark.   Your true TDC will be the midpoint between those two points.

I did this on my 340 and found that my zero mark for TDC was off about 1.5 degrees.   I bought a harmonic balancer label from MSD to reflect the corrected location for zero.

I'm not an engine guru by any means but 42 degrees advanced "all in" seems pretty high.  I have 34 degrees on my 340  with no vacuum advance and a lock out plate.

[xx88man]

Tell us more.  What do you know about the engine specs.  What cam do you have, what compression?

The car is new to me. Didn't run when I bought it. Previous owner knew nothing lol. I'm figuring it out. I'll go buy a piston stop and go from there. Thanks for the replies guys

[RUNCHARGER]

On a smallblock you can even bring it up near TDC and put a screwdriver in the spark plug hole and feel it while bringing the piston the rest of the way up. Probably get within 5 degrees anyway.

[xx88man]

On a smallblock you can even bring it up near TDC and put a screwdriver in the spark plug hole and feel it while bringing the piston the rest of the way up. Probably get within 5 degrees anyway.

Ya that's what I'm going to do instead of searching for a proper stop today. Thanks Sheldon

[headejm]

This is my favorite reference for setting up Mopar distributor curves.

https://www.mymopar.com/downloads/elecignconv.pdf

I don't think you are that far off considering you said the car runs good. On the low end of the curve you want good startability. On the high end of the curve you want to avoid detonation. My 383 with a mild cam is about 15 degrees at idle, 27 degrees mechanical advance, and about 10 degrees of vacuum advance. Around 52 degrees total advance. You are not that far off IMO.

[xx88man]

My timing mark on hb is right at 0

[bdschnei]

Maybe I missed something but are you saying the timing marks are indicating 42 degrees advanced timing at idle with the vac advance capped off? And it cranks and starts OK? That's a head scratcher for sure  I'm still wondering about a slipped harmonic balancer since earlier I think you mentioned an engine vibration on this 360. As other's have suggested, since the car is new to you verify the timing marks using a piston stop.

[xx88man]

Maybe I missed something but are you saying the timing marks are indicating 42 degrees advanced timing at idle with the vac advance capped off? And it cranks and starts OK? That's a head scratcher for sure  I'm still wondering about a slipped harmonic balancer since earlier I think you mentioned an engine vibration on this 360. As other's have suggested, since the car is new to you verify the timing marks using a piston stop.

That's correct! Doesn't make any sense especially since I verified the timing mark today is 0 at TDC. I thought for sure it would be the balancer but SURPRISE it seems okay. I'll be trying some other things this afternoon

[xx88man]

I was able to bring the idle down to about 1100 (according to the factory tach) but it is barely running when I put it in gear (900 according the tach). Lower idle doesn't change my timing reading so... maybe this engine just has a big cam? It does sound lopey but who knows

[bdschnei]

You've probably checked this already but just in case.... make sure the centrifugal weights of the distributor aren't stuck swung out in the advanced position. That would mess with the base timing.

[MoparLeo]

This sounds like it is going to be a crystal ball tuning session. Impossible to really do any good adjustments without knowing what you are dealing with. Vacuum is not a timing adjustment.

Tell us more.  What do you know about the engine specs.  What cam do you have, what compression?

[/font] This information is key unless you want dart board guesses.
https://www.onallcylinders.com/wp-content/uploads/2016/03/31/vacumm-reading-1.png
https://www.enginebasics.com/Engine_Basics.html
https://www.tpocr.com/dodge2.html

[Cuda Cody]

    Yup, without knowing some details about the engine it's going to be a little hard to help without being there.  The cam section is a HUGE part of how the engine will react to changes and how it preforms in different situations.  Sounds like you have some things figured out, but the unknown cam scares me the most.