Timing advance question

[Mr Roadrunner]

I have a fresh 383 on a break in stand and am puzzled about the timing. After the first startup everything seems fine, except it wants around 40 degrees of advance to idle smooth. I have the vacuum advance unhooked at the moment and have a timing tape on the balancer for true TDC. New mopar performance dist. and an MSD box. Mild cam. If I try to retard down to around 12 or so the engine is laboring and dosent idle smooth. Any thoughts? Also did a quick check for vacuum leaks. Nothing severe or easily found.

 

[Meep-Meep]

I can't imagine why an engine won't idle with less than 40 deg of advance. Could you have missed a tooth on the timing chain?

 

[Mr Roadrunner]

I degreed this cam in. It is a Hughes engines cam, and I was insturcted by Dave at Hughes to concentrate on the intake closing. It came in approx. 1/2 degree off.

 

[65affair]

Assuming that it starts fine with the 40 degree advance, I am not sold on the timing tape being correct. check top dead center on number 1 and double check the tape. go back to the basics.

 

[Cranky]

That is a little odd even for a low compression engine. What is your CR btw? So far I've had the pleasure (or displeasure) to work on two different engines that liked a total of 50 to run their best ET's. One a small block and one a big block but both idled well at around 20 initial which I thought was kinda high but it was what it was. Both engines barely had 8-1 compression with the small block being closer to 7.8-1

 

[RustyRatRod]

Somehow....whether it's you or the timing marks or tape, the reading is wrong.

 

[Mr Roadrunner]

The CR is 9.322. I checked the marks on the damper when I degreed the cam and it was about 1 deg. off. That is why I put a timing tape on it. I am having to retard the dist. some to get it to start, but then advance it back to get it to idle smooth out. I am thinking something in the dist. is not right, but not sure what it could be. The timing is steady at idle. If something were hung up in the mechanical weights I feel I should be able to adjust it out and still get a initial timing under 20 deg. Thanks for the help guys, keep the ideas coming please. Im confused.

 

[67 coronet]

have you twisted the rotor on the dist to make sure the advance is not frozen?actuating the vac advance isnt a bad idea to check either.

 

[IQ52]

The wires to the distributor may be reversed.

 

[RustyRatRod]

The wires to the distributor may be reversed.

How dare you interrupt our senseless conversation with something that makes perfect sense. They warned me about you.

 

[440roadrunner]

The wires to the distributor may be reversed.

This HAS happened. Google "rotor phasing"

But you can easily check the timing tape. Just measure around the outside of the balancer with a small flexible tape ACCURATELY, then use math to figure how many inches comes out to say, 40*. Then just use the measure tape to measure off that distance from TDC and confirm/ deny that the timing tape matches.

Do NOT use dividers for that, you must "go round" with a tape.

 

[IQ52]

How dare you interrupt our senseless conversation with something that makes perfect sense. They warned me about you.

Well, I took apart a Mallory distributor once and put the magnet back in 180 degrees out, had the same problems. Switched the wires around and it ran great. Rotated the magnet and put the wires back and have had no further problem.

So it could be that............or...........uneven lugnut torque.

 

[RustyRatRod]

I thought it was a bad muffler bearing when I first read it.

 

[Mr Roadrunner]

I am going to start with the wires first. That is a possibility since I wired a plug onto the MSD box harness. Will then look into rotor button phasing. Not sure I have my brain wrapped around this completely yet, but I see how to check things. My oldest son turned 7 today, so I havent had much garage (quality) time today. Will respond if I come up with a solution. Thanks again guys.

 

[67 B-body]

I had the same thing when I had the reluctor set in the small block location "roll pin" for the opposite rotation...... Might be worth confirming its correctly installed...

 

[Mr Roadrunner]

Finally got around to checking the dizzy out. Completely disassembled it and the only thing I found out of sorts was was the arm from the vacuum canister was not engaged in the hole completely. The hole had a pretty big burr. Cleaned it up and reinstalled everything. Reset air gap on pickup and put dizzy back into motor. Was able to time it around 15 to 17 advance and it ran great. Was still trying to adjust timing and ran out of gas. Will play with it some more this weekend hopefully. BTW I also checked the phasing on the rotor button and it looks ok. A little gas and some more run time and I think all will be well. Thanks again guys for the knowledgeable input you all took the time to pass along. Until next time.....

 

[Budnicks]

Mr.RR thanks for the update, I was wondering what happened... I had a similar situation were the centrifugal advance weights, would hang up after it would reach full advance, it would start great the 1st time, then be a real bear to start afterwords, thought it was hanging up at a high idle, but was fine on initial start up, "I thought", after a little looking around, I tore the distributor apart, found really rough drilled/stamped or forged holes in the Mr.Gasket weights, cleaned them up, problem solved... I've had the upside down magnetic pickup phasing problem before also...Good luck & happy Moparing

 

[Benji]

I was going to suggest checking the air pressure in the glove box but I see you already have your answer.

Benji

 

[Darter6]

I see in your first post that the MP distributor was new. I hate when that happens.As the old saying goes"Just because it's new don't mean it's right" Thanks for backing that up for us !