Hi guys, i have a 1967 Satellite with a 383 motor. About 5 years ago i had it rebuilt , boring out 30 thou and adding a livelier cam. I am using a Carter 650 competition carb , after the rebuild i set the advance timing to 10-12 btdc. my total advance was read ou at 36. The car seemed to like this setting and ran well on the street. I have noticed in the last few months that at low rpm it ran great but as i got up to 3000 plus it seemed to lag. I decided to reset the timing to see if it helped. I am now at about 16-20 btdc and total advance about 40. It is running great low end and top end. Any thoughts on why the change was needed.

 

Gasoline formulas. I'd bring the 40 down to 36.

 

At 36 i loose at least 10% of my horsepower

 

I highly doubt that you lose ten percent of your power going from 40 to 36 degrees. Of the two bb I have the 9.5 motor 39 was the number and the other was 38. The 9.5 motor has open chamber 452 heads and the other has 915 closed chamber heads that are finished and flow better. Head flow is what determines total timing needed. My little Ford has great flowing heads and only needs 33 degrees of total timing.
One thing that I noticed is both motors ran quicker in the car with 40 or 41 degrees total.

The thing I would look at if your running a stock damper is verify TDC of number 1. Stock dampers are known for spinning the outer ring. If that's the case you must replace or have it rebuilt.

 

I would play with the initial and try 14 to 18 degrees but you will need to have all your advance in by 2500 rpm and limit total to 38 degrees.

 

When i lower the total to 36 the engine labors a higher rpms, at 40 it surges

 

Like I said check the damper.

 

I will look into the damper , I have never heard of this issue

 

Sen -

Assuming there's nothing physically wrong with the motor, set the timing as high as you can and NOT get any pinging under load or run-on after you shut it down.
Sure, the dampener could be off or the cam timing wasn't set correctly, but the motor will tell you what it likes.

Archer

 

At one time I hadn't either but the rubber gets hard in the stock damper and loses it ability to hold the outer ring, I've seen the outer ring come off and when they do its usually with damage under the hood.

 

The motor was just rebuilt 5 years ago so im not sure if any seals or rubber should be worn out, i set the idle advance at 12 btdc and found the total at 1500 rpm to be at 24 , I guess the real issue is my idle advance. For me i need it to be around 20 to hit 36-38 . The car seems to run best at 22 idle and 40 total.

 

I am just making sure i do not damage anything, the car seems to like 22 to 24 at idle

 

I lined up the timing mark with 0 on the timing tape, removed the number 1 spark plug, due to the location i used a 6 inch i/4 inch rod and placed it into the opening for the spark plug and inserted it until i hit the piston head,. marked the rod at the exterior and measured 1 inch. I believe that confirms the cylinder is at top dead center. This i believe confirms the timing mark, If so could there still be a problem with damper? pete

 

LOL, not quite.
Using the rod rotate the motor by hand until the rod just starts going down then turn the motor the opposite. You mark where it starts going down on the damper then reverse the rotation until it starts to drop then mark the damper again, halfway between the two mark's is top dead center. For an accurate tdc you would use a dial indicator or a piston stop.
You do this because there is a certain amount of dwell in the crankshaft rotation where the piston doesn't move, in the center of that dwell is tdc or bdc.
The amount of dwell depends on crankshaft stroke and connecting rod length.

 

No problem i will confirm this tomorrow

 

Alright so i used a 11/4 socket and turned the crank, first clockwise and the piston started traveling down at the 10% atdc mark, i reversed and the piston started going down at the 10% btdc mark so the timing mark is dead center. So back to my original issue. If i set the advance at 12 btdc at idle i get only 24 total at 2500 rpm and the car is sluggish from 2000 to about 3000 rpm, If i set the total advance at 2500 to 40 the car runs great but my initial is at 20-24. Just to confirm i am doing the testing correctly, I disconnect the vacuum hose to the advance and plug it, i put tape on the advance so that hole is also sealed, at idle i check the timing using timing mark and metal tape on engine, moving the distributor i set the advance to 12 btdc. then i set the total timing readout to zero, after increasing rpm to 2500 i use the gun t check timing mark, i keep increasing the number and when the timing mark meets the 0 on the timing tape i take my reading...

 

I'm not following this. /|\

Ideally you set the timing at idle by what the motor needs depending on the cam used. A stock cam will work with 10 degrees but a cam with plenty duration might want 20°then you want your total advance to be all in at 2100 to 2500rpm, that's usually 38° or less depending on the heads. You probably dont have enough timing in the 2000 to 3000rpm range so it needs to advance quicker. But I don't think that you need 40° total timming so the curve might need to be shorter like 22 to 25° advance total. But I suspect that you don't have enough timing in the 2000rpm range.

 

What cam and distributor do you have?

 

its a competition cam part 21-221-4 grind # crb xe256h-10 The distributor is stock but i replaced the points with a pertonix electronic ignition

 

You definitely don't need 20° initial timing, only 10 to 12. I've never found the stock distributor easy to limit and recurve, you need to weld so you can limit it and I'm not sure you can get springs for it now.

 

This is 100% what I've had to do with all my mopars. For some reason, whether it be luck or a Mopar thing, I just can't get 'em to time with a gun/light. It's gotten to where I can ear time in a hurry and get some nasty performance out of these guys.

 

Its funny you say that, when i was much younger the only way we set up timing was by ear, just turn the distributor forward until it ran rough, then back until it ran rough and stop somewhere in between when it seemed to run smooth. Now i try to set timing at recommended specs , funny seemed easier before.

 

Back when I set them by ear I only had $150 in a junkyard motor, I fought with keeping points in my duel point and didn't know why. Yep those were the days.

 

After looking at all of this.... My 2 cents are, You just are covering up for a fueling system issue. Adding the timing after all this time is just covering up the read problem that is just going to worse with time.

 

Could the weights be dirty not allowing for total advance? the car sits 7 months of the year and i have never touched the distributor, lastly should i upgrade the distributor and if so what would match a 383 ?

 

Check the weights for movement with the cap off the pivots might need oiling.

 

how's the gas in the area? decent or crap like here in socal? do you put stabil in the tank?

 

If there is an issue, what type of oil? a few drops of 10w 30 ? and where do i place the oil? thanks pete

 

I just pulled off the vacuum advance line and tried to draw on the advance, no restriction at all like there is a hole or something, i checked the line and it is solid no holes or tears . do i need to buy a vacuum pump or should i be able to cause enough draw to at least move the distributor?? pete

 

Try a minimum amount of penatrating oil and get the weights moving freely.