timing issue. I've just replaced the stock top and front of my 65 289 (Full Version)

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timing issue. I've just replaced the stock top and front of my 65 289

  

Passing Time -> timing issue. I've just replaced the stock top and front of my 65 289 (5/8/2008 4:20:26 PM)

harmonic balancer should be right on .   It is new and the marks lined up with timing mark on front cover when installed.

A.  When timing using vacume and running WAO uphill and adjusting to ping/no-ping, the tiiming light shows about 30 BTC static with about 20 ft/lb  manifold vacume.

B.  When timing about 16 BTC, engine will idle and run smoothly at 700 curb rpm but will serioulsy cut out with any load or acceleration near idle speed.

C.  If I compromise and run at about 18-20 BTC static 35-40 total timing, vacume is a smooth 17 -18 @ 700.  The engine does not cut-out (die) under low rpm load, but does have a flat spot that is easier to drive around.

Engine is 65 casting 289 with XE256H comp cam that I just put in.  Intake and carb are the original cast and autolite 2100, that I reinstalled to break the build in because I knew that they were reliable.

Questions:
1.  I realize that 30 BTC is waaaay to advanced to run, but what makes the engine run better, including idle, road speed, and accleration at this timing if it is so wrong?
2.  Is there anyway to tune out the flat spot that I get with low rpm acceleration?
3.  Why at 16BTC, which is nominal, does the engine simply not run worth a chevy?
4.  Suggestions on where I run it based on the above.

No need to make fun of the cast stock intake, exhaust, and 2V carb unless these are what are not meshing with the new cam and higher compression (160-170).
It is a work in progress and I am upgrading one step at a time.

Thanks in advance,  Brad.


  
Haywired -> RE: timing issue. I've just replaced the stock top and front of my 65 289 (5/8/2008 5:24:07 PM)

I have the same setup as you except I have a 570 VS holley on a cast Ford manifold.
Had  the same issues as you with base timing and total advance.
Got in touch with Comp and they gave me the specs to set the timing at 6 BTDC, had to readjust everything to get it to idle properly.

It runs much better now with this setting and a total of 36 degrees at 2800 RPM than it ever did at 30 degrees base.

I have a solid 15 inches of vacuum a 750 rpm now, and excellent off idle response with no flat spots or bogs.

Cam was installed striaght up on the marks

Comp also stated that the 256 has more duration and over lap than a stock 289 cam so it will run a lower vacuum at idle

Hope that helps

Starfury -> RE: timing issue. I've just replaced the stock top and front of my 65 289 (5/8/2008 5:55:15 PM)

It sounds like something's wrong with your advance.  If the engine runs without pinging uphill at 30* initial, your mechanical advance isn't functioning properly.

Set the initial at 12* or so with the vacuum advance disconnected.  Rev the engine to 3k and check the advance at that point, then report back.

Passing Time -> RE: timing issue. I've just replaced the stock top and front of my 65 289 (5/8/2008 6:02:09 PM)

So... set it at 6 BTC and then re-adjust everything from there.

That seems so far off base from where I am, I was thinking that it was running pretty good at 18-20 except for the low end loading, but I'll go from your experience and their advise and give it a try this weekend.

Thanks for your input.  After I try this and compare to where I am (nothing to lose from trying), I'll post back with results.

Brad.

Passing Time -> RE: timing issue. I've just replaced the stock top and front of my 65 289 (5/8/2008 6:06:04 PM)

I know that at 16 static, total runs 30+.
The scale on the balance stops at 30.  So, it I was guessing I would guess 32 total.
The advance is nearly new.

Stepman -> RE: timing issue. I've just replaced the stock top and front of my 65 289 (5/9/2008 12:07:20 AM)

I'm with star on this one. Make it easy and unplug vacuum. Set you timing at 10 (round number) and make sure it advances at higher (3k) rpms. Also make sure vacuum is hooked to right port. If you are starting off at 20-30 degree, you should have a hell of a ping.

If you're  only getting what ,15 degrees advance....maybe the two are working against each other.

Passing Time -> RE: timing issue. I've just replaced the stock top and front of my 65 289 (5/11/2008 5:10:14 AM)

OK
Timed to 10 static. 
advances to 20 at 900 rpm when vacume advance reattached at idle.   Vacume 16 @900
Total timing approx 33 at 3000.  (scale stops at 30)

Runs much better now.  Still has very mild flat spot, but very good throttle reponse and a nice exhaust note at idle speed and on the road.
I'm going to try 6 BTC as suggested above and compare.

Questions.

Should I be getting nearly 10 advance at idle speed?

Am I getting enough total advance?


Thanks for the help so far she's starting to sound pretty good. :)



69FECoupe -> RE: timing issue. I've just replaced the stock top and front of my 65 289 (5/11/2008 6:41:15 AM)

At idle, there should be no change in timing when you connect the vacuum advance. It sounds to me like you are connecting it to the wrong port. The port should have no vacuum at idle. 

imnotmy77stang -> RE: timing issue. I've just replaced the stock top and front of my 65 289 (5/11/2008 7:09:29 AM)

FYI if your balancer only goes to 30 you can buy timing tape from MSD for like 10 bucks or less.

Starfury -> RE: timing issue. I've just replaced the stock top and front of my 65 289 (5/11/2008 10:11:35 AM)

Vacuum hose is definitely connected to the wrong port.  It's possible to set the engine to run off full manifold vacuum, but I don't recommend it for most people.  Find the ported vacuum port and hook the hose up to that.

Also, recheck the total timing with the vacuum advance disconnected.  You're trying to check the function of the mechanical advance alone.

Passing Time -> RE: timing issue. I've just replaced the stock top and front of my 65 289 (5/11/2008 11:51:19 AM)

I'll test the mechanical advance and post back.

The vacume advance tube is the original metal tube threaded into the front passenger side of the autolite 2100 body. 

Haywired -> RE: timing issue. I've just replaced the stock top and front of my 65 289 (5/11/2008 1:41:09 PM)

Things are sounding like its getting close. Put your vacuum gauge on the port on the carb, and if there is any reading at idle that is not the right port.
I suspect your flat spot is from to much vacuum advance to quick causing the engine to lose power. Just my .02 cents though

Good luck

Passing Time -> RE: timing issue. I've just replaced the stock top and front of my 65 289 (5/12/2008 4:14:19 AM)

With vacume advance removed/plugged,  mechanical advance advances to 20-25 smoothly then is a little jittery when maxed out around 30-32.
In fact total timing mark is jittery with or without vacume advance.

I'm almost positive that the vacume advance is in the correct port on the autolite with the original pre-bent vacume line.  It is located on right side of the carburator body toward the front.

However, I am getting get a solid 10lbs of vacume idling at 900rpm in park at the vacume advance.  Ported vacume tops out at about 20-22 at higher rpm.

Questions:
 
Should my timing mark be smooth when advanced beyond 25 or so?
Why am I getting 10 vacume at the advance port at 900 RPM?  (port is correct  :)  )
 

kalli -> RE: timing issue. I've just replaced the stock top and front of my 65 289 (5/12/2008 5:01:16 AM)

Hiya, as you have the autolite 2100 on at the moment, mine has only one port for vacuum. the correct ported one.
Only if you are 100% sure the timing markings are ok, then do as follows:

1. initial idle at lets say 8 degrees with vacuum disconnected at vac advance side and plugged (plug the hose to carb, not the advance itself)
2. rev up to 2500. you should get 35 degrees max (prefer 32 for the moment). if not change springs in distributor (skip if it's anywhere between 30 and 38 for the moment) all this still with vac advance disconnected and plugged
3. back to idle. Hook up vacuum advance. the timing should not change (1 or 2 degrees max. most setups 0 degrees)
4. disconnect the vacuum hose again. this time at carb side. plug carb port if possible. then suck on the hose connected to vac advance (with mouth) you should see the ignition advancing. when it does, block the hose with your tongue. The vacuum should hold as well as the timing advance. this confirms good vac diaphragm

How is it running then? can you confirm all of the above?
As well please check on the choke of the carb. make sure that this thing is fully open when test driving.

Kalli



Passing Time -> RE: timing issue. I've just replaced the stock top and front of my 65 289 (5/12/2008 6:13:18 AM)

With vacume advance removed/plugged, idle speed 900 in park, and static timing set at 8 the mechanical springs advance smoothly with rpm until almost 25 BTC with a max of 32 that is jittery under the light.

Also, at idle (900rpm in park) I am getting 10 pounds of vacume from the carb port that advances my timing from 8 static to 19-20 BTC when plugged onto the distributor .

total timing with all connected is 33-34 at 3000rpm.

stumbles when initially starting and requires continuous gas pumping.  runs smoothly and starts instantly when warmed up.


kalli -> RE: timing issue. I've just replaced the stock top and front of my 65 289 (5/12/2008 6:26:08 AM)

quote:


With vacume advance removed/plugged, idle speed 900 in park, and static timing set at 8 the mechanical springs advance smoothly with rpm until almost 25 BTC with a max of 32 that is jittery under the light.

that sounds ok from the values, but I don't get the jittery part.
It could be 2 things
a) is it an inline strobe or one with inductive clamp. If inductive clamp make sure it's the right way round and you pick up at the lead on distributor side, not plug side of lead
b) the mechanical advance is no good. Have you tried oiling them (very very slightly). is it a new distributor? or 40 years old?
c) try at engine stop to move the distributor shaft forth and back. It must not move, only turn.
When you turn it, it should snap back without hesitation

quote:


Also, at idle (900rpm in park) I am getting 10 pounds of vacume from the carb port that advances my timing from 8 static to 19-20 BTC when plugged onto the distributor .

as Tad says: must be the wrong port on carb. You should have no vacuum at idle when hooked up to ported vacuum
If there's only one port (maybe take picture. if you do make sure we get to see the whole carb, not only the port), then maybe you have curb idle too much and rtegulate the idle down with the idle mixture screws?
They should be as follows (rough estimates): both idle mixture screws one and a half turns open from seating. Curb idle screw just so that it opens tyhe throttle for a tiny bit

quote:


total timing with all connected is 33-34 at 3000rpm.

that sounds fine with vac advance disconnected and plugged

stumbles when initially starting and requires continuous gas pumping.  runs smoothly and starts instantly when warmed up.

edit: do you have breaker contacts in your distributor or do you have inductive pickup (electronic module) ?

  

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