Falling flat on its face at 3800rpm. WHY?

3

3spd on floor

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Aug 13, 2002

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Acworth, GA

Sep 11, 2004

#1

• Sep 11, 2004

• #1

Well i took the stang out for the first time in a while today(hadnt run since april), and it doesnt seem to want to pull past 3800. In neutral it will happily rev well past 3800 though. I checked the timing, and it appeared to be set 3 or 4 degrees AFTER TDC. So naturally i bumped it up a bit, around 6. It pulls a little better now, but still not great. The vaccum advance is working, the timing advances a lot when you rev it up. How far should i advance the timing? And should i verify that the TDC mark is indeed at TDC? I was really surprised to find it set below TDC. ALso do they make a tape or soemthing that you can wrap around the balancer to make it easier to read the degrees?

Does this sound like just a timing issue? or possibly fuel as well?

motor is a bone stock 4 barrel 289 with longtubes.

thanks guys

 

ratio411

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Apr 21, 2002

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Pensacola FL

Sep 11, 2004

#2

• Sep 11, 2004

• #2

The timing should be set before TDC, not after.
10-12 degrees before.
Dave

 

ratio411

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Apr 21, 2002

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Pensacola FL

Sep 11, 2004

#3

• Sep 11, 2004

• #3

Just food for thought, I doubt it, but the outside of the balancer can slip. It's not common, but does happen.
Not only would this throw off your timing marks (but not timing), it also throws off the balance of the engine.
I don't think this would cause the engine to lose power, unless the balance was shifted 180* and causes bad harmonics in the engine as rpm increases. Never heard of that, but I guess it could happen.
In short: If all else fails, check TDC.
Dave

EDIT: Now that I think for a minute, I think the balance weight is on the crank side of the dampner, so the idea of being out of balance might not even be possible. It's been years since I have eyed a dampner up close.

 

3

3spd on floor

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Aug 13, 2002

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Acworth, GA

Sep 11, 2004

#4

• Sep 11, 2004

• #4

yeah i know it should be set to fire before TDC, thats why i was so surprised to find the initial timing set 3 degrees after. would this have caused it to feel so sluggish? i would have thought such poor timing would have made it barely run at all.

Tomorrow i'll verify that the balancer hasnt gone haywire on me and re-set the timing to 10 or 12 degrees before TDC.

on a side note, when setting timing, i've heard people say that you should keeping upping the timing til you get the highest idle speed, is this correct?

thanks a lot dave.

 

P

PONY XPRESS

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Jun 15, 2004

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Sep 11, 2004

#5

• Sep 11, 2004

• #5

Sounds like fuel, float may need adjusting or sticking, or filter clogged.

Timing max about 32-34 full advance at 2500rpm. Put on a vacuum gauge & set to max vacuum, then check your timing just for kicks.

 

88 Fox GT

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Nov 18, 2002

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Iowa

Sep 11, 2004

#6

• Sep 11, 2004

• #6

3spd on floor, disconnect your vacuum advance and plug the line. Set your base timing at around 10 degrees BTDC. Then reconnect the vacuum advance.

Did you put new gas in it when you took it out? Gas sitting since April may be stale or turning stale.

 

rbohm

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Apr 12, 2002

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tucson,az

Sep 12, 2004

#7

• Sep 12, 2004

• #7

usually when an engine wont rev above a certain rpm, it is because of fuel related issues mostly. likely low float level, low pump pressure, partially clogged fuel line or filter. with timing as far out as yours though, you hit on the exception, but definately check over the fuel system as well.

 

dodgestang

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Dec 15, 2003

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Cecil County, MD

Sep 12, 2004

#8

• Sep 12, 2004

• #8

MIght even be something even more simple.

1. Make sure when you floor the pedal in the car, it actually pulls the throttle on the carb all the way open.

2. Confirm that the secondaries open on the carb. If you are running on 2 barrells only the car will feel like it runs into a wall at or around that RPM level.

 

3

3spd on floor

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Aug 13, 2002

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Acworth, GA

Sep 12, 2004

#9

• Sep 12, 2004

• #9

well i checked the balancer out and its ok, TDC is correct. so i blocked off the vaccum and set the initial timing at 10*. it pulls SOO much harder and longer now, 5 grand is no problem, but thats about it on the stock heads/cam. now i'm left wondering how the timing could have gotten so far off when it was just sitting there.

 

88 Fox GT

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Nov 18, 2002

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Sep 12, 2004

#10

• Sep 12, 2004

• #10

3spd on floor said:

well i checked the balancer out and its ok, TDC is correct. so i blocked off the vaccum and set the initial timing at 10*. it pulls SOO much harder and longer now, 5 grand is no problem, but thats about it on the stock heads/cam. now i'm left wondering how the timing could have gotten so far off when it was just sitting there.

Click to expand...

Glad to hear you got it corrected. Hard telling why it would be off, maybe someone twisted the distributor when you weren't watching?

 

golf4283

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May 30, 2003

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Orland Park, Illinois

Sep 12, 2004

#11

• Sep 12, 2004

• #11

I know you fixed it but another cause might be the 5 month old gas that was sitting in your tank. Just a couple mor eoptions to figure out what it was.

 

3

3spd on floor

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Aug 13, 2002

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Acworth, GA

Sep 13, 2004

#12

• Sep 13, 2004

• #12

i would have suspected the gas, but the tank had been out and completely empty, i also drained the carb bowl and pumped the lines with new fuel before starting it up. I suppose the carb could be gunked up also, but thats for another day.