[Guest]

I posted a message the other day, 289 Stalls Under Load, looking for some other possibilities.

The engine idles but sputters and wants to stall under load when the transmission is engaged. Managed to take it around the block though.

Here are the details:

I've got a re-built 289, Federal Mogul CAM, new pistons, Crane lifters, pushrods and rockers (adjustable) ... everything was machined back into specs. Re-built 302 heads on a 289 block ... 8x1 compression.

Installed an Edelbrock Performer manifold and 600 CFM carb. Car dies/stumbles when put into gear. Timing is set at 8 degrees but runs much better around 15 or higher. Hard to keep running with the vacumm advance removed, especially at 8 degrees.

Vacumm reads steady 10-11 at 700 RPM (idle). Vacumm taken off of the right front of the Edelbrock carb for Trans Modulator and Dist. Advance. Vacumm taken from throttle body for PCV. Neither seem to be leaking but slight improvement w/ the PCV disconnected and plugged. Left vacumm port on edelbrock unused, rear large port is plugged.

Car has stock exhaust manifolds with no exhaust system yet ... my original question was can the lack of back pressure cause the stalling under load condition?

Brand new plugs, wires, cap, points, condensor. Plugs set at .044, dwell is 23 degrees. New fuel pump and filter. Coil is old and in unknown condition ... problem here?

Valve timing used the "O" setting on the CAM gear.

I have since rechecked all of the rocker arm adjusments ... seem good.

Any help is appreciated.

 

[Teebone]

your vacuum reading is a bit low..I think you have a vacuum leak somewhere..and I would also check the dist..make sure it is on the money..if the engine is running better at 15 degrees..I have a feeling your dist is one tooth off..or your cam is..

 

[Guest]

With no load, the engine runs smooth, especially when I give it some gas. Would it run smooth if the Valve timing (CAM) was off a tooth? I took a picture of the CAM/Crank gears when installed, looks aligned but it is hard to see 1 tooth error.

 

[Teebone]

it would also idle rough if the cam were a tooth off..lets assume you have a vacuum leak..or your dist is a tooth off..at least these things are easier to check..the fact that it runs better at 15 degrees BTC..leads me to suspect the dist is off

 

[Teebone]

it would also idle rough if the cam were a tooth off..lets assume you have a vacuum leak..or your dist is a tooth off..at least these things are easier to check..the fact that it runs better at 15 degrees BTC..leads me to suspect the dist is off

 

[Guest]

If the distributer was off a tooth, doesn't turning it further basically correct the problem? If I turn it far enough, wouldn't it make up for the 1 tooth?

 

[Guest]

Is there an easy way to find a vacumm leak? It's not the vacumm advance, PCV or trans modulator. Only thing left is the manifold and carb.

 

[Teebone]

try some oil around the manifold..use a spray type..WD should work..do it while the engine is running..if it's leaking it will draw the oil right in..do the same around the base of the carb

 

[Teebone]

you might not be able to turn it far enough..I have a feeling you are off one tooth..you will need to pull it and drop it in again..making sure its right on

 

[camachinist]

The old-fashioned way to check for vacuum leaks is to direct a tube-nozzled can of carb cleaner at various points along intake/carb gasket junctions, listening for an increase in engine rpm resulting from the cleaner being ingested and burned...

I recall some VMF'ers using a safer method than this, especially considering your open exhaust manifolds in the engine compartment....try doing a search for "checking vacuum leaks" using the "all words" option in the search engine.

The more time goes by, the more I think there's a vacuum leak somewhere...

Under no load, if you quickly open the throttle and then release it, does the engine accelerate quickly then snap back to idle? Or does it just settle back with a seeming delay...this is a sign of a vacuum leak...

Usually an engine with a sizeable leak won't idle as low or as smoothly as yours has...

So the confusion continues, eh?? *G*

You can always borrow a known-good carb and stick it on there...

 

[68restomod]

If you have a stock cam with 10 inches of vacuum I would be worried about a leak. You should have 18-20inches. Got power brakes? Try diconnecting that hose and plugging the port. You can disconnect one hose at a time and plug looking for a leak. I would use the carburetor cleaner method to check the intake gasket. If the vacuum is steady I would guess the valves are opening and closing fine. The back of a good Chiltons book shows the vacuum gauge sinarios and conditions. You might take a look there for ideas.

 

[C0V3R]

I had almost this exact problem a few weeks ago. Id suggest you try rotating your dist a bit, by increasing the timing I got upwards of 6 inches of Hg, and an engine that ran a hell of alot better.

Go here for more info.

 

[Guest]

Couple of things, I noticed your plug gap is .044, maybe you need to go with .035, but with 8:1 it should be alright depending on your ignition, not sure what your 289 had stock. Also what balancer do you have on it, I have heard of the outer ring on a stock balncer spinning or moving from it's original position which could give you a false reading, or are you using an adjustable timing light? How much pre-load did you put on the hydraulic lifters. When you put it in gear does it try to idle, maybe you have the idle to low, does it idle down to much. Does it run smooth otherwise, drive ok when you took it out?

 

[Guest]

I once had a similar problem on a chevy. It was one of the unused carb stud holes in the (Edelbrock) manifold. It had a pin hole punched thrugh the bottom where it was drilled too deep. As the engine warmed up, the hold got bigger. Can't begin to tell you all the crap I replaced on that motor trying to fix the problem. Final fix was a carb stud screwed in with thread locker and cut off with a hack saw. But I did go through two carbs, a new distributor and countless sets of plugs and wires.

 

[Guest]

I've gotten a lot of good suggestions and will try them over the weekend. I also contacted my engine shop and they suggested that I've overtighted the adjustable rockers. I followed directions in a small block Ford restoration book that said to go 3/4 turn past the point when the pushrod has no slack. So, here are my plans:

1. Re-adjust the valves (cold) to 1/8-1/4 turn
2. Separate the Vacuum advance to the passenger side port and the Tran. Modulator to the driver side Port.
3. Re-set timing to 15 degrees
4. Re-set idle to 800 RPM
5. Re-adjust idle mixture to obtain maximum vacuum reading

Re-assess.

If vacuum is still low, I'm going to use the Carborator Cleaning spray method to try and find the leak. Going to take a close look at the manifold to see if any of the pre-drilled holes go through to the engine and leak.

Either way, I'll report back to the group and thanks for all of the help so far.