Hi All,
I have a 1980 L48 350. I need some direction on what system I should be concentrating on...Fuel or ignition. The car runs idles nice and revs nice in neutral, but once in gear it bogs down and has no power. It also sounds like a Volkswagen engine under load. This has happened a couple of time in the past and it comes on suddenly and also will fix itself and run nice. I have changed the fuel filter and spark plugs, but nothing is working. Any suggestions??

 

could be several things, look carefully at the distributor cap, lookfor carbon tracking, check plug wires. Could also be a carb problem, trash in the needle valve, etc. Start with a thurogh look at the ignition.

 

I have heard that the fuel pick-up strainer in the tank can plug up and cause the engine to experience fuel starvation, during acceleration. Something to think about

 

Does this car still have the original cat? If so, change it out for a modern high flow unit. Run the standard ignition setup. That is:

1) Connect a timing light.
2) Disconnect the vacuum advance.
3) Start the engine and record the ignition advance at idle.
4) Run the engine speed up until the mechanical advance stops advancing or you reach 3500 RPM. If it is still advancing at 3500 RPM you have a slow advance curve and will need to fix that before you continue. Get a re curve kit.
5) Change the advance weight springs until you get the advance all in by 3000 RPM. This all in number should be "about" 36 degrees BTDC. Move the distributer to get this number then lock it down.
6) Reconnect the vacuum advance.

This will have the ignition sorted out "ok" for now. Now start on the carburetor. Don't be surprised if your "carburetor" problem is now gone.

Your hesitation under load is probably the accelerator pump. You're going to need a good Rochester carburetor manual so you should get it now. One thing you should remember whenever you have the top of the carburetor off is that whatever the problem is that your chasing, checking the float level is ALWAYS part of the procedure to fix it. Whenever you have the top of the carburetor off, for whatever reason, check the float level and correct it if need be. Improper float level will cause more strange problems than any other single issue in the carburetor.

BigBlockk

Later.....

 

I agree with BigBlockk's analysis and recommendations.

 

Thanks for the excellent suggestions,

1.) I have replaced the distributor cap and rotor earlier, still looks OK.
2.) I replaced the cat three days ago....no improvement.
3.) Timing has always been a problem; couldn't get it to work. Years ago I bought a timing light, but could never find the mark. I moved the pickup to wire 7 and then noticed the mark. Figured I was doing something wrong..Gave up. Yesterday I turned the engine to 0 degree TDC and pulled the distributor cap and found the rotor pointing between #5 and #7. I've since pulled out the distributor and set it to #1. Maybe I can set the timing now. I will take your advice on timing BigBlockk.

Off to replace my broken spark plug and empty beer supply!

Thanks

 

If you set the engine to 0 degrees BTDC on the balancer timing mark and then found that the distributer was pointing between #5 and #7 the ring on the balancer has moved. You will never get this thing timed correctly like that. You're going to need a piston stop.

http://www.jegs.com/webapp/wcs/store...tegoryId=28015

This is what you need to do.
1) Remove the drivers side valve cover.
2) Clean the balancer ring and wrap it with masking tape.
3) Rotate the engine (clockwise when looking at the front of the motor) until the intake valve on #1 cylinder just closes.
4) Install the piston stop in #1 spark plug hole.
5) Continue rotating the motor until the piston contacts the stop. Mark the masking tape on the balancer.
6) Rotate the engine counterclockwise until the piston again contacts the stop. Mark the masking tape on the balancer. Exactly half way between these two marks is the true top dead center on #1 cylinder.
7) If your distributer rotor is not pointing very close to #1 terminal you need to pull it out and re-clock it correctly.
8) If the original timing mark on the balancer ring does not match the mark on the masking tape (true top dead center), replace the balancer.

BigBlockk

Later.....

 

Thanks BigBlockk

I guess I just assumed that the balancer ring was correct.

I appreciate the link for the TDC locator! I will try it and hope for the best.

Is it possible to replace the balancer ring with the engine in the car?

 

no problem removing or installing the balancer on the car..first remove the fan then you have to get a puller that screws into the balancer to pull it off.. to install it there a few tricks.. one is to heat the new one in hot water to make it expand so it will go on easier,or, you can get a longer bolt with a bunch of washers or rent the instalation tool.. I had the same problem on my 81 ,the ring slipped

 

In reading the thread you can figure a rough TDC on #1 with the valve cover off to check rocker Positions and Remove #1 spark plug and, with finger on plug hole, crank engine until compression is felt in #1 cylinder. Place screwdriver into plug hole and feel for highest piston height while manually turning engine. Look at Balancer/Damper if timing marks aren't in alignment with or close to TDC (0*). You more than likely have a bad damper. Replace it with a known good one before doing anything else.
It is possible to have other issues but having a known condition of the damper/balancer is the starting point for what has been described so far.
This should take about 10 minutes and then you'll know the baseline.

 

Again thanks for the replies..

I did order the piston stop already, should come in for the weekend's nice weather. I will start with checking on the balancer ring. Any hints on turning the engine by hand? My present method is to climb under the car and turn it using the bolt holes on the back side of the plate.

Looks like I have bigger issues with frame though....shouldn't have climbed under the car.

 

Take the fan off and use a ratchet on the center bolt on the balancer.

BigBlockk

Later.....

 

Sounds like a stopped up cat converter to me.

 

I tried the center bolt, did not budge engine. The car was out of gear and the spark plugs were all out. Didn't move. I was afraid I was going snap off the head. It's not too bad under the car, I just can't see the valve movement or piston action.

I have replaced the cat. I sounded nice at idle and revving, but as soon as I drove it the engine bogged down. Worked out anyways; I found only one loose bolt on the cat holding the rear end of the exhaust system (bolts on hangar were gone too). The four rusty, fused, $#%@ bolts on the front side of the cat were the exception. That would have been a pretty sight if that let go on the highway!

 

Try and Loosen up all the belts and use a 1/2" beaker bar to turn the engine you should be able to do it from the top...at least on mine you can.

 

Ahhh...the belts!! Forgot about about. That should make a difference.

Thanks VetteLS6!!

 

I hope that replacing the Balancer/Damper fixes your problems. I had sort of the same problem. The car would start and idle fine, but if you started to drive, it would die. Wait a little bit and it would start right up. Check your fuel lines and gas tank. The "s" hose that goes from the hard lines to the pump were in bad shape and were part of my problem. They are easy to replace. Then I dropped the tank and found that the supply and return lines were crossed over the tank and were crimping each other off. Not all the way, just enough that when i would push the gas peddle, it would close. Replaced the lines with new ones and all is well. If you have the tank out, make sure that you check (or better yet, replace) the filter sock as mentioned before. Good luck.

 

Yes, I hope the balancer ring works too. But from recommendations on this forum about the condition of my frame, it looks like I'll have plenty of opportunity to inspect and/or replace sections of my fuel system when I get a new frame.