Wisp

Hi....

I have some problems with my engine.

New Dizzy.
New Edelbrock RPM intake.
New Holley 670 Street Avenger.
New Wires.
New Plugs.

The Engine runs GREAT until 30 min or so. Then it starts to Ping/engine knock at half throttle. Not a little.... Its very much. The RPM also start to fluctate....
After this I remove the Vacuum can, and the Ping/engine knock goes away but the RPM fluctating still stays...
After 5 more mins or so, it wants to stall, and there is a huge stumble at part throttle...
Exhaust sound changes very much in the last scenario...

Running 16 base timing.
36 at 2800.
Vacuum can ads 10/Full manifold.

I am thinking missing fuel... But will this also course Engine Knock?

Fuel boiling?

Best regards Søren

AzMotorhead

I suspect fuel systems trouble. Fuel pump failing,clogging filter, fuel line touching a hot component.
All things to look at
I assume you've adjust the carb per Lars's specs?

Wisp

Hi...

Yes the carb has been adjustet as lars paper. Fuel filter is brand new. Missing fuel will also course Engine Knock?




Søren

Eddie 70

Have you checked your timing to make sure the distributor has not moved and your timing is still where you set it at?

dannyman

I see you changed the spark plugs. Did you by any chance change the temp range of the spark plugs?

OzzyTom

Just a few other things to try.....
I was having intermittent issues with my new engine when I first installed it... OK at startup... then poor running after 30 minutes... and worse if I went over bumps in the road.
Over a period of several weeks, I eventually found the problems....

I found the Bat+ lead was NOT seated correctly on the HEI distributor. The contact crimp connector was NOT secured correctly in the plastic socket, and even though the socket looked like it was seated, the connection to the terminal was not.

Another problem I found was with the aftermarket car alarm module I had installed. The relays which isolated the ignition power to the distributor were intermittent. Bypassed the alarm, and then OK.

This may or may not help, but I mention it as sometimes we overlook the simple items. I changed my leads, plugs, coil and HEI module without success before finding the above solution

rclinton

Long shot, but easy to check. You might want to check and make sure the fuel tank is venting. Check to see if there is a vacuum forming in the tank. Seems like it would be causing many of the symtoms you are experiencing.

The Money Pit

What are the engine temps doing? I had similar issues when I first got my 406 running, and ended up going to an aluminum radiator. Now it'll stay cool no matter how hard I run it.

This could explain a short period of decent running, followed by the pinging, and other issues.

dtamustang

it usualy doesn't take 40 minutes but an overheated coil will do some pretty strange things

Wisp

Hi, and Thanks for all the input.

When the problems are there the timing are still the same. No change in timing.

I dont no about the plugs. I will check.

I will check if the fuel tank is under vacuum.

I have no problems with Engine temp. I can see when the thermostat opens, and then it falls down to around 150 F and stays there.

After I shut the engine down, and manual operate the gas level, the squirts that comesout of the primæries is not constant. Like its filled with air. After a couple of pumps it gets constant.

A new thing I disovered. If I hammer it, under these problems, it runs normal when the secondaires kicks in....

Fuel boiling in only the primæries?
I will check my fuel pressure next week...

Any input are wellcome....

Best regards Søren.

gingerbreadman1977

150 sounds low to me. i thought a car like a vet should run on at least 175 and no higher then 190 would be a good starting point. i would be checking your temp gauge is accurate if your on 150, maybe its really sitting on 250 when all this pinging is going on.

Wisp

Hi again...

Checked some things....

Engine running at 175 F constant.
Fuel pipe to carb is 140 F and on the bowls it reads 122 F. Is this to much heat in the fuel?

There where no vacuum in the gas tank.

Søren

BB72

I was going to say what you mentioned, it's just enough time for the fuel to boil up. Maybe lower your floats and put an insulator between the carb and manifold.