230 motor won't pass 2800 max rpm

[MLively]

Here's my issue.  Just completed ground up restoration of a 48 Power Wagon.  Everything was rebuilt or replaced.  I sent the 230 ci motor to a local mechanic to rebuild.  I had every confidence in his ability, he was a helicopter maintenance crew chief in the military during Vietnam repairing helicopters.  His son told me if he didn't sign off it didn't fly.  Anyway, I gave him the motor with a complete rebuild kit.  He bored out the cylinders to .060 over, resurfaced the head, new everything inside including an Isky performance cam.  Sadly, three weeks after he delivered the motor he was killed in a car accident.

 

On the first start up of the motor it ran fine but would backfire through the carburetor at high rpm.  We figured a timing issue since I was still running the original distributor.  I replaced the distributor, electronic coil, wires and plugs.  It runs better but after playing with the timing and carb settings the most rpm I can get is 2800.  When I take the truck on a level highway it only gets up to about 38 mph, any more throttle after that and the engine just drops off.  I should note, the peak performance I have been able to achieve is 2800 rpm with the idle timing at 34 degrees Before TDC.

I checked compression down the head: 130#, 130#, 125#, 125#, 110# and 130#

 

It's been suggested that the cam might be off a tooth since I am having to advance the timing so much.  That possibly the valves aren't seating at the right time and therefore not getting enough compression when it counts.  Also, three of the plugs have electrodes that are white on one side and black on the other.  Granted, these trucks new only produced about 4,000 rpm max with top speed of 45 mph but I'm not getting anywhere near that.

 

 

Edited August 20, 2021 by MLively

[Plymouthy Adams]

check to ensure the spring on the points is properly affixed so to prevent point float at the higher speeds

[belvedere]

My first thought is cam timing.

[MLively]

I should have added we replaced the original distributor and coil with the Stovebolt mini HEI setup.  This helped initially with the backfiring in the carburetor and got me from 2250 to 2700 rpm.  Disconnecting the vac line to the Weber took it to 2800 but that's all we have been able to do.

[keithb7]

There are instructions in my old Motors Manual about how to check valve timing. Depending on engine model size degrees of valve timing differs. A measuring device is inserted in #6 cylinder pipe plug. You also reference the valves to see when they begin to open and close.

 

Maybe start thing about how to access the front cover to remove it. Fan out, rad out. Crank pulley off, support front of engine. Remove front mount. Take timing over off. Align to TDC.

[MLively]

30 minutes ago, keithb7 said:

There are instructions in my old Motors Manual about how to check valve timing. Depending on engine model size degrees of valve timing differs. A measuring device is inserted in #6 cylinder pipe plug. You also reference the valves to see when they begin to open and close.

 

Maybe start thing about how to access the front cover to remove it. Fan out, rad out. Crank pulley off, support front of engine. Remove front mount. Take timing over off. Align to TDC.

Yeah, everything is pointing to taking the front apart.  Finally got to drive it after 3 years and now I have to tear it down.  I was hoping someone would say to just tighten the Fetzer valve or add ball bearing fluid and she'd be good as new.

[Veemoney]

You mentioned Weber and the Langdon HEI. Langdon used to sell a smaller weber for a dual carb set-up, they were for 4 bangers like the pinto and worked well when 2 were used on a 6 cylinder engine. Do you have the right carb size on your 6 cylinder comes to mind if it falls flat? 

Edited August 20, 2021 by Veemoney

[desoto1939]

34 degrees before TDC does not sound correct. I know on my 39 Desoto it is set at 2 degress before TDC.

 

Do you have a service manual on this Power wagon that will tell you the eact spec's. Might suggest that you back to the original dizzy these old cars and trucks run fine.  Might also suggest getting a NOS breaker plate for the dizzy to insure that everything is setup properly with the internal of the dizzy.

 

Also check that you do not have any sideways or up and down movement in the dizzy shaft this will also cause issues.

 

If yuou are running electronic ignition like a petronics you will also need to use resistor sparkplugs try the Autolite 306 and set the gap at 35. If you are running the old standard plugs thye would have been gapped at 25.

 

Checkon these suggestions.

I have been running points in my 39 desoto for the last 35 years that I hav eowned the car and it has the original dizzy and has always run points.

Rich Hartung

desoto1939@aol.com

[Plymouthy Adams]

57 minutes ago, MLively said:

Yeah, everything is pointing to taking the front apart.  Finally got to drive it after 3 years and now I have to tear it down.  I was hoping someone would say to just tighten the Fetzer valve or add ball bearing fluid and she'd be good as new.

 

 

your Fletch is showing...!!!

[keithb7]

“Isky Performance Cam” might also be a clue?
 

What’s your valve clearance, cold?

[ptwothree]

Check throttle to see if it's opening all the  way.

[martybose]

With the vacuum hose removed and plugged I only had 6 degrees advance at idle on my HEI.

 

Marty