Thank you for your advice.

Hello everyone . I've been doing body work and little other work to my truck. Haven't figured out the power issue yet. I have another problem that might be related.
It takes at least 30 cranks and pumps to start my truck. Sometimes the battery dies before it will stay running. Once running it's good for the day. Let it sit a few days and same issues of not starting up right away only after a 20 minute or longer ordeal. Worried about the strain on my starter. I'll post pictures soon. Have to many projects and my 75 d100 is on the back burner but want to drive it more but it's not reliable with the starting issue. I'm really depressed about all the time and money I have into it and I can't even drive it. Thank you all.

You really need to adjust the valve lash before you do anything else. Find someone who can help you do it if you are not confident yourself. Your symptoms fit the idea that you have valves that are too tight. One easy thing you could do is simply remove the valve cover, find the 3/8" head adjuster screws on the passenger side of the rocker arms (just above the pushrods) and turn each adjuster screw 1/4 turn counterclockwise (loosen them). Start the engine and see if it runs better. If yes, then you need to carefully adjust all the valves before you drive the truck again. There are procedures on this site for doing this, or you can get a factory service manual.

http://www.slantsix.org/forum/viewtopic ... ht=#p72139

Best of luck and hopefully you can start enjoying your truck soon...

Lou

_________________
Home of Slant6-powered fun machines since 1988

I second checking the valve lash. Hot and running it should be .010" on the intake valves and .020" on the exhaust. There are several videos on YouTube showing the process.

I once bought a car where the lash was reversed, .010 on the exhaust is far too little clearance, and it started easily, but then ran really badly when warm. I know this isn't your situation. It sounds to me like you have a fuel pump with a bad check valve allowing fuel to drain back into the tank. This means lots of cranking to get fuel to the carburetor. Pull the fuel line from the carburetor and direct the line into a can or jar. Have a friend crank the engine. If fuel doesn't appear within a couple seconds, at the most, you have a fuel delivery problem. Also, if the choke is working one pump of the gas pedal to set the choke is all that should be needed. Take off the air cleaner, open the throttle while observing the choke. If the choke doesn't snap closed when the throttle is opened then you have a choke thermostat or linkage problem. Further, you should check the carburetor accelerator pump. If you operate the throttle with fuel in the carburetor you should see a steady stream of fuel sprayed in.

Good luck and check back in if you have questions.

_________________
Joshua

Thanks Joshua.

Thank you everyone