I need help getting my trucks engine running!!

[1968_K20_4x4]

Hey All,

Looking for some help to get my truck running. I recently bought a 1972 K20 with a 307 (I believe it is a marine engine. It says OMC 225 on the valve covers. An internet search told me it is a marine 307, thats about all I know about it). The truck was fixed up about 10 years ago but had been sitting in storage and not running for a couple of years. When I picked the truck up it ran very roughly, and would not stay running, but ran just enough that I could drive it on the trailer if I revved it up. It also smoked like crazy (Thats why I named the truck Smokin Ochre! lol). Once I got it home I checked the oil and noticed that it was quite a bit over full. I drained it to the correct level, and fired the truck up. It ran great! for about a minute, and even idled. Then it quit.

When I tried to restart it, it would crank, fire up to 2-3000 rpms for a couple seconds and oil pressure registers on the guage, and then it dies. I thought it was a fuel problem, so I have since replaced the fuel tank (the old one was stored empty so it was all rusted on the inside). I have also installed a new fuel pump and filter and cleaned the lines. I tried to start the truck, but each time it does the same thing. Fires up, runs for a couple seconds, and then dies. I tried pouring a little bit of gas into the carb and even tried spraying inside the carb with brake cleaner (Saw it on Roadkill...lol!) Whatever I do the truck keeps doing the same thing and will not run for more than 2 or 3 seconds. I have checked the oil level and it is still good.

This is my first attempt at firing up a truck that has been sitting for a couple years, so I could use some help to guide me through what to do next. Thanks in advance! I have added a pic of the truck at the dealer I bought it from and also a pic of my motor. Any help here is appreciated!!

[Getter-Done]

Nice looking truck.
With the info you provided.
I would suggest to buy a new Carb or rebuild the one you have.
Replace the fuel filter and make sure to
clear the fuel lines of any blockage.






.

[rjs53]

Definitely rebuild or replace the carb. A little tuneup wouldn't hurt, the oil may have been over full do to carb running extremely rich. I'd drain the fuel tank and clean it also. Run some gas line from a gas can to the fuel pump, see if the pumps working when you crank it over. Just noticed the crabs a Holley, very easy to rebuild and inexpensive. Take the float bowl off and clean it, also see if the floats working. You can get to jets and every thing from there.

[Minkota]

Agreed, it has been sitting a long time. That Carb needs to be replaced or rebuilt. Personally I would purchase a new one.

[Ol Blue K20]

I betting carb. Pull a bowl of and look. I bet they're nasty and varnished up. If that's the case it needs a good cleaning and a rebuild.

[geezer#99]

Before you start rippin’ And tearin’ and rebuilding everything Pull the air cleaner off and take a pic.
Looks like you have a manual choke.
Likely it’s not working.
Take a pic!

[dflarsen77]

I've always used the procedure on this website:
http://www.how-to-build-hotrods.com/...an-engine.html

[Ironangel]

Originally Posted by geezer#99

Before you start rippin’ And tearin’ and rebuilding everything Pull the air cleaner off and take a pic.
Looks like you have a manual choke.
Likely it’s not working.
Take a pic!

^This,^ and the fact you never mentioned changing out the plugs? Did you?

[Wrenchbender Ret]

First thing get that old oil out of there & change the filter. It may be diluded with gasoline.
George

[Chris_oz]

Nice truck, congratulations.

You can make that truck run without a carby fitted, you have proved it runs.

I would be looking at power supply to the coil.
If the voltage to the coil positive from the key is low, they will run like crap or not at all. but will fire up when cranked as they get full power to the coil when the starter is in.

Take a small jumper cable, and hot wire it straight to the positive of the battery to the positive of the coil.

It should start and continue to run.

[Mike C]

Be interesting to see if the whole motor is from a boat. That's cool. My buddy built a 4 bolt main 327 using a large journal steel crank from a 307 boat motor and an early 80's 350 from a truck.

Hope you get it running easily.

[1968_K20_4x4]

Hey everyone, thanks for all the great replies! I appreciate the help.

So before I start taking stuff apart I took a few pics of my carb to show you what I have to work with. Its stamped 1850-3. A quick internet search says its a 600cfm.

I like the idea of rebuilding the carb to save some money. My knowledge about carbs is very limited and I have never taken one apart but I am sure I could learn how to do it especially with some help from the forum.

I have not removed the spark plugs yet. Next chance I get I will pull those and see what they look like.

It does have a manual choke, and the choke plate does open and close with the choke knob.

Thanks again for all the help so far guys!!

[1968_K20_4x4]

As far as the motor being from a boat, thats what I found when I searched for the decal on the valve covers. It says OMC 225 which I read means its a 307, and the 225 means 225 Horsepower. The block, heads and valve covers are all blue but the oil pan is orange.

I read that a boat motor was designed to run at high rpm all the time, and I thought that sounds like it would work well in a truck with low gearing. Its not the most powerful motor out there but should work good for a driver truck

[demian5]

Originally Posted by 1968_K20_4x4

I like the idea of rebuilding the carb to save some money. My knowledge about carbs is very limited and I have never taken one apart but I am sure I could learn how to do it especially with some help from the forum.

Google the carb number and rebuilding and you will have tons of videos.

Those carbs are difficult because of the fuel transfer tube. They leak just looking at them. Double up the O-rings if you have them.

Those are way easy carbs to rebuild though, but way easy to not know how to dial them in. Get all of the gasket material off of the float bowls, carb body and the metering block. Get the blue gaskets.

[geezer#99]

Nice pics!
Sure lots of cobbled togethor brackets.
Not hard to see your carb has been flooding. Shiny residue on the intake below the primary side shows that.
Decals are cheap. Likely the 225’s are just added for looks.
You need to determine exactly what motor you have.
Pics and info in here for casting codes.

https://www.mortec.com/

Info here for suffix codes.

http://www.nastyz28.com/decode.html

And contrary to popular belief you can’t double up on the o Rings!

[franken]

Might check to see if the accelerator pump squirters are squirting as the throttle is opened. That will tell if the carb is getting gas...

[Sparky dave]

If it’s a boat engine does that mean it could be a reverse rotation engine? 100 mph in reverse down highway seems sketchy to me ����

[1968_K20_4x4]

Thanks for all the replies guys! Really appreciate it. So I decided to buy a new carb instead of attempting to rebuild the old one to help move my project along a little more efficiently. I went with an Edelbrock 600cfm unit. Once it gets here I'll bolt it on and hopefully will be in business! I'll update on how the new carb works out

[1968_K20_4x4]

So while I wait for my new carb to arrive I have a couple little updates. Checked the casting number on the block and it checks out to be a 69-73 307 2 bolt. Also, pulled a few spark plugs. Not sure if you can tell if they're good just by looking at them. They're very dirty and one had oil on the thread. Here's a couple pics of the plugs for your consideration

[Steeveedee]

Running rich. Also, it looks like you have two taper-seat plugs and one with a flat bottom and a washer?

[AussieinNC]

Take a pic of the casting shapes on the front of each cylinder head...it looks like someone just threw in any old spark plug to fill the holes!

Also post a pic of the spark plug seat area in each cylinder head...where the plugs screws in....

Is the distributor an standard points type or a HEI unit? Edit....dont bother...its a HEI unit from the pic of the carb....it could have been incorrectly wired when someone changed over from points to HEI....check the power wire for the distributor has full 12 volts when key is in run position....sometimes folk forget to replace the resistor wire in old points systems when changing to HEI

Thanks

[Steeveedee]

If he's lucky that J-type plug won't have scored the seat in the head.

[Abomb]

Originally Posted by Wrenchbender Ret

First thing get that old oil out of there & change the filter. It may be diluded with gasoline.
George

This...your oil was almost certainly “over full” of gasoline...then, carb cleaning, holleys are easy, other than the pesky power valves, plugs, check timing and voltage to distributor, points cap and rotor if still equipped, once all that is good, it should run...

[72 k15]

Originally Posted by 1968_K20_4x4

So while I wait for my new carb to arrive I have a couple little updates. Checked the casting number on the block and it checks out to be a 69-73 307 2 bolt. Also, pulled a few spark plugs. Not sure if you can tell if they're good just by looking at them. They're very dirty and one had oil on the thread. Here's a couple pics of the plugs for your consideration

Wow they all look to have different threading and tapers on the spark plugs. all look rich to me.

[1968_K20_4x4]

Here is a pic of the heads on my motor. Sorry for the crappy pic of my old spark plugs but they are all taper fit. Forgot to get a pic of the spark plug holes on the heads but they look to be taper fit. There were two different brands of plug. NGK UR4
And A.C. Delco R44T. I replaced them all with new A.C. Delco R44T plugs all around. Also changed the oil and you guys were right, it had a bunch of gas in it