Hi guys and gals!
This is my first post so correct any of my mistakes. Sorry in advance!

I have some really burning questions about my Canadian 300 Inline. Hes not exactly the happiest turkey in the barn. (Pun intended - He spent time on turkey farms)

Heres what I know about it so far:
Duraspark Ignition, Carter YF-B Single bbl Carb, Unchecked PCV, Funtional Heat riser system, and it was fully rebuilt around 80,000 Miles in 1995. Currently at ~153,000. Ive changed the engine oil and filter. I have also set the timing to the specs indicated on the VECI label. I have personally never been inside this motor in particular. It is a Non-Catalytic truck. It was an A/C truck, then while he sat, some sub-par individuals stole the A/C system out of it. Im guessing this was around 2008. It sat since 2002. I revived it in 2020. It does not have a Smog pump or anything associated with Smog control, and these were not installed at the factory.

He runs great and starts easy, but being a fairly fresh revival from bench warming for 18 years, hes got some quirks that I'm not exactly fond of.

After starting, it runs ok. Im saying OK because he runs like valve issues. Misfires and idles erratically. When revving gently, it retains that misfire until its been revved after bringing RPMs down several different times before it runs great, then idles good for about 15 seconds then begins to slowly return to misfiring. I dont have any issues with having to set valve lash and preload. If this is a required procedure, I can carry this out if needed. I have confirmed it is not a vacuum leak.

Oil pressure is questionable. While idling, it rises to normal at a normal pace. While loading the engine at idle or if doing alot of rocking side to side on a bumpy road, oil pressure drops to below normal if not drops below Low on the gauge in the dash. I used the recommended viscosity of oil shown in the Haynes repair manual, but I used Synthetic. I have not added any but I am considering adding STPs ZDDP to the oil. I put in the 6 US Qts that they say it needs.

Any help is much appreciated and I would really love to hear if any of you guys/gals have any suggestions for me! Thanks in advance! I can send Images if needed.

 

Do a compression check. Check the timing again and install a vacuum gage. See what it reads at idle and at higher rpms. With the timing light, watch how the timing changes and observe min and max at diff rpms. Install an oil pressure gage to see what the pressure actually is.

 

Liam,

John is correct in his note above. A couple of other things to look at. You have probably replaced the fuel filter, but not a bad idea if you have not already. A partially clogged filter can give erratic results. Somewhat unlikely, but we can all get a bad tank of gas from time to time. Has this misfire occurred thru more than one tank ? A couple of the little bottles of dry gas never hurts. Fuel pump pressure is also a concern, but not as easy to check.

The duraspark ignition box can also give erratic results. Not super easy to check unless you know someone with a known good unit of the same year you can swap out to test. However the dist cap, rotor and plug wires are worth a look. The spark plugs tend to fail slowly, over a long period so probably not an issue here.

You will get lots of good advice from this site.

 

Maybe a vacuum leak

 

All,

Thank you guys so much for the help!! Really Appreciate it.

i have not replaced the fuel filter on the carb, i am however running a clear inline filter to see the quality of the fuel. I am running to ORiellys later and I intend on getting one + a rebuild kit. I have been noticing bad fuel coming up from the tank, and I intend on pulling and cleaning the tank as well as a Fuel Level sender replacement (Fuel gauge went out). I have replaced the fuel pump with a new one from Rockauto. I belive the Duraspark is factory, so I can look into that. I have also cleaned the cap and rotor, and the plug wires were next to new when he was parked in '02, and they look to be in great condition. They might even be MSD wires. I was told by the original owner that it was parked with the reason being a intake leak. I do hear it whistling from time to time. If this is a cause for a misfire, then I can pull the intake and replace the intake manifold gasket. I (for some dumb reason) have not had the plugs out yet. I can look into those sometime soon and get back to you guys.

Again, thank you guys so much for the help! I will look into these things as soon as I can.

--Liam

1978 Ford F150 Ranger XLT -- 300CID 4.9L I6 w/ unknown (New Process maybe) 4sp H-Pattern floor shift w/ Granny 1st.

 

I word of advice on the gas tank. If you happen to find pinholes/leaks, don't waste the time or money with flushes, cleaners, or sealants or trying to patch them. Just use those funds towards a replacement. We tried to patch a couple of pinhole leaks after flushing, cleaning and sealing and the patches didn't hold.

Just my .02 cents.

 

Tighten the intake hold downs and bolts. On some of these, usually mid '80s, they constantly work loose.

 

An intake leak on a cylinder or two would also cause a misfire beings are your sucking in more air than fuel and not getting a proper mixture ratio. If you pull the spark plugs you should be able to see a difference and figure out which cylinder might have the gasket leaking at. An intake gasket could solve your problems if that was the reason they parked it. I’m guessing it hasn’t been done yet.

 

You say it was parked because of a intake leak and you can hear it so guessing not fixed?
You also said you checked for vacuum leaks how did you do that?
I am going to say vacuum leak is the cause.
Dave ----

 

Hello All,

I have discovered the source of the intake leak and misfire (After replacing the spark plugs and rebuilding the carb with new base gaskets and a phenolic spacer)

As I mentioned, someone had rebuilt the engine in the mid-90s. They however missed a few minor details. There was a carb base to intake gasket, and it was in the most terrible condition. Definitely the source of the intake leak.

I installed two new gaskets and a new spacer, and rebuilt the ol' Carter YF, put er back on, set the idle, new plugs, and BOOM! Whole new motor. Misfire is gone, idle and rev smoke cloud and stink is gone. I also replaced the fuel level sender, and the chunks in the fuel shouldnt be an issue anymore. Fixed the fuel gauge that was stuck too! The fuel filter appeared to still flow freely as well.

All thats left to do on this truck is some homework, and fix the parking brake pedal that does not ratchet. Thats just a simple fact of uninstalling it, degreasing, re lubing, slappin er back in.

Greetings from West Central MN! Thank you all for your help!!!