Ok 140k 78 f150 302
Truck sat for 5 years got it running recently. Was running decent but not drivable.

Today it started running really ruff so I did a compression test all were about 140-150 but #2 big fat ZERO

Pulled the valve cover rockers move up and down i can see piston going up and down, the vavle springs look good rockers are not loose and look like they are even.

What next?
Remove head?

 

You need to do a bleed down test or if your compression gauge has a removable gauge like mine you can attach an air hose to it and put the #2 on compression and add air and see where it leaks. That will tell you if its the rings or valves. I am thinking a burned valve.

 

I can do that will give it a try today.
I took the rockers off #2 and check the push rods all was good.

Thanks!

 

Ok sounded like its leaking out the valves. I started to take the top end apart.
When I took the drivers side valve cover over about a quart of oil spilled out. The holes that let the oil drain back down are clogged. I think the best thing would be a full rebuild but my wallet says NO.
Gonna pull one head off and see what the pistons look like and cylinder walls and figure out what I'm going to do.
Seen a 5.0 out of a 96 Unkown car unkown mileage on letgo. May look into that seeing its a roller motor.

 

Most likely a burned valve and that will cost about 300 to 400 for machine shop to redo the heads way better than a rebuild. If you got that compression I bet you are ok just to redo the heads more than likely the cylinders are ok well for 120000 miles LOL

 

Pulled the head off and the exhaust valve on #2 looks bents. It is not sitting flat. Not sure how that happened?
Also the number two piston is clean the others are black.

There is a lot of crud built up on the heads oil was not changed much in this truck I think.
Kinda scared just to redo heads only for the oil pump or something else stops after I get it back together.



Crud build up

 

No telling on the valve could of hit some debris or well who knows. The clean cylinder well that was probably caused by head gasket leak and water got in the cylinder while running and water will make it look new LOL.
But that’s a lot of crud typical of High mileage 120000 not to high up like you said oil used may have contributed to that. If you rebuild your self you are looking at give or take around 1500 parts and machine shop cost total. Just got done with my 351 she has about 2500 miles on her. A long block can be had for around the same price but you are relying on someone’s else’s work me I don’t trust no one but me to do that work.

 

Heck, I'd hit the junkyard and look for a set of e7 heads from a late 80s truck that still had a flat tappet cam and use those. Way better than the 70s heads. I will bet that valve was sticking from sitting an bumped the piston enough to get bent

 

Thanks for the info. I have found a engine for sale if I looked it up correct it out of a 92 thunderbird.
That would be a roller motor? E7 heads?
Would that be a good swap? He is asking 500 but think he would go cheaper on it.

 

 

It may have the e7 heads, I'm not super good with the car parts. I do know that some Lincoln's and Crown vics had e6se heads which aren't much improved over the 70s era heads other than being newer.

 

Update I picked that motor yesterday. Got it for $225. Got a cherry picker and engine stand from a friend so gonna pull engine and trans. Fix leaking trans and swap timing chain cover water pump and oil pan and drop it in.
Gotta see about pilot bearing needs to be chained and remain seal.

 

Old motor was in pretty bad shape lots of sludge in the oil pan and timing chain had plenty of slack.
Figured out the replacement motor has E7 Heads ��. So now gotta save some money for parts and clean clean clean.

 

Do you have a manual or an automatic? And did the engine come with a flywheel or flexplate? Some time in the early 80s the balance changed so you will need to use a flywheel/flexplate for the newer engine

 

I have a auto so I dont need a pilot bearing use to working with manual trans. Very good point Mudsport96. The motor didnt come with the flex plate so I will have to get a 50 OZ flex plate.