Ive recently gotten a 1977 f150 with a 351 w and a c6 auto trans the engine was rebuilt 20 years ago and only has 22 thousand miles on it but its having issues its low on compression in 2 cylinders could the valve lash be wrong or would it be a stuck ring? Thanks in advance Matt

 

You can squirt oil in the cylinders and try the test again. The oil will seal the rings but not the valves. If it set for a long time you might have sticky valves. Run Mystery oir or Sea Foam through the carb till it stalls, let it sit for 30 minutes and then drive it hard.

 

Ill try that thanks

 

It also runs pig rich smokes black when you stat it and if you try to get on it it just bogs you can feel the 2 cylinders down on compression missing hard I hope its just a valve lash issue

 

based on that additional if, the plugs could be fouled...have you pulled them and looked at them?

 

yes and they were very black and smelled of fuel on all cylinders

 

Replaced them and it still runs like ***

 

351W not installed in F150/350 & Bronco until 1981, so if it is a 351W, it has been swapped in.

351W has 6 valve cover bolts per side, 351M has 8 and would have been an option for 1977/79 F100/350.

 

Incorrect 77 was the first year for the 351 in f150s I know its a windsor and its the original engine I got it from the original owner there are lots of forums about this check them out.

 

All the information I see says a 351w wasn't offered for 73-79 trucks.

 

It could be stuck piston rings, but if two adjacent cylinders are down on compression that points to a defective head gasket. Fouled plugs means weak ignition and/or carburetor needs work. Maybe blown power valve, high float level, etc.

 

Did Not happen in 77 , you can post the numbers off the block might help , but unless it was a van which I think did get the 351w or a car had them but no f100 or f150 came out with a 351w in 77 , most likely you have a 351m

 

And I know you weren't being nasty when you said check out the other forums (at least it didn't look like it to me!), but with over EIGHTY SIX THOUSAND posts, I'm pretty sure NumberDummy has checked out the other forums!
Unless you meant others off of FTE that is. In that case you're probably right. With all those posts here I don't think Bill ever has time to visit other sites. Unless he no longer sleeps?

But I'm with the others. I'd never heard of a '77 coming with a 351 Windsor. However, a 2wd '77 could have had a 302, correct? I don't remember all the different combos between 2 and 4 wheel drive trucks, but I'm sure it's out there to find if I look.
Are you familiar enough with the Windsor family to tell the difference in a 302 and a 351W? Sounds like it, but I wanted to ask anyway.

Just to be sure though (if it matters?) 6.9 IdI, is yours a 2wd or 4wd version? I'm assuming 4-wheel drive since it's a 150, but even that catches me sometimes as to when they dropped the 100 completely from the lineup.
But in 4wd at least, I'm with the others and think the only engines that would have been in a 77 would have been an FE360 (early '77) or a 335-Series 351M (later '77).

I've been wrong before, and will be again. But that's how I remember it.
Bottom line though, is do you have pics we can see? Not just to see what you've got, but because we like seeing pics of other trucks to check out!

And back to your original question, if the engine was sitting for that long of a time and you have not had much time to drive it yet with it running so crappy, like was said the rings could definitely be needing to get some use.
What about firing order? How are the plug wires routed? Did you renew those as well and check them when you did the plugs?
What type of carburetor is on there? Air filter type?
Is the choke even opening up? Checked for vacuum leaks while it was running? Fuel pressure?

Lots of stuff can make an old engine run rich. Even a too lean mixture can flame out and act somewhat like it's overly rich. Not as rich as it sounds like in your case, but lean can send mixed signals at least.

Good luck.

Paul

 

Its a 2wd 77 f150 explorer no I wasnt trying to be nasty by telling him to check out the forums I dont know if the firing order is correct ill have to check that I know for sure its not a 302 im very well versed in these engines when I bought it I was told by the original owner that it was a 351 w and by looking at it it definitely is at least thats what my opinion is

 

Blue oval tech is where I read an article saying that the 351 w was introduced in the 77 f150 delivering close to 20 more horse than its older cousin the 360 also talks about the 400 small block making 9 more horse than the 390.