One lean cylinder?
Post Fiend
Joined: Dec 2007
Posts: 8,521
Likes: 16
From: Lost
I agree. Oil and lean tend to support the possibility of an intake leak on the lower portion.
FTE Legend
Joined: Jul 2010
Posts: 32,875
Likes: 48
From: Northeast, OK
Ken - If you don't have a leak-down tester I made one by drilling a .060" hole in a solder-filled fitting. That dimension was found on the internet as being a standard for engines this size. But that made mine very sensitive, and I'm thinking that is due to the sharp entry/exit the drill bit left. I have all the parts to re-work the unit by using a Holley #60 jet, which should not only make it a bit less sensitive but would also make it repeatable.
RW- That's an interesting approach. Presumably you would pull the PVC valve from the valve cover but leave it connected to the vacuum source so the amount of air being introduced doesn't change?
RW- That's an interesting approach. Presumably you would pull the PVC valve from the valve cover but leave it connected to the vacuum source so the amount of air being introduced doesn't change?
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Cargo Master
Joined: Aug 2007
Posts: 2,558
Likes: 69
From: New Zealand
There is a small (1/2" mercury), regular flick on the vacuum gauge at idle, which probably makes a leak-down test more valuable to do.
I should have put 2+2 together on all of this earlier.
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Cargo Master
Joined: Aug 2007
Posts: 2,558
Likes: 69
From: New Zealand
Ken - If you don't have a leak-down tester I made one by drilling a .060" hole in a solder-filled fitting. That dimension was found on the internet as being a standard for engines this size. But that made mine very sensitive, and I'm thinking that is due to the sharp entry/exit the drill bit left. I have all the parts to re-work the unit by using a Holley #60 jet, which should not only make it a bit less sensitive but would also make it repeatable.
RW- That's an interesting approach. Presumably you would pull the PVC valve from the valve cover but leave it connected to the vacuum source so the amount of air being introduced doesn't change?
RW- That's an interesting approach. Presumably you would pull the PVC valve from the valve cover but leave it connected to the vacuum source so the amount of air being introduced doesn't change?
Post Fiend
Joined: Dec 2007
Posts: 8,521
Likes: 16
From: Lost
Thanks RW, I'll do that; audibly the truck has a good idle, so it's not a huge leak.
There is a small (1/2" mercury), regular flick on the vacuum gauge at idle, which probably makes a leak-down test more valuable to do.
I should have put 2+2 together on all of this earlier.
There is a small (1/2" mercury), regular flick on the vacuum gauge at idle, which probably makes a leak-down test more valuable to do.
I should have put 2+2 together on all of this earlier.
Years ago, I had an FE that had a weak cyl at idle, but over ~1K RPM it ran smoothly. I suspected a burnt valve, but dad wanted to rule out an intake leak before doing a compression test, since it was so much quicker to do. Until that point, I had never even considered the possibility.......
In the end, I was right. But I still learned a valuable lesson from the "master"..... He also told me the smoke was likely from a plugged oil drain in the back of the head. I dunno if I ever told him he was right about that part..... I popped the valve cover off, and oil was pooled at the back, running down the outside as it came off. Piece of wire to clean it out, and it never smoked again.
Post Fiend
Joined: Dec 2007
Posts: 8,521
Likes: 16
From: Lost
I'd rather pull an entire W, than lift the intake of an FE........ Prolly why that aluminum FE intake is still sitting in the house, and the cast iron one is still on the engine. Only had that aluminum intake for 2.5 years........
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Cargo Master
Joined: Aug 2007
Posts: 2,558
Likes: 69
From: New Zealand
I fixed this issue a long time ago, but just came across the thread again & realized it was never updated.
For anyone it might help in the future......the problem was one bad valve stem seal, allowing a small trace of oil into that cylinder & causing the plug to burn white without any exhaust smoke.
The oil was also making that cylinder ping at times; the pinging got progressively worse & the exhaust began to smell of oil at an idle.
I replaced all the stem seals while I was in there.....problems over
For anyone it might help in the future......the problem was one bad valve stem seal, allowing a small trace of oil into that cylinder & causing the plug to burn white without any exhaust smoke.
The oil was also making that cylinder ping at times; the pinging got progressively worse & the exhaust began to smell of oil at an idle.
I replaced all the stem seals while I was in there.....problems over
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FTE Legend
Joined: Jul 2010
Posts: 32,875
Likes: 48
From: Northeast, OK
Thanks for the update, Ken. Glad to know it was that simple.
I wonder what the situation is with Paul's intake.
I'll bet he is still running the cast iron one. Man, those FE intakes are massive!
I wonder what the situation is with Paul's intake.
I'll bet he is still running the cast iron one. Man, those FE intakes are massive!
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Cargo Master
Joined: Aug 2007
Posts: 2,558
Likes: 69
From: New Zealand
I've never really worked with FE engines; my only experience was removing some broken exhaust manifold studs (bolts?) from a 390 head for a customer once. I did take it for a drive a bit later - torquey!
FTE Legend
Joined: Jul 2010
Posts: 32,875
Likes: 48
From: Northeast, OK
The intake is massive! In fact it is so wide it goes well under the valve covers. When I was about 25 I changed the one on my '72 F250 myself and had no leaks. Looking back on that I'm still amazed I got it done - without a shop crane.
