Slick 60's

Good morning to all. Shortly after bringin 'Limestone' home, {my very neglected and 'Buzzard Bait 66 F-250 pickup truck}, i did a compression test on all the cylinders on the old 352fe motor. Keep in mind that i ran this old truck for over a year with this head lookin the way it did. #5 cylinder wasn't even fireing though there was plenty of spark out the plug. No. 8 was fireing but extremely low on the test i gave it. '0' compression on #5 and about 20 on #8. The rest of the cylinders ran about 120 pounds. Late last year i switched to synthetic Motorcraft oil with the fourth quart being Marvel Mystery oil and ran it for about a month, then began adding the 'Lead Substitute' from 'Gomout' to every tank full of 93 octane unleaded gas. Ran that for about a month, then i performed another compression check. All cylinders was showing up at 145 to 150 pounds on the scale, except for 'again' #5 and #8. Both showed '0' compression. Ruled out bad compression rings by squirtin a few tablespoons of oil into the cylinders, which would provide a temporary seal and therefore hold compression to near normal until it burns off. Didnt make a bit of difference when i rechecked it again. It was still '0' compression on 5 and 8. Now look at these...........



Holy smokes. Intake valves are beyond a standard valve job.

And this...............



and 'finally' this.................



Hard to beleive that old 352 still ran the way it did. I could still run it up to 60 or 70 mph without much of a fuss.

Glad to see you finally got around to that much needed valve job you have been talking about.so whats the other side look like or did you just start this morning? Just looked at the time stamp and I assume you just got started.

robert

Other side was in good shape. It's the other head {drivers side} thats in such poor shape. Hopeully the machine shop work and new valves won't cost me an arm and a leg. Should be ready to go by next weekend.

Limestone66 wrote:Hopeully the machine shop work and new valves won't cost me an arm and a leg.

Nah, just fingers and toes. I wonder why that happened to those exhaust valves.

charliemccraney wrote:

Limestone66 wrote:Hopeully the machine shop work and new valves won't cost me an arm and a leg.

Nah, just fingers and toes. I wonder why that happened to those exhaust valves.

Looking at the position(s) of visible damage; inline with the flame front, and being the #5 and #8, I would immediately suspect pre-ignition, possibly detonation induced. If this were an EGR engine, I would immediately suspect faulty EGR.
It's a given that close examination of the piston crowns on the affected cylinders is called for. "Sandblast" effects around the piston edges would merit further teardown.
I know this is not what you want to hear, but if you choose to just install a repaired head, another cylinder pressure test would be advisable ( once the engine has ran long enough to fully restore oiling to the affected cylinders).
Hopefully the damage is the result of long-term problems, although pre-ignition usually results in fairly quick failure.
Paul

ive seen worse

heres the y block heads from my old engine





lucky at the time i had pleny of spare heads to steal valves from and a friend with a valve grinding machine.

but after doing the heads the engine really became an oil burner so i ended up swapping it out last summer

I wouldn't say pre-ignition. Looks like the stock induction hardened valve seats just sunk over the years from the lack of leaded fuel. The valves can only sink so car before they start hanging open and burn. Hardened exhaust seats and at least two new exhaust valves are in order. The rest of the valve job, probably need new guide liners installed, check the cam and lifters to see if any lobes are going flat. Probably run like a clock when you are done.

MeZapU wrote:I wouldn't say pre-ignition. Looks like the stock induction hardened valve seats just sunk over the years from the lack of leaded fuel. The valves can only sink so car before they start hanging open and burn. Hardened exhaust seats and at least two new exhaust valves are in order. The rest of the valve job, probably need new guide liners installed, check the cam and lifters to see if any lobes are going flat. Probably run like a clock when you are done.

+1

Extremely hot valve (hot enough to burn) and chamber + fresh fuel charge = pre ignition = answer to Charlie's query.
No dispute of root causes.
"run like a clock"; maybe, see Iceman's post. Then carefully compare the damaged combustion chambers to the adjacent ones.
Paul

MeZapU wrote:I wouldn't say pre-ignition. Looks like the stock induction hardened valve seats just sunk over the years from the lack of leaded fuel. The valves can only sink so car before they start hanging open and burn. Hardened exhaust seats and at least two new exhaust valves are in order. The rest of the valve job, probably need new guide liners installed, check the cam and lifters to see if any lobes are going flat. Probably run like a clock when you are done.

Y.D.R. 'MeZapu'. I've seen this before on other engines that ran leaded gas, only to fall by the wayside after years of runnin unleaded fuel and more notably ethanol. Burns hot and plays havoc on unhardened stock seats and regular stock valves that thrive on leaded gas. As before i ran a compression test on each of the cylinders last year after i bought the old girl, and all of them peaked out at 120 to 130 pounds, except #5 and #8. Those were '0' compression. Then i started adding a bottle of 'Lead Substitute', hoping it would help it, and it did. It actually gave me a little bit more performance and better mileage despite it's ailments. Ran another compression check late last year and all cylinders had jumped up to nearly 150 pounds, except 5 and 8. Compression on those cylinders just wasn't there. I ran the old 352 that way since March of 2012, keeping the old truck confined to this county alone and not venturing off. With two dead cylinders inside of an old truck that had been terribly neglected, it still fired up each and every day and took me wherever i wanted to go. Sure, gas mileage was terrible but it still ran just good enough to keep the inevitable and much needed valve job on the back burner until me and my woman could get through what mess we went through. It hasnt been easy for us, i'm here to tell ya.

I need to pull my heads, I just havent felt well enough to go out and get into it.

I have my 390 4v manifold, HEI dizzy, Summit 600cfm carb, and gaskets all ready to go, as well as my 390 heads on standby if I need them.

I picked up a 2.75 rear end out of a dent to replace my 3.25 gears with, thats also on the to do list. The calculator says that will drop my 70 mph revs from 2790 to 2361, then down to 2238 when I go to a 235-75-15.

bmcgc wrote:I need to pull my heads, I just havent felt well enough to go out and get into it.

I have my 390 4v manifold, HEI dizzy, Summit 600cfm carb, and gaskets all ready to go, as well as my 390 heads on standby if I need them.

I picked up a 2.75 rear end out of a dent to replace my 3.25 gears with, thats also on the to do list. The calculator says that will drop my 70 mph revs from 2790 to 2361, then down to 2238 when I go to a 235-75-15.

Hope you get to feelin better 'bmcgc'. Ruby has faith in ya!

Thanks, Im going in for a stress test on the 1st. I have no energy and feel exhausted all the time. It sucks.

I bought a running 390 only for the shortblock to rebuild and put in my truck. It ran really well for what it was. Had a little pop in the exhaust but I thought it was from the terrible headers that were on it and leaking. It idled nice and didn't smoke. When I pulled the heads #8 exhaust valve was burnt worse than yours and the rest of the exhaust valves were sunk pretty bad. These things can run pretty well with a down cyl or two.

With the way this thing ran, i quickly ruled out bad compression rings just by driving it. I wanted to run a 'leak down' test on those two cylinders but did'nt have the fitting for it to hook to my compressor. At idle, it would gradually increase, then decrease constantly at the traffic lights. Treating the NP435 like you would a three speed cuz of 1st gear being the very notorious 'granny gear', i could go through the gears enough to get my speed up and at least keep up with the traffic if not better. Like i said, it will do 60 all day long and thats not flatout either. Afeared to go any faster it being what it is and how it runs. Extremely Heavy Duty old pickup truck F-250 with the Dana 60 axle and 4.10 gears. Absolutly no oil burning out the exhaust pipes, no oil leakage anywhere cuz i looked hard and every week i'd check the oil. Pretty damned clean like darkfired amber. Go figure!

UPDATE................Machine shop wants to know if i want the hardened valves and seats to run unleaded, or just stay with the regular and add the lead substitute for better performance. 'Geeez'. You mean i actually have a choice? I'll stick with the regular{Old School}.

It would be a waste not to go with hardened seats as the same machining steps need to be accomplished to restore the exhaust seats anyways. Its just the hardened seats are a bit more expensive per hole. Then once its done run em forever with plain old pump gas.

Duly noted. I'll check on that. Thanks

How is running lead substitute and softer valve seats better for performance? My wife's 390 has unmodified heads on it and we run lead additive in it my 352 has hardened seats and its so nice to just get fuel and go. Were going to get her heads done with hardened seats soon.

oldtruckfanatic573 wrote:How is running lead substitute and softer valve seats better for performance? My wife's 390 has unmodified heads on it and we run lead additive in it my 352 has hardened seats and its so nice to just get fuel and go. Were going to get her heads done with hardened seats soon.

Better but not best. Over time and many tankfuls of unleaded gas, the lack of lead in its properties will eventually wear the valve components down on unmodified heads, pistons and rings. Everybody should know this. Unleaded fuel burns differently and hotter in these old engines that thrived on lead for it's performance characteristics and high pollution. Good question that you asked, but my results speak for themselves when i ran a series of compression checks before and after adding the lead substitute. Even though that old 352 ran like a dog, everything jumped up when i started using the lead substitute that not only gave me better performance as sick as that old motor was, but a little bit better gas mileage as well. Still and sad to say, i am prolly better off going with the hardened valve seats, that way i can still run south of the border gas and not hafta worry over it. Now let me ask you this, Why do you hafta run this lead additive in your wifes 390? Because it fails to perform with regular straight unleaded fuel. Performance wont be as good without it. IMO