41/53dodges Posted March 12, 2019 Report Posted March 12, 2019 Good morning guys, been forever since I posted a new topic but this one's got me stumped. Last winter I built up a 265 Spitfire engine for my B4b, used an edgy cam, shaved head, and heavy truck manifolds for now. Ran like a Swiss watch. I parked it in fall just before the snow started but usually light it up every month or so. I've noticed that when I start it, #1 exhaust valve keeps hanging open, usually it will come free on it's own accord once it warms up but this time no dice. Had to pry it back down with a screwdriver, and it stuck again immediately. Even tried running it and being the valve spring. Darn thing just sticks up, and makes it sound like a messed up Harley! Has anyone seen something like this before? Josh Quote
jeffsunzeri Posted March 12, 2019 Report Posted March 12, 2019 I've found it to be something of a weak point on the flatheads. Valve stem lubrication is not the best aspect of these motors. Especially on a new rebuild with tight tolerances, cold, damp weather, and hung valves are fairly common. Generally, after a few hours in service, this will stop happening. Suggestion for now is to get lots of lubrication down the valve stem, removing the head if necessary, so that the stem is not sticking. Check to make sure the spring is not broken. Add an oil additive such as CamGuard which will leave a nice film on the moving parts. You may want to play with oil viscosities a bit to see if that will help. Quote
Dodgeb4ya Posted March 12, 2019 Report Posted March 12, 2019 New engine with tight stem clearance. sticky valve..worse in a unheated garage. Quote
kencombs Posted March 12, 2019 Report Posted March 12, 2019 Agree with all the other posts. The exh guides have a recess in top of the guide. The main purpose of that recess is to retain what little oil splashed into the valve area to lube the exhaust. Intakes have that recess down to prevent that very thing. I think you can reach the valve stem with an oil squirt from an aerosol can with the little tube extension. With the spark plug removed and the exh valve open. Probably not important what type of oil you use, just soak it well before storage. And, add one of the magic gas additives to aid valve lube to the gas. Marvel Mystery oil is one, or ATF works for me. That should help until you get enough miles on it to free things up. 1 Quote
Dodgeb4ya Posted March 12, 2019 Report Posted March 12, 2019 The exhaust guide counterbore is up to protect the valve stem from carbon build up and also to help prevent exhaust valves from sticking. 1 Quote
MBF Posted March 12, 2019 Report Posted March 12, 2019 (edited) Give it a shot of Marvel Mystery oil down the carb, and run some in the gas. We've had to do that for years with our flattys-they sit too much. Edited March 12, 2019 by MBFowler 2 Quote
NiftyFifty Posted March 12, 2019 Report Posted March 12, 2019 100% agree...Marvel Mystery was what brought my rebuild back to life as well. I had all new guides/valves, pistons and rings and after the truck sat for a year during some body and interior modifications, I lost almost all my compression...I let it soak for a few days with MM, then ran some down the carb, in the fuel and in the oil...no more issues and back to 120-130 psi hot on all cyl’s. Quote
MBF Posted March 12, 2019 Report Posted March 12, 2019 I've seen these stuck so bad that they've pushed the valve guide up out of its original position. Still have that engine-truck sat for years outside, but it ran great when it was parked! I bought a 46 2 ton dump a few yrs back. Got a deal on it because it was running on only 5 cyls. When they delivered it he started it on the trailer, I choked it off on MMO and a short time later I heard it clunk. Started it back up-hitting on all 6. Sometimes you get lucky, and sometimes the bear bites you. Quote
thisoldtruck Posted March 13, 2019 Report Posted March 13, 2019 Yes, Marvel Mystery oil is good. I've used it in the gas for top cylinder lubrication. Even poured some down the spark plug holes and the carburetor. For long term storage, I use a can of fogging oil. Quote
Cordell Posted March 13, 2019 Report Posted March 13, 2019 This is the best topic I seen on the flatly had the same problem. I’m going to try Kroy oil Quote
Dodgeb4ya Posted March 13, 2019 Report Posted March 13, 2019 My solution was to run my new engine way more often....never had any valves stick again. 1 Quote
Merle Coggins Posted March 13, 2019 Report Posted March 13, 2019 I had this same problem the first few years after I got my truck together. It always seemed to rain a lot between uses and every time I'd try to start it up it would crank funny and be very hard to start. I quickly realized that sticky valves was the problem. Once I would finally get it to start it would run rough for several minutes then gradually smooth out. I tried adding MMO to the gas, when I'd remember. I can't say if that really helped or not. I have not experienced that anymore in the past few years, so maybe it had something to do with it. Or things are just wearing in now. Quote
41/53dodges Posted March 13, 2019 Author Report Posted March 13, 2019 Thanks for the thoughts guys, I was kinda figuring it had to do with getting damp and probably rusting up the stem. I'll have to try the marvel mystery oil, or I've got some outboard fogging oil in the garage. The big pain in the rear is that it's the exhaust valve, so it just keeps blowing back through the intake! Funny how that works... Quote
Jeff Balazs Posted March 13, 2019 Report Posted March 13, 2019 I put about 4oz of MMO in my gas tank every other time I fill up. It really helps with the fuels we have these days. We have a winter fuel formula here in SoCal that makes for harder starting if I forget to dose it with MMO. My daily driver has a 230 that I revived rather than doing a full rebuild. I change the oil about every 2000 miles and use MMO in the fuel. Over 20k miles and it does not smoke or let me down ever. Jeff Quote
Dodgeb4ya Posted March 13, 2019 Report Posted March 13, 2019 4 hours ago, 41/53dodges said: Thanks for the thoughts guys, I was kinda figuring it had to do with getting damp and probably rusting up the stem. I'll have to try the marvel mystery oil, or I've got some outboard fogging oil in the garage. The big pain in the rear is that it's the exhaust valve, so it just keeps blowing back through the intake! Funny how that works... Odd that the sticking open exhaust valve causes " blowing back through the intake!" 1 Quote
MBF Posted March 14, 2019 Report Posted March 14, 2019 I think you've got a hanging intake valve if its blowing back through the carb. 2 Quote
41/53dodges Posted March 14, 2019 Author Report Posted March 14, 2019 Nope, already popped the side cover off to check! That was my first thought as well. Best I can figure, the exhaust charge from the other cylinders pressurizes the one with the stuck exhaust valve through the whole cycle, including intake. It seems to blow back and pollute the charge for #2 as well, because that cylinder goes down at the same time but maintains spark and compression. Wierd eh? Quote
Merle Coggins Posted March 14, 2019 Report Posted March 14, 2019 If that's the case you have some pretty high exhaust back pressure that needs to be addressed. Maybe its because the heat riser flap is vertical? #1 exhaust valve is the first valve from the front of the block. Quote
41/53dodges Posted March 14, 2019 Author Report Posted March 14, 2019 Heat riser flap was staked in the open position, since the spring was gone. Trucks got 2.5 ton school bus manifolds, so 2.5" straight back exhaust and a glasspack. But that does make me wonder if a mouse might have climbed up in there and built a home... Thing doesn't sound constricted when it runs on all 6, but definitely food for thought... 1 Quote
Dodgeb4ya Posted March 15, 2019 Report Posted March 15, 2019 What are 2-1/2 ton bus manifolds.....pictures ? Quote
41/53dodges Posted March 15, 2019 Author Report Posted March 15, 2019 They're not a whole lot different from standard truck manifolds, but the intake is a tiny bit bigger and the exhaust is a huge 2.5" 4 bolt dump. Would be very good for a turbo... Here's a picture from when I finished the motor 1 Quote
thisoldtruck Posted March 15, 2019 Report Posted March 15, 2019 (edited) I got the same manifolds on my 251 in my power wagon. I've got an industrial 251 in my truck though. Yours has the heat riser valve, mine does not. I'm thinking of modifying it as it would help in winter startup and driving. I also need to drill a couple of extra holes in the intake manifold for the windshield wipers and brake booster. Edited March 15, 2019 by thisoldtruck Quote
Dodgeb4ya Posted March 15, 2019 Report Posted March 15, 2019 Nice looking engine. Yep... all the 1-1/2 ton up use the 4 bolt 2-1/2" exhaust manifolds for better breathing...the intake is basically a car intake..? Quote
41/53dodges Posted March 15, 2019 Author Report Posted March 15, 2019 Pretty much! I think I measured like a whopping 1/32 difference in the intake bore. Which I why I've got an Ellis intake on hand, whenever I find all the stuff to get it together. Quote
Jeff Balazs Posted March 15, 2019 Report Posted March 15, 2019 1 hour ago, 41/53dodges said: Pretty much! I think I measured like a whopping 1/32 difference in the intake bore. Which I why I've got an Ellis intake on hand, whenever I find all the stuff to get it together. That 1/32" is probably all it takes to turn one of these engines into a roaring beast........? There has to be times when we all dream of just a few more ponies. I have a few steep hills on my commute where I thin even one more would help Jeff Quote
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