340 Hydraulic lock inspection update...

-
Found water in #7 cylinder. after pulling all plugs. No water in oil. When I add water to my radiator, it flows out the #7 plug hole! Pulled the intake and valve covers to find #7 valve spring busted and push rod bent like an S, #7 valve stem loose but won't pull completely out. Looking into the head passage with broken valve spring from the lifter valley I can see the head casting in cracked and broken apart around threads. See photos.
moparodbuster said:
I need some seriously good advice. My 340 12.6:1 pro streeter was running fine for days and days after overheating but after not running for about 5 weeks I went to start it and it ran really rough like it had a fuel issue. When I finally did get it to fire it ran like it was on 5 cylinders and really rough. I thought it might be old fuel or a stuck jet so I tried to clean it out by giving it some revs but it wouldn't idle and eventually died. When I tried to crank it over again it turned over a few times without firing then did not want to turn over at all and I felt a solid resistance in the block when turning the key. I haven't taken the spark plugs out yet but I'm thinking I've got hydraulic lock from a leaking head gasket into the cylinders. Any advice on what to look for what to watch out for and how to identify what size head gasket to get would be helpful all I know from the previous owner is that it's a 30 over 340 from a '71 Cuda with x Heads.
I work away and only home 1 day a week. have to pay a mobile mechanic by the hr to come do it while I'm away so I need to educate myself as much as possible to make sure I'm directing him to do everything right. He's not a mopar guy just a heavy equipment mechanic. So I'm basically paying him to be my hands and eyes.
Soooo... I'm guessing pull plugs, tap starter and look for water coming out of cylinders and see if she turns over, if I see water, mark that cylinder and then pull heads and look at gaskets, cylinder walls and check piston heights for possible bent rods then put straight edge on heads to check for warp... am I right? Am I missing something?
Click to expand...

20180701_152851.jpg
 
Found water in #7 cylinder after pulling all plugs. No water in oil. When I add water to radiator, it flows out plug hole! Pulled intake and valve covers to find valve spring broken off and push rod bent. Removed rocker shaft. Actual valve stem is loose but won't pull completely out. Looking into head passage from lifter valley, I can see head casting is broken/cracked inside around threads... see pic.
 
Looks like head is toast. Wondering if I should spend the money finding, porting a replacement steel x-head to match the other side or replace them both with aftermarkets... be nice if I could still use my crane alloy arms, shaft, etc on the new head. Or would it be wiser and more cost effective to get 2 new heads ready to go
?
 
Sounds like re-doing another iron head is most cost effective, IF you can find the data or the original porter to make it flow the same. That is one issue to solve.... how to get the new head flow the same as the other one.

Your rockers and shafts ought to transfer to any new head(s), but we don't know what was done to get to that high compression ratio. The aluminum Edelbrock heads and Indy/RHS heads have much smaller head chambers than stock cast iron X heads, so unless the X heads were milled a bunch to get that SCR up to 12.6, then there is a compression ratio question that needs to be examined if you change to new heads.

If you like, post info on the pistons and any work done to the heads, plus head gasket numbers, plus cam info, so some better advice can be given on the direction for the heads.

Valve spring info would be interesting too.... it may be that the valve spring broke, and dropped the valve enough to let the valve head jam and the stem bend.. which got pushed up into the guide crooked. You may see the chamber cracked when you pull the head. If any valve marks are on the piston.... then the rod needs examination and maybe even the crank. If the piston head is free from any valve marks, then that would be good.

I'd suspect that there is at least a little coolant in crankcase; if it gets out the plug hole, then some is very, very likely to seep past the rings.
 
nm9stheham said:
Sounds like re-doing another iron head is most cost effective, IF you can find the data or the original porter to make it flow the same. That is one issue to solve.... how to get the new head flow the same as the other one.

Your rockers and shafts ought to transfer to any new head(s), but we don't know what was done to get to that high compression ratio. The aluminum Edelbrock heads and Indy/RHS heads have much smaller head chambers than stock cast iron X heads, so unless the X heads were milled a bunch to get that SCR up to 12.6, then there is a compression ratio question that needs to be examined if you change to new heads.

If you like, post info on the pistons and any work done to the heads, plus head gasket numbers, plus cam info, so some better advice can be given on the direction for the heads.

Valve spring info would be interesting too.... it may be that the valve spring broke, and dropped the valve enough to let the valve head jam and the stem bend.. which got pushed up into the guide crooked. You may see the chamber cracked when you pull the head. If any valve marks are on the piston.... then the rod needs examination and maybe even the crank. If the piston head is free from any valve marks, then that would be good.

I'd suspect that there is at least a little coolant in crankcase; if it gets out the plug hole, then some is very, very likely to seep past the rings.
Click to expand...

It is (was) a dli motor. I remember Dick's son telling me that I was lucky to have him do the head work because most other shops wouldn't know how to go to extent he did on the x-heads safely and that there was basically nothing more anyone to do to improve their flow now because he machined them to their safe limits. Over $1k in head work alone that everyone always said e would have been better spent on alloys.
I'll see if I can find the cam, spring, head spec's and let you know.
Thanks for the advice!
 
moparodbuster said:
It is (was) a dli motor. I remember Dick's son telling me that I was lucky to have him do the head work because most other shops wouldn't know how to go to extent he did on the x-heads safely and that there was basically nothing more anyone to do to improve their flow now because he machined them to their safe limits. Over $1k in head work alone that everyone always said e would have been better spent on alloys.
I'll see if I can find the cam, spring, head spec's and let you know.
Thanks for the advice!
Click to expand...


If all it did was break off material off the guide I'd fix that in a New York second. There no reason to throw away a head for that.

I'll add when you see something like that break it's usually because you have a valve train issue.

I'd fix that head. And I'd fix the work that DLI because I don't do **** like that.
 
as YR says you can replace the whole guide
right now you have a screw in insert- like a K line- you can bore out the old guide and press in a new one
If you do not know an excellent machine shop in so cal PM me and I'll give you a couple of names
from the best- "you want it when" to cost effective
see if you can find out the brand of valves, sizes and if they were back cut
ps- with unleaded fuel I knurl and ream even new guides and I od hone the stems
still bad gas varnished up some guides on my 440 and I bent a set of smith brothers pushrods when I fired up after sitting for several months
 
yellow rose said:
If all it did was break off material off the guide I'd fix that in a New York second. There no reason to throw away a head for that.

I'll add when you see something like that break it's usually because you have a valve train issue.

I'd fix that head. And I'd fix the work that DLI because I don't do **** like that.
Click to expand...
It sure might same some other work and cost. But the perplexing question (to me) is where/how the water is pouring into the cylinder..... I can't see the material out the side of the guide doing that per se, unless it is cracked up into the water jacket. Or the material fell into the cylinder and jammed between piston and head and 'ker-rack'. Pulling the head will tell a lot more.
 
Head off now. Valve head punched through water jacket and machine shop said it was a throw away and couldn't guarantee a weld repair. Motor still won't turn over. From what I can see, cylinder wall looks fine. So far it looks like I'm up for...
1. One replacement x or j head machined to match the other side and a replacement trw high compression domed piston/pistons if I can find them. Ideally because I keep my 475+ hp.

2. Two new eddy heads machined to limits and lower compression flat tops. Not ideal beacause I'll struggle to have 475 hp.

Then who knows what ill find when I look at the rods, crank!

20180706_121431.jpg


20180706_121859.jpg


20180706_124859.jpg


20180706_124910.jpg


20180706_124931.jpg
 
That explains the oddly angled 'valve seat' that showed up in the first pix. Rod & crank 100% should be be checked now, both for any bending. I personally would also have the block pressure checked to detect any hairline cracks... when a valve and/or valve head start flipping around, the forces and pressures can go in odd directions.

You can get Eddy heads ported to get to the flow you need. Or others.
 
If the head passed pressure test I'd put a seat in it and run it.

Those are pretty beefy Pistons. I'd drop that piston out and if it didn't smash the ring land down on the ring, I'd buff the piston up a bit and run it too.

You damn sure need to figure out why that valve broke. Weak springs. Maybe just a bad valve. But you need to be sure.
 
nm9stheham said:
That explains the oddly angled 'valve seat' that showed up in the first pix. Rod & crank 100% should be be checked now, both for any bending. I personally would also have the block pressure checked to detect any hairline cracks... when a valve and/or valve head start flipping around, the forces and pressures can go in odd directions.

You can get Eddy heads ported to get to the flow you need. Or others.
Click to expand...
 
Someone had a set of those for sale awhile back, buying a whole used set, prob easiestcheapest. Check the for sale section and perhaps post a wanted ad. good luck, as it happens, I just trimmed a set of those pistons for the third time, down to 10 1/2ish.

Also check with member - whitepunkonitro
 
Last edited:
yellow rose said:
You damn sure need to figure out why that valve broke. Weak springs. Maybe just a bad valve. But you need to be sure.
Click to expand...
Yes to this.... I've had a friend's engine drop a valve with similar results (the cylinder wall split too) due to the rockers hitting the retainers and eventually releasing the keepers out of the valve stem. It can be a very subtle thing.

moparodbuster said:
Finding a high enough compression head/piston combo to match the hp that I have with my current setup is looking impossible so far.
Click to expand...

What cam spec's do you have? And is the 475 a dyno measured number? If so, at what RPM is the peak?
 
You need to find out where the water is coming from--the seat in the head or a split cylinder wall? Also looks like heavy 3/8" valve stems--Why? Was this engine built in the 80's? Pics of the other side (good) valvetrain could help. Looks to me like valve float from too much RPM for the spring package--intake valve tagged the piston bending it slightly--then the valve head just bends back and forth everytime it slams down on the seat until it snaps off. J.Rob
 
Dwayne Porter did my X heads and I’m pretty sure he can get everything you can out of them, but unless you are required to run a cast iron head or just want to run them. I’m not sure why you would have one done to match the other side. You would end up in a better position having a pair of CNC ported aluminum heads done. Without the ticking time bomb of other heads valves/springs/ect. I like Ferrea valves, in my experience they tend to bend when abused and not have the head pop off.
 
yellow rose said:
If the head passed pressure test I'd put a seat in it and run it.

Those are pretty beefy Pistons. I'd drop that piston out and if it didn't smash the ring land down on the ring, I'd buff the piston up a bit and run it too.

You damn sure need to figure out why that valve broke. Weak springs. Maybe just a bad valve. But you need to be sure.
Click to expand...
inertia said:
whitepunkonitro
Click to expand...
RAMM said:
You need to find out where the water is coming from--the seat in the head or a split cylinder wall? Also looks like heavy 3/8" valve stems--Why? Was this engine built in the 80's? Pics of the other side (good) valvetrain could help. Looks to me like valve float from too much RPM for the spring package--intake valve tagged the piston bending it slightly--then the valve head just bends back and forth everytime it slams down on the seat until it snaps off. J.Rob
Click to expand...
The motor was built in the 80's, yes. The pic's from my previous post show the water is coming from where the valve has snapped, tumbled upside down and pushed back up by the piston through the surface the head behind the seat.
 
The OP reports coolant pouring into the cylinder, so somethign won't hold pressure. I think the gash is visible.... look at the last pix in post #34. I think that is it at 11 o'clock above the broken stem on the valve head, in the pocket.
 
You must log in or register to reply here.
-

Back
Top