29 years after a rebuild....

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B'cuda

B'cuda

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I rebuilt it 29 years ago, a mild, mostly stock 340, and it has been strong and reliable. Recently when I saw metal dust in the oil filter. I did a semi tear down and found the valve spring retainers are scuffing the stamped rocker arms. Its been along time and my memory these days is crap. The build is a 69 340 with stock X heads. The cam was a 280ish 474 lift DC purple cam with DC valve springs that were good to 500 lift. I shimmed the springs, I think 005 or 010 to get the height at 1.75". The valve train is stock, and the block was decked an unknown amount to remove surface rust.(unkept spare) I used over the counter felpro blue head gaskets no consideration of thickness.
I know this is a geometry issue, and I'm a general math guy. Any advice on what to check will be appreciated, hopefully in layman's terms would be great.
 
Or the exhausts have receded into the seats with the no-lead fuel. Sounds like something has worn enough for the retainers to move. If the spring height was indeed set to 1.75" (not 1.65"), then the retainers were sitting high to start with.....Deep valve seating?
 
nm9stheham said:
Or the exhausts have receded into the seats with the no-lead fuel. Sounds like something has worn enough for the retainers to move. If the spring height was indeed set to 1.75" (not 1.65"), then the retainers were sitting high to start with.....Deep valve seating?
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Yes, I'm thinking that the valve seats are recessed, even though the wear is on both rockers in most cylinders. Hardened seats only for exhaust right? Yeah I'm not positive on the install height number, dosnt that measurement apply to the spring only, not including retainer or shim? I can check them. I'm agreeing with you guys that the heads are probably wore out. With no port work, but replace valves, guides and exhaust seats, valve job, is it better to buy reconditioned iron heads condsidering they flow better?
 
Spring height w/o retainer or shim is correct.

Can't see any re-conditioned head flowing any better; they don't port them. (Maybe you are thinking of something like EQ heads? n That won't happen without a number of changes....)

Seats may be needed on both sides. If the old seats were just ground down, then they all may be down in the heads too far. Re-con heads are a crapshoot for what you get there, so I'd just as soon take my own to a good shop and have them reworked and the valve heights set properly. (You might even have the throats below the seats turned with a Serdi cutter to get things smoother for a bit more flow.) May be more $$ that way, but you know what you are getting in the end for sure.

And of course there may be some wear in the rockers/shafts that is part of this situation.
 
nm9stheham said:
Spring height w/o retainer or shim is correct.

Can't see any re-conditioned head flowing any better; they don't port them. (Maybe you are thinking of something like EQ heads? n That won't happen without a number of changes....)

Seats may be needed on both sides. If the old seats were just ground down, then they all may be down in the heads too far. Re-con heads are a crapshoot for what you get there, so I'd just as soon take my own to a good shop and have them reworked and the valve heights set properly. (You might even have the throats below the seats turned with a Serdi cutter to get things smoother for a bit more flow.) May be more $$ that way, but you know what you are getting in the end for sure.

And of course there may be some wear in the rockers/shafts that is part of this situation.
Click to expand...

I meant something like the Huges LA heads, I'm just not sure what castings they use and they probably have a core exchange. I don't think I'll ever need a set of aluminum unless the price was comparable.
 
Are you sure it is the retainer that is hitting? If the newer valve springs have a larger inside diameter than the originals, and you used the original retainers, it is possible for the valve spring to contact the rocker arm.
 
1969reddart said:
Are you sure it is the retainer that is hitting? If the newer valve springs have a larger inside diameter than the originals, and you used the original retainers, it is possible for the valve spring to contact the rocker arm.
Click to expand...
Just the corner edge of the retainer is making contact.
 
A guess, recessed valves. Whatever it is, valve recessed/guide wear/rocker wear/ valve tip wear. It all adds up to rebuilding the heads or going new heads. Pictures of the mating surfaces and putting a straight edge across the valve tips will point you in the right direction. My feeling is this is a rebuild or replace thing instead of just correct your single issue.
 
B'cuda said:
I meant something like the Huges LA heads, I'm just not sure what castings they use and they probably have a core exchange. I don't think I'll ever need a set of aluminum unless the price was comparable.
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That's what I thought.... beware that all anyone has right now (as far as I know) are 'LA intake' heads, meaning that they are the Magnum rocker system heads but with the intake mounting drilled for an LA intake. The LA-X type head with the LA shaft rocker system has gone out of production; but I have not checked with anyone for several months to see if a new foundry for the LA-X type castings has been found and brought on-line. (IMM Engines or Hughes might have some new info on that matter.)

And, those are closed chamber heads with about 10 cc smaller chambers. You'd need tall head gaskets to work with the stock type pistons that stick up out of the 340 block, unless you have the later lower compression pistons. And even then, the compression ratio would jump up a point. That would be OK for the lower compression 340 stock-type pistons. It would take some examination to be sure it was OK with the higher compression stock-type pistons.

Do you know which pistons you have? 2 eyebrow or 4?
 
040" over 10.25 comp. And the block was parallel decked so yeah, they stick out alittle. Thanks for the info on the heads. I didn't consider the magnums head. I did assume the LA-X would be a rocker shaft head. I'm also assuming if mine are worn out I may be better finding a better pair to put my money into.
 
'Worn out' would be in the guides and seats... no big deal in putting in new guides and installing seats. Very probably the cheapest route.

Since you like numbers and math, here are some numbers for other options, all of which I have computed here based on nominal dimensions (I don't just throw numbers like these out). Some verification of the amount your pistons stick out of the heads would be needed before final decisions, and I have assumed these are flat top pistons with 2 eyebrows (standard higher compression 340 types) :
  • Your present CR is actually around 9.4-9.5; the 'advertised' numbers back then were typically .5 to .75 higher than reality.
  • Your present dynamic CR with your cam at nominal timing is around 7.1. So you probably never had any detonation issues with the present setup unless you got bad fuel or your ignition timing was out of whack.
Any closed chamber head like the Magnums or MA-X or LA-X, are gonna require a thick Cometic head gasket. For example, a Magnum with 62 cc chamber and a .060" thick Cometic head gasket to get to a nice quench gap of around .040", which would put static CR right around 10.2-10.3. Dynamic CR will be in the high 7's with your cam at nominal cam timing, which is fine on pump premium. But you will have to swap out the rockers and such to Magnum's, and swap the lifters and pushrods for oiling through the pushrods.

Or you could go with the new 'latest & greatest' with Trick flows and have nearly the same static CR with that type of thick head gasket; a chunk more in $$. Dynamic CR's would be in the mid 7's. You could use the present rockers. Push rods may not be the right length; IDK on that.

There is an Edelbrock AL head ''open chamber' version that has a recess milled in the head that is .060" deep in the round shape of the cylinder; that is meant to be used with the stock-type 340 pistons that stick up out of the deck. It is PN 60179. The breathing will be a distinct step up from what you have. Jegs has them for about $720 each with the standard flat tappet valve springs and a $100 discount on a pair. You'll end up with around 10.7 static CR with these heads and a .028" thick head gasket, about 10.4 with the .039" thick 1008 Felpro head gaskets, and right around 10.1 with the Felpro 8553PT standard kit head gaskets. So you can adjust the static CR where you are comfortable. Even with the thinnest head gasket above, your dynamic CR will be 8.1 or 8.2 even at sea level, so that is runnable on premium pump fuel.

With your slow ramp cam and modest lift, the stock Edelbrock springs ought to be OK. Valve lift is good to .575" for those. I have not looked at the other head option for springs at this point, but I am sure there are good options.... you cam is not challenging to any run-of-the-mill 'hi-po' spring..

Moving up to around 8 for dynamic CR with any of these combinations needs some attention paid to ignition timing but it is quite doable with pump premium.

If you are interested in doing these computations, I can share the program I like to use.
 
nm9stheham said:
'Worn out' would be in the guides and seats... no big deal in putting in new guides and installing seats. Very probably the cheapest route.

Since you like numbers and math, here are some numbers for other options, all of which I have computed here based on nominal dimensions (I don't just throw numbers like these out). Some verification of the amount your pistons stick out of the heads would be needed before final decisions, and I have assumed these are flat top pistons with 2 eyebrows (standard higher compression 340 types) :
  • Your present CR is actually around 9.4-9.5; the 'advertised' numbers back then were typically .5 to .75 higher than reality.
  • Your present dynamic CR with your cam at nominal timing is around 7.1. So you probably never had any detonation issues with the present setup unless you got bad fuel or your ignition timing was out of whack.
Any closed chamber head like the Magnums or MA-X or LA-X, are gonna require a thick Cometic head gasket. For example, a Magnum with 62 cc chamber and a .060" thick Cometic head gasket to get to a nice quench gap of around .040", which would put static CR right around 10.2-10.3. Dynamic CR will be in the high 7's with your cam at nominal cam timing, which is fine on pump premium. But you will have to swap out the rockers and such to Magnum's, and swap the lifters and pushrods for oiling through the pushrods.

Or you could go with the new 'latest & greatest' with Trick flows and have nearly the same static CR with that type of thick head gasket; a chunk more in $$. Dynamic CR's would be in the mid 7's. You could use the present rockers. Push rods may not be the right length; IDK on that.

There is an Edelbrock AL head ''open chamber' version that has a recess milled in the head that is .060" deep in the round shape of the cylinder; that is meant to be used with the stock-type 340 pistons that stick up out of the deck. It is PN 60179. The breathing will be a distinct step up from what you have. Jegs has them for about $720 each with the standard flat tappet valve springs and a $100 discount on a pair. You'll end up with around 10.7 static CR with these heads and a .028" thick head gasket, about 10.4 with the .039" thick 1008 Felpro head gaskets, and right around 10.1 with the Felpro 8553PT standard kit head gaskets. So you can adjust the static CR where you are comfortable. Even with the thinnest head gasket above, your dynamic CR will be 8.1 or 8.2 even at sea level, so that is runnable on premium pump fuel.

With your slow ramp cam and modest lift, the stock Edelbrock springs ought to be OK. Valve lift is good to .575" for those. I have not looked at the other head option for springs at this point, but I am sure there are good options.... you cam is not challenging to any run-of-the-mill 'hi-po' spring..

Moving up to around 8 for dynamic CR with any of these combinations needs some attention paid to ignition timing but it is quite doable with pump premium.

If you are interested in doing these computations, I can share the program I like to use.
Click to expand...
Thank you for the information, very nice of you to go through the trouble, your right, I have never had any detonation/knocking etc. I have a few questions on rebuilding, new seats would require new valves correct ? Are there any known problems with seat inserts? I really would like to go with the aluminum eddys but I think for my application ( street cruiser I can leave to the wife and kids) it's probably overkill. On the other hand if I found a set of X heads in decent shape is there any fuel additives that actually prevent the valve recession or is that wishful thinking?
 
1969reddart said:
Are you sure it is the retainer that is hitting? If the newer valve springs have a larger inside diameter than the originals, and you used the original retainers, it is possible for the valve spring to contact the rocker arm.
Click to expand...
The springs are about 1.5" diameter, and slightly larger than the stock retainers
 
B'cuda said:
Thank you for the information, very nice of you to go through the trouble, your right, I have never had any detonation/knocking etc. I have a few questions on rebuilding, new seats would require new valves correct ? Are there any known problems with seat inserts? I really would like to go with the aluminum eddys but I think for my application ( street cruiser I can leave to the wife and kids) it's probably overkill. On the other hand if I found a set of X heads in decent shape is there any fuel additives that actually prevent the valve recession or is that wishful thinking?
Click to expand...
No problemo... glad to help as much as I can. Seats can fall out if poorly done.... there is a thread here about 'pieces of steel in cylinder' where one fell out. The OP thinks thinks the engine got overheated and that caused the seat to fall out. But it can be poorly installed too, and he had rebuilt heads IIRC so that could just as well have been one improperly installed seat.

I suppose there may be some tetraethyl lead additives to help with recession but it obviously won't fix what is done. Seats are old hat and are in all AL heads anyway, production or aftermarket. So nothing to be afraid of IMHO. It more is a matter of the process and quality of the work. No problems that I am aware of with Eddy's or TF's or properly done iron heads.

if you get used heads, then they could well have had the valves done before and the seats ground down into the head. So, you'd have to examine them to see. As for guides worn and seats and needing new valves.... not necessarily. When I have had heads redone, usually a few valves get replaced. Perhaps the machinists can share their info; they see it every day. But stock valves, guides, & seats themselves cost very little relative to the labor and skill that goes into this work.
 
Here's an update, when I started this investigation , I removed the drivers side valve cover and rocker shaft and initially overlooked the wear under the rockers, as it was minimal. I then removed the timing cover, replaced the chain and gears and added a stacked plate tranny cooler with fan and new radiator shroud. Yesterday I pulled the passenger valve cover and the wear is much, much worse. I took some measurements and the valve spring height is at least an 1/8" too tall. Recessed I guess. They all seem even a cross the tips though. In my mind the question still comes up how expensive to rebuild everything as opposed to rebuilding a set of used heads in better shape. Tomorrow I will be calling a few machine shops. I have one more spare x head and a 202 valve spare J head to work with and know of a set of x heads for sale reasonable price

20191004_224743.jpg


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That is a LOT of movement somewhere. Could some of that 'clearancing' on the rockers have been ground intentionally?

Reading your ruler, height looks like about 1.700-1.710".... about .050-.060" above stock.

Can you show a pic of the chambers with the valves closed?
 
nm9stheham said:
That is a LOT of movement somewhere. Could some of that 'clearancing' on the rockers have been ground intentionally?

Reading your ruler, height looks like about 1.700-1.710".... about .050-.060" above stock.

Can you show a pic of the chambers with the valves closed?
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I don't think they were clearenced., I know I didn't and that was the worst one. With a straight edge the valves seem aligned with each other and the same height. No, I have not pulled the heads off yet, don't anticipate doing that until end of the month unless something changed in my schedule.
More pics, spring diameter, and one of the rockers with less wear.

20191004_223016.jpg


20191004_215335.jpg
 
On the lighter side, a book I used as guide on this and an earlier build, "how to rebuild your SMALL-BLOCK MOPAR" (1982), had this picture used to help identify the differences between types of rocker trains, check out the same type wear on the rockers. Of course the author does not acknowledge the wear.

20191006_163136.jpg
 
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