The Stovebolt Site Forums The Shop Area Engine Shop 1960 235 engine has poor compression

After 6 months I finally got my title from the seller. Now I can start spending some money on getting the motor running. A quick check shows only 30 lbs of compression in #1 and #2 (I had to walk away before I got further....Bummer).So now I'll put some oil in the cyl's and check again. Any advice on going thru this head? Hardened valve seats for unleaded, or just let em' stay? This truck wont see many miles, its just gonna be a toy.

My 1st stovebolt engine (and still the current powerpalnt for my 49 3100), was a 216 that sat for over 40 ys.
Similar to yours I had very low compression in 3 cyls and too low compression in the other 3. Needless to say it wouldn't run.
Pulled the head and all the valves & seats were burnt and would seal. Luckily it had no cracks.
Had the head checked & rebuilt for around $300 (all new everything) and it runs like a singer sewing machine.

I'm currently in the process of rebuilding a 54 235. It had 0 compression in cyl 1 but the other 5 were above 100. Pulled the head and found piston #1 with a big ole hole in it.

So to shorten the story. I doubt you'll get acceptable readings even w/oil squirted in the cyls. The dry readings are just too low.
If you know for sure that the valves are fully opening & closing and you ran the test w/the throttle plate wide open then you're going to have to pull the head and inspect.

You'll find many differing opinions on installing hardened valve seats in these heads. I had them put in mine but many will tell you they're not needed. That'll be your call..
Once you get the head off and inspected you'll know what you'll need. I recommend to take it to a machine shop and have it magnafluxed and checked for cracks. No sense in putting $$$'s in a boat anchor head...
I'll be dropping my 235's head off sometime this week or the next for the same checkout.
Good luck
Dave

Was the engine running or sitting for a long time? An oil change and a seafoam treatment may clean things and get some compression. If it is only those two cylinders, it may be a head gasket. Is there water and oil mixed in the radiator? The only way to tell anything is to complete the compression test. I would go with hardened seats just for insurance, won't hurt. Just yesterday was at the machine shop having a similar talk. Magnaflux is the key event in this process.

A cylinder leak down test can tell you where you are loosing compression.
http://www.harborfreight.com/cylinder-leak-down-tester-94190.html

The issue about hardened valve seats has many pro's and con's. When trying to decide if you should or shouldn't have them done you need to define what your going to do with your truck and how much your going to use it.

Thanks Dave, Don and Mike. Can wait to get my hands on that engine tomorrow, its been a long time coming. I'll post the results of my tests to see if anyone can steer me right. Anyone know a good machine shop in the Denver/Littleton area? Thanks again bolters......best site around! <a href="http://s867.photobucket.com/user/marko27271/media/SAM_0794_zpsecfb2556.jpg.html" target="_blank"><img src="http://i867.photobucket.com/albums/ab231/marko27271/SAM_0794_zpsecfb2556.jpg" border="0" alt=" photo SAM_0794_zpsecfb2556.jpg"/></a>

Anyone who does not install hardened seats is in for trouble, unless they have a load of leaded fuel or are running on propane!
The hardened seats are a must for unleaded fuel, unless you want your valves to prematurely sink into the seats. I would be surprised if any engine shop did not install them.

Why skip them and wait for failure?

I beg to differ on the hardened valve seats. I've been running mine for years without issue. Do a little research on the quality of gas from the days when these motors were new. Now, if your working your motor really hard you may want better seats installed. The blanket statement that you need them is false.

Lead (TEL) was added to gas in the early 20's (Hello, Ethyl!) and was phased out beginning in the 70's.
The lead was the "lubricant" that kept the deposits off the valve sealing surface. When lead was phased out, valve life took a bit hit, thus the need for hardened seats and induction hardening.
Some engines, if used lightly and little, may last a while, but even highway driving can ruin an engine in a relatively short time if unleaded fuel is used with unhardened seats.
You make your choice and take your chances.

I'm with Don, I've run original 235's and 283's thousands of highway miles on unleaded without problems .... this has been discussed to death here, these old low compression, low power stovebolts will run fine on unleaded fuel until something else creates the need for a rebuild if you don't abuse them - if you have the engine torn down and are rebuilding, not a big deal to do the seats, but there's no need to pull things apart just for that, and if you decide to pinch the pennies and don't do them on a rebuild, the engine will still last your lifetime for the easy use it'll get as a toy

Bill

The only place hard seats are a must would be in a Propane-powered engine. I worked at a concrete plant in California where most of our off-road equipment was Propane powered and we installed hard seats in all of those engines. The "lead is a lubricant" myth was debunked a long time ago, at least with all but a few diehard machine shop owners who see an opportunity to pad the bill when an older cylinder head comes in for a valve job. The shop where I managed the connecting rod rebuilding department did dozens of valve jobs a month, and we only installed hard seats in a very few situations with very special circumstances. We had virtually zero comebacks involving valve regression into the cylinder head on non-hardened valve seats. These are facts supported by actual excperience, not the equivalent of an "old wives' tale" that has been repeated by well-meaning but misinformed people. I call them "old mechanics' tales". Real world experience trumps a good-sounding theory any day.
Jerry

Re: "if your working your motor really hard you may want better seats installed"

The intake valve sees exactly the same seat pressures regardless of how hard it's working. The exhaust is the same, with somewhat elevated temperature - which makes an un-interrupted cooling path (direct to the casting, not through the insert) even more important.

Sorry Hot Rod, but I must disagree with you on this one. My experience comes from working with the TRW company on engine development programs. Valve recession with unleaded fuels is a very real problem, and gets worse with speed and load, but even continued highway driving could rapidly ruin a head. It may vary with different engines, but it is a real issue, not some mechanic's myth!

The intakes are cooled by the intake charge, and don't need inserts. The exhaust valves are not. Their temperature increases with load. It has nothing to do with seat pressure.

Woods, we're talking about engines that do best below 3000 RPM, and that will likely never even see the loads they were designed for, let alone overloads .... as I said above, I've put thousands of miles on original engines on unleaded fuel with no problems, it's NOT an issue with these old trucks, very few of which will see daily use

Bill

Heat is the real enemy of any valve. Materials have changed, aluminum will need an insert. Iron? not so much. When deciding on inserts, consider the gain (Longer life) and the risk (Insert fail). When the materials for valve faces went to a hardened material the need for an insert was limited to softer casting material like aluminum. In an engine with modest valve spring pressure, and good castings, the cooling of the valve is what makes it last. Intakes are cooled rather well by the incoming air fuel mix. Exhaust valves, only through contact with the head and guide. Adding an insert at this point won't help cool it at all. The only good reason to install an insert would be to repair an already badly eroded valve pocket. The last land speed engine I was able to see up close had an iron head with the inserts removed and the biggest valve seat possible cut into the casting. And it was an air cooled engine..go figure. Welding of the valve face to the valve seat under extreme loads has been taken care of by changing the material at the valve face. That was the real reason that old valves were so fragile back in the day. Flat heads run very high valve face temps, the valve sits on an uncool ed port. We have good cooling in our castings, and fairly long valve guides. Our valves are in a pretty good place. So unless you need to repair a badly worn valve seat I don't think you need an insert. Seat pressure can make a difference, but temperature will be the real monster.

Red58, I understand the usage. But don't tell me valve recession is a myth. I examined many durability engines and field engines. There are many contributors to the problem; for example, valve rotators. So engine design plays a big part.

Steve H., iron heads went to induction hardened seats instead of inserts. It was not the valve material.

So how many miles were on that land speed engine? It is irrelevant to the discussion.

Real life experience beats some sort of scholarly study every time.
Jerry

Woods, I've not said valve recession is a myth, I said it's pretty well irrelevant to stovebolt engines and the use folks here will put them to .... we're not discussing engines for use in destructive testing

Bill

Not you red58, but HotRod Lincoln. Real world results as seen by engineers in the trade (valve manufacturers and OEM engine manufacturers) are not "scholarly studies".

Jerry, go back and lay in your garden awhile.

Woody, find another congregation to preach your sermon to.

no Woods, they're not "scholarly studies" indeed, nor do they have any relation to low power 50's street engines .... and don't ask Jerry to move from his hospital bed we'd like to have his decades of practical experience to draw on in the future

Bill

BEAM ME UP SCOTTY! THERE'S NO INTELLIGENT LIFE DOWN HERE!

Looks like somebody had someone else get all up under his bumper, broke him loose, and pooshed him into the wall. Oh well, these things happen.

I am putting in hardened seats, mostly for spite. None of you has anything to be proud of after this little go around.