Howdy everybody Today, I picked up my "462" Camel hump sbc heads from the machine shop, after getting a valve job. When I got home, I unwrapped them to get them ready for install (paint and what not), I took a straight edge to the top of the Valve stems and... on one head, two of the valves are not toching the staight edge, they are down about 1/16"....on the other head, same thing on three other valves. I called the machine shop but they have closed up until Monday.. I really wanted to get this engine running tomorrow.. This is not going to be a race engine, so is this acceptable? Thanks, DAN
Any difference in the height of the stem end of the valve will be taken care of with the rocker adjustment. Unless I'm missing something you should have no issues with what you describe. Frank
It's just that he dressed the existing seats. Me personally I take'm apart at home and check for concentricity. Theres a difference in height due to previous wear. If he had replaced the seats with hardened ones and had installed new valves too then they'd be sitting pretty. Run the dang things,,each valve is still gonna open the same amount they're at (but different heights). Let me say if you are breaking in a new flat tappet hydraulic camshaft you must run oil additive like Royal Purple. That camshaft will die qwik using regular oil.
It seems to me that if the if some of the valves are recessed in to the head more or less than others, that each combustion chamber is going to CC differently depending on how the valves seat. It would be up to you if that is acceptable or not.
Bolt them on. the adjustable rockers will take care of the rest. were the valves all new ? they may have touched up the stem end of the valve to remove any wear marks if they are used, which is why they are a little short.
Yes 52Pk is right,,However the amount wouldn't be noticed on a street putt though. The seats being hammered is why some are tall, the short ones have more meat in the seats. Someone didn't want to spend the big bucks and go thru them,,just freshen 'em up.
Just make sure that you check and set the spring height on each valve. Maybe they did this when you had the valves done. Sometimes a shop won't do this and you'll different tensions on each spring. If they thought about it, there should be a shim under some or most of the springs.
Take them back and dont run them. How do you set spring hight when the valves arent the same hight across? Do you have those springs bind or tight? You will have trouble down the road.
Totally agree that valve spring tension is probably all over the place! Yes, the adjustable rockers will make up the valve lash adjustment differences. But they sure as hell ain't gonna make up the differences in valve train geometry caused by the different valve tip heights! That can only be corrected by push rod length changes. Do a little research on sbc valve train geometry, the tech section of the Comp Cams catalog is a good place to start. If the rocker arm doesn't contact the valve tip at the right area, you're gonna get excessive valve train wear on the valve tips and rocker faces. Dave
Is it a street engine, or a strip engine? Street, it will be fine, if you want high end performance it is a bad thing. There are many reasons why the valves are proud of the others, nothing you can fix without machine work, but yes it will run, and run fine, maybe even better than your neighbors.
Lot of speculation here. If this is just a cruiser, not planned for regular racing, you are all set. MILLIONS come out like this every year for generic overhauls. The variance could be as simple as how much he dressed off the top of the stems. If you were planning to race this motor, you would probably want it blue printed to ensure all installed heights of the springs and valves were uniform and seat pressure in spec. If you were serious about that, you wouldn't be here asking, you would already know. You would likely have new valves, springs, etc. that would reduce or eliminate the variance. Put your engine together.
Thank for all the info, it is a street engine for a cruiser, I will however shim the springs for correct installed height, for what they are worth, its not worth the gamble...
i have been building cylinder heads for 16 years from 1500hp pulling tractors down to a darn lawn mower engine so i am not going to feed you a line of crap.. PUT YOUR HEADS ON.. stem height can be changed by how much the seats were cut how much the valves were ground or how much they took of the tip of the valve when they refaced it... as for the installed height dont worry about it unless you cam has over .480 lift or you plan to rev it over 5000rpm on a low tension stock style spring under 125# seat pressure 1/16 shim probably wont change the spring pressure more than 5#.. install your heads and enjoy your car.... have a good one.......
I already posted at the start of this thread and it's good to see that a reasonable responce is ending it. There were almost 100 million SBC's made duing the production run and I can assure you there at least a few million running around with the valve stem variation you describe and they have powered cars for hundreds of millions of miles. Some people tend to overthink things and this is one time when it's rediculous. Frank
I would run them, just make sure your valve lash is correct. If you take them back to the same machine shop one of two things are going to happen. First scenario is they say thats what you paid for if you want it to be perfect it's going to be $XXX more. Second is they say okay we'll fix it, come back tomorrow. In the second picture they're going to take out the valves that are sitting higher and grind them down until they're even, regardless of spring tension, seat height, shims etc. just because they want you to go away. I've never had an issue like this before, I usually just get a call saying it's going to cost more to get it perfect and if you don't want to pay the extra come get your parts. Different machine shops I guess.... just my opinion.
I have owned many sbc back in the late 60's and we use to regrind the valve faces a lot and never had a problem . Would grind some more off than others on a single face cut of 45 degrees . We didn't do those multi angle jobs either. We all had some really strong engines and ran them hard . Never had a problem and they were not all the same length either . Won't make a damn bit of difference with yours too ! You are not building a 6 sec. machine so don't worry . So stick those camels on there , set the lash and have some fun ! Drive it hard and enjoy all your hard work ! RetroJim
Thats normal after a vlave job, some valve seats you have to take out more material to get the sealing surface right, just check you installed spring hieght be sure that is equal, or shimed on the ones that are deeper in the head
I also say on a mild cruiser with low spring pressure the difference is so minimal I wouldn't bother shimming them. Put them on and go.
The Jalopy Journal
