VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc Looking for lift on a 1950, 216 stock cam?

Does anyone know where I can find the stock camshaft specs for a 1950, 216? I would like to check to see how much wear there is on the cam that’s in my engine. Not interested in the rest of the geometry just looking for I&E lift.

Denny Graham
Sandwich, IL

The valve "lift" for the intake is .2941" and exhaust is .3118"

Thank you Gene, just what I needed. Ya mind telling me where you came up with those numbers? They do seem kind of odd don't they?
Got three shows to go to this weekend, Saturday morning is over, number two tonight and three in the morning but when I get home tomorrow I'll pull the cover and check the lift.

Thanks again,
Denny Graham
Sandwich, IL

Its a secret............


In the 1950 GM info pack.

The old froged cams seldom wore out. Some times the initial lift corner would wear a little but never saw one loose a lobe, like the later cast cams used in the V-8's

Thanks Gene, I've got the info pack here somewhere in the pile. Never thought to look there.
I know what you mean about the V8's, I had to change out the one in my small block Blazer back in the late 80's at about 50k.
I'm still looking for a reason for the lack of response and hesitation in my ’50, 216. I just want to check the cam to eliminate that from my problem. I’ve about run out of ideas I just finished up another 1950, 3104 for a friend that is a twin to mine as far as the engine goes. They’re both stock '50, 216's except for the W-1's which I’m trying on both. Both have the same gearing, SM420 and both have a good number of miles on them. His pulls nice and strong, real smooth all the way up in all the gears with no hesitation,. Lug it down to 15mph in 4th. and it’s the same thing, i.e., nice and smooth strong pull all the way up to speed with no hesitation. I swapped out carbs and distributors and there is now difference in the performance of either one. Man it really has me baffled, there just taint anything left to check that I can think of.
He’s not a purist so he’s talking about putting a 235 in his and I told him as soon as he does that, I’d take his 216 off his hands. Now if I go as far as swapping his entire engine for mine and it’s still sluggish and has that hesitation, I’m gonna just end it all and shoot my self.
Thanks again,
Denny Graham
Sandwich, IL

Denny
Check the rear axle ratios, a high speed rear end will not pull as hard as the lower ratio.
Tony

As I said Tony, same ”˜o, same ”˜o, both got um 4.10 gears. The half-ton is stock with a 4.10 and in my stock 4.57 in my three quarter-ton I swapped out for a ’70, HO52, 4.10 last summer. The only difference in getting the power to the pavement would be the tires and there taint a whole bunch of difference in their height, at least not enough to account for what I'm experiencing. There is most definitely something askew with my 216, just can’t nail it down, let me add, yet!

Denny Graham
Sandwich, IL

It is possible you have a brake dragging or something other than the engine causing the problem? Just trying to think out of the box.

Naw, we can put that one back in the box Chipper, I touch up the brakes every thousand miles or so. In fact I just brought them up to snuff a few weeks ago before the shows started for the season. Here’s a few pics of the original rebuild just to show ya it wasn’t just a brake shoe swap out.
Besides, this sluggish performance has been there ever since I first brought the truck home, in spite of everything in the driveline being rebuilt.
DG

Drat, guess we all still need to scratch our heads on this one. Already have scratched a wide part so need to back off a little on the scratching but maybe not the thinking.

All righty, got a chance to check the lift on my 216 this afternoon. This is the setup I was using in case there might be a question about the method. http://www.pbase.com/dennygraham/image/114892256
I’m still a little stunned by what I’m seeing. Gene’s earlier comment on the longevity of the forged cams made me think that I might be missing something, so I spent several hours checking and rechecking all the measurements. I tried several different points of contact to take out any inaccuracy because of the arc that is swung by the rocker but the results repeat each time.
So here are the results.
Factory specs are intake .2941” & exhaust .3118” a difference of .0177”. All of the measurements that I took this afternoon were just over .200”. The average for the six intakes were .2091” and the average for the six exhaust averaged .2175”. The hi for the intakes was .222” and the lo was .197”, the hi for the exhaust was .224” and the lo was .212”. Average difference in intake and exhaust is now .0084"
It’s hard to believe that the wear could possibly be that even, but the indicator doesn’t lie. And this is a nice running truck, starts great runs along at 55-60 just fine it’s just that it’s been a little sluggish or flat and has had this annoying stumble or hesitation when you accelerate.
So, I’d like to hear what any of you old experts have to say about today’s revelation???? God, I hope I have a bad forged Cam!!!!
Denny Graham
Sandwich, IL

Ah, don't you think you would measure valve lift at the valve stem rather than at the lifter?

No I would not Gene, I would think that it would be measured at the lobe. I very well might be wrong in this case though. Like I said this just doesn’t make sense that I could have .100” wear across the board. Been up all night trying to logic this out. I’ve got to dig out an extension for the indicator to get a clean shot at the valve and I’ll run through them after I warm up my umpteenth cup of joe.
I did conceder the rocker arm ratio last night but I’d been up since 0400 yesterday and was getting a bit giddy by 2200. Just laying a scale across it I roughly get about a 1.5:1 ratio, that would definitely put everything right back into the ball park. Maybe I can think a little more clearly with the six hours of sleep I got lastnight. I’ll give it a try in a few minutes.
DG

Well folks, the ChevGene comes through again. Taken right of the retainer they are all falling right into place considering it's cold and that the valve lash needs to factor into it. DRAT IT, now I'm back to square one! I'm kind of curious what the numbers would look like cold, with the lash taken up to zero, I would think they should be just about right on the factory spec, or am I out of the ball park on this one too?
And once again Mr. Schnider, thanks for straightening me out. Hope this lesson will help someone else pondering the same thing down the line. I've only taken measurements on a few of the exhaust but I'll finish the rest after I get my "big ol' wife" off to the salt mines.
If anyone cares to see the NEW corrected results I’ll post them.
DG

Denny
The setup you used measures the cam lift and if I am reading the specs noted above are for valve opening. Try setting the dial indicator at the valve end of the rocker and remeasure as the rockers are longer at the valve end than at the push rod end.
Tony

I see your up with the sun also Tony. Yeah, your right, thought about the rocker arm ratio last night but wasn't thinking to clear and just didn't want to go looking for an extention for the indicator at bed time. I think I got her covered in the two earlier posts this mornin' if ya read back. Tks
DG
Oop, just remembered your upside down, must be about time for you to hit the hay down under rather than roll out?

Denny, do you have a GPS that you can check your ground speed with? How about checking the valve train timing against the piston travel? one notch difference in the cam gear from where it should be on the crank gear is a lot since the camshaft turns one rev compared to two revs of the crankshaft. How many miles do you have on the engine since it was overhauled?

Where does the ground speed enter into it Mack??? Never been overhauled from what the original owners told me. The maintenance man from the town it came from said they bought it new in ’50 and he had maintained it since the late 70’s. It had 53k on it when I bought it with a burned valve on #3, I did a complete valve job in ’06, hard seats, guides and new valves. As far as I know that was the only time the engine has been apart.
Never drove a truck that had the cam out a tooth but I wouldn’t expect it to run as well as this one does if it were. If the timing gears were worn I would expect to see the timing marks jumping all over with the timing light on it but this one is as steady as a rock.
And I finished up checking the rest of the lift, at the valve this time Gene, and they are all just fine. The intake average is .302” and the exhaust average is .314” so it looks like once I got the correct method the cam looks just fine.
And as I said before,,,,, back to square one!
DG

maybe your speedometer is off a lot, due to the wrong speedometer gear, rear end ratio, tire size if you are compareing the performance to your friend's truck. A GPS gives good accurate speed on level ground. If the timing cam to crankgear is off one or two teeth you would never see any jumping around of the timing light. The distributor timing to the crankshaft (flywheel) won't show you any change. the valves will simply all be opening and closeing wrong. It also won't effect the compression test. The only way to check it is to pull the timong gear cover and use a straight edge to check the alignment of the mark on the crank and the mark on the timing gear and the center of the timing gear and the crankshaft gear. The key in the crankshaft is the starting point for valve to piston timing. I would suspect that if all the tuneup and carb functions are correct that your problem is in the fuel/air delivery/exhaust system. A stoppage in either the air cleaner to combustion chamber, or a stoppage in the exhaust from the combustion chamber to the tailpipe. Do you know that the exhaust manifold and exhaust is clear?

I agree with Mr. Mack as to possibly timing gear may have jumped.

Question here. If compression is at max with piston at tdc and both valves closed at the correct time, than at what point or how many teeth off would the cam gear have to be before compression is affected??

I have timed Chevy 6's with jumped gears enough to get them running until repaired, but they lacked a lot of power.

Jim.

Oh, I see where you’re coming from Mack, no that’s corrected. Mine is a 3600, it had a stock 4.57 gear when I got it and I drove it for the first summer like that, i.e., 45-50mph topped out. Then last summer I found an HO52 with a like new 4.10 gear in it up in Wisconsin. Now of course the speedometer reading would be off because of the pumpkin swap and I was unable to find any way of correcting it. Both gears have to be changed in the transmission and after many months of searching all I could find was the 4.10 driven gear. Never could find the drive gear, which would have had to come from a 3100 with an SM420 factory option. The new tires are the same height as the original tires we were careful to make sure of that when we bought them. By using a little simple math its easy to figure out the correction from the 4.57 to the 4.10 which comes out to just about 10% so I simply add that to my reading, i.e., 30mph=33, 50mph=55. I live in a small town and got the local gendarme to shoot me with the radar making several passes, that verified that the speedo was calibrated. And I check it often against the roadside speed control robots that all the towns seem to be getting, and which will no doubt soon be taking your picture so they can send you a ticket and pull in more graft. So, yes the speed thing has been entered into the equation and as I said earlier, except for slight tire size difference, both drive lines are the same.
But how would the timing gears be off if there wasn’t any wear???? If the gears were worn enough to skip a tooth then the timing mark would be jumping all round. I also mentioned that the engine hadn’t been apart at least not in the last 30+ years according to the mayor of the town that bought it new and who did the maintenance all that time, and he said he couldn’t find any record of any thing being done to it previously. The only way I know to check that would be to tear the front of the engine off and check the marks.
Had the manifolds off when I did the head in ’06, looked great, all clear, unless there was a rat stuck in the muffler that I couldn’t see!
Ya know, there is one thing, just one thing wrong here, and sooner or later it has to jump out. With out exaggeration I’ve probably tried a thousand ideas over the past 2 1/2 years and not a one has made a difference. I’ve been very meticulous about the way I approach the work on this truck. Having a father that was a journeyman mechanic and older brother that had built many street rods for him self and others, introduced me to mechanics early on so I’ve been messing with cars as a hobby ever since I was a kid. So you can imagine how this is just about driving me nuts.
And finally, don’t read this wrong, this engine starts and runs just fine except for a persistent hesitation when you accelerate and it being slightly flat and sluggish compared to the other 216 that I’ve been working with this summer. I’ve driven it 8,000 miles in the last two summers and to most people it just seems like an old low powered 6cyl engine.
DG

I thought that there was a possibility that the cam gear may have been installed a tooth or two off, or the key on the crankshaft had sheared. I guess from it being a 1950 that you have a Carter carb? Have you tried a later model Rochester? I have been driving Chevys since the first one I owned, a 1934 Chevy 1/2 ton my dad gave me. I know how frustrating it is to have one that stumbles when you give it the gas and won't pull good and strong. It is hard to recall everything that can be wrong without getting hands on the truck.

Think I've been through this before so I hope I don't bore those that have read it already. But no, '50 would have been the first year for the new Rochester 'B'. I had the same problems with the original carb and several other ”˜B’s that I had rebuilt and tried so I decided to try a Carter. The W-1 for ’49 had been touted as a very good carb as opposed to the new Rochester’s and that's the reason why you see a lot of the later 216's with a W-1 installed. However, I've found that the W-1 on this engine has not changed the performance one bit. It still has the same problems with hesitation, percolation and feeling flat. Been lookin’ for almost two years now for a later high top Rochester ”˜B’ for the 216 as would have been on the ’52 but haven’t been able to find one. I don’t mean a $300 rebuilt one, I just need a good core that I can rework my self. I don't have a complete reference library but I believe the number I'm looking for is 7004475 or 7004600?

I still haven’t ruled out the possibility that the problem may stem from the timing gears. I just don’t want to tear down the engine this summer and tie it up for a month because I enjoy driving it and going to the local shows. I will definitely get into it as soon as the weather turns sour on us up here. If there is nothing wrong with the timing gears then there is simply nothing else to check, that is the last stop along the trail on this agonizing journey.
Denny Graham
Sandwich, IL

Denny, A friend had a similar problem many years ago and went so far as to replace the engine. The new engine ran as bad as the old one. We discovered, quite by accident, there was an obstruction in the exhaust system. We cleaned it out and it ran like new. Maybe you could try disconnecting the exhaust and driving around the block (not on a Sunday morning) and see if that makes a difference.

ArtM

I haven't ever seen a Chevrolet six with the pair of gears slip a tooth, but I have had experiance with a crank key sheering and the gear turned a few degrees and the sheered key locked the gear. Also a Caddy V/8 engine with the chain slipped a notch and it was a real bear to find. The engine didn't have the right power and one of the cylinders would miss until you put the timing light on and set it right on and the points with just the right dwell. in a hundred miles it wouls start missing again. when it was cold it was hard to start. Everything was replaced or rebuilt in the ignition and fuel air delivery systems. One really cold morning It acted like it would start then nothing. The chain had slipped another notch and at two notches off it would not fire. A new timing chain fixed it. The Chevy six that had a valve timing problem acted much the same way. A shade tree mechanic had done an "overhaul" on it and got the alignment of the cam gear a notch or two off because he just "eyeballed" it on when he put the new gear on and didn't use a straight edge to line the gears up. Now what Denny has seems to me to be more like a stoppage in the exhaust, maybe a partial blockage in the exhaust pipe, muffler or the tailpipe It may also be the intermediate or the high speed fuel circuit, but surley he has changed out the entire carb with a known good one by now.

I don't know for sure but a newer model Rochester carb may fit on the 216 if you use the 216 cast iron throttle body. There is a slight difference between the 216 and the 235 intake flange where the carb mounts with the two bolt studs. One of these days when I get into the stash of Rochester carbs I will check that out. I try to use the manual choke bowl off of a 235 truck on all my 235 engines, I like the Rochester because it is easy to get into the innards and clean up the circuits. I also have had good luck re-jetting the carbs with smaller main jets and larger jets for higher powered trucks, I also like to use dual Rochester model B carbs and rejet theb to small jets for economy, The 235 and 261 engines always seem to me to be in need of more cubes of air than the single barrel will provide. I don't like the Rochester BC automatic choke at all.
The best straight six I ever ran was a balanced 54 261 with a 235 head, dual Rochesters, a custom split exhaust and the stock camshaft and a Mallory Ignition, that I built when I went to college. That car screamed.

As far as a restriction in the exhaust it would have to be in the muffler and the only way I could check that would be to pull the muffler and if I went that far I might as well just replace the exhaust system. If you’ve ever worked on an exhaust system then you know what I mean. Blocked exhaust systems have give a lot of clues especially at higher rpms when the gas flow is at a much higher rate. The truck will run right along at 60-65mph and I don’t hear any hissing or any other indication that there is a blockage in the exhaust.

Mack, I used the method outlined in the service manual to check for misalignment of the timing gears or wear. The engine is brought up to the triangle and an indicator is set to .044” on no.1 exhaust valve. This puts the lifter at a given point on the ramp and then you drop the lifter to the base circle and it should be with in +/- .004”, this one is between .005” and .006” which would indicate a very slight amount of wear. So this was the last thing that can be checked on this engine and I’m now left with now other ideas.
Denny Graham
Sandwich, IL

My dealership expeeriance with a restricted exhaust system is the engine will get up to a certain RPM and more or less level off. Had that with the laminated exhaust pipes in the '60's and plugged converters in the later years. The engine will run OK up to the point that the exhaust restriction is too much and it limits the incoming mixture.
The mufflers used on the 1950 trucks was a straight through design, you could see straight through it. If the present muffler is correct you will see that both the muffler inlet and outlet are centered in the ends of the muffler.