Thread: Adjusting SBC Valves

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My book doesn't say anything about hot or cold. It says bring #1 to firing position and 1 3 4 8 exhaust valves & 1 2 5 7 Intake valves can be adjusted. Bring # 6 to firing position and # 2 5 6 7 Ex & 3 4 6 8 In. When all play is removed tighten the nut one full turn (360 deg). The first time I did it it was cold, the I did it again when it was warm.

O wait, you said two complete revolutions, my book said 1 revolution. After adjusting the first set, Was I suspose to turn the engine and bring #1 to firing position again, then go to #6 to adjust the second set of valves?

I started to do that once. I had one lifter the Literly shot out 1/2 qt of oil before I could adjust the first one. Just one was a steady stream of oil going all over the place. I have adjusted valves a long time ago with my dad and I don't remember any oil coming out that much. I don't have an extra set of valve covers, these have the bolts in the center. I tried putting some card board there try to keep the oil where it needed to be and it just got it everywhere. All over the windshied and the complete opisite side of the motor. And only one is like this. the others that had oil coming out, was just right except for the few with no oil. So I guess I am just going to make a big mess.

No offense taken. All good.

hey man that's cool! Thanks. I'm going to see if I can get some of those.

Originally posted by Hurst01
Why are you adjusting the valves with it runing? Much easier and MUCH less messy to do it on a "still" engine. If you don't have the correct procedure let me know.

Ed

What is the correct pocedure for adjusting the valves? I have not been able to find it with any luck!

I finally had to get it with the engine running.
Loosen till the rocker clicks, then tighten just till it stops. Turn an aditional 1/4 turn and go to the next one. If all are clicking you might have to back through them all a second time to make sure they are all good.

would you be so kind as to post or email me with the valve adjusting sequence for a sbc. have installed a solid roller cam in my 406 and would like to adjust the valves before i install the engine into the car. thank you.

Originally posted by inkslinger
would you be so kind as to post or email me with the valve adjusting sequence for a sbc. have installed a solid roller cam in my 406 and would like to adjust the valves before i install the engine into the car. thank you.

HERE'S THE SKINNY ON IT FROM CRANE....
All pushrod engines using mechanical (solid) lifters, or mechanical roller lifters, must have an adjustable valve train so that precise adjustment for “Valve Lash” can be made to match the camshaft’s requirements. Valve lash is the running clearance that exists between the tip of the valve stem and the valves mating surface of the rocker arm. (It is expressed in the Crane Catalog as “Valve Lash” and on the camshaft specification card as “Valve Setting”. Both terms mean the same thing.) The amount of valve lash can vary between camshaft profile designs, being as small as .010” on some and as great as .035” on others.

It is important to use the recommended valve lash when you first test the performance of the engine. You must also be concerned with thermal expansion of the engine components. (This is especially true if using aluminum alloy cylinder heads, or block.) For this reason, Crane requires that the valve lash be set with the engine “Hot” on all pushrod engines using mechanical lifters. This will insure that the minimum required clearance (valve lash) is maintained throughout the engine’s operating temperature range.

Compensating for a Cold Engine when Adjusting Valve Lash
When installing a new cam, the engine will be cold but the lash specifications are for a hot engine. What are you to do? There is a correction factor that can be used to get close. We mentioned that the alloy of the engine parts can be affected by thermal expansion in different ways, therefore the amount of correction factor to the lash setting depends on whether the cylinder heads and block is made out of cast iron or aluminum. You can take the “hot” setting given to you in the catalog or cam specification card and alter it by the following amount to get a “cold” lash setting.


Iron Block Iron Heads Add .002"
Iron Block Aluminum Heads Subtract .006"
Aluminum Block Aluminum Heads Subtract .012"


Remember this correction adjustment is approximate and is only meant to get you close for the initial start up of the engine. After the engine is warmed up to its proper operating temperature range, you must go back and reset all the valves to the proper “hot” valve lash settings.

Setting Valve Lash on Mechanical Cams
All the valves must be set individually and only when the lifter is properly located on the base circle of the lobe. At this position the valve is closed and there is no lift taking place. How will you know when the valve you are adjusting is in the proper position with the lifter on the base circle of the cam? This can be accomplished by watching the movement of the valves.

When the engine is hot (at operating temperature) remove the valve covers and pick the cylinder you are going to adjust.

Hand turn the engine in its normal direction of rotation while watching the exhaust valve on that particular cylinder. When the exhaust valve begins to open, stop and adjust that cylinder’s intake valve. (Why? Because when the exhaust is just beginning to open, the intake lifter will be on the base circle of the lobe, so the intake is the one we can now adjust.)

Use a feeler gauge, set to the correct valve lash, and place it between the tip of the valve stem and rocker arm. Adjust until you arrive at the proper setting and lock the adjuster in place.

After the intake valve has been adjusted, continue to rotate the engine, watching that same intake valve. The intake valve will go to full lift and then begin to close. When the intake is almost closed, stop and adjust the exhaust valve on that particular cylinder. (Again, when we see the intake valve almost closed, we are sure that the exhaust lifter is on the base circle of the lobe.) Use the feeler gauge and follow the procedure described before in step 3.

Both valves on this cylinder are now adjusted, so move to your next cylinder and follow the same procedure again. In the future you may find shortcuts to this method, but it still remains the best way to do the job correctly.

Using Valve Lash to Help Tune the Engine
The engine only responds to the actual movement of the valves. Since the valve cannot move until all the running clearance (valve lash) has been taken up, the amount of valve lash you use affects the engine’s performance. For example, if you decrease the amount of (hot) valve lash, the valve will open slightly sooner, lift higher, and close later. This makes the camshaft look bigger to the engine, because of a slight increase of actual running duration and lift. If you increase the amount of (hot) lash the opposite occurs. The valve will open later, lift less, and close sooner.

This shows the engine a smaller cam with slightly less actual running duration and lift. You can use this method on a trial basis to see what the engine responds to and keep the setting that works the best. Just remember, the more lash you run, the noisier the valve train will be. If the clearance is excessive it can be harsh on the other valve train components. Therefore, for prolonged running of the engine we do not recommend increasing the amount of hot lash by more than +.004” from the recommended setting. Nor do we recommend decreasing the hot lash by more than -.008”.

Warning:“Tight Lash” camshafts cannot deviate from the recommended hot lash setting by more than +.002” increase, or -.004” decrease. “Tight Lash” cams are those which have recommended valve settings of only .010”, .012”, or .014” on the specification card. These lobe designs have very short clearance ramps and cannot tolerate any increase in the recommended valve lash. The extra clearance can cause severe damage to valve train components. With “Tight Lash” cams, we recommend using only the prescribed amount of hot valve lash, and that close inspection of the engine be maintained.

Hello Tech,
Good reply and interesting info. Seems that everyone has their own way of doing things. I have yet to see anything that you have posted to not be true and accurate. Very impressive.
I don't get into the replies much anymore. I have tried explaining ways that I have learned over the years that have paid their way many times over and has saved a lot of time and trouble. Been snapped at a few times by those that don't understand and have their own way of doing things.
I don't know you but I would like you to know that I respect your knowledge. That said, can you tell me how to get 500 HP from my lawn mower?

Ed

Originally posted by Hurst01
Hello Tech,
Good reply and interesting info. Seems that everyone has their own way of doing things. I have yet to see anything that you have posted to not be true and accurate. Very impressive.
I don't get into the replies much anymore. I have tried explaining ways that I have learned over the years that have paid their way many times over and has saved a lot of time and trouble. Been snapped at a few times by those that don't understand and have their own way of doing things.
I don't know you but I would like you to know that I respect your knowledge. That said, can you tell me how to get 500 HP from my lawn mower?

Ed

No.

But thanks for the kind words.

I just did my valves and roller tip rockers. With the lifters not pumped up, you turn the engine over until an exhaust valve starts to open. At this point, you tighten down on the intake valve until there is zero lash, you will feel some resistance on the pushrod as you rotate it with your fingers. Then turn 1/2 turn more. Rotate the engine until the intake valve is past maximum lift and is 1/2 to 2/3 of the way to being closed, adjust the same way as the exhaust valve. Repeat for the next cylinder until all 8 are done.

Originally posted by 76GMC1500
I just did my valves and roller tip rockers. With the lifters not pumped up, you turn the engine over until an exhaust valve starts to open. At this point, you tighten down on the intake valve until there is zero lash, you will feel some resistance on the pushrod as you rotate it with your fingers. Then turn 1/2 turn more. Rotate the engine until the intake valve is past maximum lift and is 1/2 to 2/3 of the way to being closed, adjust the same way as the exhaust valve. Repeat for the next cylinder until all 8 are done.

That'll work great for hydraulics, but he's running a solid roller.

thanks for the crane article. my cam calls for .015 lash. years ago i remember setting valves by a 2 rotation method. starting a #1 tdc you adjust both intake and exhaust. then you turned the motor 180 and do some others etc. then another 180 and do a few more etc. i'd like to preset these on the engine stand cold. boy, i hate getting old and having been away from this for the last 25 years. can't remember s#*@.