Been helping my neighbor the last few days swapping out the engine in his '69 C10. We got everything together tonight and lit it for the first time! Oh Yeah 8) , fired right up and P-O'd the other neighbors for a good 1/2 hour during cam break-in. But only after we solved a strange problem!

We were missing one of the "Big Three". We had Ignition, we had Carburation, but no Compression. Drove us nuts.

This is what we found. During assembly my buddy followed the mfg's recommendations and set initial valve lash as follows: Tighten the rocker nuts until he could just twirl the pushrods with finger effort, then 1/2 turn more. Pretty standard stuff? What we found out (after belching fire out the carb and farting through the pipes) was the valves weren't seating! We pulled the covers, backed off the rocker nuts the initial 1/2 turn (plus a bit), buttoned it back up and Vrooom! It fired immediately and we went through the standard 1st fire checklist!

Anyone else have this happen??? Wierd!

Probably there was no oil in the hydraulic lifters. I always pressurize the oil system with a shaft that replaces the distributor. Either use a the modified shaft from an old distributor or one the the more expensive oilers that can presurive the oil gallery to feed oil to the lifters. The cheaper oil shaft tools don't do this and are worthless. Use a heavy duty drill on the shaft and this is important, have someone slowly turn the engine over with a breaker bar. After a minute or two you will have fed oil to all of the engine bearings and pressurized the hyraulic lifters. Then go ahead and adjust the valves and crank her up.

That's the wierd thing. We spun it over about a dozen times with the starter and the hot to the HEI disconnected (until the fuel bowls were full and the Oil pressure read 30 psi.), hooked up the juice and were rewarded with cooked eyebrows! After we backed off the rocker nuts 1/2 turn it fired and ran beautifully!

Be very careful about spinning a new engine with flat tappets. Even the short time you are turning the engine over with the starter motor can be harmful because the pressure of the valve springs can cause hard contact between the camshaft lobes and the tappet. It is far safer to pressurize the oil system before cranking the motor. And yes be sure the carb fuel bowls are full and the ignition timing is close, you don't want to keep cranking for very long without starting. I've seen too many cams get wiped out because of poor startup procedures.
In any case you got it running and it seems strange that the valves were too tight, you adjusted them properly. Chock it up to one of those unexplained mysteries.

I know what happened....no oil in the lifters during adjustment. What the manf should say is turn the adj. nut down to where it just starts to move the plunger and then 1/2 a turn more (this procedure is for new lifters not filled with oil). Or try this trick on new lifters...tighten adj nut to zero lash and loosen 1/2 a turn. What this does is bottom out the plunger in the lifter and then unloads the plunger to work properly. One note, if you float the valves or have a valve sink into the seat...piston to valve interference is very likely.
George