Hi all! Question on Pontiac 400s. I have a 68 bird 400, original engine. Did a compression check which came back fine. On the leak down test however, the #2 cylinder was 88% and #4 was 65%. The mechanic wants to do a valve lash adjustment. Now, my understanding is that there is no "adjustment" on Pontiac valve trains. The rockers just get torqued down. Any thoughts on this? Should I be looking for a new mechanic shop?

I don't really want to rebuild the engine or top half right now. The engine runs good otherwise. Is there any other option if adjusting the valve train is out?

Thanks in advance for any advice!

My first question would be, "why the compression check?"

Next, ask the technician where the leak was coming from, Intake = intake valve, Exhaust pipe = exhaust valve, Crankcase = rings.

If it's running good and you don't want to spend money now...you've answered your own question.

And, no, there is no valve lash adjustment on a stock factory valve train for Pontiac's...the tech thinks he's looking at a Chevy motor maybe?

The only things I would add to what the good doctor said would be how is the car driven? If you have been just mostly putting around for the last ten years it could be hard carbon deposits built up on the valves. Also by original motor do you mean never rebuilt and without hardened valve seats? if so and you are just using pump gas the exhaust valve seats could be somewhat pounded in causing tight valves and possible leakage. If this is the case you can have a tech. install adjustable poly locks so you can adjust your valves correctly. If you do have tight exhaust valves you don't want to leave them or they will get burned.

Thank you! I'll try to make this short, lol. I bought the car about 4 years ago...running project. I bought it from a flipper, but I was able to get in touch with the previous owner. He never responded to me when I asked about the motor. I don't know if it has been rebuilt, but it does not smoke and has good compression. It has an 11 bolt water pump and HEI, so those changes were made at some point. I asked for the compression test because I don't know the condition of the insides. The tech recommended the leak down and valve adjustment (can't do) prior to final tuning.

I take it easy driving the car. Not knowing the condition of the rotating assembly or heads, I don't want to blow something up stomping on the accelerator. I use 93 octane premium in the car and recently switched to Valvoline VR1 oil. I believe the PO was pretty hard on it, but it sat for about 4 years before I got it.

Get yourself a cheap boro-scope on Amazon, the kind you plug into your smart phone. Then pull a spark plug and take a peak inside. See what the tops of the pistons look like. Clean? Dirty? Oily?

I hear you but it is ok to jump on it once and a while to keep her honest and clean her out just don't rev to max rpms. By the sound of it you would rather have a mechanic work on your car if that is the case try and find someone familiar with Pontiacs Maybe join a local Pontiac club and network to find someone. To me if you are pulling decent and more importantly balanced compression and as long as your exhaust valves are not to tight I would just enjoy the car and not worry about it, after all it is not your daily that you have to absolutely rely on and you can deal with problems when and if they show up. Again if the mechanic who recommended the valve adjustment did so because of a proper diagnosis you can purchase a product called Polly locks to replace the stock lock nuts on your rocker arms and make them adjustable.