Guys
I adjusted my valve springs the other day, first time ever, and I was doing it by one of the threads on here. I put my finger over #1 spark plug hole and got it at top dead. I adjusted the intake and exhausts by the book for top dead center. I then went over and put my finger over #6 cyl and felt no air being sucked in or blown out. 8 and 4 had intake and exhaust. Whats going on? Thanks in advance

 

Hydraulic lifters do not need periodic adjustments. It's possible you have them adjusted too tight.

To adjust a hydraulic lifter you start withe the rockers backed off and the piston at TDC so that the lifters are on the base circle of the cam. Tighten up the rocker nut until it just snugs up on the pushrod. Tighten the rocker nut 1/2-3/4 turn more. That's it. You can turn it down even more but that adds too much preload to the lifter and if the plunger in the lifter bottoms out, you'll start opening the valve.

If you had a dead cylinder, the spark plug would have been fouled up and you would have felt a miss.

Find #1 TDC again by feeling the air coming out the spark plug hole. Get it closer by making sure the timing mark on the balancer lines up with the pointer. It doesn't have to be exact but should be close.

With #1 at TDC you adjust

INT 1,2,5,7
EXH 1,3,4,8

Now rotate the engine 360* so that the mark on the balancer lines up to the pointer again. You'll now be at #6 TDC. Adjust these valves

INT 3,4,6,8
EXH 2,5,6,7

SBC valves are EIIEEIIE

 

Thanks for the detailed response. I really appreciate it. Here's the thing. This is a 355 I am swapping in. I personally have never had this motor running before. My buddy had it running twice. In the swap, we took off the rockers to clean up the top of the heads. I did the procedure you stated, but I did not feel anything from 6. So I decided to tighten it down anyway just to see. I thought I got the nut down kinda far (3/4" from top of pushrod) and still had tons of play in the rocker/pushrod. Any other ideas.

 

might have a bent valve.

 

Take the rockers off #6 cylinder. Apply air pressure into the cylinder through the spark plug hole. It doesn't matter if it's at TDC or not because with the rockers off, both valves will be closed. The engine will probably rotate as the piston is pushed to the bottom. Use a compression tester adapter or a rubber tipped air nozzle to put in the air. You'll get some air leakage past the rings which is normal. If air comes out the intake, the intake valve isn't closed. If air comes out the exhaust, the exhaust valve isn't closed. They could be bent or burnt but you're isolating the fault. If a lot of air goes into the crankcase, you have a damaged piston, some badly damaged rings or a bad head gasket. If air goes into a coolant passage, it's a bad head gasket or a cracked casting (head, block)

 

Thats great help too. I'll give that a shot. I'll post back with my results for final confirmation. Dumb question...Does it matter if the pushrods are taken out or not for the test. And with air coming out ither intaker or exhaust, that just tells me where the motor is in its round, yes? Thanks for all the help.

 

Pushrods can stay in. With the rockers off and air pressure applied to the cylinder, there's no place for the air to go. If the piston isn't directly at TDC, the air pressure will push it to BDC. Having it at the bottom of the cylinder allows you to check all of the cylinder walls for leakage (cracks) although it's unlikely they will be cracked.

With the rockers off, the valves will stay closed even if the crank rotates to BDC. The only place you should get any leakage is past the rings. Rings are not a 100% seal so some leakage is normal. A leakdown tester will tell you how much percentage leak you have. You should not hear any air escaping from intake or exhaust ports and should have no air pressure going into the cooling system.

All these tests will do is isolate a problem. A teardown will then confirm the exact cause of the problem but you need to know where to start.

 

AlkyIROC, great info. Good job.

 

I've been a mechanic since before many of the youngest third gen owners have been alive. I've learned a lot of basic diagnostic skills. It's the newer electronics I don't have a lot of knowledge on.