[hobbygto65]

427 Chevy aluminum head head bolt washers work perfect.

[geeteeohguy]

Originally Posted by "QUICK-SILVER"

Ben,
When you say it hangs up are you thinking piston to valve contact? Or something else?

Unless you swapped in a or some extra long pushrods, piston to valve contact doesn't happen with a 7M5 headed 455 with a 068 cam.
Don't know exactly how much over but I know .500" intake valve lift doesn't hit with a piston at TDC. Add to that, the only time valves are open at TDC is during overlap when valves are just barely open. With a intake valve open .500" you can turn the crank to put a timing chain on and the valve doesn't hit.

Tight pushrods is normal when valves are open. Even after sitting a while, if the valve is open further than plunger travel in the lifter, the pushrod will still be tight. So unless you did put in a or a few extra long pushrods I'd have to say there's nothing wrong with valve adjustment. That's given some do feel like they are suppose to.

Something else...
Does the crank bump to a stop when you turn it or just get harder to turn?
Bump to a stop: I'd be afraid something went down an intake port and is laying on top of a piston. Unless you've got a wrench or socket missing that might have fell down to the crank while the cam was out.

Springy feeling when it comes to a stop, like a pushrod fixing to bend, I'd be looking for a stuck valve or valve spring binding up for some reason.

Just harder to turn might be normal feeling you get when the cam raises a lifter and starts opening a valve.

Before I went crazy and tried to force it to turn...I'd turn the crank the other way and see what happens.

Clay

Best reply so far. When I installed some lower compression heads on my '67 400 ten-twelve years ago, I simply tightened the rocker nuts (I upgraded to BBC studs) to 20 foot pounds and buttoned it up. That was thousands of miles ago, on a Melling 068 cam installed in the '80's. Stock rocker arms and pushrods. All standard stuff. No need to grind custom washers and install band-aids on a basically stock combo. Go slow, and do what Quick-Silver stated,

[ponyakr]

'...I simply tightened the rocker nuts (I upgraded to BBC studs) to 20 foot pounds and buttoned it up..."


Sorry, but I don't understand this , at all.

You used BBC studs, which are 7/16, all the way up. Then tightened the nuts to 20 foot pounds ???

Since there is no bottle neck to stop the nuts, does that mean that you simply tightened the nuts 'til they ran out of threads on the studs, and at 20 ft lbs the adjustment was just right ??? If this is the case, were these factory BBC studs, or some aftermarket brand, and what was their length above the head, & what was the length of the the threads ??? Please help me understand this.

I suppose that if the lower end of the threads are only very slightly too low for the correct adjustment @ 20 ft lbs, you could put washers under the studs. ???

And, for those who wanna use the factory bottleneck screw-in studs & nuts, but have had some cut off the deck & heads, the washer under the stud method might work ???

[NeighborsComplaint]

Unless you installed longer pushrods or installed the springs at a different (taller) installed height, there would be no geometry issues. Valve recession does not typically exceed the hydraulic lifter's ability to take up the "slack" in the clearance.

I think you just missed the boat on doing the adjustment on the base circle of the cam. With the valley cover off, it is pretty easy. The intake closing/exhaust opening method gets a little complicated.

["QUICK-SILVER"]

Originally Posted by NeighborsComplaint

I think you just missed the boat on doing the adjustment on the base circle of the cam. With the valley cover off, it is pretty easy. The intake closing/exhaust opening method gets a little complicated.

No adjustment on the stock 72' 455. Cam/lifters can be in any position when you torque the nuts down. Just harder to run the nuts down when you're compressing the valve spring. Once the nut bottoms out and you put the torque to it...it's done.

Clay

[NeighborsComplaint]

Originally Posted by "QUICK-SILVER"

No adjustment on the stock 72' 455. Cam/lifters can be in any position when you torque the nuts down. Just harder to run the nuts down when you're compressing the valve spring. Once the nut bottoms out and you put the torque to it...it's done.

Clay

Fine. Let me restate, torque (I said adjust) to 20 ft-lbs, no adjustment required if that makes you happy.

If done by the method you suggest, you tighten the nuts to 20 ft-lbs with the lifter on the base circle. If you aren't on the base circle, you will never know what you have torqued the locking nuts to since it takes about 55 ft.-lbs to get the nut to bottom out as you compress the valve spring. It doesn't work.

[Ben M.]

Thanks for all the info guys. It's a stock head that has never been off the engine with stock pushrods and rocker arms. It's not a valve to piston clearance issue regarding sticking nor is it bottom end related as it'll rotate just fine with the rocker arms backed off. I know that the lifters and pushrods should be tight once torqued down, but they should also spin slightly too when the lifter is at the most relaxed (base of the lobe). I checked 3 other stock-ish engines I have here and they both spin the pushrod and lifter (not easily when the lobe is fully up and valve open obviously).

I've done a few engines over the years and I have a decent idea of what it should feel like, which is why I stopped once I noticed that the two cylinders did not want to cooperate. I got #6 adjusted correctly and it "feels" like it should, slightly springy with very little movement when you push down on the rocker arm and the pushrod will rotate with the lifter.

Clay's suggestions got me thinking and I think he's on to something. This morning I got a quick minute before church to check things out and noticed that several of the lifters were a little reluctant to compress but started to when I leaned on them a little. They also soaked in oil overnight so maybe they were a little sticky due to sitting on my shelf for the last decade? I also bopped the top of the valves in question with a rubber mallet and they opened and closed slightly, so perhaps the 2 valves are just sticky from sitting? They just turned 47 years old last month after all... I'll resume work on it tomorrow and see if the combination of soaking the lifters in oil longer and manually opening the valves freed something that was just a little "off" and I was being overly cautious to avoid damaging hardware.

(I have a '73 455 on the stand next to it and it has 2 bent pushrods in it even though it ran fine, so it's definitely possible to screw something up)

[lust4speed]

No reason why you can't double check the preload the same as you do for polylocks or crimp nuts with the standard Pontiac torque-to-spec nuts. With the lifter on the base circle of the cam (choose your favorite method), bring the nut down while feeling for zero preload. Once you achieve that, the nut should only go another half to full turn before bottoming out. If you have to turn the nut over a full turn before bottoming then you can't use the stock method - and it's time to go with crimp nuts or polylocks.

[TAQuest]

Ah, that makes sense, sticky valves. Old school was to use transmission fluid to loosen them up. They probably have some fancy stuff for that now.

[SRR]

Originally Posted by Ben M.

Thanks for all the info guys. It's a stock head that has never been off the engine with stock pushrods and rocker arms. It's not a valve to piston clearance issue regarding sticking nor is it bottom end related as it'll rotate just fine with the rocker arms backed off. I know that the lifters and pushrods should be tight once torqued down, but they should also spin slightly too when the lifter is at the most relaxed (base of the lobe). I checked 3 other stock-ish engines I have here and they both spin the pushrod and lifter (not easily when the lobe is fully up and valve open obviously).

I've done a few engines over the years and I have a decent idea of what it should feel like, which is why I stopped once I noticed that the two cylinders did not want to cooperate. I got #6 adjusted correctly and it "feels" like it should, slightly springy with very little movement when you push down on the rocker arm and the pushrod will rotate with the lifter.

Clay's suggestions got me thinking and I think he's on to something. This morning I got a quick minute before church to check things out and noticed that several of the lifters were a little reluctant to compress but started to when I leaned on them a little. They also soaked in oil overnight so maybe they were a little sticky due to sitting on my shelf for the last decade? I also bopped the top of the valves in question with a rubber mallet and they opened and closed slightly, so perhaps the 2 valves are just sticky from sitting? They just turned 47 years old last month after all... I'll resume work on it tomorrow and see if the combination of soaking the lifters in oil longer and manually opening the valves freed something that was just a little "off" and I was being overly cautious to avoid damaging hardware.

(I have a '73 455 on the stand next to it and it has 2 bent pushrods in it even though it ran fine, so it's definitely possible to screw something up)

I did an in car rebuild once on a 389 in my 65 Catalina. Replaced the rod bearings and pistons, lifters, timing chain assembly. Darn thing would not start, had fuel, spark, all the usual things you check for. Decided to check compression and found "0" in a few cylinders. WTH I thought and decided that the valves were not closing for some reason until I backed off on the rocker nuts and she started right up and I tightened each one slowly down to spec and the engine ran smooth and quiet. The lifters were a little sticky and were holding the valves open just enough to not build compression.

[KEN CROCIE]

SB Chevy head bolt washers. Buy a set of 34 and you will have 2 sets and some extras.
My first thought was that the cam is in wrong. Still think that

[SRR]

Originally Posted by KEN CROCIE

SB Chevy head bolt washers. Buy a set of 34 and you will have 2 sets and some extras.
My first thought was that the cam is in wrong. Still think that

What is wrong about it?

[quicksilver97ta]

Larger base circle?

[Ben M.]

Just a follow up: let the lifters sit a few days and 3 that were sticking freed up just fine and the rockers tightened to 20 ft-lbs and all valves now open and close correctly. Verified compression on all 8 cylinders too. Engine is fully assembled and ready to drop on car once it stops raining...

[b-man]

Nice.

["QUICK-SILVER"]

Think I'd squirt some oil on the valve stems and let it seep down the guides before I fired it up. Just might help prevent some galling if rusty guides had the valves stuck.

Clay

[77 TRASHCAN]

I use a tiny dab of moly paste on the rocker balls and ends of push rods (@ rockers), also dribble some oil over the tops of rockers before starting.

My engine builder was a player in the alky dragster world before he retired from driving (his own car, which he did ALL the work on...). Between rounds when servicing the valve springs, he had a foaming lubricant he would shoot through the valve springs, after checking each spring...