Thread: I think I have a BIG problem

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Chevy Gen 1 with Fast Burn heads, hydraulic roller cam, roller rockers. With #1 at top dead center and the rockers adjusted to zero lash, I can compress the exhaust lifter internal plunger spring by pushing down on the rocker. I cannot do that on the intake lifter. It's solid as a rock. I checked every other lifter in the motor, and all have some free play. To confirm, I took the rocker arms completely off, and pushed down on the exhaust pushrod and get the play I expect, but not on the intake side.

I think the internals of the lifter are toast. Opinions?

https://youtu.be/1ZT29cSy8xw

Originally Posted by Henry Rifle

I think the internals of the lifter are toast. Opinions?

https://youtu.be/1ZT29cSy8xw

I'd agree with you Jack, and assume that you're chasing a lifter "tick" or rough running condition?

Roger, I suddenly got a lot of clatter and a miss, so I pulled both valve covers and ran the lifters again. That's when I ran into this on #1 cylinder. I did note that at TDC with no rockers installed, both pushrods were at the same lift.

Denny, I did put significant pressure on it, but got no movement at all. I guess I'll have to pull it to check, but on this car, it's a boatload of work. No choice at this point, though.

Motor1.JPG

Motor2.JPG

Jack,
I'd be tempted to put 1/2 can of SeaFoam in the crankcase and take it out for a drive, keeping the rpm's up to see if maybe that one lifter will flush out. I would not be looking forward to pulling that intake, either....

Both pushrods will be at the same lift even when the cylinder is not on the compression stroke

You may have lost galley plug at end of that lifter galley and hence lost oil presure to to lifters resulting in that condition

can you see if the dogbone is holding the lifters in alignment??????

And what did that spark plug look like?

Jerry,

Both pushrods will be at the same lift even when the cylinder is not on the compression stroke

Nope. When the piston is on the intake, the exhaust pushrod will be higher, since that valve is closed.

You may have lost galley plug at end of that lifter galley and hence lost oil pressure to lifters resulting in that condition.

Good thought, but I didn’t mention that I had 50 psi of oil pressure. However, I did mention that all the other lifters had some travel when at TDC.

Can you see if the dogbone is holding the lifters in alignment?

Nope. No way with these heads without pulling the intake.

And what did that spark plug look like?

Normal. I didn’t drive it very far after I had the problem.

Jack-you got it wrong---------when a valve is closed, the pushrod will be lower

And if you are at top dead center on the compression stroke, both valves closed and push rods down low(no cam lift) and if on top dead center on the overlap (exhaust stroke changing to intake) both valves will be open and the pushrods raised-------they should be equal(or very close) as this is the OVERLAP and how many cams are timed by using two equal length flat tappets and a straight edge across them------

Also, your problem may be associated with roller failure loosing bearing pins which will give you some play----------

Please elaborate on the straight edge cam timing technique

Allright---------when doing lots of engine stuff at races, etc and you want to change cams, or just the timing of them----in the cylinder that is 180 opsitite of #1---( in chev/mopar firing order it will be #6)you put two pieces of round stock that is lifter diameter and exactly same length into the 2 tappet bosses--with a straight edge across the tops you can determine when the cam lobes are exactly same rise and that will equal exact split valve timing centerline------at that point set the crank back from tdc to advance cam timing and forward from tdc to retard cam timing----it is helpful to have a cam drive like a Jessel belt or Donovan etc gear drive to make easy the adjustments


over the years of racing--I've had several cams ground that had the exact same base circle so I could quickly change cams without having to adjust the valve gap clearance

Jerry, you're right on the push rod position. I was very, very tired and frustrated.

Denny, the engine had been sitting for several weeks, since right after I noticed the problem. I was just 100 yards up the street, and turned right around. Right away, I put it up on jack stands and took care of other problems, such as a bad trans output seal and a leaky transmission oil pan. I'm going to take a more detailed look at it tomorrow.

I'm still dog tired, BTW. Thanks, guys.

Denny, it's tomorrow. I did what you suggested about leaving the valve open. No luck. Still frozen. I've got it about 3/4 torn down already. Film at eleven . . . or whenever I get the urge.

I removed the top half of the motor in a couple of hours this morning and pulled #1 I & E roller lifters. The exhaust lifter would compress with finger pressure. The intake was dead stuck. I couldn't move it at all. Totally different 'feel' than the exhaust.

I removed the retaining clip, disassembled the lifter and couldn't see any dirt or anything else wrong. Then, I completely cleaned it with solvent. When I reassembled it, it seemed to work OK. I'll probably replace it anyhow.

BTW, as soon as I took this photo, I plugged the I & E exhaust ports and covered the galley completely to keep the junk out.

Cleanup and reassembly will take a bit longer.

TearDown.JPG

So no pushrod guide plates----are the rockers those that straddle the valve tip?????
Didn't those fastburn heads have bigger valves and some offset location??? If so you may have a serious geometry problem----

Originally Posted by jerry clayton

So no pushrod guide plates----are the rockers those that straddle the valve tip?????
Didn't those fastburn heads have bigger valves and some offset location??? If so you may have a serious geometry problem----

Jerry, The rockers do straddle the valve tip, and there is NO geometry problem. I didn't build or modify this. I bought it as a Fastburn crate motor.

Denny, they are absolutely dead center left to right. Of course, as the valves lift and fall, the roller does sweep across the top of the valve. However, I have checked them through several full cycles, and sweep about the same amount from center each way.

Jack do you know if the valve locations are offset??? It is common in sbc performance heads to put larger valves in they move the exhaust valve over so that they can also move intake valve away from edge of chamber---------Glad your sure that you don't have a geometry problem----

Whose/what company rockers are on engine and what ratio????
I've seen a few cases of the fast burn heads having valve seat ring get loose because of temp differance in aluminum head and as it moved down it holds valve open some creating an odd clattering noise before it eventauly creating a mess in the cylinder with a dropped valve, pieces then getting into intake and over to other cylinders-------