[Tims67]

Your local parts store probably has a valve compressor you can borrow. Pop a few valves out and show us.

I have, at least, confirmed that the balancer mark is correct and #1 is currently at TDC (using #6 also being at TDC for reference) so I can get the timing right now when I drop the distributor back in.

Gotta take the positive view sometimes.

 

[Tims67]

If they look ok I would replace the head gasket and reinstall. If you really want to know what the cam is, and I would, now is the time to pull it out and see what you have or what you want. You may want to wait to install the head as your spring requirement may change if you want t o change cams. You can do the other head on the car.

I definitely do want to know what the cam specs are on it, so I may go ahead and pull the timing cover and look.

I am kind of worried about the lifters, as well, as some of them look like they are at more of an angle in the bore than they should be and, possibly, more depressed than they should be. I am not sure, exactly, how far the lifter is supposed to collapse, though.

 

[rp930]

If it was me I would ditch the cam and go hydraulic roller. Get a recommendation from Chris Straub, not that expensive, put it together and enjoy.

 

[Tims67]

If it was me I would ditch the cam and go hydraulic roller. Get a recommendation from Chris Straub, not that expensive, put it together and enjoy.

I have definitely thought about that since learning about the difficulty some have had with flat tappet cams. I would like to have something similar to the one in it, as it sounded exactly the way I wanted when I brought it home.

How would I get in contact with Chris?

 

[srode]

If you take the heads out into your driveway (for safety) and put enough gasoline in each intake port with those ports looking straight up, you will be able to check for wetness / seepage around those valves and will know in a few minutes if you valves are leaking. Flip them and do the exhaust next.

 

[rp930]

I have definitely thought about that since learning about the difficulty some have had with flat tappet cams. I would like to have something similar to the one in it, as it sounded exactly the way I wanted when I brought it home.

How would I get in contact with Chris?

Chris will help you pick something out. Ask for him. https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwi2qq_H5OnvAhVPjp4KHdxGBXUQFjAAegQIAhAE&url=https://straubtechnologies.com/&usg=AOvVaw37zJUpKxantHa0YDVs2roz

 

[SoCal805]

Or should I go ahead and pull the other head off and check that side out, as well?

IMHO you are in it this deep and given whoever built the motor made an error in putting on a head gasket with debris and head gaskets come in sets...pull the other head and inspect

Bench working on heads to remove valves. With spring off, spin the valve while keeping it against the seat to feel if there is and "play" or roll the stem on glass and watch the flat end to see if there is any run out. Or just have a machine shop check out your seats/valves and lap them and confirm springs are installed at spec height for whatever springs you have

 

[rp930]

No need to worry about the springs you have until you decide on what cam you are using. I agree, pulling the other head would give you some peace of mind.

 

[RifRaf]

If you take the heads out into your driveway (for safety) and put enough gasoline in each intake port with those ports looking straight up, you will be able to check for wetness / seepage around those valves and will know in a few minutes if you valves are leaking. Flip them and do the exhaust next.

Kinda like the video below. The video also shows a neat test by blowing compressed air onto the valve seat and looking for air bubbles within the fluid poured into the intake/exhaust ports.

P.S. If this were me.... I would not be reassembling the engine until I identified what was causing the release of air pressure while doing the "leak down" test and resolved the issue.

 

[Tims67]

If you take the heads out into your driveway (for safety) and put enough gasoline in each intake port with those ports looking straight up, you will be able to check for wetness / seepage around those valves and will know in a few minutes if you valves are leaking. Flip them and do the exhaust next.

I actually tried this a few minutes ago. Exhaust valves had 0 seepage or leakage. Intake valves on 2, 4 and 6 had seepage, but I wouldn't call it leakage. It was enough to wet the carbon in the chamber, but never enough to drip. #8 was good to go.

 

[Tims67]

P.S. If this were me.... I would not be reassembling the engine until I identified what was causing the release of air pressure while doing the "leak down" test and resolved the issue.

I am not sure what to even look for that could be causing the air leakage at this point. Any suggestions? If the cylinder walls look good and the valves are closed, I should have a closed cylinder and it should hold pressure with the exception of the gap in the rings. The air coming out through the gap in the rings should go into the crankcase, not out the intake ports, correct?

When I pulled the head off, I fully expected to see major damage of some sort. Instead, everything seems to be in decent condition except for the coating of carbon.

The amount of seepage around the valves is minimal, though concerning, but I honestly don't see it allowing enough air to leak out to cause my compressor to run steadily, even though it is a small craftsman compressor from Lowe's.

 

[rp930]

When you decide on a cam you will likely need new springs. Take the springs and retainers, etc, new valve seals have the heads touched up and call it good. They will need to know spring height.

 

[scblucam]

If the leakage is minimal and valve guides are good you could use a lapping compound on the valve seats, spin the valves and maybe make the seal better. Still a lot doesn't make sense.

 

[ilikeike]

Wow ! 14 pages now.
I’d have thrown in the towel and started the rebuild. 😀

 

[Tims67]

Wow ! 14 pages now.
I’d have thrown in the towel and started the rebuild. 😀

Some of us aren't quitters...

Just kidding. It started out as what should have been a quick fix and has pretty much snowballed into a mystery cylinder leakage and a partial teardown.

 

[RifRaf]

I am not sure what to even look for that could be causing the air leakage at this point. Any suggestions?

It seems like you are doing the right things to investigate your engine issues... but nothing seems to "jump out" as wrong. I would remove the valves from the #6 cylinder and inspect those valves, valve guides, and the valve seats.

If the cylinder walls look good and the valves are closed, I should have a closed cylinder and it should hold pressure with the exception of the gap in the rings. The air coming out through the gap in the rings should go into the crankcase, not out the intake ports, correct?

Yes... that would also be my understanding.

I would also be very confused not to find any clues to the "pressure leakage" issue on the head removal (at least you did find the compromised head gasket at the #2 cylinder). The earlier compression test and the recent leak down test just don't make sense.

I agree with rp930. Once you decide what to do about a cam, take the heads... and any other associated parts (springs, etc) to a competent shop that can inspect, touch-up and assemble the heads.

• Note: I also think that installing a hydraulic roller cam would be a wise move. If you go this route, be sure to confirm the distributor gear is compatible with the cam gear. A lot of aftermarket distributors are now coming with melonized/hardened gear. You're also going to need a cam button. If you intend more "street" driving with this engine, you may also want to consider changing to a distributor that also has vacuum advance (discussed back in post #77).

It would also be helpful to identify how large the domes are on your current pistons... to calculate the compression ratio.

 

[Tims67]

I am new to this area and I also have not used a machine shop in over 20 years. Does anyone know what I could expect to pay to have the heads cleaned up and new seals and such installed after checking to make sure the valves are not damaged?

 

[Tims67]

Also, where is everyone getting parts right now? I was thinking about just putting on a matched top end kit, such as the 540 hp kit that Edelbrock offers, but they are out of stock everywhere and the estimated ship date is in June. If I could get a matched kit with aluminum heads, cam, lifters and intake, I could go that route.

It seems like this engine was built mostly for the track and I will only be using it for street duty. I don't plan to use nitrous, but was going to leave it on just to make people wonder, should they happen to glance under the hood.

The single plane intake and the large intake runners, coupled with no vacuum advance doesn't really seem to be the best combo for street duty. I still want it to have over 500 hp and sound mean but, chances are, I will never race it.

 

[rp930]

Again, check with Chris Straub.

Straub Technologies

That said I think I would get what I have running and see if I like it. A machine shop shouldn’t be that expensive. Price a valve job and go from there.

 

[SoCal805]

At this point do you really feel good about the bottom end (read was it built right, bearing clearances, etc)? If its a 2 piece RMS, flat tappet motor than.....

A one piece RMS, full roller cam motor with AL heads...

might want to look into Blueprint engines

for example (there are several more to chose from)

GM Compatible Big Block Crate Engines – Tagged "Displacement_496 c.i., Horsepower_501-600" – BluePrint Engines