motor is missing at low RPMs

[simplyconnected]

Jonesy, my hat goes off to you. I admire that you're doing your own work. even if it is to save money. That's exactly how I got started wrenching.

I am sorry that you're going through this again. There are some advantages, though. Novice-Mechanic days are behind you, now. It's all uphill from here.

I take it that you will go with Edelbrock heads? If so, they are a direct bolt-on replacement. Pushrod lengths remain the same, rocker shafts remain the same... it's all good. The only 'custom' calculations I had was due to the roller cam I installed. Roller lifters are at least one inch taller, making the pushrods one inch shorter. You won't have that situation.

You said your machine shop 'squared' your block. They probably shaved your heads as well, to make them flat. Did you change pushrod lengths? Probably not. Hydraulic lifters are awful forgiving, even though your machining 'stack' pushed them down about .030". With new Edelbrock heads, you're going to get some of that back (unless you mill the new heads).

Follow my build pictures and suggestions. They will save you time and money. By all means, take hundreds of pictures as you are tearing down and building your engine. They are wonderful references. If you don't use them maybe someone else will. That's the attitude I took when I documented the Penelope build. (Remember, I don't own a Thunderbird except for the '58 convertible model that Eric Taylor sent me.)

I'm glad you are on this forum. Given the chance, Squarebirds.org offers tons of experience and knowledge that most garage mechanics are missing. Use this forum to 'talk problems out'. We can only suggest the direction you should go. Ultimately, you will do what you think is best. - Dave

[fcar]

Congratulations, Dave. Your perseverance is/has paid off, and I know that I've learned from this thread.

[davidmij]

Awesome, I'm glad I don't have to worry about tolerances etc. with the hardware.
Yes, the decks and heads were milled, shaved, (whatever the terminology is). I think I still have my old card board boxes that I used to organize all the pushrods and fasteners.

I have over 500 photographs, many from the first time I pulled it all apart, and just like you advised a year and half ago, those WILL come in handy for doing it again.

In about 3 years I'll be ready to retire, and when I do I'll have tons of time to play with this hobby. The plan has always been to do as much as I can myself. It's not much of a hobby if you pay some else to do the work. I've actually got a pretty good budget right now. After I get it all apart and verify what work has to be done, (and whatever else might need fixing) I'll order the hardware.

I just bought a 2 ton engine lift on Friday. I found it on Craigslist for $120, - it's almost new. I just may be putting it to use sooner than I thought!

Funny, some of my buddies call me "Jonsey". Some of them call me other things too. I'll leave it at that.

[simplyconnected]

...I have over 500 photographs, many from the first time I pulled it all apart, and just like you advised a year and half ago, those WILL come in handy for doing it again.

As a tradesman, I always worked as if I might need to redo this, like changing motors, etc. Many times it was someone else but we could always tell who did the work. Some electricians wired motors with wire nuts, others with butt splices. I used crimped lugs with screws and nuts. So if the same motor went bad on my shift, I appreciated the extra effort that was already in place.

The point is, you never know who will work 'behind' you on any job. It might just be yourself. Having those pictures are a tremendous help because it's impossible to remember all the details. When you put those pictures in your computer, do not downsize them. Leave them large so you can zoom-in on details. If you want to post some, then downsize and have two copies, but don't alter the originals.

...I just bought a 2 ton engine lift on Friday. I found it on Craigslist for $120...

Funny, some of my buddies call me "Jonsey"...

That's a decent price for the cherry picker. You can always sell it for the same money.
I took the liberty of calling you 'Jonesy' in hopes that I'm one of your buddies, too. - Dave

[davidmij]

Got the heads off one side and see the problem. Not sure if these pictures will show it very well, but the exhaust valve on #8 is tilted slightly. I'm guessing #4 will show the same.

I also thought I'd show a cylinder and two other valves. The cylinder wall shows a slight scratching, however if I touch it I can't feel it there.

Anyway, I'm going to order some Edelbrock's once I get advice from Barry Rabotnick, owner of Survival Motorsports. He's on the FEpower forum I visit for advice sometimes. I'll give him all my engine and cam specs and I should end up with what'll work best on this motor.

stay tuned for more from Dave Jones and his Bird with a broken wing.

[jopizz]

There are a number of reasons why the valve is not closing. It could be slightly bent; there could be a buildup of carbon on the seat or the seat could be damaged. Without removing it it's hard to tell what is going on. As far as the cylinders go you should see crisscross scratches. This is part of the honing process. This helps retain oil and reduce cylinder and ring wear.

John

[simplyconnected]

To me, that valve looks like the piston closed it. The problem with that is, the valve stem is not in line with the piston bore, so the valve 'cocks' to the side, sticks in the guide and the valve bends.

This usually shows up when you 'pop' it with a rubber mallet, smacking the valves down. Bent valves tend to stick and an open valve sounds quite different from all the rest that close properly.

It's not a receded valve but one that never closes, none the less.

So, what causes a valve to bend? Floating your valves from rev'ing to very high rpms and/or no oil going down the guides.

The valve train is massive and hard to move fast. Racing engines use very strong valve springs and shims to overcome the kinetic energy to return a valve. Overhead valve trains cut down on kinetic energy by eliminating the pushrod and keeping the lash-adjuster (lifter in your case) from moving. With fewer things to return, that's why their rpms are so much higher.

Starved oil can bind a valve stem. That's why it's so important to keep your rocker shafts clear, for oil to freely flow in each rocker arm. Each one only needs a little oil but it has to be there. - Dave

[davidmij]

Dave and John, your comments had me taking a second look this morning. In these pictures of the top of the piston in question you can see that the eyebrow seems to have a ding in it on the exhaust valve side. Sure looks like possible valve float. The first picture shows #8, the second picture shows a good cylinder without a ding in it.
The cross hatch cylinder polish lines that you talk about John are there. They look good. I just noticed that there are some veeeery slight in line marks showing up in the number 7 cylinder. It's not detectible by palpating the cylinder though. I don't think it's anything to worry about.

I wish I had one of those higher end tachometers so I could see what the actual rev was when I missed a gear power shifting. I saw it at 6000rpm, but who knows how much above that it actually went.

Anyway, I think I'll try to sell these heads and just go with the Edelbrocks. Years from now I plan to go to a 445 stroker and will eventually want them.

Later today I'll get the other side off and post pictures of that side. It's be interesting to see it the #4 did the same thing.

I don't understand the pattern, or layout of the oiling paths in the heads, so maybe you guys can tell me; does the firewall end of the heads not get as much oil as the rest of the head and valves?

thx, Dave J

[simplyconnected]

...I don't understand the pattern, or layout of the oiling paths...

On the driver's side (LH), look down the rocker shaft bolt hole, second from the front. Both heads are identical so the RH head would be second from the rear.

Right next to the bolt hole is the oil feed hole. I covered this with an oil restrictor in my Penelope build. That bolt in the rocker assembly tower should look skinnier than the other three, to give oil more room to travel up the stand and into the rocker shaft center. Once inside the shaft, oil should come out every rocker arm in two small holes, each. Of course, when you built this engine, you would have cleared out those holes with a small drill bit when all the rocker arms were off their shafts. They tend to varnish closed, trapping dirt that acts more like cement from so many years of dirt settling and cooling.

I'm concerned about your piston-to-valve clearance. What is it? - Dave

[davidmij]

I remember the holes now Dave. When I took the motor out of the donor car I took the rockers completely apart and sprayed cleaner through all those holes per an article or instruction that I had found.
The heads and rockers were completely rebuilt by the guy that did my motor. That included valve job, surfacing the pair, thin wall brass guides, spring height sets so they would all match, regrinding etc.

I too am VERY concerned about the clearance Dave. How can I check it? I've been told that the Edel heads have a slightly smaller chamber size than stock. I'll make sure and talk this over with the guys from Survival motorsports to see what they think or recommend. I'm sure they'll want to know the clearance too.

Dave J

[simplyconnected]

...I too am VERY concerned about the clearance Dave. How can I check it?...

Pull the valve springs off of a pair of valves from any good cylinder. Hold the valves up with anything (tape is good) from on top. Replace the head with the head gasket and torque it down.

Slowly hand crank it until you can feel the exhaust valve touch the piston. At the highest point, with the least amount of 'lash' or clearance, measure the valve stroke. It won't be much so measure it carefully.

Now let's check with your cam. Put your rocker shaft and pushrods back on in the cylinder you are checking. Again, with no valve springs, hand crank and feel the highest point at which your valves touch the piston. Do NOT let the valve drop down the cylinder or you will start all over. Some guys put a very light spring on the valve to check it. When you get to the closest point where it has the least lash, you can use feeler gauges between the valve and rocker arm. Do each valve separately.

None of these tests cost money but they should have been done at the time your engine was built. The problem with that is, most mechanics won't spend the time because they'd need to charge you more money. Now you know why I do my own.

BTW, check the bent valve's guide. It may be broken at the bottom. - Dave

[davidmij]

Thx Dave, I think I can follow that. I wasn't able to work on it today. Family stuff with my dad's health, and getting a resume together this weekend. It'll probably have to wait once again until next weekend.
The builder told me that they shimmed all the valves to be at the same height, or stroke, if you will.
I just did the rubber mallet test on the passenger side, I haven't taken that head off yet. I can definitely tell the #4 and maybe even the #3 exhaust valves are hurt as well. I kind of found that out already via the hollow spark plug and air compressor test anyway.

Dave J