Stuck Ford V8 exhaust valves - help!

david moore · #1 29-03-07, 04:23

Having got around to sorting out the engine for my F8, I find that three of the exhaust valves are sticking as I suspected from low (no) compression. I have the inlet manifold and the heads off and a vey light tap on the sticking valves allows the spring to close them , but next turn on the crank they stick again. I have tried plentiful lube and liquid wrench but no luck.

Normally I would just remove and clean them - they look in good shape otherwise - but knowing the horrors of getting the valves out I'm balking at that.

Any ideas?

Keith Webb · #2 29-03-07, 11:35

There's a section in the latest DVD, Year of the Armoured Car where John Belfield reveals how he frees stuck valves (available in NTSC and PAL)

Basically he uses a bent screwdriver to gently ease the valve down after applying a penetrating lubricant....

The caution is to be very careful as it is of course possible to bend the valve stem in which case you'll have to remove the heads and valley cover to remove the offending valve and guide assembly.

chris vickery · #3 29-03-07, 15:53

David, whats the idea here? Are you just trying to free up the engine figuring on it running and not re-building it?

I have had plenty of experience with flatheads and trust me, if they are stuck at all they usually need a rebuild.

The valves may unstick but all the gunk and rust etc in between them and the valveguide can spell disaster. All the valves should be removed and at least cleaned up and lapped back into place.
A broken or bent valve at any rpm can destroy your motor and who knows if any of them are actually bent or broken or cracked until you pull them out.

cletrac (RIP) · #4 29-03-07, 16:13

Chris,
A stuck valve on an overhead valve engine can cause instant grief when it contacts the piston, but on a flattie there's nothing for it to come in contact with. If you run it too long it might damage the camshaft but that's about it other than the miss. When you have the heads and intake off though it's a relatively simple job to pop the valve and guide assembly out of the block and clean it up.

chris vickery · #5 29-03-07, 19:27

Yes David, I agree with you on the O/H vs flathead setup.
I have seen a case before of a shattered valve head smashing the crap out of the head and the valve guide being torn to pieces.

I was suugesting that while the motor is apart, do it right the first time.

There is never time or money to do it right the first time but there's always time and money to do it right the second round...

Max Hedges · #6 30-03-07, 01:21

what I done once was to crank the engine with the stater to push the valve up and then tap it down with a hammer, that fixed them.
Max

Mike K · #7 30-03-07, 15:15

Stuck guides are a common problem too . I once owned the special tool for hitting the split valve guides out from above .

It's a length of rod bent to fit around the valve head . A section of the rod is machined/ hollowed out to form a tube , this allows it to slide down the valve stem .

You slide the tool under the valve head onto the stem and down on top of the guide . You can now hit the tool head and the split guide comes out .

Ryans in Melbourne sold these special V8 tools in the 1950's and 60's .

There was also a bar for levering the guide and removing the spring clip .......

I know who has the tool, and I can get it back if anyone needs it .

Mike

david moore · #8 30-03-07, 20:10

Thanks for the input re my sticking valves (they close on their own some of the time now!).

Common sense tells me that having got the engine out, heads off etc. it would be the right thing to get the valves out and at least cleaned up.
However, I have been very influenced by the Ford Flathead website ( http:www.vanpeltsales.com) which says how difficult it is to get the old style valves out.

I don't have the correct tool to lever the retainer tabs out but I can compress the spring with an old blunt screwdriver levered against the inside of the block - I pulled hard on the tab after compressing the spring but no movement. Should the tab just pull straight out once the spring force is removed - or is it recessed up into the valve guide and have to come "down and out"? I don't want to force it where it shouldn't go! Even when the tab is removed, presumably the valve guides have to be forced out by getting down alongside the (open) valve stem before the spring and the valve itself can be removed?

The manual isn't too helpful on these details!

Bob Carriere · #9 30-03-07, 20:48

Bonjour David

A while back Princess Auto had some large C clamp shaped valve compressor tools for sale.......... I was looking at it to work on a Dodge flat head....... not of snap-On quality but to do a few engines it might save your knuckles..... or at the very least it will look impressive hanging on the tool panel above your work bench.

Bob

Alex Blair (RIP) · #10 30-03-07, 21:28

Dave
It's been I while since I rebuilt a flat head buy the Compressor clamp that Bob Carrier is talking about just hold the top of the valve down and compresses the spring..Once the spring is compressed the "Tabs',which if I remember correctly are little half round tapered wedges that fall out once the spring is compressed...
THen the spring and retainer washer comes out and the valve can be pulled up out of the block,and then the guide can be smacked out with a drift..
I'm going by memory but I don't remember it being a tough job..but I did have the right valve spring compressor..
Doing the valves with a lap stick and adjusting the clearances by grinding the end of the stem is something you want to be sober for...

Grant Bowker · #11 30-03-07, 21:29

David,

Although I haven't been playing with a flathead, I have checked a online copy of "Repair Manual Ford and Mercury V8 Engines" that says that the "valve guide bushing" has to be pulled down before removing the valve guide retainer. Hope this helps.
On edit: Other reading suggests there were two types of valve stem, one that would match Alex's description and another with the equivalent of the tapered keys built into the valve stem so that the process of moving the bushing to remove the retainer and then pulling the bushing and valve as a unit out of the block would have to be followed.

Grant

Keith Webb · #12 30-03-07, 22:50

from memory the tool (a bar similar to a pinch bar but with a wider mouth) was pushed through the spring and engaged the valve guide bushing which was then levered downwards slightly as Grant mentions, then removing the retainer at the top. When this is out, the lever is used to gently lever the assembly out of the block where another tool is used to compress the spring and remove the collets holding the valve retainer at the bottom. The guides are in two pieces.

Tony Smith · #13 31-03-07, 00:45

The original '39- 48' engine used in CMPs had a Mushroom head onthe valve, used in conjunction with a C shaped reainer and split valve guides. The '49-53' engine used straight stm valves with a 1 piece valve guide and 2 collet retainers. Both types of valve assmebly are removed in the same way, and your engine may have had the later type of valve if it has been rebuilt in the past some time. To just remove the valve to clean it up and reface it, you will need to remove the Mushroom head valve and the split guides together, while the straight stem type you will just need to compress the spring to release the collets and slide the valve out to clean or replace it.
See this pic;

david moore · #14 31-03-07, 02:06

My valves are definitely the older non-adjustable variety. I will try to get hold of a proper spring clamp, otherwise just two hands will be far from sufficient! I'm not sure if there is a good "purchase" for the clamp to be able to compress the spring DOWN instead of UP.

The book talks about engaging the ridge on the valve guides to help pull them down but I cant see much of a ridge outboard of the retainer slot on the older variety of split guides. Maybe there is a small ridge just visible in your photo, Tony?

I suspect that my retainer clips are well and truly "welded" into place - and the guides too but maybe some tapping/pulling/jiggling once the springs are clamped out of the way will work.

Does the cam follower simply pull up out of its housing with the valve?

Finally, not having the official valve gap gauge. anyone know what the valve/ cam follower gap +/- should be in thou's when that particular valve is closed and the cam out of contact, assuming that I have to grind them in a little and then grind a little off the stem mushroom, too?

Keep the comments coming - very useful so far.

david moore · #15 31-03-07, 02:10

Forget my question about extracting the cam follower! I can now see that once the valve guides and retainer clip are out, the valve and spring can come up and out through the valve guide space.

Alex Blair (RIP) · #16 31-03-07, 02:42

That "Cam follower" is the solid lifter,non adjustable..that is why you grind the valve stem or lap the valve down into the seat to get the proper clearance..and a light touch on the valve stem will save a hell of a lot of agravating work with the lapstick...but there is always the electric drill...
The lifter shown in Tonys posting seems to have some kind of adjusting nut on it...not sure about that..

Grant Bowker · #17 31-03-07, 03:02

....are widely advertised in Hemmeings Motor News etc. They may not be original but look as if they should make valve adjustment easier if they work as claimed. Experienced user input?
The V8 manual quoted above gives .010-.012 for intake, .014-.016 for exhaust. It is not a military manual in case that makes a difference.

Barry Churcher · #18 31-03-07, 03:15

David, I have one of the bars and a C clamp. You are welcome to borrow either or both. If you buy the coffee I could meet you at "Tims" in Bellville. The adjustable lifters are readily available from Ford tractor dealers. When we raced flatheads that is what we used. Perfect fit.

Cheers,
Barry

david moore · #19 31-03-07, 03:58

HI Barry

Thanks very much for the offer - I'll certainly take you up on it. You'll get a donut of your choice with the "roll up the rim to win" - explain that to non-Canadians later!

What would be a good time to meet up in Belleville - Im OK pretty well any time weekday or weekend. Good to be retired innit?

Cheers
David
613 544 7258

Lynn Eades · #20 31-03-07, 04:44

A little trick I saw used to free up astuck engine, might help here.
The guy had a siezed motor (fronm sitting, head off exposed to the elements) What he did was to pour a quantity of diesel on the pistons, and set fire to it. It burned with a weak flame, but over time the localised heat expanded things in relation to each other. the result being the motor freed up nicely.
These v8's are notorious for sticking the guides in the block pretty tight, and often its the motors that have sat around, that are the worst.
If you attack without caution you may well end up breaking someone elses special tool, or part of your motor.
If your motor is out, try setting a fire in your valley around the guide you wish to remove, and let it burn until the diesel is gone(you will have to roll the motor to a suitable angle, and maybe block the odd hole)
The guide does have to go down (in) a little to allow the removal of the circlip, before the assembly.
Time / money, spent getting the valves right is worth it, and is one of the main reasons why these motors are expensive to rebuild

Tony Smith · #21 31-03-07, 13:39

Quote:

Originally posted by david moore
The book talks about engaging the ridge on the valve guides to help pull them down but I cant see much of a ridge outboard of the retainer slot on the older variety of split guides. Maybe there is a small ridge just visible in your photo, Tony?

Keep the comments coming - very useful so far.

There is a ridge on the valve guide, to engage a "Fork" shaped special tool (new versions of this tool are avail from Mike Davidson under Products>Valve Tools):

Tony Smith · #22 31-03-07, 13:40

Then:

Tony Smith · #23 31-03-07, 13:41

Step 3 ("Scythe" shaped special tool from above link required):

Tony Smith · #24 31-03-07, 13:48

And finally. As the valve guide is being pulled from it's nice clean bore out through a coke caked, crusty port (particularly on the exhaust valves), some effort might be required.

Phil Waterman · #25 31-03-07, 14:29

Quote:

Originally posted by Tony Smith
And finally. As the valve guide is being pulled from it's nice clean bore out through a coke caked, crusty port (particularly on the exhaust valves), some effort might be required.

Tony- Your pictures are excellent, shame that most modern shop manuals do not have pictures or diagrams of that quality.

MLU has turned out to be such an amazing place for sharing information.

david moore · #26 31-03-07, 14:49

Tony

Just great pictures and instructions! Once I get the tool, I'll let you know how I get on.
One thing in my favour - the retainer clips on my engine have a convenient "tab" with a hole in making them much easier (hopefully) to get hold of and pull out

Tony Smith · #27 31-03-07, 14:59

Quote:

Originally posted by david moore
Tony
One thing in my favour - the retainer clips on my engine have a convenient "tab" with a hole in making them much easier (hopefully) to get hold of and pull out

All of the retainer tabs should have a hole in them, but be careful if it is hard to pull as that "Scythe" shaped remover has an amazing amount of leverage and can rip the tab clear off the retainer. I ought to post a pic of some of the mangled ones I have killed. Lube all around the retainer with some kind of penetrating oil a couple of days before you start the job to help slide it out smoothly.

Robert Farmer · #28 01-04-07, 13:05

After reading this thread i'm glad I have a Chev!

Barry Churcher · #29 03-04-07, 02:26

Hi David
I had to do some looking today at the garage but I found the tool. Things that are not regularly used seem to get hidden. I actually thought for a while that it had walked. I can meet you one day this weekend in Bellville if you want. We are sticking our necks out and closing the garage for a 4 day long weekend so whatever day suits you.
Cheers,
Barry

david moore · #30 03-04-07, 03:30

Barry

Great. How about Friday - or will this interfere with your devotions?!

How about 12 noon - or any other time you suggest. Which Tim Hortons by the way since I assume that there is more than one in Bville?