Observations on a GT4 engine pull.

Although, technically, and according to my Bluejackets Manual, it was really a "line" trick. "Rope" is a general term applied to both fiber and wire rope. Fiber rope usually is referred to as "line;" wire rope as "wire rope," or just wire. Rope or line, it worked. An old Navy buddy of mine explained after another friend suggested filling the cylinder with oil::

The problem with the liquid is that pressure will be equally distributed over the top of the piston (including whatever point is the weakest) and would cause piston failure if it is at all possible. The rope will tend to lie straight and if is of appropriate length and thickness will tend to lie at the perimeter of the piston which will also coincide with the minimum clearance at TDC. One piston circumference of 1/2" nylon rope inserted through a 14mm hole will lie in a perfect circle at the cylinder wall and only stress the piston at its strongest part. In theory.

So, I fed 10.25 inches of 1/2" nylon line into cylinder 1, cranked it around, and nothing happened. Fed in another 10" Resistance! Breaker bar applied and it pushed up that end of the head 1/4." Still stuck. Fed as much line into cylinder 1 as it would take, and did the same thing to cylinder 4. Crank again - the head lifted another 1/2".

Two more cycles of that and the head was separated from the the block by 1" and I see the tightly-packed coiled line through the gap. Then I was able to wiggle and muscle it off. The studs between cylinders 1 and 2, and 3 and 4 on the top were a little corroded. Not much. But the head is off now with no damage.

Next I need to get the intake manifold off that head (the other one came off with a little work), remove the air injection manifold and hardware, and remove a bunch of studs so the head will fit in the Sunnen Head Machine, and the heads will be off to the Machinist.
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I'm still working on getting the intake manifold off the rear head. After cleaning up the other manifold I found some disturbing evidence of corrosion. A quick check with the dial indicator shows some of that corrosion goes as deep as 0.027"

I'll check with my machinist friend and see if we can take 20-30 thousands off that surface. What do you guys think?

Now I'm really worried what the surface on the other one looks like. Won't know until after it comes off. Luckily, the mating surface on the head isn't showing anywhere near this level of corrosion, except, of course on the studs. I'll clean them up, then give them the POR-15 treatment.

The replacement cam tensioner came in and it will clean up fine after I press the old bearing off. The bearing on it feels like a ratchet when you turn it. It must have come off one neglected engine, almost made me cry. I'd hate to see what the rest of that donor engine looks like.
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Thanks, Robert. I checked, and the ones on eBay appear to be later models. Mine have the rectangular carb mounting plates - I think 107115 and 107114. I think I can salvage them with a little machine work, maybe some welding.

Bear in mind, my car has seen only distilled water and Peak antifreeze (regularly changed) for the last 30 years, and I installed a sacrificial "zinc" plug in the block drain 20 years ago. Looking at the one used pair of manifolds offered on eBay it appears to be more corroded than mine, which only shows some surface pitting. Most of the water passages look pristine, so apparently this is a design/gasket failure, which can be excused given the age of the engine.

My focus now is to devise a strategy to mitigate this happening again, POR-15 on the base of the studs, and careful application of Hylomar around those water passages is what I have in mind, maybe a dab of Hyomar around the stud holes in the gasket too.

 

Finally got the other intake manifold off the head .Cleaned it up a bit and it looks like the other one: same amount of corrosion in the same places. The gasket was soaked with penetrating oil, which means it's permeable, so that's how the moisture probably got through it. The location of the corrosion is exactly where those exposed water passages are in the head. Coolant pressure is only about 15-20 PSI so it probably just soaked through. I'm thinking I'll coat the mating surface of the manifold with POR 15, along with the bases of the mounting studs in the head to prevent future corrosion.

A lot of posters have mentioned using it on head studs, other studs, etc. to prevent corrosion. There's only a paper gasket sitting between those large passages and the flange of the intake manifold.

The gasket covers the whole outer rim above the intake ports and the flange of the intake manifold does as well. The water from the water pump goes into the intake manifold in the middle, and then into the head through the big hole in the middle, between ports 2 and 3, and the little holes next to the other ports.

What do you guys think about the POR-15 scheme?
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It's not exactly on the INSIDE of the engine. I'm talking about the inside of the mounting flange on the intake manifold. It's completely isolated from the engine by a pretty thick gasket. Other threads have recommended using it on head studs, which really are "inside" the engine, which raises another point:

This engine has never been apart in 40 years. The corrosion pattern indicates the coolant "weeping" occurred at the bottom of the manifold, closest to the head/block interface. The only head studs which showed any corrosion were those closest to the head/manifold interface, which argues for the necessity of running the engine frequently. The heat would dry out the gaskets and prevent (or mitigate) any damage the moisture would do. My car was inoperative (and not started frequently) when it couldn't pass smog in California in the late '90s, and, more recently while I've been rewiring it and in a panic over the potential of a dropped valve. Drive your car, or at least run the engine monthly!

 

I hauled the heads over to Mike's shop yesterday afternoon and we completely disassembled them and cleaned them. Everything looked very good, except for all the carbon. The exhaust valves showed a slight bit of cupping that would have ground right out, but we're replacing them anyway.

The intake valves also showed a bit of cupping, but that ground right out and the new angle of 44.5º was established.

Mike explained the concept of this operation as a "kiss" of the stone to the surface to take off as little material as possible. You can hear the contact as the valve touches the stone and you very slowly advance it until the point where uniform contact is made around the whole surface, then quit. It is a wet kiss (because of the lubricant) but doesn't go much further. The master at work:

The valve guides showed little wear and are well within tolerance, so we don't have to replace them. The valve stem seals popped right off and were Teflon - pretty advanced for the day, but since superseded with newer materiel (Viton).

Then the heads went into the Roto-Jet Cabinet of Doom. This contraption can best be described as a front-loaded washer for large car parts. Inside is a turntable and what appear to be pressure washer nozzles all around the inside of the cabinet. The heads were secured to the turntable, the huge door closed and latched and then the fun began. It moaned and screamed. Puffs of steam blasted out of several orifices. After a half-hour the heads emerged perfectly clean - all the carbon was gone!

So here's the bottom line: New exhaust valves ( on order this morning) and a kiss of the exhaust valve seats. Polish up and touch up the intake valves, and a kiss of the seats. New stem seals all around. After the valves are assembled I have to figure out a way to measure the stem length with relation to the camshaft so we can grind the stems to get within the range of adjustment with the shims

We tested the heads after they came out of the Jet and they were flat beyond .001", They don't even need to be surfaced. Mike is a performance engine builder and he pointed out to me all the little performance details in the heads, like the way the valve seats are blended into the ports, and the positioning of the valve guides so as not to obstruct intake and exhaust gas flow. He was actually quite complementary and said the swirl-polished stainless-steel intake valves were of the highest quality. All the little hand-finished port details, the quality of the parts, and the manufacturing tolerances were cutting edge back in the 70's. He said he gets new CNC-machined factory heads that don't meet the tolerances of these 40-year old sand-cast heads. He doesn't impress easily, but he was impressed.
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Robert:

No, the exhaust valves all looked fine, except for the the cupped indentation on the sealing surface and the abundance of carbon. We miked one of the stems and it was well in tolerance, even after 60K miles. We also checked the exhaust valve radial deflection in the guide, and it was within tolerance as well. When the new valves arrive we may even have to ream the guides!

I've got some more parts to run through the Jet Washer of Doom (intake manifolds, cam belt covers, etc.) next week and while they're in there I'll sandblast a couple of the old exhaust valves and measure them and post the results with photos.

When you get ready to do yours let me know and I'll send you all the research I did to find the best sources for the parts I needed. For example, I'm replacing all the lock washers, regular washers, a lot of the nuts, etc., and they can be sourced from a metric fastener company a lot cheaper than buying them from a Ferrari vendor. Other ones, like the washers under the head bolts, really should be genuine Ferrari.

While not "Ferrari Experts," my posse is comprised of very experienced and educated motor mechanics with lots of experience. They take the time to explain to me the rationale for their advice and I've learned a lot. For example, one of my buddies is a transmission expert who has been building custom performance automatic transmissions in his clean room for 50 years. We had a conversation about steel studs in aluminum castings yesterday. Bottom line: don't even try to remove them unless absolutely necessary. He won't recommend Helicoils, the latest technology is to drill the hole out, tap it and screw in a threaded insert which also has threads on the inside of the correct size and pitch for the stud.

 

Glad you're enjoying the saga. A big topic of conversation on this site and others for the last couple of years has been those exhaust valves. A friend dropped one in her GT4 a year or so ago and it did the expected damage. At the time a running original GT4 was worth about $20K. She could have the work done to fix the engine (Estimate $13K - $15K, maybe more) and have a car worth $20K. Or she could sell it with a broken engine for $7K. That was the option she took.

My car was running fine, with the exception of high oil temps when it was hot outside, or I was caught in traffic. (I've since learned others have the same problem). During a belt change 3 years ago I noticed the clearance of #7 exhaust valve was getting tighter. A compression test showed that cylinder 20% lower than all the others, which were running about 100 PSI. (Which I now surmise was because of the carbon deposits). A leak down test also showed problems with #7 exhaust. The valve my friend dropped in her car? #7 exhaust. There have been other reports of #7 exhaust valves being dropped on this site.

I did the math and figured I could refresh the heads and replace the valves for about $3K. But I have a lift, reliable and experienced helpers, and an ace engine machinist who owes me big time for keeping his computers running for the last 15 years, including the logging computer in a Top Fuel Dragster we campaigned for about 5 years. And I'm retired so I have lots of time on my hands. Everybody's situation is different.

This site has been a lot of help to me over the years and there are a lot of other regular guys who just want information about keeping these wonderful cars running. Scientia est potentia.

 

Thanks for your advice, Peter. I wasn't thinking of using POR-15 on the head studs, only on the studs securing the intake manifold(s) to the head(s). I've done some research, and the consensus seems to agree with your suggestion of anti-sieze on the head studs. Some folks recommend Walter 53D854 Rock'n Roll Ceramic Anti-Seize Lubricant because of it's high temp rating over the standard silver stuff.

Bruce: PM sent. In the immortal words of Joan Rivers: "Can we talk?"

I decided to make my very own Gauge 152-CS-7148 to help set valve stem heights, and, eventually valve shims. Aluminum bar stock showed up Friday, and I spent yesterday turning it down to the precise diameter of 24,943 mm - an exact fit to the cam journals. Today I'll finish up with a hole for the dial indicator and a lock screw.

Which brings up an idea: lots of us on this forum have either bought or made specialized tools for our cars, usually used infrequently, and hiding in the back of our toolboxes. Why not have a sticky thread for "specialized tools to be rented/leant."
I've got a couple I could list. We'd have to risk/control not getting the tools back, broken tools, etc. Any thoughts?

 

While we're waiting for the valves, gaskets, etc. to show up in the big brown truck I finished up my version of the Gauge 152-CS-7148. According to the shop manual the distance from the centerline of the camshaft to the top of the valve stem is 19,450mm - 19,950mm for the exhausts and 19,150mm - 19,650mm for the intakes. The diameter of the cam journals is 24,937mm - 24,950mm, so half of that is the distance between the centerline and the bottom of the journal, or 12,4685mm - 12,4750mm. So, basically if you measure from the bottom of the journal to the top of the valve stem and add about 12, 4718 you should get the stem heights of the valves - 19,450mm - 19,950mm exhaust; and 19,150mm - 19,650mm intake.

I turned a piece of aluminum bar stock to 24,943 mm - an exact fit to the cam journals, and mounted a digital micrometer which can be indexed to the bottom of the cam journal on a flat surface. The same tool can be used to estimate the shim size without the camshaft installed, using the same math. Of course, I'll recheck them after the camshafts are installed using feeler gauges, but I don't think the feeler gauges are half as accurate. Here's the tool:
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According to my machinist buddy you grind a bit off the stem at the top using a special fixture in the valve grinding machine to insure the surface is precisely perpendicular to the stem. There is some controversy, however, that if you take too much off it can compromise the strength of the keepers. Looking at the valve there is considerable distance between the keeper grooves and the top, so I think taking a few thousandths off won't make a difference. He gave me the choice, and I'm taking his advice. There is a 0.5mm range in the spec, and the available shim range is 3,25mm to 4,60 (0.35mm range), so we won't be cutting any stems unless absolutely necessary.

 

Sorry about the interlude, but we've been waiting on the custom valves. Been doing a lot of little jobs inside the engine bay, and I'm not in any rush. The valves finally came in last week and we started the head rebuild. The intakes looked fine, so we decided to reuse them. I was pretty sure the exhausts were sodium-filled, and I wanted to replace them.

Comparing the old valves to the new ones, I noticed the new exhaust valves were dished on the face (like the intakes), while the old valves were not only flat, they were slightly bulged out (see photo, below). Additionally, there was a discoloration on the stem about 3mm below the keeper slot. We think that's confirmation that the old exhaust valves are, indeed sodium filled. Mike the Machinist says the flat or slightly convex valve face is characteristic of sodium-filed valves, and the discoloration at the top of the stem is at the top place where the sodium chamber ends. That's where most of the heat gets transferred to. I'll cut one open to confirm, but I'm 99% convinced they are sodium filled.

I cleaned up the intake valves on a wire wheel after we soaked them in mineral spirits (paint thinner), which works much better than lacquer thinner or brake cleaner. Mike took a light grind of 46º on both sets of valves. Just a "kiss" to make sure they were round and concentric. We checked the stem-guide clearance and it was .05 mm, well withing the spec of .10 mm, so we don't have to replace the guides. Then the heads went into the valve machine and the seats were cut. The intake seats cut pretty easily, the exhausts were much harder material. The seats were in good shape, and we only had to take off a few thousandths on each. The main cut on the seats was at 45º, with an additional cut on the intakes at 35º. We'll lap them all next week to take out that 1º difference between the valves and the seats.

The last shot is of the Master at work - you want your motor machinist to have white hair.
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