Dennis Wilson

Klim,

A good machine shop will check each valve seat and valve for signs of burning/cracking, sideways movement in the valve guide, check for cracks on the head surfaces and water jacket. If everything is OK they will reassemble with the new valves seals (from your set), surface the head and charge you accordingly. The shop I use charges $50 for this service.

You can check the cam visually to see if any of the lobes have abnormal wear/flattening. If any lobes have a wider wear area or the corresponding cam follower show hollowing or pitting take them to the machine shop for actual measurement to see if they are within spec.

You can check the rod bearings by removing the cap and look for signs of scoring, wear through the babbit (lead colored coating) or pitting. Next buy some Plastigage (.001 to .003" range) from your local parts store and check the wear on each bearing. If the bearing wear is beyond spec, new bearings (mininum) or turning the crank and replacing the bearings with oversized will be required. If they are withing spec, clean, clean and clean all the surfaces, apply assembly lube and reinstall.

Dennis

mulik51

So, really, the things I will need to replace, if the heads are in good cond(like no bent valves, worn guides, etc) are valve seals and some gaskets on the cam housing? What about lifter sleeve gaskets? So, I can take the head apart, an will not need to resurface the seats or the faces. right? So, the only machine shop work is going to be resurfacing of mating surface of the head. Good.
I WSM it says to use a special tool for installing the valve seals and installing them. Wil I need that special tools ot it can be done without them?
Dennis: You mean you bring the head disassembled to the shop, the perform all that work, and then assemble it for you for 50$?(using your parts)
Thanks,

KLim

Dennis Wilson

Klim,

The only thing I would take off the head are the cam followers and make sure you keep them in the correct order. The machine shop will want to keep the valves in the correct order so taking them out is not advised. If you take them out and they find a problem, they may not warranty their work. If your shop doesn't have the "special" tool (tubular valve seat inserter) find another shop.

Yep the shop I use inspects, surfaces and puts in new seals for $50. I recently had the 931 head rebuilt and he charged $75 due to one valve seat needing a regrind. BTW a good shop will shorten the valve by the same amount as the seat regrind. This isn't usually critical on the 928 (hydraulic cam followers) but it is still a good practice.

Dennis

GlenL

Next time I'm driving to OK. The shop I use charges $250 per pair for the basic head service: take apart, inspect, surface, hot tank, re-assemble.

Dennis Wilson

Glen,

May be worth the trip. His name is Gary Robinson and he is located in Broken Arrow. He was recommended to me by the prior Porsche Dealer, Rennsport Werkstadt and Charlesworth Motors. I have his phone number at work if you ever need it give me a shout.

Dennis

Big Dave

These are rod bearings, and you can see the coating is worn. With the engine out and the oil pan off, it's an easy job to replace them. I wasn't sure if I needed to replace these, but with 117,000 miles, I just went ahead and did it.

mulik51

Ok, I will make some calls tomorrow. As soon, as I will find something, I will write it up.
Dave, how much did you pay for the rod bearings? It is not like you just take them off and them replace them? SHouldn't you gap them, or anything like that?

Thanks,

Klim
P.S. I like the 50$ a lot more then 250$ Maybe I will need to find out the shipping info to the OH...

mulik51

Hey.
I am calling the power-tech in New Jersey. This guys give warranty, and are a good name, and specialize in Porsches. So, I guess it will be the best choce(don't know the price yet, they are figuring it out, but I would rather pay 100$ over then get a bad job done). Maybe somebody knows a good mashine shop in New Jersey?

ALlright, today I got the camtower off. I put the lifters in different, numbered bags to keep track of them. Can somebody please explain how do lifters work? I thought it was just an intermidiate piece of mashinery between cam and valves, to keep it more stable. But then why are they called "hydrolic" lifters? Then in the manual it says to store them with the oil bore up. Is it becouse the oil will come out? Can I put the oil in through the suringe? Should the oil bore on th elifter align with the oil bore in the sleeve?

Thanks a lot,

Klim

docmirror

Klim, can you please summarize where you are with the block, and then with the heads? I'm not sure I follow all the prev posts well, and there are a bunch of questions still dangling. Is the engine on a stand?

Thanks,

Doc 90GT in resto

mulik51

I have 2 engines. One, 4.7 liters is a pure block, wihtout anything on it. I have another engine, 4.5L which I just pulled out. This one has all the components on it. My original plan was to simply put all the stuff from 4.5. to 4.7. But then on this forum I found out that I need to resurface the heads before putting them on. That's the end of the story, pretty much.
I got a call back from power-tech. They want 105$ per head for resurfacing, 30$ for inspection, 520$ for reassembly of the head. That is out of my budget. Completly. I could pay 300$, but not 800$.So,I will give try to find another shop. Maybe somebody can recommend one in NJ? Is it absolutely necessary to resurface the head? I mean is there anybody who didn't resurface the heads before putting them in, and the car run fine? Can I resurface the heads without disassemmbliing them?
I know, I asked this questions allready, but I didn't get an answer.

Thanks,

Klim
P.S. BTW, what is the best way to get the old gasket off the head. I mean cam gasket and head gasket.

Thanks

docmirror

Okay, this isn't really what I was looking for, but let's see if we can't get you back together. It looks like you want to build a 4.7L but without any crankshaft, pistons or rods, it won't run very well. Next, it sounds like you're on a tight budget. And when you say 'Porsche' you should not say 'budget'. It's like oil and water, they don't mix well.

So, I've gone back over the prev posts again, let's see if any of this helps. I noticed you didn't answer my question about the engine stand, so we'll deal with that later.

Once pistons and rings are installed in a bore and run they take a 'set' to that bore. Microgrooves develop on both that are similar to the lands a grooves in a pistol barrel and bullet. You cannot(should not) move pistons and rings to another block. To do this, remove and discard the rings. buy new rings, hone the block, then wash (this is Aluminum, so use a very fine grit) per WSM. Install one ring, center it with the piston and check ring end gap. It must not be more than 0.0035" per inch Dia of bore. So, for a 3.5" bore, the max would be 0.0035 X 3.5 = 0.012" gap. If larger, get oversized rings, and a ring end file and make it so.

If you leave the rings and piston in the bore, and want to clean the top of the piston, put the engine on a stand(buy or rent), turn the crank so that a piston is at the top, then TURN THE ENGINE UPSIDE DOWN so the piston is facing the ground. Now, lay on your back, with some rags, and small wire brushes, and a bowl of cleaning solvent or thinner(I use spritz carb cleaner). Clean the piston, and the junk will not fall in the piston and bore gap. Use carb cleaner to finish up the cleaning process, then move to another piston.

While the engine is upside down, remove and inspect one of the rod bearings, by taking off one cap and gently tapping the cap loose. Look at Dave's photos. Clean the cap, and look for grooves, or wear on the facing of the shell. Rotate the crank CAREFULLY away from the rod journal. Clean and inspect the bearing in the rod end. It should be uniform color, and minimal grooves with no gouges, and no flakey stuff. Lube and reinstall the bearing torque the cap bolts per WSM. If you see bad things, plan on all new bearings.

Heads: This is where the power is. Trying to save money here will cost you money down the road. I didn't know that you must surface the heads to get them to fit on a different block. It is always a good idea to surface the heads to improve sealing, but it may not be required. If you are really cheap, proceed as follows:

Get on Ebay and buy a ROLL of sandpaper 2' X 50'. You will only need a few feet, but it can't be joined, so you need a roll. 220 Grit or 300 or higher, wet type is better. Find a piece of glass that is fairly thick, and about 3' X 4'. Cut some paper off the roll, tape it to the middle of the glass, then wrap it around the end of the glass, pull it tight and wrap it around the other end, then tape that to the glass using duct tape. You now have a home made 'surfacer' tool. Put the glass on a hard, flat surface, then spray water on it, and then set your head on the paper on the glass (I can't believe I'm doing this). The idea is not to take off a bunch of material, but to get the sealing surface smooth and uniform finish. Work the head back and forth on the paper on glass tool, and take it off regularly to check the finish. When you have taken a small amount off the whole head, stop. Do not put a lot of pressure on the head. Do not keep grinding until you are awash in aluminum. Go gently, and you will have exactly what the shop does for $100 each.

Valves: Use a spring compressor and remove all the springs, keepers, retainers, and seals. Clean the heads of the valves. Leave the valves in place. Buy a tube of 'Lapping compound' and a valve suction tool, and put compound on the seat of each valve. Lube the valve shaft and use the suction tool in a drill to set the spin the valves to the seats. Don't go overboard here either. Just mush it around for a bit, and don't push too hard. Your valve job is done. Clean and reassemble using new seals, old springs, keepers and retainers.

Cams, lifters: inspect the cam lobes & lifter faces for small pits, or areas that show uneven wear. If there is damage, this must be replaced or reground(not recc). Soak your lifters in an oil bath overnight. Keep the face down, and don't loose track of the location they go back in. Install the lifters in the correct bore right from the oil bath. Install the cam, but be very careful to tighten it in small increments, cams are very brittle.

Your engine is ready for assembly. If you followed the steps above, and use new gaskets, it should seal quite well. This is NOT a rebuild! but it will get you down the road for quite a while. Think clean. Lube everything. Follow the torque specs in the WSM carefully. If it says to lube the head bolt threads, just do it! I don't know if it's an interference or not, but to be careful, align the crank at +45 degrees from #1 TDC. Once together, set the cam timing either by the marks on the gear, or by the more accurate depth gauge method.

Next installment; 'how to paint your car for $50 and make it shine like glass!' Jeez.....

Doc

GlenL

The lifters are hydraulic in that they are pressurized with oil. This gives some cushioning as the cams work the valves.

That head work price is high. I want to do engine work for Porsche owners, too. I'd have a bigger boat. Hell, I'd have a boat.

The gaskets can be scraped off with a razor blade. Careful though are the razor will dig into the aluminum quite happily. A straight blade "window scraper" type works well. Then it's time for the 3M pas and solvent.

mulik51

Doc: thanks a lot for your thourough answer. I have the 4.7 block on the stand, and 4.5 engine on the crate. About the budget thing, you are right, but there is a limit I think. I love my car(even though I never heard it working), and want to restore it. I am not cheap, I mean I can spend 300$ on the head, but not 800$. I just don't find it prudent. I am a student, so, I live on the budget. Becouse I am reparing this car, I actually found a job, but stll, it seems not enough. I didn't change the pistons. The 4.7 block has all the insides in it. So, I am just going to put all the outside stuff on it. The problem with the heads is that they have 15000 miles on it. And when I removed the cam housing and lifters, I was amazed by them. I don't know how a worn lifter looks(how, BTW?), but this ones looked like they never have been used. Not a scratch. So, the heads shouldn't need rebuilt. Howerver I am ready to spend 300$ for quality inspection, resurfacing, and puting it back together with new seals.I can lap the valves myself(isn't the hand technique for valve lapping better then drill?) The technique you proposed for head resurfacing looks really appealing, but I would rather assemble the heads by myself then do that. CAn I assemble the heads without that special tool for the seals? Thanks for the great answer again, it is like Chilton's abridged.
P.S. My car has a great paint job, so if I won't ruin it, it shouldn't really need a repaint.
P.S.S. Great idea on the fliping the engine. Simple, and theoretically effective.
Glen:Thanks. Inside the lifter, there is like a pad. Is this pad driven by the oil? If it is, then why does the whole lifter moves when I rotate the crank? Oh, I think I got it. It is like a shock absorber for a valve. Is that right?

Thanks a lot,

Klim

docmirror

Uh,,,,, In a prev post you said the 4.7 was a bare block. Now it's not a bare block. Man, trying to help you is pulling my hair out.

If the heads have 15,000 and not 150,000 miles they should not need anything. Take the heads to a machine shop, ask the shop for a "deck reference bar", they will set it on the deck of the head, and look for gaps in the center and ends indicating warping. If the head has less than about 0.004" anywhere across the ref bar, just clean in and put it on.

Do what I told you to do with the valves.

I don't know what your mean about assembling the heads, rather than surfacing them. You comment doesn't make sense. It's two different jobs, one cleans the seal surface, the other puts the parts back in the head???

The lifters will show wear by a slight dishing in the center of the face. In rare cases, there is pitting and galling. Cams show wear by uneven marks on the ramps and nose, and pitting.

Yes, a hydraulic lifter is like a little shock absorber for the valve train.

How dare you compare my advice to a Chilton's rag. Why, I ought to......



Doc

mulik51

Hey. I called another shop, and they want 250 for head disassemblly and assembly for both heads(with my seals), 40$ for cleaning of both heads, 40$ to resurface each, 50$ to check each for cracks. This is supposed to be the shop which does Porsche work all the time. I am waiting for a call from another shop on Monday.
About the valves, I thought that to put the seals back on, you need a special tool. And don't I need a special spring compressor, becouse each head is different? What people were saying on this forum, is that even though the heads have 15000miles, the rubber seals for example could detiriorate for 20 years. So, probably the head has no problems with mechanicall, expensive stuff(like changing guides, valves, etc), but it would be probably prudent to replace all the gaskets and seals. What do you think

Thanks,

KLim
P.S. That's what I thought too, about how the lworn lifter should look, but they are completely flat. Maybe I will post the pic later.
P.S.S. For people looking for machine shops in NJ:
1) Windsor Machine
(609) 443-3592
They want 250$ for head disassembly and assembly
2) European Perfomance Center
973-773-4870
Don't know the prices yet.
3) Power tech
Just put in the google "powertech NJ" and you will get all the info.
they want 530$ for disassembly and assembly of the heads.

KLim