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3.2 Rebuild & Modify Thread
I'm restoring my '84 911 3.2 and building it back up as street tuned turbo. I figured I'd start a thread on the engine rebuild as this is my first air cooled rebuild and I could really benefit from your expertise. The engine has 130k on the clock, has good compression, and seems to be in good shape overall.
The goal of this build is to refresh the engine and strengthen where needed. I will be running about 7 psi of boost through a custom turbo and standalone ECU. My goal is about 320hp and a 7k redline. Key parts of the build plan: - (hopefully) reuse the cylinders and pistons - Pauter rods - Aasco valve spring and titanium retainers - Regrind cams to 964 spec - Twin plug heads w/ coil on plug - ARP head studs - Patrick 60-2 lightweight flywheel - ECU Master Black ECU I have a separate thread HERE where I will detail the development of the turbo system. The rust repair, body work, suspension, etc. are all happening in parallel so this isn't going to go very quickly... http://forums.pelicanparts.com/uploa...1731951370.JPG |
Save some money and use your stock springs and retainers. You do not need Aasco valve spring and titanium retainers base on your build specs, they might even be considered a detriment for a street car.
john |
What's different about this thread, compared to the other well established thread?
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This thread is about the engine rebuild, not about the turbo. The goal here is to share the process of rebuilding the engine and get pointers along the way.
The other thread is focused on the development of the turbo system. That's a huge project on it's own. That's my thinking anyway. |
targa72e, I went back and forth on the Aasco springs. The general sense I got is that the stock springs are questionable at 7k and I'd really like to have that redline. I also like that they give some insurance against an over rev causing piston to valve contact.
All that said, I don't like titanium retainers in a street engine. They don't last forever like steel does...and dropping a valve is a nightmare. I also don't love the additional wear on the camshafts and rockers. No right answer but I already bought them so no going back now! |
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The teardown is happening. Such a treat to work on this engine.
A few notes: - Disassembly has been pretty straightforward. I eventually upgraded my engine stand as it felt insane to have a $20k engine sitting on an unstable $50 harbor freight stand. - The dots on the engine are there bc I 3D scanned it. - I cannot believe how clean the inside of this engine is. 130k on the clock and almost no varnish. The cylinder heads are about 30% bare aluminum…like the carbon just chips off. I’ve never seen that before. An air cooled thing? - The cams are pretty wrecked. Pitting on 4 or 5 lobes. Planning to send to Dougherty to regrind to 964 profile and get the rockers redone too. - The bores look really good, but we’ll see how they measure out. - As others have suggested, an oxy-acetylene torch made removing the exhaust manifold bolts easy. This is a northeast car and all other exhaust bolts had to be cut. - The tins are pretty toast. Lots of rust. So expensive to replace… Somethung to figure out. - The heads will be sent out to be rebuilt, but I’m not sure where. Ideas? I’m posting a bunch of photos in case it’s helpful http://forums.pelicanparts.com/uploa...1732677037.jpg http://forums.pelicanparts.com/uploa...1732677037.jpg http://forums.pelicanparts.com/uploa...1732677037.jpg http://forums.pelicanparts.com/uploa...1732677037.jpg |
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You eat a lot of bananas .
What engine stand did you buy ? |
Ha, I get those boxes at Costco. They are the best for parts.
I bought a “bid red” 1,500 lb engine stand on Amazon. Four wheels and much more stable. The yoke that mounts to the back of the engine came from eBay. For $240 it was surprisingly well made. It did require some grinding to clear the exhaust though. |
Engine fully torn down and looking good.
I cleaned the pistons with B12 which is my go to. It doesn’t corrode aluminum like most degreasers and it’s incredibly good at dissolving carbon. This engine made nearly zero oil pressure at idle, but I found nothing that would have caused that inside the engine. Low oil pressure at idle seems common I guess. I can also say that the low oil pressure did not result in any bearing damage. The main and rod bearings looked great. #7 showed the most wear but it’s not bad. All journals are nice and clean. The pistons and cylinders look really good. Very happy about that. The intermediate shaft gear has pitting on the teeth so that will need to be replaced. The gear in the crank looks good and hopefully that can be used. Next up will be measuring everything and sending the heads to the machine shop. http://forums.pelicanparts.com/uploa...1733202959.jpg http://forums.pelicanparts.com/uploa...1733202959.jpg http://forums.pelicanparts.com/uploa...1733202959.jpg http://forums.pelicanparts.com/uploa...1733202959.jpg http://forums.pelicanparts.com/uploa...1733202959.jpg http://forums.pelicanparts.com/uploa...1733202959.jpg |
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Bolt the case together with the nose bearing, torque to spec and measure the journal sizes. Should be 65.00-65.019mm.. I see lots much larger than that.... |
I agree Mike. I was actually hoping to find something obvious but didn't. I tore the pump down and it looks mint inside.
Before I tore the engine down I confirmed nearly no oil pressure at idle with an external gauge. Installing cam box oil restrictors solved it, but I'd rather than run the restrictors. I am going to run a GT3 pump which has a pressure side that's 30% larger (I think) but I still need to figure out why I had low oil pressure. I will be measuring everything and will share back here. |
I started measuring tonight and have some indication on where the oil might have been going. The crank journals (main and rod) are all on the low end of the spec range. Thankfully within spec but right on the bottom end.
The journals all look so clean and bearings show so little wear that I suspect that the crank started life on the low side of the spec. I did a quick plastigauge check with the old bearings and the mains showed 0.002" to 0.003" of clearance. Impossible to be precise with plastigauge but it's definitely up near 3 thousandths on a few journals. I suspect that I'll end up going to a coating to get the main bearing clearances down to 1.5 to 2 thousandths. I'm okay running ~2.5 thousandths on the con rods but I think the mains need to be tighter. Next I'll measure the case bores and see how they compare to spec. Once I get the new bearings I'll also compare those to the old ones. http://forums.pelicanparts.com/uploa...1733283507.jpg |
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Good call mikedsilva, I measured the case bore and it's way out of spec. I'm pretty surprised as this engine has never been taken apart and everything was in such good shape. I thought the aluminum cases were solid.
I'm getting 65.045mm - 65.060mm which was a long way from the max spec of 65.019mm. The funny thing is that when I do the calculations with the bearings I measured (all very consistent at 2.495mm) and crank journals (all on the lower edge of the spec ~59.972mm) it indicates that I should have a clearance of nearly 0.1mm or 0.004". The plastigauge was showing between 2.5 and 3 thousandths. At any rate, I'm going to send the case to Ollie's to have it line bored and I'll have the crank cross drilled while I'm at it. |
Quick update on the rebuild:
- Case was sent to Ollie’s to be surfaced and bored back to stock - Also sent rotating assembly to Ollies for complete balance - Heads were sent to Craig for rebuild - Cams and rockers went to Dougherty for 964 grind and refinish It’s going to be a while before I get everything back, but I have plenty of work to do on the car to get the shell ready for paint. In the meantime I had the parts on hand vapor blasted. Some people find the finish too bright but I love it. I cannot believe how well it worked on the heat exchangers and crossover pipe. They were rough looking. http://forums.pelicanparts.com/uploa...1734657483.jpg http://forums.pelicanparts.com/uploa...1734657483.jpg http://forums.pelicanparts.com/uploa...1734657483.jpg |
what media do they use in the vapour blasting?
Dont forget to remove your spray tubes and clean them I ultrasonic clean vapour blasted parts maybe 10 times to get all the media residue out.. it's amazing how much you find. |
I can feel the ceramic/glass on the surface. Definitely going to pull plugs on the cam houses and clean everything. Good to know that one or two good cleans will not be enough!
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For cleaning, definitely remove any plugs. The ultrasonic is a good first step to loosen up everything and get the media off the surfaces. For getting into holes/bores/internal passages, I would also get an air gun with a small needle tip. Submerse the hole part in water before you blow into the holes, and you will usually get out a lot of additional media out of it. Repeat the process multiple times, you can't overclean and it might save you lots of grief and money down the line. :eek: |
Rebuild cylinder heads are back from Craig / cgarr. Good communication with him throughout and the heads look amazing. I cannot wait to get these on!
These have Aasco springs and retainers, new valves and guides, and machined for twin plug. The case it at Ollies and will not be done for a little while… http://forums.pelicanparts.com/uploa...1739650318.jpg http://forums.pelicanparts.com/uploa...1739650318.jpg http://forums.pelicanparts.com/uploa...1739650318.jpg |
I did a test with the Audi 1.8T coils and FR5DTC plugs and the fit is good. I’m going with these coils as I’ve tuned with them before and they are bomber…and they are cheap. I’ve also used this plug before and it happens to be stick for the 964. I’ve never heard of anyone using it on a 3.2 but I think it should be fine.
The coil is very snug on the lower cover and sticks out a decent bit on the upper cover. I think a 3D printed collar will help it seal and look nice on the upper cover. http://forums.pelicanparts.com/uploa...1739653346.jpg http://forums.pelicanparts.com/uploa...1739653346.jpg http://forums.pelicanparts.com/uploa...1739653346.jpg http://forums.pelicanparts.com/uploa...1739653346.jpg http://forums.pelicanparts.com/uploa...1739653346.jpg http://forums.pelicanparts.com/uploa...1739653346.jpg |
I do like the little plastic stand offs fitted to the studs for shipping :)
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The heads look amazing!
What's up with the little dots everywhere? |
The little dots are markers for 3D scanning. I’m building a turbo system detailed here:
https://forums.pelicanparts.com/911-930-turbo-super-charging-forum/1165542-3-2-turbo-build.html |
Really enjoying this thread. The rebuilt heads look amazing - along with all the other nice pieces cleaned and detailed. Would you mind sharing the Audi coil part number? I've recently completed a 3.0 single TBI/ DBW with ECUMaster Black on single Audi COPs, but my coils seem to tower over the upper valve cover while your set appears more flush. I am going dual COP so I really need your Audi coils for the lower valve cover. I'd love to get your COP part no if you don't mind... Patrick
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The coils are for a 1.8T Audi / VW part number: 06B905115R. I get Bremi as I think they are the best and they are also only $20 each. The coils for the 2.0T engines are a little hotter but they are longer than the 1.8T coils.
I’m not sure but my coils may be sitting lower than yours due to the spark plugs. The FR5DTC plugs I’m running may be a little shorter than the stock plugs. Just a theory. |
Actually, I’m quite sure it’s the spark plug height difference as there is a photo earlier in this thread that shows my first test fit with these coils. That was with the sock plugs and the coils sat very high.
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I think I'll do some sparkplug homework and order a set of your style of plugs. I think Adapt Motorsport recommended a Denso plug that I went with. Perhaps it is a bit too long. * Guess you had the 2nd plug drilled and tapped for 14mm so all plugs are the same... This is your plug you mentioned: BOSCH Porsche Genuine OEM Spark Plug Super FR5DTC I'lll stop cluttering up your thread... I do like all three threads you have going. Quite overwhelming - all that you have going on! Thanks, Patrick |
I have a little more info on the Audi/VW coil pack fitment. There are two reasons that the coils sit lower with the FR5DTC plugs vs the OE 3.2 plugs.
First the FR5DTC is a shorter plug by about 4mm. Second, the bottom of the coil is supposed to go over (and grip on) the hex on the plug but the OR plug is too large for this to work. The coil is then not able to be pushed down fully. TLDR, if you want to use the Audi/VW coils, you need to use spark plugs with a 5/8” hex size. http://forums.pelicanparts.com/uploa...1744945278.jpg http://forums.pelicanparts.com/uploa...1744945278.jpg http://forums.pelicanparts.com/uploa...1744945278.jpg http://forums.pelicanparts.com/uploa...1744945278.jpg http://forums.pelicanparts.com/uploa...1744945278.jpg |
My case and crank just got back from Ollie’s. Very excited to build this engine!
The guys at Ollie’s decked the case and line honed the mains back to standard. They also grooved and cross drilled the crank. Lastly they balanced everything to within a fraction of a gram. I plan to rev to 7500 so the crank needed to be grooved and cross drilled from what I hear. Maybe would have been a good idea to shuffle pin the case but I think it will be fine for street use. I’ve been measuring everything first. Tedious but I’m not going to rush this build. The main bearings from Porsche very very consistent. The Clevite rod bearings were just dead on. Probably more accurate than my measuring. Everything looks great except I may have too little clearance on the rods. My clearance is coming in at about 0.001” and from what I’ve heard it would be best to be at 0.002”…maybe even a little more given that I’m boosting the engine. I’ll make some calls tomorrow and see what the pros think. Getting a thousandth taken off the rods is likey to take a few weeks… I did drop the GT3 oil pump in to test the clearing that Ollies did. Perfect! http://forums.pelicanparts.com/uploa...1744945985.jpg http://forums.pelicanparts.com/uploa...1744945985.jpg http://forums.pelicanparts.com/uploa...1744945985.jpg http://forums.pelicanparts.com/uploa...1744945985.jpg http://forums.pelicanparts.com/uploa...1744945985.jpg http://forums.pelicanparts.com/uploa...1744945985.jpg |
I found an easy way to test piston squirters. A Sharpie marker has just the right diameter and taper to (mostly) block off the oil passages and allow you to use an air gun to test the squirters.
Passenger side case half: Insert the sharpie to block off the passages inside the case bolt bore. Then use your air gun on the main bearing oil hole. I filled things up with brake cleaner and then applied pressure to give a visual of the squirter opening. The oil squirter passage intersects the passage from the case bolt bore to the bearing. The Sharpie blocks off the case bolt side of this passage so all the air goes to the squirter. Drivers side case half: This one is much easier. The squirter oil hole is visible right at the top of the case bolt bore. The Sharpie is just used to block off the outer side of the case bolt bore. Then you just need to apply air pressure to the top of the inter case bolt bore. http://forums.pelicanparts.com/uploa...1745175945.jpg http://forums.pelicanparts.com/uploa...1745175945.jpg http://forums.pelicanparts.com/uploa...1745175945.jpg |
I called the guys at Pauter about my low rod bearing clearance and they were very helpful. I was calculating clearance by measuring the rod journal, rod big end bore, and bearing thickness. Instead, they suggested I install the bearings in the rod and measure the bore with them in. That yielded almost exactly 0.0025” which is my target.
I know the other way I measured is also correct so I really don’t know where the error was coming from. I have triple checked and I’m right around 0.0025” for all rods. Good to go! |
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I'm not sure why your measurements weren't adding up when measuring the bearing shells separately, however with the bearings in the rods and the bolts torqued, this is how they are going to live in reality, so it's the measurement to rely on. Case looks awesome. |
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