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- 19 February 2008
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you can remove dowels with a needlenose
Semi-DIY Mild Engine Build for FI
- Thread starter Mac Attack
- Start date
Thanks Ross, I'll give it a try tonight.
Two pieces of thick paper sound good. Maybe you could tape the two pieces of paper together when they’re sitting on the intake and exhaust valves – then you could measure directly from that without having to trace the outline. In any case, thanks!
Mac, is that a crack in your middle spark plug hole? I cant tell.
Good eyes, thanks! I just looked and it must have been some debris in that picture.
I think I can do some more work on it tonight. Last night was car shopping.
I think I can do some more work on it tonight. Last night was car shopping.
I can’t answer your question regarding the head dowels either, but it’s great to see what you’re doing!
While the cylinder heads are off, is there any chance you could measure the included angle between the intake and exhaust valves? It looks like it should be about 61° based on Honda’s drawings, but it would be nice to cross check that with a real measurement.
Also: could you measure your cam lobes along the two axes in the picture?
Honda lists the cam lobe heights on page 3-2 of the 1991 Service Manual, but not the diameter of their base circles. Next time I take my "high lift" camshafts out, I can then measure how much more lift they really give than the stock camshafts.
I transferred the angle to paper that I can measure tomorrow at work. Thought I had a protractor at home, but was glad to realize I didn't :wink:
Using my trusty calipers that were free to me, here are the following front bank cam lobe measurements for my manual transmission OEM cams with ~130k miles:
Intake Cam (inches):
----------S/M Lobe New----My Lobe----Diameter
Primary_____1.4601________1.4585_____1.2380
Mid________1.4975________1.4960_____1.2460
Secondary__1.4695________1.4680_____1.2380
Exhaust Cam (inches):
----------S/M Lobe New----My Lobe----Diameter
Primary_____1.4393________1.4345_____1.2350
Mid________1.4724________1.4680_____1.2425
Secondary__1.4465________1.4420_____1.2350
The SM doesn't give any service limits. Do cams wear? My intake lobe measurements were consistently 0.0015" less than new specs. My exhaust lobe measurements were consistently 0.0045" less than new specs.
Hope that helps,
Dave
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Thanks – those measurements help a lot. Now I’ll be able to see how much lift my Comptech camshafts give and will post up the results when I have them.
Unfortunately yes, cams do wear but I’d contact Larry Bastanza or Shad Huntley to learn how to judge their condition.
Unfortunately yes, cams do wear but I’d contact Larry Bastanza or Shad Huntley to learn how to judge their condition.
It looks like my exhaust cam diameters I measured above for the primaries and secondaries is questionable when I look at them this morning. Let me recheck those tonight.
I measure a valve angle of 62 degrees.
Also, the valve pocket angle on the Wiseco pistons is 30 degrees:
I measure a valve angle of 62 degrees.
Also, the valve pocket angle on the Wiseco pistons is 30 degrees:
so what is this "pocket angle" exactly ?
I edited my above exhaust cam diameter measurement. Now the primary and secondary diameters match like on the intake cam.
I'm curious what your Comptechs measure
Thanks for the measurements!
The pocket angle is the angle of the valve pockets in the top of the piston relative to the top of the engine block. The angle of the intake pockets in the Wiseco pistons is 30° relative to that and the exhaust pockets are angled 30° in the opposite direction. So the shape of the piston top matches the shape of the combustion chamber in the cylinder head, which Mac Attack measured as having a 62° included angle.
I wonder why Honda chose such a wide angle, though. Such a large angle creates a banana-shaped combustion chamber (in profile) because the piston has to have a hump in the middle to achieve a decent compression ratio and that valve angle precludes having the intake charge flow into the cylinder along the axis of the piston. Maybe the VTEC system simply required such a wide spread. Maybe Honda wanted 35mm intake valves but didn’t want to enlarge the bore as much as would have been required at the time to create a more efficient combustion chamber shape. Or it was something else.
Thankfully, NSX cylinder heads seem to flow very well despite the wide included angle between the intake and exhaust valves.
The pocket angle is the angle of the valve pockets in the top of the piston relative to the top of the engine block. The angle of the intake pockets in the Wiseco pistons is 30° relative to that and the exhaust pockets are angled 30° in the opposite direction. So the shape of the piston top matches the shape of the combustion chamber in the cylinder head, which Mac Attack measured as having a 62° included angle.
I wonder why Honda chose such a wide angle, though. Such a large angle creates a banana-shaped combustion chamber (in profile) because the piston has to have a hump in the middle to achieve a decent compression ratio and that valve angle precludes having the intake charge flow into the cylinder along the axis of the piston. Maybe the VTEC system simply required such a wide spread. Maybe Honda wanted 35mm intake valves but didn’t want to enlarge the bore as much as would have been required at the time to create a more efficient combustion chamber shape. Or it was something else.
Thankfully, NSX cylinder heads seem to flow very well despite the wide included angle between the intake and exhaust valves.
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I'm still wondering why they used a 90 degree V6 configuration too.
whatever the reasons IMO they've engineered it to perfection. From 5,500 - 8,000 rpm my NSX engine is amongst my very favourite all time machines
- Joined
- 19 February 2008
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what he said ^^^^^^^^^^^
Pulled off the oil pan, pickup and windage tray.
As I dumped out the residual oil from the pan, I noticed this sludge on the bottom... WTF?
I replaced my pan almost two years ago when I changed to the '97+ manifolds. TiDave welded a baffle in and powdercoated the pan. I'm guessing this might be rust from the uncoated parts that settled out? I need to get my mirror and look.
Anyways, took off the oil pump and main seal. Now I need to remove the cylinder wall ridges before I force the old pistons out. Even though I'm not reusing the old pistons, I'd like to knock some of the ridge off and not break the ring lands. The SM says to use a ridge reamer, but I'm a little leary for fear of screwing up the wall. My plan is to use 400grit sandpaper and carefully remove some of it.
Oh, I couldn't take 3 out of the four cylinder head dowels out of the block. For fear of doing any heating and risk cracking it, I'm just going to let the machinist do this.
As I dumped out the residual oil from the pan, I noticed this sludge on the bottom... WTF?
I replaced my pan almost two years ago when I changed to the '97+ manifolds. TiDave welded a baffle in and powdercoated the pan. I'm guessing this might be rust from the uncoated parts that settled out? I need to get my mirror and look.
Anyways, took off the oil pump and main seal. Now I need to remove the cylinder wall ridges before I force the old pistons out. Even though I'm not reusing the old pistons, I'd like to knock some of the ridge off and not break the ring lands. The SM says to use a ridge reamer, but I'm a little leary for fear of screwing up the wall. My plan is to use 400grit sandpaper and carefully remove some of it.
Oh, I couldn't take 3 out of the four cylinder head dowels out of the block. For fear of doing any heating and risk cracking it, I'm just going to let the machinist do this.
Well, the engine exhaust has never been white or had a coolant smell to it. It's never lost any coolant or gained any in the overflow bottle. It's just a little bit of yellow sludge in the oil pan. It's never driven on short trips - mostly 20 miles or over at a time. PCV should be working fine....
Maybe it's because I've taken so long between the time I removed the head gasket and removed the oil pan? I'm sure coolant has dripped down to the oil pan and sat there for what, three weeks now? Maybe I'll pour a little bit of coolant in a cup of oil and observe what happens after a few weeks.
Anyways, made some more progress. Finally, almost down to the bare block But then I look at my workbench and wonder "what have I done?"
The pistons can only come out from the top. According to the SM, it says you should use a ridge reamer to remove the carbon at the top of the cylinder wall. Otherwise, you can crack the ring lands on the pistons if you shove them out forcefully. I'm not reusing these pistons, but still didn't want to damage anything. A quick internet search shows ridge reamers can do more harm than good most of the time, so instead I gently used a wire brush and 400grit sandpaper to clean off the carbon.
Just be gentle and don't scrape into the cylinder wall and you'll get this:
Then, you can set the crank for bottom dead center on a particular piston, remove the rod cap, slip a cover on the rod studs so you don't scratch the crank when pushing out the piston, and get someone to help catch it as it's pushed out:
Having fun spinning the crank... After looking at this picture again, I'm glad the pulley didn't fall on their toes :redface:
There was virtually no wear on the rod bearings. Now onto removing the crank. I had already untorqued the main caps before removing the pistons. I couldn't find any proper untorquing steps in the SM, so I just went backwards from the torquing procedure turning the bolts 1/8th turn at a time in sequence. After they are all untorqued, the SM says to screw two of the big bolts in each cap as shown to help remove them. They are doweled and a tight fit, but can be wiggled and pulled up. Last cap to remove:
Just #2 and #3 bearings had some wear on them. The crank is smooth as can be:
Main cap bearing side:
Guess I got lucky. Besides a tad of coolant sludge in the bottom of the pan (need to test my theory on what caused it during engine disassembly), the engine is in good shape overall. This is the first engine I've ever taken apart, and I'm certainly no expert, but it seems to be clean and in good shape for being 20YO with 130k miles on it (and saw redline daily for a good 6 years as my daily driver).
Looking forward to handing everthing over to the machine shop!
Maybe it's because I've taken so long between the time I removed the head gasket and removed the oil pan? I'm sure coolant has dripped down to the oil pan and sat there for what, three weeks now? Maybe I'll pour a little bit of coolant in a cup of oil and observe what happens after a few weeks.
Anyways, made some more progress. Finally, almost down to the bare block
But then I look at my workbench and wonder "what have I done?"
The pistons can only come out from the top. According to the SM, it says you should use a ridge reamer to remove the carbon at the top of the cylinder wall. Otherwise, you can crack the ring lands on the pistons if you shove them out forcefully. I'm not reusing these pistons, but still didn't want to damage anything. A quick internet search shows ridge reamers can do more harm than good most of the time, so instead I gently used a wire brush and 400grit sandpaper to clean off the carbon.
Just be gentle and don't scrape into the cylinder wall and you'll get this:
Then, you can set the crank for bottom dead center on a particular piston, remove the rod cap, slip a cover on the rod studs so you don't scratch the crank when pushing out the piston, and get someone to help catch it as it's pushed out:
Having fun spinning the crank... After looking at this picture again, I'm glad the pulley didn't fall on their toes :redface:
There was virtually no wear on the rod bearings. Now onto removing the crank. I had already untorqued the main caps before removing the pistons. I couldn't find any proper untorquing steps in the SM, so I just went backwards from the torquing procedure turning the bolts 1/8th turn at a time in sequence. After they are all untorqued, the SM says to screw two of the big bolts in each cap as shown to help remove them. They are doweled and a tight fit, but can be wiggled and pulled up. Last cap to remove:
Just #2 and #3 bearings had some wear on them. The crank is smooth as can be:
Main cap bearing side:
Guess I got lucky. Besides a tad of coolant sludge in the bottom of the pan (need to test my theory on what caused it during engine disassembly), the engine is in good shape overall. This is the first engine I've ever taken apart, and I'm certainly no expert, but it seems to be clean and in good shape for being 20YO with 130k miles on it (and saw redline daily for a good 6 years as my daily driver).
Looking forward to handing everthing over to the machine shop!
Clevite has a nice bearing failure analysis guide here:
engineparts.com/publications/CL77-3-402.pdf
According to this, it looks like the symmetrical wear on my center bearings is due to a distorted crankcase or crankshaft, or both. Then, the other bearings had foreign contamination. My oil sample reports over the years have said the silica contents were a little high. I've only used the OEM air filter, and then the Unifilter in the past five years.
I'll see what the machinist says.
Another thing... There is a REALLY nasty smell when removing the main caps and bolts. Almost like vomit stench. Is that from 20YO assembly lube or oil? I had to open the garage door a few times to air it out.
engineparts.com/publications/CL77-3-402.pdf
According to this, it looks like the symmetrical wear on my center bearings is due to a distorted crankcase or crankshaft, or both. Then, the other bearings had foreign contamination. My oil sample reports over the years have said the silica contents were a little high. I've only used the OEM air filter, and then the Unifilter in the past five years.
I'll see what the machinist says.
Another thing... There is a REALLY nasty smell when removing the main caps and bolts. Almost like vomit stench. Is that from 20YO assembly lube or oil? I had to open the garage door a few times to air it out.
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that's some document on bearing failure - normally I'd store such a doc for future ref. But do I really expect to do a bearing? nah, never!!
First of all, everything wear. Considering the enormous amount of stress the bearings are subject to, its amazing that they hold up as they do. Breaking down an engine, Honda or not, that has seen 20 years, 130 k miles with daily 8000 rpm travels, you should expect some wear.
Let the machinist get all the measurements of the parts, that should point you to if the wear is normal or over excessive due to malformations or contaminations.
Good news is, that you are in fact rebuilding the engine so everything should be brought back to specifications so you should have another 20 years, 130k, redline driving ahead :biggrin:
You're exactly right! With my first engine, I just don't know how much is to be expected.
I'm also glad this is being rebuilt. But I'd like to know what caused a coolant leak for the sludge in the oilpan (hopefully just condensation), and also the seemingly weird bearing wear patterns. If it's foreign contamination from silica (like my oil analyses said), then I will probably consider better air filtration in the future!
Thanks,
Dave
Removed the coolant drain bolts from the block and everything else. The block is now STRIPPED. Wheeled it outside and degreased it even more. Then cleaned up the exterior with some wire brushing. Be careful and don't ever wirebrush any machined sealing surfaces! Back outside for a final clean and rinse. Make sure to immediately put some oil or WD40 on the cylinder walls or surface rust will form.
Now it's ready for dye penetrant testing. I wanted to clean off the outer layer of oxide and crud in preparation. I doubt this test will show anything (because of the low probability of having cracks, and also of the even lower probability of a NDE noobie like me correctly identifying them). Oh well. It's cheap, simple, and a good thing to do.
http://www.ndtsupplies.com/01-5970-48.html
Getting tired of engine and workbench pictures yet? Monday I'll pick up some calibrated precision micrometers from work to calibrate my dial bore indicator (for bore "before and after" measurements from the machinist).
Now it's ready for dye penetrant testing. I wanted to clean off the outer layer of oxide and crud in preparation. I doubt this test will show anything (because of the low probability of having cracks, and also of the even lower probability of a NDE noobie like me correctly identifying them). Oh well. It's cheap, simple, and a good thing to do.
http://www.ndtsupplies.com/01-5970-48.html
Getting tired of engine and workbench pictures yet? Monday I'll pick up some calibrated precision micrometers from work to calibrate my dial bore indicator (for bore "before and after" measurements from the machinist).
no way ! the more the better
x2 Keep us updated Dave. :smile:
Not sure I'd use WD40 on the walls. I'd probably use Corrosion X or Rem oil.
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