Ouch. Two race weekends, two #2 bearing failures?
05-24-2019, 11:08 PM
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Ouch. Two race weekends, two #2 bearing failures?
Help! My race engine blew up (#2 bearing) last month. In just three weeks I sourced a new one, freshened it, and swapped it into the car. Then that one appears to have had a serious lack of oiling too.
I’d like your help in identifying the root cause of what appears to be an oiling system issue.
The entire story is on my Grassroots Motorsports build thread, but I will try to distill it a bit here.
https://grassrootsmotorsports.com/fo...105890/page18/
ORIGINAL ENGINE: Four HPDE's, Two Race Weekends. Spun #2 Bearing
It’s an ’88 944 NA which I bought in 2015. I ran four or five HPDE events, then turned it into a race car in 2016. I ran two races in it, and in Fall 2016 I took it to a NASA HPDE at Watkins Glen and spun the #2 bearing on the last session of the weekend.
JUNKYARD ENGINE: Two Race Weekends. Sold to another racer.
I bought another ’88 engine (not running) and transferred all the good pulleys and stuff to it. I didn't touch the internals, and left the internal oil cooler alone. I got the car running again for the last race in 2016 and a couple in early 2017.
REBUILT ORIGINAL ENGINE:
Meanwhile I rebuilt the original engine with all new pulleys and stuff. I did everything I could to prevent a rod bearing failure:
My rebuilt engine ran the following NASA races:
RACE ENGINE FROM A SHELF: One Half Race Weekend. Oiling Issue Causing Rough Running
I had sold the junkyard engine, so I had to source another ’88 924S engine from a fellow racer. It was full of milkshake, so I freshened it with new rings and rod bearings, and bought a new oil cooler, new lines, and rebuilt the oil console and oil thermostat which appeared to be stuck due to metal pieces.
All the internals remained the same:
Am I "Doing It Wrong"?
I’d like your help in identifying the root cause of what appears to be an oiling system issue.
The entire story is on my Grassroots Motorsports build thread, but I will try to distill it a bit here.
https://grassrootsmotorsports.com/fo...105890/page18/
ORIGINAL ENGINE: Four HPDE's, Two Race Weekends. Spun #2 Bearing
It’s an ’88 944 NA which I bought in 2015. I ran four or five HPDE events, then turned it into a race car in 2016. I ran two races in it, and in Fall 2016 I took it to a NASA HPDE at Watkins Glen and spun the #2 bearing on the last session of the weekend.
JUNKYARD ENGINE: Two Race Weekends. Sold to another racer.
I bought another ’88 engine (not running) and transferred all the good pulleys and stuff to it. I didn't touch the internals, and left the internal oil cooler alone. I got the car running again for the last race in 2016 and a couple in early 2017.
REBUILT ORIGINAL ENGINE:
Meanwhile I rebuilt the original engine with all new pulleys and stuff. I did everything I could to prevent a rod bearing failure:
- Oil pan baffle w/oil pickup skirt
- External oil cooler w/ turbo oil cooler console
- Cross-drilled crankshaft
- Forged rods
- Michael Mount’s “Rod Mod” to accept harder Clevite bearings
- Rebuilt oil pump
- New factory oil pickup
- Ishihara-Johnson Crank Scraper
My rebuilt engine ran the following NASA races:
- May 2018 @ VIR
- July 2018 @ Pitt Race
- November 2018 @ Summit Point
- March 2019 @ VIR
- April 2019 @ Summit Point <— #2 bearing failure led to #2 piston/wrist pin failure. The rod exited through the oil pan.
RACE ENGINE FROM A SHELF: One Half Race Weekend. Oiling Issue Causing Rough Running
I had sold the junkyard engine, so I had to source another ’88 924S engine from a fellow racer. It was full of milkshake, so I freshened it with new rings and rod bearings, and bought a new oil cooler, new lines, and rebuilt the oil console and oil thermostat which appeared to be stuck due to metal pieces.
All the internals remained the same:
- Cast rods
- no “Rod Mod”
- no cross-drilling
- no crank scraper (except for the oil pan which had one built in)
- I didn’t touch the oil pump
- I cleaned the oil pickup w/ skirt from the old engine and used that.
- May 2019 @ VIR <— In Race #1, an apparent oiling failure caused high temps and “grindy” noises in the cam tower.
Am I "Doing It Wrong"?
05-24-2019, 11:12 PM
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Behavior at Failure
Behavior at Failure
The behavior of the temp gauge was similar between the two consecutive weekends of engine failure. The water temperature was slightly elevated.
The oil gauge behavior was a little different:
When the #2 bearing failed in April, the oil pressure was pegged to the top when I started it before warmup. It was a cold morning, though. On track, the gauge was down to around 2 bar just before it blew up. I think the #2 bearing was completely gone at that point.
In May, the water temp gauge was elevated, which made me start to listen carefully. The engine was making some whiny noise. I immediately pulled off the track. The oil pressure gauge was again pegged to the top.
Oil Thermostat: Stuck?
When I disassembled the destroyed engine last month, I took the oil thermostat apart. It was wedged in there and took some vice grips to get out. After cleaning it up it moved freely again. I had NOT rebuilt the oil thermostat when I first put it on the engine, though. I didn’t know it was there. Rookie mistake, I guess. So I don’t know the condition of the oil thermostat or whether it had been working properly ever since July 2017.
Oil Temps: Unknown
I wanted to put in an oil temperature gauge with the sensor right at the oil filter. That would measure the oil temperature right where it is re-introduced to the engine. I didn’t have time to engineer all that before HyperFest, though. Unfortunately, I don’t have any of that data either. I promise I’ll have that the next time.
So after rebuilding the oil thermostat and installing it on the new 924S engine, I wanted to see if the thermostat was operating. But I couldn’t get all that oil up to temperature (105C) in my driveway. At VIR following warmup and qualifying, I did check the oil cooler and the lines to be sure that when the car came off track, there was evidence of hot oil flowing through the cooler and the lines. They were both hot, so I’m sure the thermostat had opened.
Any ideas?
So I’d like any ideas you might have for what these failures might have in common. The only things the two engines had in common were the head, the oil cooler console, the OPRV, and the DESIGN of the external oil cooler. I had replaced the oil cooler and the AN lines to be sure there wasn’t any bearing debris.
The behavior of the temp gauge was similar between the two consecutive weekends of engine failure. The water temperature was slightly elevated.
The oil gauge behavior was a little different:
When the #2 bearing failed in April, the oil pressure was pegged to the top when I started it before warmup. It was a cold morning, though. On track, the gauge was down to around 2 bar just before it blew up. I think the #2 bearing was completely gone at that point.
In May, the water temp gauge was elevated, which made me start to listen carefully. The engine was making some whiny noise. I immediately pulled off the track. The oil pressure gauge was again pegged to the top.
Oil Thermostat: Stuck?
When I disassembled the destroyed engine last month, I took the oil thermostat apart. It was wedged in there and took some vice grips to get out. After cleaning it up it moved freely again. I had NOT rebuilt the oil thermostat when I first put it on the engine, though. I didn’t know it was there. Rookie mistake, I guess. So I don’t know the condition of the oil thermostat or whether it had been working properly ever since July 2017.
Oil Temps: Unknown
I wanted to put in an oil temperature gauge with the sensor right at the oil filter. That would measure the oil temperature right where it is re-introduced to the engine. I didn’t have time to engineer all that before HyperFest, though. Unfortunately, I don’t have any of that data either. I promise I’ll have that the next time.
So after rebuilding the oil thermostat and installing it on the new 924S engine, I wanted to see if the thermostat was operating. But I couldn’t get all that oil up to temperature (105C) in my driveway. At VIR following warmup and qualifying, I did check the oil cooler and the lines to be sure that when the car came off track, there was evidence of hot oil flowing through the cooler and the lines. They were both hot, so I’m sure the thermostat had opened.
Any ideas?
So I’d like any ideas you might have for what these failures might have in common. The only things the two engines had in common were the head, the oil cooler console, the OPRV, and the DESIGN of the external oil cooler. I had replaced the oil cooler and the AN lines to be sure there wasn’t any bearing debris.
05-24-2019, 11:13 PM
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Possible Causes?
Here are a few possible causes:
- inherent design flaw… oil cooler sizing? AN fittings too small (they’re -10 size)? AN fitting bends too severe?
- OPRV allowing oil to recirculate
- Blockages somewhere in the block or the head?
- Oil pressure sensor blocking the oil passage
- Oil thermostat stuck in the open or closed or in-between position
- Oil thermostat not working when it gets really hot?
05-25-2019, 07:46 AM
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My regards sir, you have accomplished a massive amount of mayhem!
First, here are some articles I have written on the subject:
https://newhillgarage.com/2013/06/25...tem-explained/
https://newhillgarage.com/2018/01/12...ump-explained/
I would say with the Michael Mount bearing mod and the crank scraper, you already had what I would consider to be a bullet proof engine. So I'm struggling to give you some good advice. But here goes.
First, what is your redline. Is it limited electronically? Have you ever been accused of having "red haze" problems and thus maybe being rough on the engine? I have to ask, don't take offense.
What oil do you run? What filter? Oil change interval?
Regarding the AN fittings, it's not a bad idea to review these size wise but generally unless you put in reducers or some crazy thing, the effect of local constrictions on the overall system pressure is negligable. That is also, in reverse, why I don't think cross drilling the crank has any benefit but that is another story.
So my number one suspect is your oil pump. You say you rebuilt it but it is not really rebuildable in my eyes. It may have an issue where it is "cavitating", which produces a lot of bubbles in the oil, which is hard on the number 2 bearing. There is no way you can diagnose this condition without expensive lab equipment but it seems to be a common part in several of your engines. I know they are expensive but I would attempt to purchase a new OEM pump.
Are you sure you are running the oil at the right level? To be absolutely sure, at your next tear down you need to dump the factory specified amount of oil into your pan and mount the dipstick to confirm how it reads. The pan with the built in scraper holds more oil than the earlier pan, on my cars. So you need to do a little research and determine what model year car your pan came from and then match up it to the factory recommended fill spec. You don't want to run too low but also not too high, which induces foaming.
Also, check your plastic baffle in the oil pan and make sure the enclosed part (the hollow part held together with screws) is not leaking and thus filling up with oil. The earlier design with little plastic tabs has a problem in that the tabs break off. You need to have the one with the screws. If the cavity were to fill up with oil, you can loose a quart there without knowing.
That's all I've got for now. I know historically folks think the 944 has a problem with the #2 bearing but the actual reported failures here on Rennlist seem to be few and far between. Especially with the later engines like yours. So I think the basic design is sound. You have done an impressive list of things to combat the problem and don't seem to be cutting corners, which is to be commended. Here's hoping your luck turns around!
Harvey
First, here are some articles I have written on the subject:
https://newhillgarage.com/2013/06/25...tem-explained/
https://newhillgarage.com/2018/01/12...ump-explained/
I would say with the Michael Mount bearing mod and the crank scraper, you already had what I would consider to be a bullet proof engine. So I'm struggling to give you some good advice. But here goes.
First, what is your redline. Is it limited electronically? Have you ever been accused of having "red haze" problems and thus maybe being rough on the engine? I have to ask, don't take offense.
What oil do you run? What filter? Oil change interval?
Regarding the AN fittings, it's not a bad idea to review these size wise but generally unless you put in reducers or some crazy thing, the effect of local constrictions on the overall system pressure is negligable. That is also, in reverse, why I don't think cross drilling the crank has any benefit but that is another story.
So my number one suspect is your oil pump. You say you rebuilt it but it is not really rebuildable in my eyes. It may have an issue where it is "cavitating", which produces a lot of bubbles in the oil, which is hard on the number 2 bearing. There is no way you can diagnose this condition without expensive lab equipment but it seems to be a common part in several of your engines. I know they are expensive but I would attempt to purchase a new OEM pump.
Are you sure you are running the oil at the right level? To be absolutely sure, at your next tear down you need to dump the factory specified amount of oil into your pan and mount the dipstick to confirm how it reads. The pan with the built in scraper holds more oil than the earlier pan, on my cars. So you need to do a little research and determine what model year car your pan came from and then match up it to the factory recommended fill spec. You don't want to run too low but also not too high, which induces foaming.
Also, check your plastic baffle in the oil pan and make sure the enclosed part (the hollow part held together with screws) is not leaking and thus filling up with oil. The earlier design with little plastic tabs has a problem in that the tabs break off. You need to have the one with the screws. If the cavity were to fill up with oil, you can loose a quart there without knowing.
That's all I've got for now. I know historically folks think the 944 has a problem with the #2 bearing but the actual reported failures here on Rennlist seem to be few and far between. Especially with the later engines like yours. So I think the basic design is sound. You have done an impressive list of things to combat the problem and don't seem to be cutting corners, which is to be commended. Here's hoping your luck turns around!
Harvey
05-25-2019, 09:08 AM
#6
Rennlist Member
Last engine failure, one with oil milkshake. Did you remove the oil pump and the 2 oil galley plugs? Did you then clean the block and flush all the oil passages and flush the internal oil passages of the crankshaft (I use the manual car wash stall)? Lots of sludge and remaining oil particles from failed oil thermostat are still in the internal oil passages, affects oil flow, OPRV operation and scores bearing babbitt which increases bearing clearance and localized low oil pressure.
Did you disassemble the camshaft tower and clean the internal housing? Did you clean the hydraulic lifters by soaking them in ATF and pump them to remove sludge?
I am building a new engine. Eventhough the block and crankshaft looked very clean, they received a good washing and flushing at the car wash.
Did you disassemble the camshaft tower and clean the internal housing? Did you clean the hydraulic lifters by soaking them in ATF and pump them to remove sludge?
I am building a new engine. Eventhough the block and crankshaft looked very clean, they received a good washing and flushing at the car wash.
05-25-2019, 09:21 AM
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Hand tightened the oil pump pickup tube flange. My fear is the o-ring gasket is not "compressed" sufficiently to seal completely, air was entering into the oil flowing to the oil pump and entrained as it flowed to the bearings.
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05-25-2019, 09:26 AM
#8
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Engine 1. Rebuild. Did you do all the cleaning of the block and camshaft tower as posted in previous engine cleaning post? Did you hand tighten the oil pickup tube flange?
A crowfoot wrench is used to properly torque the flange.
A crowfoot wrench is used to properly torque the flange.
05-25-2019, 09:43 AM
#9
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What oil weight do you run?
The turbo oil cooler thermostat will still allow oil to flow even when it's cold because there's a bypass passageway...however it's only a little bit and if thermostat is stuck closed there will be very little hot oil going to the cooler.
The stock turbo oil cooler Matrix itself is barely marginal, and really you should be running a larger cooler 13 row minimum setrab/mocal.
If the hoses were really really long, then the fitting size might matter more. However I have been using -8 size lines and fittings for over 10 years on my car and I've never had an oil pressure problem. For about seven of those years, I had 2x 13 row coolers in series and probably 11 feet of -8 hose so it was a very long skinny oil path. This still kept the oil cool in 110F ambient where i live, but not a racer.
Are you allowed to advance the camshaft in your series? It will make more power at all RPM but not require you to wring out the engine past 6000 anymore.
The turbo oil cooler thermostat will still allow oil to flow even when it's cold because there's a bypass passageway...however it's only a little bit and if thermostat is stuck closed there will be very little hot oil going to the cooler.
The stock turbo oil cooler Matrix itself is barely marginal, and really you should be running a larger cooler 13 row minimum setrab/mocal.
If the hoses were really really long, then the fitting size might matter more. However I have been using -8 size lines and fittings for over 10 years on my car and I've never had an oil pressure problem. For about seven of those years, I had 2x 13 row coolers in series and probably 11 feet of -8 hose so it was a very long skinny oil path. This still kept the oil cool in 110F ambient where i live, but not a racer.
Are you allowed to advance the camshaft in your series? It will make more power at all RPM but not require you to wring out the engine past 6000 anymore.
05-25-2019, 10:41 AM
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Sorry for your loss.
There's just not much to say that hasn't already been said so many times.
There's just not much to say that hasn't already been said so many times.
Last edited by odurandina; 05-25-2019 at 11:04 AM.
05-25-2019, 07:45 PM
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Thanks for the replies!
odurandina, thanks, and you are absolutely right.
Redline: That's an interesting one... I had a big tach and a shift light that would come on around 5800. Which meant I ended up shifting around 6000-6200. And I have to admit that on the rebuilt engine, I did rev it pretty high. And from what I've read since, that's a factor. I never had a "money shift" but I definitely should have kept the revs below 6000. The 924S engine never saw revs above 6000. Last year I rewired the dashboard and controls, and I haven't put that big tach and the shift light back in. I intend to when I figure out how to display all the stuff that the stock instrument panel shows.
I run Valvoline VR1 20w50, and I changed it after every other race weekend. Several of those race weekends were cut short by other mechanical issues, so it never really saw more than maybe ten short sessions between changes. I used either K&N or Mahle filters.
Cutting corners: I guess I cut a few in my hurry to get the 924S engine into the car in less than 3 weeks between events... Firstly, I did not clean the cam tower from the 924S engine. I made a sandwich: 924S cam tower + original 944 head (with a couple valves from the 924S) + 924S block. I wiped the block down wherever I could reach in it. I didn't clean out all the passages and oil galleys in it.
So... the milkshake engine (924S) was not my failure - it was the prior owner's race engine, which he says he didn't put enough anti-freeze into. I didn't fully understand the story behind it, but he seemed to think the head gasket was bad as a result. I inspected everything and could not find any cracks in the block or the head. So I just cleaned it all up as best I could, and used the cleaner head from my destroyed engine (the piston remained in place and protected the head).
The oil pump has been different in each engine... the original's ate some bearing material, so the rebuilt original got a used one that I fully disassembled, cleaned, and reassembled with new screws and the red goo in all the right places. The 924S engine's oil pump was not removed, disassembled, or cleaned, despite the milkshake. We'll see what that looks like when I get in there.
The oil is most likely at the correct level. The oil level sensor works, and the idiot light was on just after initial fill up, and a quart both brought the oil to the right level on the dipstick and put out the idiot light. The '88 924S and the original '88 944 engines are the same engine... and the 924S engine didn't come with a dipstick. I transferred the 944 dipstick, and it seemed to work properly as I mentioned.
I cleaned the oil pan including removing the plastic baffle, and it looked good - no cracks. So I'm pretty sure it's not harboring extra oil.
Oil pickup o-ring theory: The oil pickup was hand-tightened, yes, but the flange goes all the way down against the cradle. If the nut isn't loose when I take this thing apart, I'm going to assume there was no air making its way in there.
The original rebuild did receive a complete block cleaning by Michael Mount including removing the freeze plugs at the end of the oil galleys and installing new freeze plugs. The 924S engine did NOT get that treatment, but my assumption was that there wasn't hard metal debris in the 924S engine... and that it would simply take an oil change or two to get it clean enough.
One of my fears is that my oil cooler wasn't quite large enough, now that you mention it. I bought the exact same cooler because it was easier to just re-use the mounting brackets I made. It didn't occur to me that it might be too small. I have friends who distribute Mocal, so I'm thinking I'll go with a larger one of those next time. The outdoor temps were 90+ degrees at VIR when the 924S engine failed. The hottest event I did on the previous engine was at Pitt Race last July, and that wasn't even very hot (maybe 85 at the hottest).
The oil cooler I was using both times:
https://www.summitracing.com/parts/bmm-70265
Thanks for all your questions and ideas... I'll post more here as I discover it.
odurandina, thanks, and you are absolutely right.
Redline: That's an interesting one... I had a big tach and a shift light that would come on around 5800. Which meant I ended up shifting around 6000-6200. And I have to admit that on the rebuilt engine, I did rev it pretty high. And from what I've read since, that's a factor. I never had a "money shift" but I definitely should have kept the revs below 6000. The 924S engine never saw revs above 6000. Last year I rewired the dashboard and controls, and I haven't put that big tach and the shift light back in. I intend to when I figure out how to display all the stuff that the stock instrument panel shows.
I run Valvoline VR1 20w50, and I changed it after every other race weekend. Several of those race weekends were cut short by other mechanical issues, so it never really saw more than maybe ten short sessions between changes. I used either K&N or Mahle filters.
Cutting corners: I guess I cut a few in my hurry to get the 924S engine into the car in less than 3 weeks between events... Firstly, I did not clean the cam tower from the 924S engine. I made a sandwich: 924S cam tower + original 944 head (with a couple valves from the 924S) + 924S block. I wiped the block down wherever I could reach in it. I didn't clean out all the passages and oil galleys in it.
So... the milkshake engine (924S) was not my failure - it was the prior owner's race engine, which he says he didn't put enough anti-freeze into. I didn't fully understand the story behind it, but he seemed to think the head gasket was bad as a result. I inspected everything and could not find any cracks in the block or the head. So I just cleaned it all up as best I could, and used the cleaner head from my destroyed engine (the piston remained in place and protected the head).
The oil pump has been different in each engine... the original's ate some bearing material, so the rebuilt original got a used one that I fully disassembled, cleaned, and reassembled with new screws and the red goo in all the right places. The 924S engine's oil pump was not removed, disassembled, or cleaned, despite the milkshake. We'll see what that looks like when I get in there.
The oil is most likely at the correct level. The oil level sensor works, and the idiot light was on just after initial fill up, and a quart both brought the oil to the right level on the dipstick and put out the idiot light. The '88 924S and the original '88 944 engines are the same engine... and the 924S engine didn't come with a dipstick. I transferred the 944 dipstick, and it seemed to work properly as I mentioned.
I cleaned the oil pan including removing the plastic baffle, and it looked good - no cracks. So I'm pretty sure it's not harboring extra oil.
Oil pickup o-ring theory: The oil pickup was hand-tightened, yes, but the flange goes all the way down against the cradle. If the nut isn't loose when I take this thing apart, I'm going to assume there was no air making its way in there.
The original rebuild did receive a complete block cleaning by Michael Mount including removing the freeze plugs at the end of the oil galleys and installing new freeze plugs. The 924S engine did NOT get that treatment, but my assumption was that there wasn't hard metal debris in the 924S engine... and that it would simply take an oil change or two to get it clean enough.
One of my fears is that my oil cooler wasn't quite large enough, now that you mention it. I bought the exact same cooler because it was easier to just re-use the mounting brackets I made. It didn't occur to me that it might be too small. I have friends who distribute Mocal, so I'm thinking I'll go with a larger one of those next time. The outdoor temps were 90+ degrees at VIR when the 924S engine failed. The hottest event I did on the previous engine was at Pitt Race last July, and that wasn't even very hot (maybe 85 at the hottest).
The oil cooler I was using both times:
https://www.summitracing.com/parts/bmm-70265
Thanks for all your questions and ideas... I'll post more here as I discover it.
Last edited by CrookedRacer; 05-25-2019 at 07:51 PM. Reason: added stuff about the tach.
05-25-2019, 07:53 PM
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On the morning of the failure of the second engine, I said I wouldn't ever rebuild another 944 engine if this one failed. And it did, of course. Am I a man of my word?
I'm seriously considering a VW 1.8T swap like Van is planning on doing. I so want to follow along with him.
Van, keep me up to date with your build!
I'm seriously considering a VW 1.8T swap like Van is planning on doing. I so want to follow along with him.
Van, keep me up to date with your build!
05-26-2019, 07:51 AM
#13
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Oil pickup o-ring theory: The oil pickup was hand-tightened, yes, but the flange goes all the way down against the cradle. If the nut isn't loose when I take this thing apart, I'm going to assume there was no air making its way in there.
I believe that if there is any distortion in the girdle as it mates to the block, the sealant might not cure properly because that flange nut is to be torqued to spec so the girdle squeezes the sealant.. The sealant only cures anaerobic. Could have had a small air leak at the girdle/block interface.
I believe that if there is any distortion in the girdle as it mates to the block, the sealant might not cure properly because that flange nut is to be torqued to spec so the girdle squeezes the sealant.. The sealant only cures anaerobic. Could have had a small air leak at the girdle/block interface.
05-26-2019, 07:56 AM
#14
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Did you buildassemble your 1st engine with the Michael Mount upgrades?
On engine oil, I use Brad Penn semi-synthetic 20W-50 with zinc additive. The engine has 35+hours with rod and main bearings replacement. The main bearings and rod bearings were coated, not a Michael Mount rod bearing conversion.
Test the oil after each season, no bearing babbit found. Test company is Blackstone Labs
On engine oil, I use Brad Penn semi-synthetic 20W-50 with zinc additive. The engine has 35+hours with rod and main bearings replacement. The main bearings and rod bearings were coated, not a Michael Mount rod bearing conversion.
Test the oil after each season, no bearing babbit found. Test company is Blackstone Labs
Last edited by T&T Racing; 05-26-2019 at 08:42 AM.
05-26-2019, 08:37 AM
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On the second engine, I didn’t remove the girdle. I only did the rod bearings and rings. So the removal of the nut holding the oil pickup tube was the only one that was disturbed.
Michael Mount didn’t build my first engine. He helped me a lot, though! He cleaned the block for me, cleaned the pistons, modded some factory forged rods for clevite bearings, checked a salvage crank for cracks and trueness, polished the journals, cross-drilled #2 and #3 rod journals, and checked oil clearances. His shop cleaned the head, installed new valve guides, and did a competition valve job (three angles on the seats, I think... not “ported”) and assembled the head. (That’s why I used that head instead of the one from the 924S - it was still the better piece.)
I then put it all together.
On the first engine, when I myself put the girdle on, I did hand tighten the nut, but it was in sequence, and I did my best to approximate the same torque in each round. I think the channel was sealed from air, but I like your thinking.
Michael Mount didn’t build my first engine. He helped me a lot, though! He cleaned the block for me, cleaned the pistons, modded some factory forged rods for clevite bearings, checked a salvage crank for cracks and trueness, polished the journals, cross-drilled #2 and #3 rod journals, and checked oil clearances. His shop cleaned the head, installed new valve guides, and did a competition valve job (three angles on the seats, I think... not “ported”) and assembled the head. (That’s why I used that head instead of the one from the 924S - it was still the better piece.)
I then put it all together.
On the first engine, when I myself put the girdle on, I did hand tighten the nut, but it was in sequence, and I did my best to approximate the same torque in each round. I think the channel was sealed from air, but I like your thinking.