Some questions in engine rebuilding....

[leung23c]

Hi guys. I have some questions in my mind about engine rebuilding.

1. I know tomei poncam supposed to be drop-in application that require you to re-shim to get the required clearance but that's it. But I have also read many articles saying if you put in new camshaft you also need to use new lifters and at first start up the engine must rev to 2000rpm for 20 mins to mate-in the surface between the lifter and cam lobe. Which is true?

2. Let say I have a rebuilt engine (new camshaft new lifter) installed with zero km and zero start up, and let say I should do the 2000rpm 20mins to break in camshaft, does that mean I must not try to start the engine and must leave it to the hands of tuner to get all setting right and they do the break in? How can I know if I do my job right? Or I can't know until the tuner tries to start it?

3. Let say it is true that I need to break in the camshaft using the method described above, isn't that contradictory to what you should do to break in the piston-rings? Like you should move your revs ups and downs for piston ring to get more lube to mate with the cross-hatch.

4. Is a regrounded crankshaft any good?

Thanks for the opinions.

[Dragon Humper]

1. I know tomei poncam supposed to be drop-in application that require you to re-shim to get the required clearance but that's it. But I have also read many articles saying if you put in new camshaft you also need to use new lifters and at first start up the engine must rev to 2000rpm for 20 mins to mate-in the surface between the lifter and cam lobe. Which is true?

Pon cams are total drop in, no shimming needed...you should still double check the clearances though. OHC motors are not that critical to use new followers for the cam, as long as they look good with no pitting or scuffing, they are good with stock valve springs. OHC motors don't need the 20min. thing either, 5 min. is plenty.

2. Let say I have a rebuilt engine (new camshaft new lifter) installed with zero km and zero start up, and let say I should do the 2000rpm 20mins to break in camshaft, does that mean I must not try to start the engine and must leave it to the hands of tuner to get all setting right and they do the break in? How can I know if I do my job right? Or I can't know until the tuner tries to start it?

Your tune should be within reason before you even think about firing that new motor up. As long as you are still using the MAFs and/or stock displacement, your old tune should be fine.

3. Let say it is true that I need to break in the camshaft using the method described above, isn't that contradictory to what you should do to break in the piston-rings? Like you should move your revs ups and downs for piston ring to get more lube to mate with the cross-hatch.

Nope, 20 to 30 min run with no load won't hurt the ring breakin. How to do that is a real debate, I am in the "load the snot out of it to break in the rings quick" camp.

4. Is a regrounded crankshaft any good?

Yup, just make sure it has been re-hardened afterward if it is forged. The grinding will remove the top layer of the surface hardening and it must be redone.



Jon.

[leung23c]

Thanks!

2. What if injector, afm, displacement and camshaft profile are all changed?

And Oh yes

5. How to achieve that torque to tighten the crank bolt? I found the piece that can lock the flywheel in place but the torque required is 460nm. I checked on snap-on website the torque wrench in that range of torque they sell is like 800Usd! Now, do I really need to sink that cash to tighten that all important bolt!!??

[Black BNR32]

I just bought this one:

http://www.princessauto.com/pal/en/Torque-Wrenches/3-4-in-dr-Click-Type-Torque-Wrench/2926939.p

and went a little over the max

[Dragon Humper]

The bolt does not have to be that tight, it's ridiculous. No other dampner short of a bigass diesel needs that much. Some live by the letter of the OEM manual but I don't do ridiculous. 150lb/ft is plenty.

If you are changing that much, I hope you figured out the tune before you rebuilt the motor. A new motor needs a crisp tune to break in right. If it is way off and pig rich you will glaze the cyls. and the walls will have to be honed to get that sh1t off.



Jon.

[MarusGTR]

5. How to achieve that torque to tighten the crank bolt? I found the piece that can lock the flywheel in place but the torque required is 460nm. I checked on snap-on website the torque wrench in that range of torque they sell is like 800Usd! Now, do I really need to sink that cash to tighten that all important bolt!!??

Go to a heavy machinery/big rig shop before closing time and ask if you can loan their 1" drive wrench and give it back as they open the next day. I got a freebee loan that way.

The bolt does not have to be that tight, it's ridiculous. No other dampner short of a bigass diesel needs that much. Some live by the letter of the OEM manual but I don't do ridiculous. 150lb/ft is plenty.

Question: is the diameter of the crank's stud bigger than in other cars? In any case, if its ridiculous, there's a reason. Just going by gut, by cutting 200lb/ft you're cutting some crucial deflection stress in the threads. Might not matter for street but I certainly would worry if I'd get into high-power high-rpm harmonics.

[rvander1992]

didn't you also snap the shops torque wrench marus? I'm hoping to borrow our shops 1 inch drive wrench as well but i don't wanna buy the socket for it. Hopefully they have. I'll just use my 250 ft/p wrench otherwise and overtorque the wrench. If it breaks its mastercraft go get a new one =\

[MarusGTR]

I snapped my chrome mastercraft 3/4" to 1/2" adapter and fell on my ass, yes. You'll need impact-grade sockets throughout. These big wrenches should come with their own adapters/sockets, but the shop didn't have my socket size or an adapter for 1/2".

Trust me, that thing wouldn't snap with a measily 350lb/ft. It could go above 800 on the dial.

Edit: Oh and one last thing, you'll need stubby adapters and sockets if you want the wrench to fit in between the crank and the rad support.

[rvander1992]

our shop is for torqueing transport wheels on. I'm not sure how far it goes(snap-on 1" drive torque wrench) and is like 3 or 4 ft long. I'm hoping it makes it in. The socket i have is an impact socket but its for 3/8th drive =\.

[Dragon Humper]

Question: is the diameter of the crank's stud bigger than in other cars? In any case, if its ridiculous, there's a reason. Just going by gut, by cutting 200lb/ft you're cutting some crucial deflection stress in the threads. Might not matter for street but I certainly would worry if I'd get into high-power high-rpm harmonics.

Let me put it this way...the LT1 used a balancer that was also the serpentine drive (8"...huge) , the hub was only pressed onto the crank, no retaining bolt. The balancer was bolted onto that (no press fit) with three dinky little 14mm head bolts torqued to 25 lbs. This balancer drove ALL acc. from a single point with a belt 7ft long. Imagine the stress on that thing at 6000rpm with all acc. doing their jobs.

The RB one is pressed on as well..so much so that you dont even need the bolt....it's way overkill. But thats just me...do what makes you sleep better.



Jon.

[MarusGTR]

^ You trumped me on that one, that's (literally) insane! I'd never design something like that. But you also have to admit that the LT1 is a slow revving V configuration engine which is (IIRC) easier to phase than a high revving inline 6, let alone one that can go to 8.5k. Consider that the kinetic effects in this difference in speed isn't linear, its exponential. Going from 4k to 6k is considerably less energetic than 6k to 8k.

But yeah, this may be a case of apples to oranges, a case of too much vs too (*******) little.

Admitedly, vibrational mechanics are way behind me, I wish I'd know more about engine balancing. I guess a compromise would be to max a 1/2 drive torque wrench (250lb/ft) with a dab of thread lock.

[Black BNR32]

The bolt does not have to be that tight, it's ridiculous. No other dampner short of a bigass diesel needs that much. Some live by the letter of the OEM manual but I don't do ridiculous. 150lb/ft is plenty.



Jon.

For the newbs, I recommend not taking this as gospel. Jon's opinion on this is likely in the minority. Get some opinions from professional engine builders, and engineers with experience in bolt design, and see what they say. Then make your decision.

[caliber676]

Most Japanese cars have very tight crank bolts. I would recommend using a 1/2" torque wrench at 250ftlbs. It's not accurate at that level of adjustment but it will give you 250ftlbs plus or minus a few pounds. I've used this method before and never had an issue. Not everyone is gonna blow money for one bolt, best get it as tight as you can. I do however agree with dragon humper, it's definitely excessively tight for the purpose it serves.

[nimblestix]

I've always just used A 3/4" impact gun on the crank bolt. Never have I seen/had an issue. Take it for what its worth.

sent from a galaxy far, far away

[caliber676]

I've always just used A 3/4" impact gun on the crank bolt. Never have I seen/had an issue. Take it for what its worth.

sent from a galaxy far, far away

Guaranteed to give you enough torque or more with a big who's-your-daddy impact like that. Is it the anvil style?