Think I blew a head gasket?

[OneQuikSix]

I was thinking line bore issues when I saw that first bearing photo and how it was worn on the outside. I'm no machinist, but I wouldn't expect a forged crank to flex enough to cause that. Sorry for the bad news.


Sent from my iPhone using Tapatalk

 

[Flyin Brian]

I am taking my block and rods to a different machine shop tomorrow. I took the crank to a crank shop today and found out lots of interesting things. Just measuring with a micrometer showed my main and rod journals are tapered. 8 ten thousandths difference from center to edge on the mains and the rods were no better. He said this was not uncommon to find on not only K1 but Callies, Eagle, and anyone else's cranks that are made in China. He also said that this is a well known problem and that my engine builder and any engine builder should be aware of. This is disheartening to say the least. He is going to put the crank into the lathe to accurately check everything and let me know the outcome. So now I am going to be getting the rods and block measured up and possibly honed/re-sized to be correct, then giving the measurements to my crank guy so he can know what to grind the crank to to get the correct oil clearances. Then I can buy more bearings and get this thing put back together right the third time. Lesson here is that just because you buy a new crankshaft does not mean you can just drop it in and have everything work. I did not know this but my engine builder should have.

 

[Nascar83Fan]

On the brightside at least it'll be done right and it's now in more knowledgeable hands than before.
Sucks that the other builder didn't know to do a few things and it cost you spending more money to make it right.
Now you know who not to trust to do the work and who to go to the next time you get an engine built locally. Glad to hear you found someone that is gonna right the mistakes and make it durable & good this time around.


Posted from the TurboBuick.Com mobile app

 

[Flyin Brian]

I heard back from the machine shop today. The main bores are all well within factory tolerance and the rod bores are fine too. He also said the main bore alignment is good. I will be triple checking everything when I put it back together. My crank guy is going to have to cut the crank .010/.010 to get the journals straight but they will be perfect then. He said he could have tried to get it perfect and stay standard diameter but it would have taken a ton of time/money to try that and it still may not have been possible so we just decided to go .010/.010 and be done with it. Now I just have to buy a set of .010/.010 bearings and get them chamfered. I jumped the gun on getting a standard set of bearings and getting them chamfered before I knew all the facts. Oh well. Anyone want to buy a set of Speed Pro std/std main and rod bearings that have been chamfered?

 

[bison]

I am taking my block and rods to a different machine shop tomorrow. I took the crank to a crank shop today and found out lots of interesting things. Just measuring with a micrometer showed my main and rod journals are tapered. 8 ten thousandths difference from center to edge on the mains and the rods were no better. He said this was not uncommon to find on not only K1 but Callies, Eagle, and anyone else's cranks that are made in China. He also said that this is a well known problem and that my engine builder and any engine builder should be aware of. This is disheartening to say the least. He is going to put the crank into the lathe to accurately check everything and let me know the outcome. So now I am going to be getting the rods and block measured up and possibly honed/re-sized to be correct, then giving the measurements to my crank guy so he can know what to grind the crank to to get the correct oil clearances. Then I can buy more bearings and get this thing put back together right the third time. Lesson here is that just because you buy a new crankshaft does not mean you can just drop it in and have everything work. I did not know this but my engine builder should have.

You've found exactly what I've found many times with over seas cranks. My solution was .010" under so the clearance could be hit. .0008" is a mile in manufacturing. Tmk K1 didn't have cranks. Their rods were very good quality back when Molnar was working there. Now he has his own company and product which is also top notch. What method was used to check main bore alignment? Everything needs to be checked. Not checking gets you jammed up 99% of the time


BPE2013@hotmail.com

 

[Flyin Brian]

You've found exactly what I've found many times with over seas cranks. My solution was .010" under so the clearance could be hit. .0008" is a mile in manufacturing. Tmk K1 didn't have cranks. Their rods were very good quality back when Molnar was working there. Now he has his own company and product which is also top notch. What method was used to check main bore alignment? Everything needs to be checked. Not checking gets you jammed up 99% of the time


BPE2013@hotmail.com

Hey Brian,
I have done a ton of research since this started and found the same thing. All cranks should be checked thoroughly no matter who makes them. I just wish my builder would have known this. If he would have told me on day 1 that the crank needed work before installing and it was going to cost an extra 200 bucks or whatever I would have said to do it. I may have just assumed the crank was K1, it is the one that GN1 sells. The K1 rods were good. They are slightly bigger across the bolts as compared to direction of the piston force but I think that is normal. The main bore alignment is difficult to check from my understanding. My new machinist visually checked it using the straight edge method with a feeler gauge. Based on looking at the cross hatch pattern left by the hone and the fact that the block recently had the 2 center main billet caps installed and align bored he said that the bore alignment was most likely ok. I realize that this is not a perfect way to check the main bore alignment but what is?? I plan on taking my crankshaft specialists advice and installing the crank with the new bearings and using plastigauge on all 4 mains at once and torquing the caps down. This should show me something if the alignment is off correct? The old school GM engine building book says that if you install the crank and torque everything down, with assembly lube on the bearings of course, that the crank should spin freely and this would indicate that the main bore alignment was ok. I plan of doing that too. Short of all that I don't know how else to check the main bore alignment. What is the most accurate method of checking the main bore alignment?

 

[bison]

The line bore can be checked in the boring jig preferably with the heads if there's room or torque plates installed. The drag no drag method is crude. To use platigauge to determine if the bore is lined up you would need to check a high percentage of the rotation of the crank. Keep in mind if it's off .0005" then that amount must be figured into the minimum bearing clearance. If you have .002" clearance mathematically based on the bore and journal diameters and the bore is out of line .0005" you have more or less clearance on one side depending which direction its out. .0015" on one side and .0025" on the other. Some are so far out that it theoretically shouldn't have turned at all.


BPE2013@hotmail.com

 

[Flyin Brian]

Thanks Brian. I will check with the guy that actually did my line bore and steel cap install if he can check it with the heads installed. If I bring it to him with the heads torqued on maybe he won't charge me too much to check the bore alignment.

 

[ek02]

One of the forged cranks I have has allegedly been nitrited with plasma gas and, according to the manufacturer, should not be polished because it destroys the nitriding. I had the mains polished on it and have had no problems. It still looks good after 2 sets of bearings. If you cut the crank .010, I wonder if it will still work ok without being nitrided again?

 

[Flyin Brian]

One of the forged cranks I have has allegedly been nitrited with plasma gas and, according to the manufacturer, should not be polished because it destroys the nitriding. I had the mains polished on it and have had no problems. It still looks good after 2 sets of bearings. If you cut the crank .010, I wonder if it will still work ok without being nitrided again?

I don't know if the GN1 4340 crank gets any surface hardening treatment? Gas nitriding can go deeper than .010" depending on how the manufacturer does it. Somewhere I saw a crank manufacturer that said not to cut it more than .020" or it would need to go through the surface hardening process again. My crank guy mentioned that in serious racing applications like Pro Mod, that the engine builder would have the crank ground to their standards, then sent out to get surface hardened again, and then get polished to final spec. to maintain a Rockwell hardness of C56 or higher. Hopefully in my application cutting the crank .010" won't have an adverse effect. I could probably send it out to get re-hardened and have my guy give it a final polish afterwards but that would be getting quite expensive at that point.