I dropped my motor off at my engine builder for a new crank .. Basically, I screwed up the snout of my crank because of a fuct up tensioner/too much pressure running a blower, etc etc.. The Eagle forged crank that was in there now has a snout that is tapered

Basically, I dropped the motor off to have him balance the new crank and reassemble.. After taking apart the motor, he said the front main bearing shows signs of stress on one side of the motor (the side the blower was pulling on).. The middle bearings look fine and the last bearing he says has about 1/3 of the bearing that doesn't look like it's been touched (mainly because it was pulling to one side I suppose)

Now here's the question, he suggests line honing it to "make sure it is straight" .. The motor has about 2000 miles on it before the crank got screwed up, it was bored with torque plates before that then line honed ..

1) Your thoughts on line honing it? Does it NEED to be done?

He is suggesting new rings .. He said just put new rings on it and have a nice fresh set.. I can see this if I am gonig to line hone it.. But if not

2) Why would I need new rings?

I mean, it does only have 2000 miles on it.. And at least 500 of them were REAL easy while it was breaking in, and 1500 of it, had a few 1/4 mile passes in it and a few tears down the street..

THanks in advance!

--Sean

 

As I see it, line honing the main bearing bores in the block has nothing to do with new rings in the cylinder bores. That's a decision based on bore condition and leakdown past the rings. Your driving doesn't sound like it would screw the ring seal in 2000 miles unless it wasn't built very well.


On the other subject, if the stress on one side of the motor (the side the blower was pulling on) was shown on the main bearing inserts and not the bearing bores, line honing probably won't do much. If it got to the block, you had some kind of bad alignment/loading problem. I don't understand how the rear bearing showed abnormal wear from the loads on the front bearing, especially with the center mains looking fine. Were the mains align honed on the first build? If not, it's probably a good idea. If they were, something's fishy.

IMO, curing the cause of the side load on the crank snout is job one. Have you considered a BBC size snout on your crank?

How far from the tining chain cover is the blower pulley? If it's way out there, and the belt is 2 inches wide, you are probably going to overstress most SBC size snouts.

My $.02

 

I think a round of new parts is going to fix the snout problem.. new ATI Superdamper & Custom Hub (BB Chevy OD, SB Chevy ID) and a new tensioner for the blower should fix the added stress the crappy ATI tensioner was causing ..

There's some pics here.

www.csionline.net/~dawulf/images/SDConcepts

Maybe I have some of my terminology wrong regarding honing .. I never was an engine builder .. I thought line honing was to hone the cylinder walls, but, I know they do some kind of honing for the mains as well, maybe that is what line honing is, in which case, you're right, it has NOTHING to do with the rings..

Yes, the first rebuild had the mains honed for sure ..

I believe the builder was suggesting a line hone just to make sure everything is straight .. Maybe I misunderstood him, but I think he said the middle mains were 'fine' .. I can see how the frong was screwed up, I Mean, I was putting over 500 lbs of tension on the snout with the crappy tensioner.. I can see if the front one was pulled, then the whole crank would be pulled and the rear aone would be the most out of whack because it is the farthest away..

On another note ...
The cylinder walls still are showing cross hatching, why the hell would I need new rings?

--Sean

 

 

No way of getting that blower pulley closer to the damper.. It has to be that far away to clear everything on the way up to the blower..

I am pretty sure this is going to fix the problem.. I spoke with Scott @ SD Concepts for quite some time, he explained a lot about why this keeps happening.. Mainly because the stock tensioner unit from procharger is a piece of garbage .. IT would put so much strain on the front of the crank that 1) the keyway in the hub would break and 2) the hub/tensioner would spin off..

SD Concepts claims the new tensioner only uses 220lbs of pressure to keep the belt from slipping, while the stock one from procharger uses over 500 lbs ..

I figure with the new bigger hub, the superdamper and the new tensioner, I should have amuch better chance of fixing this problem..

I installed the charger and the tensioner (as it comes from procharger) so, I suppose I have no one to blame but myself and maybe procharger ..

I would think that the mains are straight, it's not like it ran this way for 50,000 miles .. According to the builder, the bearings are showing strain on the 1 side up front, and not showing any marks on the rear one in 1/3 of the bearing .. I dunno.. damn it..

I guess I am just looking to not spend money I dont need to spend .. I originally was going to just reinstall the pistons/rings with new bearings and a newly balanced crank and go from there.. He now wants to pull the cam bearings and check everything (just in case there's metal floating around while we have it apart.) Which, I agree with, might as well check them, but to do new rings, a clean-up hone, and a new align hone is going to cost another $400 or so .. $400 is $400 no amtter which way you look at it..

Thanks,

--Sean

 

Its obvioous where your wear is coming from, why line hone it ? I think the tensioner and pullies (as the other guys have said) is where your problem lies. If they have to machine the block I would change the rings, if not then the rings should be fine that are in there. But if they remove the pistons from the bore you might as well put new rings in, unless you bought fancy gapless or expensive rings.