Paul Bell

iTrader: (9)

I'm not getting it either. While it is possible for a cylinder to have both it's valves closed during it's power stroke, the other cylinders will be in some sort of open valve state.

The broken section of the cam couldn't have moved forward-the rest of the cam is there. AND the pump drive gear was still meshed and holding the cam from moving fore/aft. The lifters stayed on the lobes.

Regardless, the heads/valves are good. I'd still pop out the valves and have a good measure of them. Sometimes the bend can't be seen by eye.

gregrob

iTrader: (8)

Guys... think about something for a minute. When the cam broke the valve springs were trying like hell to close the valves with almost no resistance from the cam... they could have easily caused the small piece of the cam to spin to a point where NONE of the valves being controlled by that piece of the cam were on the nose of the lobe... It followed the path of least resistance and rotated that part othe cam so that those valves were closed, and/or barely open. It would be pretty bizzarre for them to be hung wide open, it goes against physics. The only cause for that would have been if that piece of the cam got bound up / seized at the perfect position to overcome the spring pressure and hang the valves open.

If the valve springs can control the valve at 7000 RPMS, don't you think they can react faster than the piston moving in the bore at IDLE. Assuming a 700 RPM idle setting, the piston would have only been moving at 406 FPM...

Paul Bell

iTrader: (9)

In keeping an open mind about this, I suppose this is possible. Given the fact that there was no damage, and often the simplest answer is the often best answer, this is probably what happened.

gjohnsonws6

iTrader: (12)

In the begining you said you re started it after losing oil pressure? I would be very worried of more damage other than the broken cam.Did you pull a main cap?rod cap? I would pull number 1 rod and main caps.Cam bearings have to be shot.Have you rolled the pushrods also?

Paul Bell

iTrader: (9)

Good idea G. OP, tear that motor apart and do some stuff to it. The biggest hurdle to engine work is getting it out of the car. I'm sure you can do better than 411 RWHP.

Z28Camaro30Ann

iTrader: (15)

wow, really???

Thanks for that awesome and truly helpful advice.

Did it ever occur to you that I didn't WANT to do better than 411 RWHP?? Did it ever occur to you that my GOAL when I did this build was 375 RWHP and I exceeded it? Or that MAYBE my funds are kindof limited and completely rebuilding the block is NOT feesable for me??

It's not ALWAYS about the horsepower. This is a daily driven street car that does EXACTLY what I want it to do, and feels/sounds exactly how I want it to! I dont WANT to increase the HP right now.

gjohnsonws6 - Yes we restarted it for about 3 seconds to diagnose the problem and make sure it wasnt just a faulty gauge..when we heard lifter chatter and no constant knock we shut it back off and it was never restarted. The cam bearings that I could see were fine because the front 4 journals of the cam remained in place and operational, so the only one I am questioning is the rear bearing. I will take a look at it next time I am working on the engine and see what it looks like.

I have completely disassembled the engine as far as I can without ripping the guts out. pushrods were straight and had no issues. I flipped the block over and pulled the oil pan off and turned the crank multiple times to inspect the internals and there were no issues, no noises, no binding, no visible damage, no metal shavings in the oil, the pan or the pick-up screen, nothing.

Z28Camaro30Ann

iTrader: (15)

And just throwing this out there, but this is NOT an LS1....411 RWHP N/A is a damn good number from an N/A stock stroke LT1...just saying

Big Al

iTrader: (1)

My advice for what it's worth. Pull the engine, don't even think about not checking out the bottom end. Check the valves. Tops of the rear pistons will have marks if the valves hit. I would have the heads vacuum checked even if there are no marks on the pistons. Drive or push the broken cam out the back. Replace the cam bearings. If the crank saw grit the rear main will have scratches in the bearings. If it does so will the rest. My feeling is running the engine for a few seconds without oil probably didn't hurt anything, but I would look. You admitted to starting it a number of times with no oil pressure. That's why I would look.

From the pictures it looks like the cam wasn't cracked before it broke. There is a good chance metal didn't go through the oil pump as the pump stopped turning when the cam snapped. But I would take a peak just to be safe. I would not be surprised to find a problem in the rear cam bearing, so be easy with it when pushing the broken cam out and examine it carefully.

Al 95 Z28

tbird31

iTrader: (22)

better be freaking $FREE.99

goodluck

gregrob

iTrader: (8)

Yes actually it clearly looks like it was cracked before it broke...

I don't know why its so hard to grasp he said he HAS been into the engine, HAS pulled the heads and everything is fine.

jaycenk

iTrader: (1)

lol great to hear the heads seem ok. Sucks that these things always happen when the funds are low Right? lol check that rear cam bearing and the one in front real good and if your up to it while you wait for Comp pull the front main bearing cap and front rod cap. Those should show all you need to know if there was any oil starvation damage problems to the bearings. If it's stock rods and bolts Shbox.com has the torque specs as well as for the mains. Just use a good torque wrench.

Z28Camaro30Ann

iTrader: (15)

I will. I have a lot of time to wait for Comp, so I will be doing quite a bit of preventative maintenance as well as repair work. I am not going to risk messing the motor up later HOWEVER I am not going to do unnecessary work or fix something that ain't broke if I don't have to.

My plans at THIS moment as far as replacement are:
Replace Cam (obviously)
New Oil Pump and Oil Pump Drive
New Oil Pick-up
Pressure Test the heads
New Oil Pressure Sending Unit (cause I made a booboo lmao)
New NGK TR6 Spark Plugs
Repaint Engine Bay
Clean EVERYTHING thoroughly
Check Cam Bearing and replace as needed
Check Rod Bearings
Paint Block
Port Throttle Body Inlets on Intake Manifold to 58mm
and more to come after I go over everything again Tuesday.

Z28Camaro30Ann

iTrader: (15)

Ok, so some additions to this list. The bearings in here are whatever Jasper put in it and I don't like when I am unsure about something...therefore, here is my plan. I can not afford all new parts, so I am going to tear the entire block apart and inspect everything, but if it is good and unharmed it WILL go back in.

I am going to be putting Clevite "H" Series Bearings on the Rods
Clevite "P" Series Bearings on the Mains
Clevite Aluminum Bearings on the Cam
ARP Rod Bolts

And everything listed above...

This way there is absolutely ZERO uncertainty and I KNOW the limits of my block and when it was refreshed...

jaycenk

iTrader: (1)

Yea just inspect each bearing as to what size they are JUST incase Jasper did something odd and used like one over sized rod bearing or some crap lol. Sounds good though. If you have spare time you can always come and paint my engine bay lol. J/k Little bit of a drive from Wyoming

Z28Camaro30Ann

iTrader: (15)

lol, a buddy of mine is gonna do the work for me for a sub I have hahaha, I just gotta buy the paint. He has his own shop.

The bay is going to be sprayed Jet Black just like the exterior, then I have a few more friends that do custom airbrushing, and they are gonna hook me up if I choose to do this, but I am thinking about having a custom red spiderweb airbrushed into the entire engine bay to go with the car's theme, then clearing everything after that...

Thoughts??

gregrob

iTrader: (8)

I think you should concentrate on getting it running instead of airbrushing and ****. But I guess if you can afford for it to be down for a while...

Z28Camaro30Ann

iTrader: (15)

I am getting a deal, and this wont be done before next paycheck because it will take Comp Cams longer than that to figure out what to do then get to it...so I might as well do SOMETHING till then...lol

Z28Camaro30Ann

iTrader: (15)

Ok, results from the week lol, some good...others bad.

Tore the motor COMPLETELY apart today. As I said before, there were NO marks on the pistons and valves/pushrods were perfectly fine. Everything looks GREAT! Bearings were fine, but I am replacing them anyways to be on the safe side. So here is what all I accomplished and/or learned today lol.

Good:
Cleaned EVERYTHING.
Painted the block Black
Ported my intake manifold's TB Inlets for the 58mm TB
Double Checked my valve clearance and lift
Got the cam sent off to Comp Cams
Inspected everything for damage with no NEED to replace anything but Cam Bearings

BAD:
Valve Seals are FUCKED
6 Valve Spring Retainers are different and I didnt catch it on install
Broke my Oil Pressure Sending Unit......that thing is in a HORRIBLE spot lmao
Cam Bearings are FUCKED lmao

The valve seals are messed up because Patriot sent me the wrong seals with their kit and I didnt notice during install, so the springs have been chewing up the seals...easy fix. I am going to have the Valve Guides clearanced for PC Seals and put those on there.

The Retainers, Patriot sent me 10 of one .050's and 6 Standards...so I have some that are slightly off and I just didnt notice it...gonna try and remedy that as well

Productive day...hopefully things will get better now once all my new bearings arrive and my cam...

Paul Bell

iTrader: (9)

SO: You've listened to every bodies advice given here and gone through the engine to confirm there's no damage, made some changes and improvements and did some performance work to improve the power you're producing.

Great! We're all looking forward to more good news from you!

Vexzer

iTrader: (1)

Looking at the separated ends of the cam, at the 'beach marks', it does appear that the stress fracture grew over time [i.e.: obviously not caused by a catastrophic event]. That being the case if it was a casting flaw, the flaw may have grown due to repeated flex cycles cause by high spring pressures. Other causes of the repetitive stress cycling could have been bearing misalignment, or too much difference in bearing clearances between the three adjoining bearings. It would seem that a loose clearance in one of the three bearings would reveal as low oil pressure, but low oil pressure may have been masked by high viscosity oil or a high pressure oil pump. With the motor out, you have the opportunity to at least align bore the cam bearing journals as a preventative or corrective measure.