Gen 4 engine builders out there...walk me though me first build.

[ckeister]

This is the continuation of my "life is like a box of chocolates" thread from back in June. Got sidetracked with a pasture fencing project and the overall business of having a newborn son. But I have to get this done and on the road before it starts snowing so the engine is back at the top of the priority list.

Got it back from the machine shop. Cleaned the block, installed Durbond cam bearings, Polished crankshaft, polished camshaft (didn't know that was a thing), honed block, and bought some rings, rods, and mains, from him. Overall, I was not all that happy. Easily the dirtiest I have ever had a motor come back from a machine shop. I think he overcharged me a bit, and found out after the fact he just ball honed the cylinders. Unfortunatley machine shops are closing left and right around here so it is what it is.

First on the agenda, after I cleaned this thing, 5 times, was piston to wall clearence.I had purchased a set of EngineTech pistons, but sent them back. Not happy with them at all. Then got a set of Silv-o-lite's that came with no pin clips. Not sure what's up with Summit Racing lately but they have been sucking big time.

Attached is a photo of my cylinder wall measurements. Hope you can read my chicken scratch. So no out of round or taper greater than .001 Mic'd all the pistons and got them all at 4.0635-4.064. Recommended finished bore diameter is 4.0655. When I did my cylinder measurements, I set the bore guage at 4.065 so overall, it seems like I will be at worst .0005 loose or tight at any point in any one cylinder bore. Interesting note...When I tore this thing down, #1 cylinder was the worst as far as cross hatching wear and pistond skirt scoring so interesting that #1 and #8 are the worst in terms of measurements....hmmmmm (Note the bottom measurement on #8 is .0005 not .005)

Weighed all the pistons and they were all within 2 grams of each other but for one which was 4 grams lighter than the heaviest one but at this point Im gonna live with it.

Any thoughts or comments? Am I correct in thinking my skirt to wall clearances are GTG? Am I missing anything to this point? As we move forward, you will see a theme that I am trying to wrap my head around as an ex-racer.....tight clearances. They are freaking me out at this point.

 

[ckeister]

So now lets talk main bearings.....Of all the low oil pressure posts, threads, and videos i've looked at this video is the one that made the most sense in my engine builder brain....

.

If you don't want to watch the video, he mixes standard and .001 over bearings to get oil clearance of .001. Makes perfect sense to me. So I start my mission to get that .001. First I used the Mahle bearings the machine shop sold me. The are all right on the money at .015 using plastiguage. Then I start mixing and matching my standard and .001 over Enginetech bearings. Everything seems to be just a shade tighter than .001. Factory specs say you can run as tight as .0008.

So here is my issue....being an old hot rodder/racer, I ran my stuff loose the only time I ever ran anything tighter than .0025 is when I was racing mini-stocks with a Mitsubishi Starion/Dodge conquest with a 2.6 motor. With this torque to yield bolt BS, unless you want to spend the money for multiple sets of bolts or ARP stuff, your re-using the old bolts. Now what about bolt stretch? Mixing and matching these bearings, you end up using the bolts 3,4 times. So having a hard time feeling comfortable running .001 or possibly tighter re-using thesse bolts and plastiguage.
Can I check clearances with a mic and dial bore guage? yes I can but again your re-using TTY bolts and my dial indicator is accurate to .0005. so trying to measure .0002 after not building an engine in 20 years would not instill a ton of confidence either.

So the crank sits with the tight clearances, caps on new bolts down hand tight. Spins freely but does feel tight. What to do, what to do.....Curiousity and the young daredevil that still lives inside this aging body says....."Don't be a ***** bolt it together and send it"
The new father in me says...."Play it safe and run the bearings at .015."

Thoughts? Anyone ever build one this tight? It's in factory specs. Tight here would offset the half a dozen other ways these things loose oil pressure but damn I've never run anything this tight before. Help me decide so I can move on......

 

[donjetman]

@ckeister
Iron block main bearing clearance should be .0025" to .0030".
Aluminum block main bearing clearance should be .0015" to. 0020"

Rod bearing clearance should be.0025" to .0030" for both.

 

[Charlie207]

Sorry you had a bad shop experience. My machinist was amazing, and walked me through all the stuff he thought I should do to save money (and his busy time). He could have easily ripped my naive *** off for an extra grand, but helped me learn about why he was doing the stuff he did. He measured all the bearings, bores, and clearances, and came to the conclusion I should reuse my mains & con-rod bearings, as they were all still in good shape and within spec. He showed me which piston rings to buy myself, and how to use gasoline and an old broken ring to clean up the pistons. The only "new" parts I needed were cam bearings (he installed those) and the new valvesprings and seals I supplied him to install during the valve-job/cylinder head rebuild.

He included a hot wash of the block and all my parts, and kept all the work to around $800, which was close to his ~$620 estimate, after I requested he do a couple extra things. I feel like I learned a ton of info, and got to listen to him banter with some old-school circle track locals at the shop.

Shoutout to Randy at River City Machine.

 

[ckeister]

@ckeister
Iron block main bearing clearance should be .0025" to .0030".
Aluminum block main bearing clearance should be .0015" to. 0020"

Rod bearing clearance should be.0025" to .0030" for both.

Hi thanks for the reply. Mine is alum block and I did not specify but this is stock rebuild. I can see from my post that could be confusing. Looking at your profile pic, are these clearances that you use for race stuff? Everything I have, from mulitple sources show factory specs at .0008-.021 on the mains and I think .0009 to .025 on the rods.

 

[ckeister]

Sorry you had a bad shop experience. My machinist was amazing, and walked me through all the stuff he thought I should do to save money (and his busy time). He could have easily ripped my naive *** off for an extra grand, but helped me learn about why he was doing the stuff he did. He measured all the bearings, bores, and clearances, and came to the conclusion I should reuse my mains & con-rod bearings, as they were all still in good shape and within spec. He showed me which piston rings to buy myself, and how to use gasoline and an old broken ring to clean up the pistons. The only "new" parts I needed were cam bearings (he installed those) and the new valvesprings and seals I supplied him to install during the valve-job/cylinder head rebuild.

He included a hot wash of the block and all my parts, and kept all the work to around $800, which was close to his ~$620 estimate, after I requested he do a couple extra things. I feel like I learned a ton of info, and got to listen to him banter with some old-school circle track locals at the shop.

Shoutout to Randy at River City Machine.

Sounds like you have a guy like my old machinist. I called him up after 20 years and he has retired and only does head porting for the racinb guys now,
I'm in California, land of Tesla's and government that hates small businesses so our machine shops are drying up fast.....
This guy was young, nice guy and I don't feel ripped off, just a little overcharged and feel he should have done some things he didn't do. I can only imagine how difficult it is right now for any machine shop here so I'm not totally hating on him yet.
Unfortunately last night, I may have found some issues that will necessitate bringing it back tp him. I have to do a lkittle more measuring.....so this thread may have to hit the pause button. I'll know more a day or two when I have more time to play with it

 

[SpareParts]

Few years ago i had a 454 short block and heads rebuilt at a fairly respected machine shop. Kind of turned into a s4it show. I could not really find much wrong with the rebuilt short block but i did not take it apart.
The heads were another story. Found 8 valve springs upside down (stock beehive), Valve stem heights were all different and varied by .20
Got it fixed, but it never seemed to run right, like it had what felt like small miss.

 

[donjetman]

Hi thanks for the reply. Mine is alum block and I did not specify but this is stock rebuild. I can see from my post that could be confusing. Looking at your profile pic, are these clearances that you use for race stuff? Everything I have, from mulitple sources show factory specs at .0008-.021 on the mains and I think .0009 to .025 on the rods.

from stock to mild

 

[rdezs]

I would go with the main bearings at .0015-.0020

 

[ckeister]

Yep had a little hiccup. This is a big deal and something to know if your building one of these engines When I tore this thing down the cam was in there nice and tight. When I installed the same cam into the new Durabond HP bearings, I thought "well that seemed a little too easy. I have built dozens of engines and never checked cam bearing oil clearance, Would have never even thought about it had I not watched this video..

Fast forward to the 26 minute mark.

So I check the cam journals with the mic, dead on the money at 2.1667. Set my bore guage and number one bearing journal is .0038 which is max per GM specs #2 is .0015 and #3 is .0028 so all over the place. Well I'm not running what is now becoming essentially a complete lower end rebuild starting out at max tolerances.

Called the machine shop and he thought I was nuts. He said i n all his time, he has never checked cam baring clearances with new bearings and stock cam. But when I told him about the video, he was familiar with Powelll Machine and said "yeah I watch him. He's a sharp dude send me the link to that video."

He calls me back a few hours later. He says he was on the phone with a Durabond Tech for over an hour and ordered 5 sets of each oversized bearing. So the engine goes back next week. My main bearing clearance is .0015 rods are between .0017 and .0019. I told him I want all the bearing clearances under .0020.

The bearing clearances on these aluminum blocks are the main culprit for low oil pressures. IMHO Everyone chases the o-ring, VLOM, barbell, etc, etc. which yes can be problems but if you got bearing clearances all over the place from the get go none of that stuff is going to matter.

 

[Marky Dissod]

Not a little hiccup. Engine wouldn't've lasted long enough to get a decent return on investment. Now it has a 2nd chance at a much longer life.

 

[ckeister]

Not a little hiccup. Engine wouldn't've lasted long enough to get a decent return on investment. Now it has a 2nd chance at a much longer life.

Yep I feel very lucky I happened to watch that video. The machine shop said, according to the Dura bond tech, the GM gen 4 and gen 5 aluminum blocks are the only family of motors they offer undersized cam bearings from .001 to .003. So this issue is specific to these aluminum block LS motos so I'm sharing this with everyone so hopefully it helps someone in the future.

 

[ckeister]

Questions for you guys that have done DOD deletes. This motor is an L9H going into a 2007 l92 that has the DOD equipment but not tuned into the ECM. The camshaft part number for the l92 has been superseded by the l9h and my understanding they have the same specs. However when I look up the cam Phaser, there are still different part numbers so what cam phaser do I used?
Second question and the million dollar one I can't seem to find the answer. If I'm keeping the VVY, Can I plug the bypass valve in the oil pan?

 

[ckeister]

Checking back to see if anyone had any info on the above questions……

 

[rdezs]

Yes, plug the bypass valve in the oil pan. That only exists to protect the solenoids in the VLOM plate/valley cover on engines with active AFM.

 

[ckeister]

Yes, plug the bypass valve in the oil pan. That only exists to protect the solenoids in the VLOM plate/valley cover on engines with active AFM.

Thanks