Oil mods At what level does the line to the rear of the block become recommended? o No: While the motors out for the bleak cold frozen hell :sleep: of a Michigan winter I want to address all possible benefits. I hope I'm not sidetracking to thread, but I'd like to throw a couple questions out. With this motor I've always had hot idle oil pressure issues (except when I had in the HV pump which caused other NIGHTMARES :eek2: uzzled: :af: ), but plenty of pressure after rpm came up slightly. I attributed this to having too much rod side clearance (I don't remember the exact number off the top of my head, like .035 +/- .02). Posts on this thread are saying clearances in the .030's are OK? Does that apply to street motors that see alot of low RPM or mainly for race motors? o No: I'll also be running a little bit better front cover with oil mods, maybe that'll do it? The motor's .030 over, .010/.010, balanced and .002/.002 rod/main Thanks in advance!
I've always questioned the bypass line, my opinion would be why would anyone ever use it? As you know, the pass. side oil gallery is what supplies oil to the main bearings. And oil is routed to the drivers side gallery through the front cam bearing. Any oil that is rerouted through that bypass line is taking oil away from the mains. And if the that line is supposed to supply oil from the drivers side to passenger side it still has to go through the front cam bearing which is a restricted feed. I must be missing something o No: If we could limit the oil to the topside (through the lifters, pushrods and rockers) and keep it downstairs we'd have much happier engines. I see a much greater benefit in the backgrooved cam bearings and reclocked oil holes, which are reduced in size to force more oil downstairs, at least on the drivers side. There's not much we can do with the pass. side, as the main gallery is shared with the lifters....not the best design when things get pushed way past the design parameters. The external line from the front pass. side sending unit location back to the rear of the pass. side gallery is a much better alternative.
Sending unit line Thanks for the reply. I was refering the the external line from the sending unit to the rear. Is it worthwhile on say a 450-475 (???) or so horse mostly street motor that shifts at 5500?
Ooooops! I misread your original post. ou: Now I see what line you meant. Its not necessary at your power and rpm levels. But with being such an easy install, it won't be a detriment either. I'd recommend a bulkhead fitting at the rear angled area above the starter, makes for a clean install.
I added a tap and sending unit to the rear of my driver's side oil gallery, just so's I'd know what the worst-case pressure is.
Amazing story of a BBB survival John The jury is in on the engine mods outlined in this post as far as my experience has been. I did everything you suggested I do to make the BBB live and everything worked except for one thing. That was a tuning error that caused a major detonation which cost me a number two main web failure just after I started the engine last May (Photos attached). The AMAZING thing is the engine lasted without a major eruption all summer. Immediately after the detonation occurred I lost some oil pressure but it was adequate idling at 20 lbs and running 50lbs at 5400 RPM shift point. I made 18 passes at the GM event in October winning my class at Mid Michigan Raceway. I had been listeninjg to a very small knock that made it presents known but it was so weak it sounded like piston slap. This February I pulled the motor down to check things out and everything looked good, very good in fact. When I pulled the top main bearings out I saw the crack in the oil galley in bearing pocket and my jaw dropped like a stone. I could not believe that this engine had not erupted like a grenade. I recovered all the pistons, rods, and crankshaft all are still useable for the next build, except for the block. If I had not used the external oil passage to the rear of the engine all bearings south of the number two main would have starved an a major catastrophic explosion would have occurred. In the number one photo the shiny suface you see along the crack line is a polished area from two sides of the crack rubbing together for so long. Thanks John, your information was priceless.:TU: Weekender
I have a souvenier just like that from detonation. I was trying to qualify Q16 at the Nats and moved the dist in the staging lanes (no light)....after a delay in the lanes the moved it a tad more. Ended up with 50+ when I checked it in the pits. Won't try that again!!!:spank:
Re: Amazing story of a BBB survival And this is what they look like without dowel's, this is #2 main also:TU: Chris
The last couple engines i've put together used edge orifice solid lifters. The thought was to reduce the waisted oil going thru the lifter piddle valves. This mod requires roller rockers but seems to really stablize the oil galley pressure. Anyone else doing this now?
I'm running them but it seems my solid lifters are noisier than with reg. solid lifters. Anyone else find this to be the case? Bruce BQUICK JAGUICK
Re: Amazing story of a BBB survival This is the exact break line mine made, how ironic. How long did it run after it broke? Weekender
This makes me worry that drilling out the oil passage weakens the block to much. This is at least the fourth block failure i've seen along the oil feed.
makes the argument that a good radius job to remove the sharp edge might help a little. Detonation hurts bad, I have often wondered, after reading from Yunick or Jenkins about it, how many engines that live way beyond "what they should" are because of good detonation prevention due to either oil control, excellent timing control, or the discipline not to "crank in a few extra degrees" trying to go faster. DAMN! that webbing is thin!
This was not caused by detonation in my eyes, there was no sign of that on the pistons, rings or back of bearings.The timing was NEVER more then 32*-34*. My thought is, if you hang a bunch of weight off both ends of the crank and there only supported on one side of the weight to boot, add 625-650 hp, 10 plus years of being beat'n like a red headed step child to a wimpy block something has to give.Just my thoughts.Chris
I believe it does weaken the block by drilling them out, even when grooving the main saddles you do not have to enlarge those oil pasages. Chris
Re: Amazing story of a BBB survival From what I have seen, most all motors that have #2 main failures are not running a mid plate.
Rick, I thought about the motor mounts, but why would the pass side fail instead of the drivers side?. All the main caps have been walking & talking big time. I thought maybe if the weight was more to the center of the crank (internal balanced) it would be way easier on the blocko No:
Are you running a girdle on that block? I know my caps looked good until I went over the 400HP shot with the nitrous. I checked my girdle pre-load, and it was off which seems to be consistant with the caps that had marks. Only #2 had chatter but #2 and #5 were loose. I can't say why it's one side or the other, just that it always seems to be #2 where the motor mounts are at. There is someone that has run a dial indicator on #2 main with motor mounts, and it moves that main just from turning the crank at the balancer. I can't imagine dynamically, it would be scary to see the movement. I run a "mid-plate" but it is just two 5/16" aluminum "ears" that mount off angles welded to the frame and it bolts to the backside the trans. It picks up the upper and lower trans bolts. One side goes thru the headers and the other over. They were setup with TA 2 1/8" headers. As to the oil passage to the main, I don't have mine drilled either. If you need more flow that what that passage gives then you have problems. There is enough volume with stock oil passages to the mains to kill oil pressure with loose bearing clearances so why does it need to be any bigger. Unless you have some "gravity feed" system that works.o No:
Rick You have brought to light an issue I had with my engine when I pulled it the left motor mount had loosen off and the torgue strap was the only thing hold the engine in place. The right side mount was tight and in place. Another issue I had to deal with is that the right mount bolt (horizonal) that holds the mount to the frame mount was out of align setting the engine a tad off the pad, resting on the bolt along rather than fully on the pad. I saw no signs of detonation in my pistons or bearings either, but it was a big event when it happened and I thought that must have caused the damage until you guys brought this issue to light. I am in the process of putting girdle on the new block for this build, do you think this will fix the issue?? Weekender
so while reading this im assuming all the pressure from the engine being torqued is going through the motor mount (if there isnt anywhere else), which causes the block to stress in the area of the #2 main cap? and that a midmount or something of the sort to help absorb or reduce some of that torque will help? with this, i would like to see some pictures of what you have done for a midmount or something of the type. even though my block is girdled, and my car will be mainly street driven (700hp street monster :Brow, i would like to protect against bad things like this, as i dont want to lose my investment in my car. thanks
