i was talking to my machine shop he was telling me to crossdrill the crank and buy 2 sets of mainbearings and use the 2 grooved ones to make it 360 degree grooved motor will be around 550-600 hp block is 1974 just trying to keep this beast alive. i got these chevy boys in a bind with this chevy malibu 455 powered bbb. any info will and would be greatly appreciated. thanks female 455.
i wouldnt crossdrill crank as it would weaken it to much i think ta has 3/4 grooved mains. if you do all the oil modifications to block and pump housing you should be fine. ta and trishield have some info on there website for oil upgrades ,and i think there is info on this site too also ta grooved cam bearings would be needed here. i might try a different machine shop just to see what they know or suggest where are you located ,there might be a good shop near enuff to you or someone on the board near you who can suggest a shop. andy
Cross drilling is a good thing in my opinion. It will not weaken it at all I spin my motor to 7200 every pass with no breakage yet. My good motor has some where near 180 pass with no major issues. We cross drill almost all of our cranks for racing. I would do the mods that you can find on the board with those you should be fine. You need to get a good builder that does quality work. I feel that most builds under 650 are fairly dependable once you make more than that you start pushing the limits of what it will hold. The key is paying attention to detail no matter how builds it. 550 to 600-horse power with good aluminum heads is still a pump gas deal if done right there are many of the builders on this board capable of that kind of power.
I don't get it There is aways a lot of talk on here about people lossing there engines and you have to do this that and the other thing to help keep them alive o No: I scewed my first buick engine together 25 years ago and have never lost one I've got about 9 lined up in my shop to rebuild for customers, the most common problem I keep seeing is builder or machine shop error which goes back to the engine builder because it's are job to find any and all mistakes.The engine in my drag car is throw together with very little mods,13:1 308s it runns low 10's and has been together for 2 seasons.People are to quick to blame the buick engine when really they just need to fier there engine builder.If I was you I would look for a new machine shop or at least an BUICK engine build because the fact that they want to cross drill your crank tells me they don't know whats going on. Chris
AM&P cross drilled my crank. They also come highly recomended as knowledgeable in the Buick community. The Steven Dove book "Guide to Performance Engines" points out this topic is controversial. I also proceeded to crack my last cross drilled crank in three places... Never spun it past 7K. HP was a tad over 600. Also, as a reference since you are "new"... (welcome), Both Bobb and Chris build motors and they can't seem to agree either. If you dig further in the racing threads, you'll see the new train of thought being to groove the main caps. TA does them as part of their prep work. I also recently spoke to Mike at AM&P and he is considering doing the same... Do your research, go with your gut, and cross your fingers. John
saddles John,you groove the main saddles not the caps.I wanted to add, my engine was together 5 years before it got throw'n back together,so its been going for 7 years. Chris
Dont use a cross-drilled crankshaft. We continue to repair many Buick engines each year that have little or no time on them with rod bearing failure. They have all had cross drilled crank shafts. This system was thought to ensure a continuous supply of oil to the rod bearings because one end of the passage drilled through the main bearing is always exposed to the pressurized oil in the upper main bearing insert. I learned years ago from being involved with Pro Stock engine building that they tried cross drilling the cranks in the mid 70s to discover that it was a mistake. It causes the rod bearing to be starved for oil. This starvation is due to the lack of ability to overcome the centrifugal force pulling the oil away from the rod journal feed. The inability to overcome this force is amplified by RPM. It may be possible to temporarily mask the situation with an inordinate amount of oil pressure but the immanent results are the same.
Guys, I have looked into this subject several times. I keep finding a mixed opinion. All of my cranks have been crossed drilled including the one thats in my engine that has seen 7600 rpms several times. I have seen NO bearing failure. BUT.... there is an issue with oil starvation once you get to a certain engine RPM. I dont know what that magical rpm number is but I have heard this from very reputable engine builders. So.... what do you guys think.... Instead of crossdrilling would it be smart to increase the size of the existing oil holes by 25%???? And then put a bigger chamfer on the holes???? Later
( NO CROSS DRILL) It is much harder to build a Buck that other gm motors. BS it takes thr same skill to build them all. If you want 2.5 Thousnads of rob bearing cleraence then how much harder is it on a BBB than a BBC? The problem is that most machine shops couldn't achieve it on either engine.The thing that saves the BBC is that it is much more forgiving, the looser the better. I onced asked a person working in one of thease shops how he fits pistins. He said he useses the manufactures specks + one thousands.I thought to my self maby they are in a hurry and if you do it quick you have a HOT BLOCK and it will shrink down a bit (out of round)I asked him about it and he said HA!. why is the manufacture always wrong? I was affraid to ask any more really technicial questions so I just asked where is the pop machine and had a Coke. The moral of the story is it is not any harder to do them all right and part of doing them right is to know the short cummings of each one before doing a rebuild. RonJ
Another helpful link with different opinions!!!!!! I think the first real question that needs to be asked is: What type of engine are you building? o No: A street/strip or an all out race engine, then what horsepower level are you talking about? After reading this link it seems that, everybody has differing opinions, but nobody has asked what type of engine is being built? Myself, I have ALWAYS crossdrilled my cranks(there is an actuall bulliten released from Buick, back in the day about doing this and how to do it, so.......the engineers must have thought that it was a good idea and wasn't afraid of "weakining the crank" speaking of that, I have never seen a Buick big block crank that broke, unless of course a rod came around and hit it.) It seems like everybody is assuming that a 800-1000hp engine is being built, I'm sure that we can all agree that a 500-600hp engine can be built to different specs then a 800-1000hp version! CAN'T WE??? The engine in my Regal has over 650 passes, with over 350 since being "freshen'd up" (the bearings looked perfect at that time by the way) Now, I only shift at 6,000 and pass thru the traps at 6,200, and only have approx. 10-to-1 comp.(pump gas is cheaper then race gas) but I have never had an issue with a cross drilled crank, maybe a 14-to-1, shift it at 8,000 engine may be different, but......nobody bothered asking that, did they? I DO AGREE that finding a competent machine shop is very important, but you also need to be able to tell them how you want your clearances set up, as you can see, us Buick guys have different opinions, what makes you think that all machine shops should agree on how to machine an engine? I assemble my own engines so I check everything that I feel is important for the level of engine that I'm building at that time. This board and these links are informitive, but....everybody thinks thiers is the only way that will work, I don't really feel that is the case!! :Smarty:
John Makes Sense! I would have to agree with John. I'm a new comer to Buicks, but they are like any engine, the machine work needs to be correct and the assemble clean and right. It has not been hard for me to build a 500 hp engine and keep it running with out too much in the way of one off fancy stuff. I see people screwing up Chevys and Fords all the time with bad machine work and poor assemble practices. Nobody thinks too much about it when they pop one of these engines, but when a Buick goes bad people are coming up with all kinds of one-off problems. I think if the clearances are correct and the pump is setup correctly, you will have oil pressure. Being a Chevy person for years, it took me a while to realize, you don't need low gears and big rpm to go fast with a Buick. I kept putting in higher gears and taller tires and shifting lower and went faster. It works for me. Jim N.
Hi guys, I've been lurking around for awhile trying to absorb all I can before posting about this. Speaking of oiling mods.. I'm having a street/strip engine built around the TA 290-08H cam "The 500HP Street Cam". I plan on highway driving to the strip, racing and driving back frequently this summer. With this kind of use in mind, is there any harm to grooving the mains saddles in addition to the the front of the block passage mods? Would this work instead of cross drilling the crank? Thanks, Electrajim http://www.gnttype.org/media/electra.mpg
My $.02 and this is what is working for me. About 2 years ago I started experiencing problems with #3 and #6 rod bearings in the engine that is currently in Oliver Colteryahn's GSE car. This occured when we started pushing past the 6,800 range. They would last for about 10 to 15 passes and that was it. I tried different oils, coating bearings, balance tube, accumulators, etc. At that point I had not grooved the main saddles or done priority oiling but I did run an external oil pump. I had heard all the pros and cons of fully grooved bearings and cross drilling but to me, no one had come up with the root cause of the problem that satisfied me. Not until Charlie Evans spent a fair amount of time really looking at the crankshaft, its oil holes and their phasing to each other. Forget about mains 1 and 5 as they only feed one rod bearing. What he found interesting is that the oil holes for rods 2 and 7 are phased 90 degrees past the oil holes for rods 3 and 6. The oil holes for rods 4 and 5 in main #3 are spaced 180 degrees apart. I never have any problems with rods 4 and 5. The small block Chevy crank's that I've seen aren't this way. The oil holes in these 3 mains are all 180 degrees apart. What he surmised is that rods 3 and 6 "could" be seeing a pressure drop as the holes for rods 2 and 7 are uncovered and 3 and 6 aren't getting the same "volume of oil" as 2 and 7 are or that 4 and 5 get. So we cross drilled mains 2 and 4 only, realizing that this may be against what is currently deemed as inappropriate but we had some special circumstances with the Buick crank. Now I had already started a priority oiling system on this engine so I had to follow through with it and we had also converted to a dry sump but if I were to put money on what fixed the problem it was the cross drilling the crank and grooving the main saddles. Now as I write this I'm thinking that perhaps I could have plugged the #2 and 7 oil holes and moved them to 180 degrees from 3 and 6. So this is why I cross drill these 2 journals and I guessing why Mike Phillips does the same. Now, perhaps there are many that get away from this problem by running high (100 lbs.+) oil pressure without the cross drilling. I this works, great! My preference was to correct what I now thought was the root cause for the problem. So far no more rod bearing issues. Bruce Kent
Hi Guys, Bruce....if you don't mind sharing, could you go into a little more detail as too your "priority oiling system" you mention above? I've studied a couple of ways to go about priority oiling the mains via a manifold in the lifter valley. I'm quite sure it will be a good read if you wouldn't mind...o No: Thanks!:TU:
Volume and pressure. YOu have to overcome centrifugal force. Its physics. THe larger the diameter the more pressure it take to overcome the force to get to the rods. SO you need pressure to overcome the large diameter. On the volume, Bobb Makely brought up a very good point, the available volume of the groove in the main bearings compaired to the pontiac. SO if I were looking to fix a problem I would add 3/4 groove bearings with larger oil gooves, groove the saddles with 45degree holes in the bearings, and stay with 10-11psi per 1000rpm. A vacuum pump will affect the pressure so get pressure reading without the vacuum and get it set before using the vacuum pump. I think you can get away from cross-drilling a crank but not without addressing the problem in another way. This is for addressing a higher rpm race setup. I have a cross drilled crank and I did not break it.....Yet. I'll try though and let you know how much it took.....I did not have bearing problems from pressure or supply but from epoxy trash getting to them. It was not bad but it did mark-up the bearings. I was running a high volume setup with a stock type filter housing. I did not have the by-passed blocked because I could not get a SystemOne oil filter so I was worried that a K&N oil filter or any oil filter would not flow enough. Otherwise I highly recommend blocking the bypass and running a high-flow screen filter to keep trash from by-passing the filter and getting to the bearings. ESPECIALLY if you run any type of epoxy in your motor.
550 to 600hp Wow,the question was how to make a 550 to 600 hp BBB live not 700 to 900 hp,I tell the machine shop the spec's,I do all my own oil mods etc,the engine builder IS responsible on assembly to find and correct any problems found caused by the machine shop or what ever.My point was find someone that knows there way around a BBB or you will have most likely have problems.After reading all these post on here I have to wonder how my engines ever lasted so long.My mom got 280,000 miles out of her BBB before it packed it in.If you can't make a 550 to 600 hp BBB live with out all these mods you should take up knitting. :grin: I think things have gotten of track here guys.Some mods are required for this hp level but not many just the basics.....Chris
550-600hp This is in the Race section, Right?? 550-600HP Under 6200 rpm, is grooved cam bearings, front cover oil passage work, high pressure oil pump spring or TA Adjustable, deep pan w/extended pickup(if this is for race use),and good machine work. You also need to open up main bearing oil hole to align with the block oil feed passage in the block. DONE! SO, NO cross drilling. You can get carried away but I would say this is the basics. Mine was .0025 mains/.002 rods 70 psi oil pressure, nitrous, and no bearing problems whatsoever. Street driven and always ran pump gas. Ran 6.80 at 102 on nitrous in the 1/8 mile. 11.40's on motor in a 3600 lb GS. Stock short block, no balancing, replacement .030 hyper' pistons. o No:
Cross drilled crank. Hi.... It works for me, I have a 70 GS stage 1 that has 600 hp and pulls the wheels up and runs 11.07 at 120 mph 60 ft is 1.53 and no breakage yet. I pray every time that it will stay together, It has a cross drilled crank and runs on pump gas and yes i did go with the lunati sp-4 cam and 1.65 TA roller rockers it sounds wicked on the street. "I LOVE IT" :beer Billy
