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i just bought an 82 chevy truck. it has a 350 and i need to know if it is a 4 bolt main. the dude told me that it might be a 4 bolt because it has a bigger then norman harmanic balancer and he said something about the location of the oil plug or filter. i dont know if that is enuff info. if anyone can help that would be cool
jerry
There is no way to tell from the outside.
82 was a big gas crunch year like now, they strayed from bigger is better. is it a 1/4, 1/2, 3/4 ton truck? it is pretty hard to truly tell without dropping the pan. unless you are going to throw alot of horses through it, it will be fine.
Look for the casting numbers on the block. They are located behind the left head on the flange where the bellhousing bolts up. If it is a 3970014 casting, it is a regular 2-bolt main. This is the most common of the 350 castings. If it is 3970010, there is a 50% chance that it is a 4-bolt. If it is a 3970010, look for a small oil plug on the front of the block, near the top center between the base of the intake manifold and the top of the water pump. If that little plug is there, it's a 75% chance it's a 4-bolt. As Mooneye said, though, you can't be 100% sure until you pull the pan off. There are other casting numbers that have 4-bolt mains also. If the casting numbers begin with 14 and end with 776, 777, 778, or if it says 5.0L next to the casting number, it's a 305...
A 2-bolt block is good for occasional forays into the 6,000 rpm range and are plenty good enough for the street. Most of the time we are loafing around at 3500 or less. If you are going to thrash it frequently at the drag strip and consistently twist it up above 6500, then you need a 4-bolt.
If you have access to a borescope, run it up through the drain plug hole.If not, I'd drop the pan.
I thought it would be nice to have a borescope, so I began pricing them the other day. YIKES!!!!!
Hey Rich, just keep telling yourself " it's only money ". Hmmm, maybe that's why I'm always broke?
if your going to twist above 6500 you need a what?????????????????? i just had to say something :LOL:
Maybe you could borrow George W's borescope he's done with it now.:eek:
Quote:
Originally Posted by JeffB2
:LOL: :LOL: :LOL: :LOL:
How many horses is it generally safe to put to a two bolt?
If your going to spend enough so that it matters, buy the right block also.
I think I read in another forum that the machine shop doing the build could machine your 2 bolt block to 4 bolts?
According to my machine shop.... In the realm of street engines, 4 bolt vs 2 bolt is the most overated SBC issue.
In my opinion, the 2 or 4 bolt controversy hinges on several things. The weight of parts in the reciprocating assembly, the rpm's and the power being made. You might be able to spin a 283 to 7,500 or even higher with no problem on 2-bolt mains, but trying the same thing with a 383 might end in disaster if using off the shelf parts. With super light parts, you could probably do it time and again. You might bolt a 4-71 onto a 283 and blow it up at 5,500 because power exceeded the design of the webbing in the block. I'm talking in a relative manner here, so take it with a grain of salt. :)
a guy i used to work with had just quit a machine shop somewhere down in california where he used to build pro stock motors all the way down to street motors. the shop went out of business after 22 years. his explanation of 2 bolt vs. 4 bolt was this. why do you need to worry about it? the force during acelleration is projected UPWARDS only on decelleration does the crank and its energy go downwards.
Makes no sense to me whatsoever.
I will try and remember this the next time I build a 15 to 1 engine on alky.Quote:
Originally Posted by gassersrule_196
Where do you think all the force goes on an engine that has 15 to 1 for a comp. ratio and turns over 8,000?
That's right, the pistons and rods are trying like hell to push the crank right out of the bottom of the block.
This has to be one of the most asinine statements I have heard in a very long time.:whacked:
Please don't believe everything you hear.
Think he's confused, Scooter!!!! he could only (possibly) be referring to the torque created when you drop the hammer at the line on a solid mounted engine.... All those explosions in the cylinders create huge amounts of pressure that trys to rip the webs right out of the block!!!! That's how an engine makes power.....Quote:
Originally Posted by gassersrule_196
I raced dirt modifieds for years and one of my best engines was a two bolt block that got splayed caps. It turned 8200 rpm with 525 hp and I ran over 30 shows on it before rebuild. I also ran alcohol for fuel. $7000.00 goes a little ways sometimes. Get an opinion from a machine shop that builds race engines not just reman stuff. You will likely be happier. just my .02:3dSMILE:
This argument can and will turn ugly in less than a heart beat. You all have hit the point of "downward thrust", etc. The 4 bolt main was designed as a misnomer. The weak spot was the bridge (arc) across the cap. Therefore, major block builders have beefed that area. The 4 bolt system as a straight through bolt was for keeping cap walk down to an absolute minumum. The bridge will still be your weakest link and needs the most amount of your building attention. The splayed version was found to be be most effective in controlling block fatigue and stress on rpm usage. It loads directionaly perportionate to the cylinder rather than "tug" away in an opposite state from the loaded arc of the crank. Rather than take my word for it, dig a little deeper into the geometry and load values of the webbing and it's supports (main caps) and see if I just fell out of my tree. My mentors from Dave Crower, Mike Troxel, Lee Beard, Robert Street, Bob Duvore, and others had to slap me around on this subject many years ago and I had to also learn the hard way of what can and will go wrong. 2 bolts live with proper geometry, Just don't try to make "King Kong " out of it. Know your limits and get wise to the money it's going to take to build "King Kong". Many race programs that are successful will be glad to answer questions in this area. Dig in and do some research, it's a lot of fun and very enlightening.
hey denny this is OT but was it you who posted some website that you can look up certain cars that were in movies or tv?
I heard that on a 2 bolt engine,replacing the factory bolts with studs finger tight and nuts is stronger than standard 2 bolt,and on a 4 bolt do the same to gain strength there too
I paid $400.00 to have my 350 block converted to a 4 bolt. Not bad because the block was free. It has Competition Products straight bolt caps.
Wayne.
Yes,ARP studs should be installed "finger tight" and then their own moly paste used on the threads or 30 weight oil and follow their torque specs.Quote:
Originally Posted by toolmantom
I like to torque in five steps.
I heard form a guy, that the 400 2 bolt is better for more horsepower built-ups, then the 4-bolt. because of the placement of the 2 other caps, he says there in the wrong place, and didnt really do much more then a couple holes in the block?
IMO any block is better with the splayed caps then the straight bolts.... Never have had much trouble with 2 bolt blocks, not a lot of Ford 4 bolt stuff out there unless you want to buy new.... Unless I'm going with a blower or nitrous I usually don't worry about it, especially on a street engine with 9.5 or 10.0 compression. Good machine work, proper assembly, and cam and heads to make power at a reasonable RPM IMO is still far more important then how many bolts the caps have...... I mean heck, if it's just a cruiser, why pretend it's being built for Pro Stock????
ok, i must be thinking of number of caps....... on all sbc's there are four caps??? 2-bolt, 4-bolt means how many bolts there are holding them down??? or is 2-bolt, 4-bolt mean number of caps??
im still kinda of new to this, but, i have a 400, and i want to give it some more power, this same guy i was talking about in the thread above said he has built many 377's and there a really strong and powerfull engine, doesnt anyone know of some configurations that could be used on this, like cam specs, intake, heads specs?? i would like to keep the same bore, only because i think the engine was fairly fresh when i got it, just new rings, any one built one of these before???
We're talking about the number of bolts per cap, 2, 4, or 6...
any the number of caps always stay the same. 4
Not necessarily, depends on the engine. V-8's generally have 5, I-6's, V-6's, V-10's and V-12's are all different.
Great pics, Denny! I really like the girdles, been using them ever since they came out, and before that we built our own cap supports for the Windsors from a piece of bar stock and a bit of flat milling on the cap. The billet girdles are soooooo nice and sooooo much easier then building your own!!!!!
With splayed outer bolts, billet caps, and a billet girdle if it doesn't stay together, then something is seriously wrong!!!!
Hey there here is a link to a site that will tell you pretty much everything you would like to know about your SBC hope it helps ya it has helped me alot when buying used motors.
http://www.nastyz28.com/sbchevy/sblock.html
dennyw is spot on..the 2 bolt from the 4 bolt both brake in the same spot most of the time.. the 4 bolt helps cap walk and some bearing issues and thats about it..
Denny has it more "ON" than you know. The point about 4 bolt mains seem to go over everybody's head and the new questions anew themselves. Now, Denny has actually supplied the pics we have been beating into the ground for a long while. (No offense Denny). The 4 bolt set up is contribed as a saviour to your woes. It is clear that it is not understood very well. The weak point is the "bridge" (radius, or "arc" if you will), not the amount of bolts to control cap ""walk". The pics show exactly where your defects are and it's not in the mating surface of the cap to block area. Most novice and wnanbee's think that the bolts you have, the stronger the webbing in the block is............nope! Concentrate on the weakness and strengths of your block and cure the weakest link, not what some hotrod magizine wrote. You wanna stop cap walk? Splay the outer bolts to the angle of the cylinders, and this is elementary basics for longevity. Not to leave you out Dave, you're right, splay 'em and keep it "square". Then there's something seriously wrong if it goes away. "Geometry, Geometry....................................."
WELL:rolleyes:the way i see it . the cap that is crack was a cast steel/iron cap. a billet steel cap you would not do that to. BUT a 4 bolt cap just adds two more holes were you really do not want them .this will not make it stronger in the block web as for the cap not walking with the add bolts ? i seen them move the caps the bolts just hold the cap in the block the holes for cap are bigger so the bolts go thru it .if they were held in by the side of the bolt they would break the bolt or stud is not made to take side load and to stop the cap from moving side to side justs to keep the cap from pulling down . the cap need to fit the rester of the block that helps keep the bearing and cap from moving side to side. if the cap stay flat and not springs up . the make up of the cap helps to .cast steel /iron. or better ductile iron . steel forged /billet . the crank is trying to pull the cap down this springs the caps then may bow them up were there is not any bolts .like denny showed . then bolts or studs will not help to lock the cap in the block... the cap must lock in to the block.....with out no bolts . the bolt do not do this what can help is a big dowel on each side of the cap or pin not just a small 1/4 pin or an open dowel or split one but a soild pin in the middle of the two bolts that way you use the bolts to hold the cap up on the block and the soild pins and using another surface to hold the cap from sprining ? keep the cap from sprining down and getting loose and skidding side to side . that the way i see it:whacked:
Amen! More attitudes can be expressed, but that pretty much covers the street attitude. Thanks Pat.
When I use "splayed steel caps" I like to use about the cheapest ones out there.
The reason being no matter what "splayed steel cap" you use it will always be stronger than the cast iron around it.