Thread: This'll Get A Rise, 2 bolt 4 bolt

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This'll ! Thats our word for the day. A month or so ago we had quite a discussion about 2 bolt verses 4 bolt main for a street engine. I could not fine that thread ,but the subject was we had a young man starting out wanting to build to build a 350 chevy on a limited budget.Street motor. Several were strongly suggesting that he start out with a 4 bolt main .My contention at the time was he could put his money to better use by applying what money he had to something that would benefit him more. Dont waste the $100 .00 or so that he would have to pay extra for a 4 bolt block. This caused quite a stir, but it was very interesting.I was looking through old magazines the other day, looking for info on heads and cams because that was what we discussing at the time. I pulled out a october 98 issue of Super Chevy and across the top read, 30 STREET ENGINE ASSEMBLY TIPS. If you still have the magazine you might want to look it up. It is a 7 page article . Tip#12 Reads -- TWO WILL DO. Are 4 bolt main caps really necessary? A famous drag race engine builder did some dyno testing on the subject and it seems the magic number is 600 horsepower. Below that the two-bolt equipment will do just fine! the side bar reads, Four bolt main caps aren't always necessary. If your cars engine is making more than 600 horsepower it is a benefit,Otherwise,most street engines need only 2 bolt caps. End of that part of the article!Getting a good size heavy boat on plane puts a tremendous strain on the bottom end of a motor and a 4 bolt is a big benefit . A stock car needs a 4 bolt for real high RPM"s,but it needs it just as much because you use the motor and the gear to slow you down in the corner. that proberly puts more strain on the bottom end than the RPM's do.My first stock car was a 57 chevy, limited sportsman class.I used a 58--283 bored to 292C.I. 12.5 to 1 trw pistons,461 heads cut to about 58 cc's,an old c3bx intake and a 780 holley with an off road z28 cam.I was using a 7:05 gear on my home track,most of the time I would turn it about 7200 RPM. After two years,I felt the motor starting to slow down and put it on the trailer.Had caught it just in time to save most of the motor,The webbing had finally given up. Backing down in the corners was proberly more a factor in the webbing breaking than the RPM's. If I had put the motor in a street car I dont think the webbing would have ever given up.Now! If I were building a pretty strong small block I would definitely want a 4 bolt. If I'm building a good running street motor on a budget,I would use the money more wisely.WHAT DO YOU THINK???

It may also depend on what brand and block your talking about. I run a 900+ HP 460 with a 2 bolt main, I use ARP main studs. Heck, I dont even have a good crank. My old 350 that was in my 71 Chevelle was a rebuilt stocker, it was a factory 4-bolt though. I used to commonly run 6500 RPM's past the high school back in the day. I never even considered that an engine could blow up, when your 16 years old and driving a black Cowl Induction SS to school...its not about being smart, it was about being LOUD! My dual straight pipes would shake the entire school! Good times back then, I guess the 80's are long gone. I still have that engine, its in the garage....kind of rough looking, but it was running when it was yanked to make room for a 460.

i agree with the 2 bolt. i ve run 2 and 4 bolt blocks but never felt that i had to run the 4 bolt. round track is lot harder on the motor than drag. the backing off is really hard on the bottom end and timing chain.

for SB Chevys I like 4 bolts when it comes to an engine that will be lugged.. like pulling applications, otherwise 2 bolts fine

Originally posted by riverhorse59
This'll ! Thats our word for the day.

I remember back on the farm we usta' have this'llz. Those things would hurt if ya' got pricked by 1. HEHEHE

I ordered the truck with a 4 bolt 350 back in '92. No real reason, I guess i had thoughts of pullin' the engine when the truck body died and rebuildin' it for a project. HHHHMMMMMM might still happen someday????????

I thought I must have left something out.. The rest of the heading of the article in Super Chevy said, STREET SECRETS.30 ENGINE BUILDING TRICKS FOR STREET CHEVYS ONLY

For SBC's I tend to agree, you only need a 2 bolter for the street, but I'm going to throw a curve ball here. suppose you had a 4 bolter, sitting under the bench ?, would you run it on the street, or sell it for $$$$ and get a 2 bolter and get something more necessary for the street with the cash difference ?

Yea, Ford makes 4 bolts from the factory, but they are very unnecesary for the BBF especially. A 2-bolt 429/460 can take 900+ HP with a 2-bolt and a nodular iron crank. The factory 4-bolt BBF's are hard to find because they were not consistant in what had a 4-bolt or what casting number had a 4-bolt. You have to pretty much know what casting number could have had a 4-bolt and then pull every oil pan on every block of that number until you trip and fall on a 4-bolt. After all that they really dont add much to the integrity of the engine. Maybe a main stud girdle does, but I dont believe a 4-bolt does in a Ford 385 series.

Southerner, I have several 4 bolt mains so I wouldn't mind wasting one ,so I proberly would .If I were only concerned with 350 horsepower because I have 4 bolt blocks I would used them ,therefore I am wasting that block. If I only had a 2bolt block I would use it and not think twice. Especially if I am working on a budget,Lets say Im trying to build the best motor I can for $1000 to $1200 Im not going to waste any of that money to buy a 4bolt block. If someone is going to give me the 4 bolt for almost then same money, then sure, I'll take the 4 bolt.

STREETS, I dont know one way or the other,But I have heard several knowledgible engine builders say with a 400 block they thought the 2 bolt was stronger than the 4 bolt. More meat in the bottom end.

if you were that worried about having a 2 bolt that was weak, you could take it to a machine shop and have them splay it. ive heard they are way stronger than any 4 bolt. Chevy had to remove some material int the webbing when they made the original 4 bolts, but the webbing on the 2 bolts is a lot beefier.