Is a 2 bolt converted to a 4 bolt reliable as a factory 4 bolt. And if so should it be done with splayed caps or normal caps.. and how does studs vs. bolts come to play with a 4 bolt because i know with a 2 bolt it is a lot stronger. Also how much would it cost to have done or could you do it with a drill and tap at home? anyone had it done before? just trying to find out since my search for a 4bolt has been a trip in the dark for the last 3 months!!
thanks, Roger

Are you really sure you need a 4 bolt?

a good 2 bolt block with studs is alleged to be good past 500HP and a lot of RPM's. my 355 2 bolt with studs can hit 7200 RPM, and is somewhere in the neighborhood of 400 HP. it has held together for 2 summers of abuse, and about 15,000 miles so far.
the machinist who did my block said that every 2 bolt he has put together for dirt track cars has lived, but the racers who insist on 4 bolts end up with blown engines. he wasn't sure if it was because the 4 bolts are weaker,or if the guys pushed it too hard- but almost every blown-up small block he sees is a 4 bolt.

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1971 Nova(looks like 69 camaro from underneath!)
355sb, vortec heads, HOT cam,T-10 tranny, 3.70 gears 16X8" IROC wheels. 12" Corvette brakes on the way.
see pics here http://community.webshots.com/user/novaderrik

I have a 4 bolt smallblock. I'm into Big Blocks. What is a 4 bolt small block worth? My guess is that mine would have to be honed out.

roglette, The racers I have talked to say they run 2 bolt with a stud kit with no problems. I had a 350 with 2 bolt mains and ARP studs that never gave me any trouble even after considerable RPM abuse. The splayed 4 bolt is better than the factory 4 bolt setup. The 4 bolt engine is not faster than the 2 bolt, just has more bolts and costs more.

If you do decide to convert a 2 bolt block, the most important thing to do is be sure to find the best skilled and trustworthy machinist available to do the work. It is VERY hard to find one where I live.

-Mark.

4 bolt engines blow up just as fast as 2 bolt blocks. It all comes down to the preparation of the engine and eliminating the weakest link - which is usually the rod bolts. If you properly build an engine with quality components it'll last. Otherwise it'll break.

IMO: You need/want a 4 bolt engine when you're spinning an engine hard all day long and you run the risk of twisting the crankshaft and/or vibrating the engine to pieces. The 4 bolt caps come in handy in keeping everything straight and where it belongs. Obviously after 4 hours of doing this, the engine is torn down and rebuilt for next weekend, but you're probably not going to be doing this.

A 2 bolt block will survive a quick 10 second blast down the strip assuming it's assembled correctly. It would probably be more cost effective to have you engine balanced rather than machined for 4 bolts. Vibration is what makes stuff come apart, among other things. You'll melt pistons & break rods & rod bolts regardless of how many bolts are securing the crank.

Not to make this too long winded, but a properly balanced engine can safely rev higher since it's not trying to shake the heck out of itself, and it also puts less stress on the weakpoints. If you're like me & most everyone else, you need to spend your money wisely.

If you are going to convert to a 4 bolt block, get splayed main caps installed (professionally). While the 2 bolt vs 4 bolt debate will go back and forth all day, not many will disagree that a splayed 4 bolt block is more rigid and makes a stronger block than the standard 4 bolt or two bolt blocks.

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68 Camaro, 383 small block with TH350 trans. 11.98's at 111mph and never trailered.

The motor will have a T72 turbo on it and will be driven everyday. It will most likely be tuned to around 600hp for daily driving and 700 for the occasional races. I need it to hold up for the daily driving though. I already have a forged rotating assembly with scat rods. so they should be good. i got an SFI fluid dampener. so would a 2 bolt with studs balanced holt. or should i go with a converted 4 bolt. and balanced as well. if the 2 bolt will hold balanced then i already have a block. i just dont' want to break this thing cause she is my only ride. as far as how high it will be revved. no more then 6600, will rarely see over 6. thanks again
roger

I have 4-bolt splayed caps in the new 406.

After boring, honing, 9" decking, cap cost/install, line boring, etc. I wish I had bought a Dart Little M.

After spending all that money I cannot re-use the block again since it's at 0.030" overbore. For the long run, and for reliability, it's hard to fault the Little M.

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The Red Beast http://www.geocities.com/casanoc

carl, you could probably sleeve it and cut it again if need be next time.
I dont think that would be a problem, maybe becuase of the siamezed cylinder bores though?