Don't worry about the 2 bolt caps on a small journal 327, we spun one to 8000+ routinely on a gas dragster, valve train issues will keep you busy enough to forget about the bottom end. Just follow tips already given here, good bolts or studs, make sure cap register in the block is a good fit, and a good balance job
I built some 6-71 SBCs, got some 'Wedge Engineering' steel caps from Al Teague at Speed-o-Motive. (1980) The 2-bolt steel caps became part of most built SBCs in my shop, for blown or naturally aspirated engines...just their cost (affordable) plus the necessary align bore that would have been performed anyway... They were akin to a 'poor man's girdle'...
Girdles=smoke and mirrors. By the time the machine work and fitting is done on a girdle, you could have had 4 bolt steel caps installed. An old trick was to "strap" the caps. Basically a piece of 3/4 X 3/4" steel was placed on top of each cap, and the bolts went thru it on each cap. A short fill, studs, and proper machine work will produce a strong block for your application. Just don't rattle it.
I know of one that my mechanic built that turned 10G any time...had two tach's in it just to prove it to naysayers...was a drag race motor most of its life....until a 5.86? gear was put in the back....then pop. The one in my 68 has seen 6500 more than once.
^^^^ that's how we did it on a 327, billet 283 crank 3/4x3/4 steel on the mains, every thing well balanced and a lot of head work, did 9000 grand many times over with no problem
Desert, I thought your comments were helpful, to the point, and on target. Its funny, everybody that writes for the magazines, and most of their "deciples" always want to disregard even the most basic math and physics, it lacks "sizzle". I find whenever I am talking to someone who REALLY knows their shit in the area of engine building, the main thing they have over me is a better grasp of higher math, not that they have read more magazines. For myself, I run into a sort of "ceiling" of understanding that I really cant progress beyond, because I lack sufficient skills in math and physics, and I find that frustrating.
As long as the crank stays in the block you can spin it as fast as possible. If the crank does come out of the block you probably went about 500rpm to much! LOL
Gotta a few things for ya. Back in the day, with 2 bolt mains. We would machine the caps flat on the mill, then on our Mag base grinder finish grind top of cap. We would use machined steel straps (1/2" thick x width of cap) that fit over the caps. Rear cap had a strap machined for oil pump cavity and oil passage, also pinned and threaded for oil pump stud. Any ways....studs, block/ cap registry checked then align honed. Later...thanks to Some companies(Milodon,Precision Perf.) that provided 4 bolt splayed caps. These small journal main blocks were pretty damn good! We used a lot of 2 bolt blocks as the main web area was heavier than the new released (large main journal) block. Later, We also used plenty of 4 bolt blocks. A good engine machine shop can balance your assembly for higher R.P.M. A better shop can "overbalance" your assembly for the highest revs. 2%,3% and maybe 4% of overbalance can be achieved. A lot of good articles on the net about this. Obviously as stated by Hamb members before me...your valve train will be another issue!
There were a bunch of guys running destroked 2 bolt main 327's and hitting 8k+. Good block and crank prep are a must.
Back in the late 60's I built a 327 with 283 crank, rods, and pistons for dirt track racing and it would really get it coming off the turns. I turned it to about 7200 at least two nights a week. It lived for about six weeks then it had a scrap iron fit it the middle of turn 3 on a 1/2 mile track, there was not much left of it.
You could also run a 4/7 swap cam. A few years ago my dad built a 307 Chevy to go dirt racing and when we put it on the dyno it only made power up to 6,200 so why spin it up to 7-8,000 R.P.M.'s ( it's harder on parts) A few years ago we ran a dirt modified in an mid western dirt racing association that doesn't allow studs girdles, straps, studs, or anything which leaves us looking for the "good" blocks and what guys have found is you want the ones with the casting number "2482" on the main caps. The other main caps are "Grey" steel ,and you can see a diffirentce in color, but I don't recall the casting number off hand.
The Jalopy Journal
