Hot Rods smallblock chevy heads

I have been reading about the 305 and 307 chevy engines, and how to build them for high performance. one thing all the articles say are that the big valve heads cannot be used due to bore size. My question is to all that know, when I was a kid back in the early 60s, how did all these guys get away with running the 202/1,6 duble hump heads on 283s that were bored .30, and .60 thousandths on their engines in the old gas, and modified production cl***es and not do damage to the piston wall, or bend a valve etc. ?

 

They will work, it's been done thousands of times. You got to RPM the snot out of the engine to make good power as you know.

 

Its really pretty simple. You are reading ********.

 

The sides of the block at the piston bores get clearanced for the valves.
Measuring and math tells the story.

 

A 307 maybe but a 305 bore is only 3.73.

 

2.02 on a 305 head
2.02 on a + 0.30 305


1.94 in 305 +0.03 bore.

 

Very good illustrations! Really drives the nail home, so-to-speak. What I saw, was the guys who would bore their 283 .125 over for 301/302, and used the stock valve size Power Pack heads (1.72/1.50 valves sizes). Talk about COPD. I am Butch/56sedandelivery.

 

I'm in to 283s and 327s and not trying to piss anyone off . As many 350s is there is laying around, why would anyone mess with 305s or for sure 307s. Just for the thrill of it?

 

A 307 is a large journal 327 in search of a boring bar... I could say something about notching bores to unshroud valves, but this is the HAMB...

 

I've personally ***embled 288's with 292 turbos and 2.05s, considering his background, I will bet Butch has done the same thing...
I dont want to have to dig out my hipwaders, so I'll just sit back now and watch it get deeper and deeper...

 

I've been told by a machinist buddy of mine that the 307 can be bored .125 over for a 4" bore which with a 307 having the same 3.250 stroke as a 327 would make for a standard bore 327.

 

I would drop $100 on sonic testing before I started spending money on machine work, but short answer is yes. but real HAMBers are "only into 327s" so they wouldn't mess around with those junky 307s, the HAMB says they arent "cool"...
Should I post a photo of my "junk" steel 307 crank?? Jeez, too bad it wasnt from a 327, then it would worth "messing with"...
Ok, I promise, I'm done now, gonna go start the popcorn...

 

Extra ****er please!

 

And worth a lot more $$$ too! Just like all those 350's that are out of Corvettes.

 

I have always wondered why some one would pay $$$$ to make something that wasn't a 327 into a 327?
those things must have been rare or something

 

Well, in case of the LG blocks you could take @falcongeorge's "Junk" steel 307 crank and put it into a 4 bolt 350 block and have a high winding 331 or you could bore out a "junk" 307 block .125 over and put splayed main caps in it along with that "junk" steel 307 crank and have a high winding stock bore 327 that would make a dandy little sleeper motor for your late 60's early 70's Chevy. Okay we are getting waaay O/T now. Have you got those hipwaders on falcongorge?

 

I'm with ya on stroker motors. and building to fit cubic inch rules in racing
just didn't know why you would do a lot of work and spend $$$ to make something that already exists in abundance

 

Hip waders? Time to don the scuba gear! George, I want to know more about this "steel" 307 crank (is it a tongue-in-cheek 327 crank in reality?); I thought ALL 307 cranks were nodular iron (?). Least wise the one I have is. There are some "circle track type racing" cl***es in which "305" is the RULE; there are even aftermarket 305 blocks! But, I'm a drag racer, so I'm a little out of my element there. MY DD truck has a 305 BLOCK in it however, but mostly everything else is 400 based; cut down 400 crank/rods, forged, TRW, 305, dished pistons (.030 over) for 334 CID (balanced). The real drawback is the stock 305, #601 casting heads with the SMALL valves; it's a bit emphysemic, and could surely use better heads. 31 Vicky's photos demonstrate the shrouding very well when using too big of valves on too small a bore engine. See those billet, 4 bolt main caps, on that "305" block; why would anyone in their right mind do that? Because it works for what it was designed for; key words being "designed for". And that should also answer the original question. I am Butch/56sedandelivery

 

307- those things are pigs
The scourge of the SBC family.
Junk that's not even suitable for a boat anchor.

 

Dead serious Butch, I also talked about it a bit on 31vickys 307 thread about a year back. I will dig it out later and send you a pic. I'll be honest, when I dropped the pan on that motor, I was pretty surprised to see a steel crank. It came out of a 307 from a Canadian manufactured 1/2 ton longbox '68 chevy PU.
I had to look up COPD...

 

I got another 307 for FREE, dropped the crank ( cast) in a 4 bolt 350 block I got off local craigslist for $100, with 6 used L2165F's I bought on ebay for $80 (had to buy two more new), topped it with craigslist 906 Vortecs, $300 with valve covers and rockers. I dont know what YOU consider $$$, but...
And if you think large journal 327s are in abundance, I wanna know where you do your shopping...

 

Valve lift had a lot to do with it too - old cam designs were rarely over .500 lift - remember a lot of double hump heads were 1.94s - that is what I have on my 283+.030

 

Get a treefidy and leave the 307s alone.

 

They relieved them.

 

^^this. And high perf BB chevys(from the factory no less), 427 heads on 428 FE's, and on and on. Its hardly rocket science, just they dont talk about it in Car ****, so its a HAMB non-starter...
I know, I know, I said I was gonna shut up and let the shoveling begin...

 

I was going to pm this to Butch, but may as well post it here. Came out of a LJ 3 7/8 block, from a truck with 307 emblems.

I will admit, in 40 some-odd years, and a HELL of a lot of SBC's, this is the only one I have run across, but you saw it here first, a crank that "doesnt exist", and thats not just according to Butch, most guys would agree with him. Probably needs a grind. I dont know if i will ever use it, I generally prefer sj motors. Would make a dandy blower motor if I stuck it in this...

 

best answer EVER...

 

I have actually torn down a couple of 307s with steel cranks. I always just figured that GM was using up some old parts. I look at it this way, if I was counting beans and discovered that I had 3 pintos and a bushel of Reds, I would just mix the Pintos in with the Reds. Hell the Pintos are paid for, I can't sell just 3 and I am selling the Reds by the bushel anyway.

 

Yep, the problem is that I'm talking a bunch of ****

 

What is the casting number on that forged, 307 crank?
I am Butch/56sedandelivery.