I got a mystery sbc I'm rebuilding

Ok so I took it apart, and so far this is what I found...
A crank I can't identify.
Comp cam 12-211-2 grind:270H
.030 pistons.
338882 heads
350 2bolt main block

What do I got here? Also any ideas what I can do with what I got?
I just wish I knew what crank I got...

 

take picture from flywheel flage and i can id it .i have an bill jenkings book from 1980 or so
looks like you have 350 or 307 crank but im not sure it is a big jurnal?

 

I think that's the wrong number anyways, might look at the center throw. Most likely a 350. You could confirm by setting the crank back in the block (with bearings) and Measure from a reference point to a rod journal, rotate 180 degrees and measure again. A 350 should measure 3.48". Roughly 3 1/2". A 327 would be 3 1/4 and a 383 would be 3 3/4".

 

A LG 307 crank also has a 3.25" stroke and it will fit the 350 block... And with a .030" overbore, it will net you 331 ci...

 

#-882 HEADS=1970'S -bigger valves than most 350's had-/72CC combustion chambers,good as was offered on stockers....

 

head part number is actually 333882...1973-1980 350 or 400 small block, depending on if the head has steam holes or not. 350 has no steam holes.

need a better pic of the crank number...

 

comp 270H is one of their Magnum series cams isn't it?

 

Looks big

 

Piston heads

 

Pistons are regular flattop replacement pistons. They should measure 4.030 if you put a mike or caliper on them.

here is a listing of sbc crank numbers that might help. http://www.fastnuf.com/crankcastingnumbers.html

It looks like that has the makings of a pretty decent little street engine with some poke to it.

 

345NP=350 cast pistons

 

comp 270H is one of their Magnum series cams isn't it?

Quote:
270H Series
Great camshafts for high performance driving in street machines. The 270H has a rough idle in small blocks and a noticeable idle in big blocks. This is the largest cam that can be used with a stock torque converter. The 270H should not affect power accessories, but should be used with headers and 4bbl carburetor.
I had that cam in my Nova. It sounded nice, good mid-range power, and yes, the largest street cam (I was told) at that time, in which you could run vacuum power accessories. I ran power disc brakes with no problems at all.
Boy, if those heads are from a 400, that's scary, because it looks like my old 350 motor, also bored .030 over. It would be a small world if that were true.

 

You have a typical mild performance street built 350.

What do you want?

 

I'm just curious what it is, especially that crank, I got the luck of having parts with no casting numbers or worn out, I just want a bad Lil motor that can pull a low mean heavy lead sled, I'm no engine expert so that's why I ask the questions, I'm just a metal faber That knows how to work led very well and painter, but I did go to mechanic school but obviously I payed more attention to metal forming, body and paint lol, main objective is figure out what I got, figure should I stick with what I got or should I switch somthing out and add for more umph! Ya feel me?

 

Let me ask u this since u had this cam, was it noticeable power?

 

Sounds to me like you would probably to ok to just overhaul the engine, and mostly leave it alone.

If you want more oomph....get out your wallet

 

Oh yeah, good power. I ran low 13's and if I tweaked it, could of been in high 12's range. I was running with a M-21 with 3:55 posi. on street tires.

 

it's a Corvette Engine !!! lol >>>>.

 

Ok, do u know how much hp out put it maybe putting out? Should i do some head work?

 

Right on, any head work? Im not sure if its 400 or 350 heads. I have 3rears to choose from i have 69 chevelle stock rear with a 3:08 and a late 70's camaro rear with a 4:11 gear in it and a stock 54 chevy rear with no clue yet.

turbo 400 ****** to tie it up.

 

I'd probably spend a little time cleaning up the heads, mainly just below the seat, in the bowl, make it so it has a gentle radius instead of a corner. Don't make things bigger, just make them smoother.

 

When I took The pistons a couple of cilinders suffered some corrosion, I honed it as much as possible but I don't think it ain't smooth enough, maybe I should hot tank it first?

 

You can, but it will mostly just clean the oil off the block, it won't do much to caked on rust, and it won't take away the rust pits. Hopefully they're not too many pits, or you might need another block. It gets expensive if you have to overbore it again, or sleeve a couple holes.

 

Find a set of #416 305 4V heads from '76-'77 and bolt those on... Those should be worth another??? 20 er 25 hp...

 

Well the cylinders Are smoother after the honing, but I'm a Lil **** I guess that comes from the metal fab n painter side of me, ha ha

 

How's does 305 heads pump more with smaller ports n valves?

 

Increased compression and port velocity.

 

Thanks for the answer, I'll hunt for some, of not any other suggestions if I ain't lucky?

 

A set of vortec heads would be better.

 

The Comp CamQuest program says that a 350 with 9.5:1 CR, Vortec heads, dual plane manifold, 600 carb, should do just a bit more than 300 hp at 5000 rpm.

I've used that 270H cam before and it's a good cam, but not the best match to a stock converter and tall gears, so make sure you address that as part of your combo. If you want a smoother idle, the off-t******lf 204/214 cams make almost as much power in that same engine combo.

Vortec heads are very good as long as you don't go over the lift limits of the stock springs. Even then, that's an easy thing to fix with the seal and spring seat cutting tools. Aside from great flowing intake ports, the chamber design has great quench and a good burn, so even with 9.5:1 you can usually run 87 octane.

Either the 906 or 062 castings are good. There was an internet rumor about 906's being "bad" but that myth was dispelled a long time ago. The only other downside is, you need a Vortec pattern intake, center bolt valve covers, and the Vortec guided rockers (unless you machine for studs and guideplates).