Coach62

EDIT - I know It's not going to be easy with stock heads, I'm either looking at AL heads painted orange, or there's a guy out there that machines Dart heads to LOOK like double hump heads. I'm NOT - NOT trying to fool any judges here, just the general public at car shows and such, I want it to LOOK stock to the average Joe.

My new-to-me 67 Camaro has a 327 small journal, original, numbers matching engine. It has only 210 HP which I can't stand Especially after owning my Z06 at over 600 HP.

I want to retain the stock look of the car, (except the color, butternut yellow). I also love 327's. The car is in far too good condition to modify much at all.

I want to substantially up the HP of the engine without getting too radical of course. Since the engine is the born-with car I don't want to risk ruining the block. Of course it's always an option to mothball this engine and store it, putting a temporary 400 sbc or other sbc in it.

So - 2 questions:

1. What can the stock bottom end of a small journal 327 handle, RPM and HP wise?

2. If I upgrade the rods, pistons, main bolts and rod bolts (I don't see any reason to change the crank, am I wrong?) what can the short block handle, both RPM and HP wise?

I understand it's pretty stout for a 2 bolt main with a forged crank and all, what are the weak spots? (OK that's three questions)

My goal would be to get reasonably close to 350 to 400 HP at the FLYWHEEL (not rear wheels). So yeah, I'm talking good heads and a roller cam, but everything painted orange of course LOL...

Thank you.

Nowhere Man

I would build it to L79 specs or just bag and tag it and buy or build a 350 383 and call it a day

Coach62

The L84 was the fuel injected version of the L79 if I'm not mistaken, and it was rated at 375 HP.

I like the idea of keeping the born with engine, but hate the idea of possibly ruining the block.

I'm not opposed to studding the mains and maybe adding a girdle.

DZAUTO

The sky is pretty much the limit, but something that a lot of people are not aware of can really wake it up and strengthen it.
Of course, as mentioned, these SAME blocks were boosted to 375hp with fuel injection for 64-65---------------AND THEY STAYED TOGETHER!!!!
First, it is just TOOOOOOOOOOOOO EASY to install a 350 crank in a small journal 327 block. All that is necessary is to round up a good 350 crank and have the main journals turned down to small journal size-----------ANY machine shop can do this. Also, to drop a 350 crank into a 327 block, it is necessary to slightly turn down the flange BETWEEN the rear main journal and the journal for the rear seal (the groove in a 327block/cap is a little smaller than the groove in a 350).
A pair of double hump heads could also be added (which would be period correct). They came in BOTH 1.94/1.5 and 2.02/1.6 valve versions. If you locate a good, rebuildable set of double hump heads that have the 1.94 valves, any machine shop can open the seats for 2.02/1.6 valves and releave the combustion chamber around the intake valve (the factory did this on heads which received 2.02 valves).
Next, the threaded holes on the bottom of the block for the main cap bolts are different for small and large journal blocks. On small journal blocks, the threads begin right at the end of the hole. On large journal blocks, the threads started about 1/4in down into the bolt hole. Have your machinist do this to your block and go with the longer 350 style bolts (even is you keep it a 327).
This compares the difference in 327 and 350 main cap bolt holes. As can be seen, the stress risers are changed to be deeper into the main webbing.


And for me personally, I like to add main studs and install a windage tray.
Here are windage tray studs for small and large journal blocks.



Studs installed. The early 327 hi-perf engines got a flat windage tray.

Donny Brass

<drops in on thread>

1. What can the stock bottom end of a small journal 327 handle, RPM and HP wise?

</drops in on thread> >

Coach62

Thank you, that's very helpful. I was seriously kicking around the idea of a 350 crank. So I take it there is no such thing as a small journal 350 crank. I haven't looked yet.

Also, it sounds like a good set of ARP studs would strengthen it up significantly based on that book. What is that book?

cardo0

Coach what I read you want here is a reliable 400hp and you prefer to use your original block, maybe original crank to. Well machine work can get expensive fast if you want to turn down a large journal stroker crank to fit a small journal block - and have it balanced to. But the more cubic inches you have the less RPM you need and the smaller the cam you can use for the same HP. High compression, high RPM and detonation is what kills motors.

So the easiest strategy here (sbc options are endless) I think just boring your block 0.060" (at least) and optimize your heads/valve train for a high lift cam of somewhat short duration on lobe separation angle LSA of 109 degrees. You need large valves installed with the chambers unshrouded and the throat reworked correctly - not just hogged out like the early pocket porters did. Use 1.6 rockers on the intake valves to maximize lift of your cam and torque. You will need to keep compression ratio below 9.5 w/iron heads. Use thin steel shim gaskets or zero deck the block to optimize quench.

This bore gets you to 337 C.i. and if you can make 1 HP/C.i. gets you close enough to your low end goal of 350hp. But no telling if done correctly could easily make 1.2hp/c.i. and 400hp goal.

Well it may not be a corvette but what the heck it's still a Chevy.

BTW studs are a great idea and I see DZ is steering you right with that.

Good luck.

al89

how about building a 302 , nasty sounding engine

MikeM

Why go any further than your own idea?

Nowhere Man

No the L84 was the L76 with a injection unit. Both had solid lifters. The L79 had hydraulic lifters

65tripleblack

If built carefully and properly balanced, the 327 has the best architecture and bore/stroke ratio of any Chevy, or for that matter, ANY smallblock engine. One can argue that the 302 is in the same category, and it is, except you leave some torque and power on the table in exchange for a higher revving motor. It's easy to build a truck motor by increasing the stroke. Much harder to make power and torque with less displacement, but there's NOTHING that comes close to the sound of a high revving SBC. If you retain the 3.25" stroke, then the small journals work in your favor, since oiling becomes more of a problem as journal size increases. If you increase stroke, then journal overlap becomes an issue if you decide to use small journals with a 3.48" stroke.

It might have been mentioned earlier in this thread, but I'll say it again: the con-rods are the weak link.

My 327 makes close to 500 HP and routinely revs past 7500 RPM. I replaced the rods with Crower Sportsmans. Used original 2 bolt caps with stock windage tray from 327/365. Used stock pistons with original crank. It also makes a very respectable 310 ft-lbs @ 2500 RPM, 250 @ 2000.

If you use a pair of fully ported double humps with 2.02/1.60s, they flow enough to support about 425 horsepower.

Coach62

Yes, but I trust the opinions of the people here I'd rather take advice here than from one of the punk-azz kiddie sites out there.

Coach62

Thank you very much, I have to go to work now, but we need to talk a bit more. That's what I wanted to hear. Also, I'll change my original post as there is a guy out there that sells Dart heads machined to look like double hump heads.

Moonlight Graham

Trick Flow had aluminum camel hump heads at SEMA


http://www.superchevy.com/news/1611-...p-head-returns

DZAUTO

That sounds very interesting, but what does he do about the threaded holes on each end of the heads???

SWCDuke

All other things equal a 350 and 327 will make about the same peak power at the same mean piston speed (Taylor's Rule), but the longer stroke engine will make more average power through the useable rev range due to greater average torque. I'm not a big fan of turning down 350 cranks because of the lost torsional rigidity due to less journal overlap.

The secret to power is head flow, and a properly massaged set of OE heads that flow at least 220/170 CFM @ 28" H2O depression, 0.5" lift will make ballpark 350 honest GHP at close to 6500 with an OE SHP cam. Some massaged aftermarket heads may do better, but keep inlet port volume at no more than about 180 cc to preserve high port velocity for decent low end torque and low speed/load driveability and fuel economy. Higher head flow on a 327 won't make much more power unless the bottom end is beefed up and cammed to turn over 7000.

You can make an equivalent L-79 relatively inexpensively. Use the L-46/82 cam with OE equivalent valve springs, but install it four degrees advanced from the as-designed indexing. Also replace the connecting rods with something like the Eagle SIR5700.

With proper OE valve spring setup the valve train limiting speed will be about 6700-6800, and it will make useable power to that point with decent low end torque, and idle behavior like a L-79/46, about 14" @ 750 with a slight lope.

I'm not a fan of roller cam conversions due to the cost. You're better off putting the money into head work and a bulletproof bottom end, and the use of the best OE valve train components from the era means OE bulletproof reliability.

Duke

Ol Blue

Trick Flow introduced an aluminum double hump head at SEMA this year.
http://www.hotrod.com/articles/small...rns-tensema16/

al89

I have a 1967 nos gm nitrided 302 crank for sale if you need a good crank

65tripleblack

I neglected to say that my Corvette is a driver/racer, and gets excellent mileage both mixed and highway. Not to mislead you, it has a 3.70 gear with a 5 speed/OD trans.

I'm not a big fan of the Dart iron heads. First of all, no matter what you do to disguise them, you're not going to fool anybody. Second, my feeling is that if you're going to spend all that money for a set of heads, then you might as well do it right and go aluminum with a state of the art combustion chamber and big ports. Don't believe that crap about big ports killing bottom end.

The Trick Flow heads ain't gonna fool nobody either. Wasting money on a disguise that could be better spent on perf/quality. Paint the aluminum heads Chevy orange if you'd like, but I prefer natural aluminum.

65tripleblack

All false.
If you ask, I'll post my dyno results to prove it.