mrg

I sure woulda liked to have had that kind of power on tap this past Sunday. .. Fast lane doing 80 in the '64........a Porsche creeps up in the rear view. Not long after, the guy puts a on a move to swing around right and does a buzz job moving in front as he goes by. It was a GT 3.

Extra horses under the hood could have sent a message too, just in case..........the old bones '64 still got something.

John
[/QUOTE]

Vettrocious

Don't have a crankshaft. The inside of the crankshaft caps measure about 2.635 (don't have the proper gage at home to measure this exactly).

Thanks,

Mike

68hemi

If that is the case you certainly don't need to spend the money for a roller cam. A standard type hydraulic cam will give you every bit of that.
I would suggest the roller tipped rocker arms though.

As you likely know, your FI system is going to be one of your choke points for power along with your exhaust manifolds compared to typical hipo builds. Nearly ALL of the off the shelf cams are designed for use with headers and ALL of the cam builders will tell you that their standard cams will be fine for your build but do NOT believe that. The GM engineers always designed their cams to be run with exhaust manifolds so those choices are much better in your application unless you want to tweek it some like I did. It sounds like your build will be very similar to my 2x4 restrictions so you likely may want the same cam as I have. We did a lot of desk top computing to come up with the cam profile we used but in the end it is close to a 327/350 h.p. factory cam. You can compare the specs for yourself.

Vettrocious

Where did you get your cam?

It looks like my block has the large journal diameter, but it's only got two-bolt mains. Did the make any that way?

DZAUTO

ABSOLUTELY, you can have the main journals of a stroker crank turned down to small journal size (from 2.45 down to 2.3in). And maybe it is possible that there are now aftermarket cranks available with those dimensions.
And yes, I've had this done ---------------believe it or not-----------to stock, iron SB400 cranks.
WAAAAAAAAAAAAAAAAY back (early 70s) before aftermarket stroker cranks and pistons were available, we had to machine our own cranks from stock, factory 400 cranks and we made pistons for stroker motors (using 5.7in 350 rods), by taking stock, DISHED 350 pistons and milling off the raised ridge around the dished area. But eventually, the aftermarket sources introduced stroker cranks (with 350 main journals) and stroker pistons for use with 350 rods. All of that is now common from aftermarket sources, at reasonable prices (383 pistons are about the same price as 350 pistons).
I've also had small journal blocks line bored to large journal size.
The main bore of a small journal is about 2.45 and the main bore of a large journal block is about 2.6 (those are not exact, but close enough for you to measure and determine which you have).

Here is a key thing that really needs to be done to a small journal 327 block to enhance bottom end strength of the block. On small journal blocks, the threads for the main cap bolts begins right at the surface of the cap register. On the 350 blocks, the threads in the block begin aout 1/4in BELOW the surface. This moves the area of stresses deeper into the main webbing (any machine shop can do this). Then use the longer 350 style main cap bolts (or studs), as below.

DZAUTO

Then you have a large journal block.
Does that block have the hole in the rear of the block for crankcase ventilation? If it does, that is great because you can go with a PCV valve setup to that hole and retain finned alum valve covers with the Corvette script.

Vettrocious

The reason for this is that the first thread of engagement is the one where the primary loading takes place. You want as much material around this turn of the helix as possible. The longer grip length also adds some stretch to the bolt, a desirable characteristic in any attachment.

Vettrocious

Yes, I chose a 657 block because it still had the breather hole and I wanted to maintain the stock valve covers and a 63 PVC system...

68hemi

I got my cam from Comp Cams. The grind # is CS XE26H-14 SN#:031824-17 PART #: 12-262-4 the spec for it are in the link I gave you in my 1st post

You are using the same block I have they did not make it a 4 bolt main although that same casting # block was used for Z28s and MAY have been modified for 4 bolt in that application. You can MAKE it a 4 bolt main but my machinist (an old successful Chevy small racer) said it was not necessary for under 500 h.p.

Vettrocious

DZAUTO

The VERY FIRST factory 4bolt block was 69, in both 350 and 302 versions.
There was never a 4bolt small journal block--------------from the factory.

68hemi

The 1967 3892657 block was used mostly for small-journal 302 and 327 engines. However, this same casting was also used for Chevy's very first 350, used in the 350 RS Camaro. Chevy simply machined the same bare casting for large journals.

Vettrocious

So my 67 3892657 block was either originally a large journal, or could have been a small journal block later machined for the larger journal. Either way, it's a large journal block now, so that's good, I can work with that...

Vettrocious

Here, we've reached another issue I'm not clear on. If the journals need turning (to true them up), how do you get the bearings' inner diameters to match the altered journal? Do bearing diameters come in various "standard", set, values, or do you normally machine them to size?

Thanks,

Mike

DZAUTO

Undersize bearings are as common as dirt from all sources: Std, .010, .020, .030 and I've even seen some .060 undersize bearings.
The crank in my 420 has had the rod journals OFFSET ground from 2.10in (standard large journal size) down to small journal size which is 2.00. This gave me a .100in stroke, so I simply used std 327 rod bearings. I built the 420 for my jet boat about 15yrs ago (using a stock, cast 400 crank) and it's still kicking without missing a beat!

65tripleblack

Gen.I, "Small Journal"
265...Mains-2.30"-Rods-2.00"
283...Mains-2.30"-Rods-2.00"
302...Mains-2.30"-Rods-2.00"
327...Mains-2.30"-Rods-2.00"


Gen.I, "Medium Journal", includes "Vortec" 305 and 350 thru '98
262...Mains-2.45"-Rods-2.10"
267...Mains-2.45"-Rods-2.10"
302...Mains-2.45"-Rods-2.10"
305...Mains-2.45"-Rods-2.10"
307...Mains-2.45"-Rods-2.10"
327...Mains-2.45"-Rods-2.10"
350...Mains-2.45"-Rods-2.10"


Gen.I, "Large Journal"
400...Mains-2.65"-rods-2.10"

GTOguy

You're going to love the 383. My '61 has an old school 383 built by a previous owner decades ago off of a big-journal '68 block......it looks like the stock dual quad 283, but with much, much more power....it'll start out easily from a stop in third gear, and rolling along at 45-50 mph, if you stab it while in 3rd gear, it'll break the rear tires loose (Positraction). Great performance, mild manners, and will flat out scream when needed. Mine has '65 461 heads, stock manifolds, and stock 2x4 270 intake and carbs. It has an unknown hydraulic flat tappet cam in it that I love....whoever built this engine back in the day knew what they were doing. When I freshen it up, I won't change a thing.

Vettrocious

Thanks, that's the kind of power I'm looking for. Nothing too dramatic, it'll never see the strip. After having had a ZR1, I found that that kind of excess is not needed for the type of street driving I do...

SWCDuke

Forget about top end power. Guys obsess over this, but how often are you going to rev it over 5000. Properly configured a 383 will produce massive low end torque, which means big power and terrific throttle response in the low to mid range, where you spend 99+ percent of driving time compared to a similarly configured 327.

Whatever cam you choose top end power is going to be more of a function of head flow than the cam, so massage OE heads or buy aftermarket heads with inlet port volume of no more than 180cc that flow at least 220/170 CFM at 0.5" valve lift, 28" H2O depression.

The L-46/82 cam would be a good choice. It will make better than 80 percent peak torque at 2000 and useable power to 5500-6000 depending on head flow. If you want more low end torque the McCagh Special cam will make about 90 percent peak torque at 2000. Massaged heads are REQUIRED for this config., and it will make nearly the same top end power as the L-46/82 cam and easily pull a 3.08 or 2.73 axle with a manual or automatic for easy highway cruising.

I do know of one 383 with massaged heads and the McCagh Special cam. It's in a Shark with an original base 350/300 HP engine and TH400/3.08 axle. I haven't been able to talk the owner into a chassis dyno test, but he says it's a beast compared to the original base engine config. Other than the cam and head work it's all OE, looks completely original, and has idle behavior identical to the original 350/300.

Simulations indicate around 250-260 maximum SAE corrected RWHP in the 5000-5500 range depending on head flow, inlet and exhaust system configuration (for comparison a decent base 300 HP engine is about 195), but in the low to mid range it makes 10-30 percent more power than an identically configured 327, and the lower the RPM, the greater the increase in power - right where it's most usable for a high performance road engine.

Duke

GTOguy

Most of the time mine is running around 1800-3000 Rpm. The torque is amazing.....very low strung and easy to drive. Very docile until you get on it. After years of driving torque-monster Pontiacs, I was very impressed at what a little 383 SBC could do. A lot of grunt in a tiny, light little package. It does everything well. Here's mine before I got the rest of the engine compartment finished. Going to drive it to Walmart in about ten minutes, too.