2 Years ago, I bought a set of Crower Sportsman small journal cap screw rods for my 327. I'm ready to pull engine for rebuilding, but, considering the possibility of stroking it 3.75".
Looking at Speedomotive crank.
Can I use the my Crowers?
If I need clearance, can mine be modified, and if so, what's the downside?

 

Critical information needed:
What's the LENGTH of those rods???

I can only guess that you bought 5.7in rods, correct?
If so, no big deal, you're in like Flint, basically.
Also, I'm guessing you are considering the small journal version (2.3in mains) of the Speedomotive crank, right?
Sooooooooooooooooo, with the cap screw style rods and a 3.75 stroke, you MAY and you MAY NOT need to grind clearance notches at the bottom of the cylinders for the rods, AND, you PROBABLY won't need to clearance the cam side of the rods.
You'll just have to do a trial assembly and check for clearances.
For trial assembly on engines which may have questionable clearance issues, years ago, I had my machine shop reduce the diameter of an old wrist pins (for both BB and SB) so that it is just barely a slip fit in the rod. After all machine work is completed, but before balancing, I bring everything back to my place and do a trial assembly with the block/crank, pistons and rods. As I trial fit and rotate each rod/piston assembly using the slip fit wrist pin, I then mark each rod/piston with a Magic Marker so that everything goes together during final assembly back in the same hole. After trial assembly, I take the rotating parts back to my machinist and have it all balanced. Why do I do all of this? First, I prefer to do all of my own engine assembly work that I possibly can (except for major machining operations). Second, I still subscribe to the philosophy that if you want something done right, do it yourself. In 40+yrs of building engines and screwing with old Chevys of all kinds, I've never had a single failure of any of the engines that I built (the cylinder that I hydraulicked and bent the rod and busted a piston and cracked the block because I got water in the boat engine was not a failure due to assembly).

Thus, building a 383 from a small journal 327 will be IDENTICAL to building a 383 from a big journal 350 block. If you're familiar with the processes of building a 383 from a 350 block, then nothing else will be different. Aside from being very diligent about checking clearances during trial assembly, I would REALLY, REALLY encourage you to use main cap studs instead of bolts!!!!!!!!!!!!!! That's really the only diviation I'd recommend aside from the typical 383 buildup.
I presume you are aware of the balance issues with a 383 or SB400? Unless you have the rotating assembly internally balanced, or, buy a crank-rods-pistons which will permit an internal balance, then a SB400 harmonic balancer and UNbalanced flywheel are required (or use a balance plate between the crank flange and flywheel).

 

Also check rod and rod bolt to cam clearance on a stroker, sometimes the rod need to be cam cut to clear.

You will need new pistons with a different wrist pin to deck distance also.

6" rods are preferred on longer strokes as they keep the rod angle lower, but the shorter rods work.

On my 3.85 stroke motor, i had to lightly grind the side of the block at the oil pan rails,a nd use a cam with a smaller base circle to clear the rods

Doug

 

Joe,
For your stroker build you may want to think about using the larger 2.1" pin rods to increase your journal overlap to .325" as opposed to a .275" overlap with the small journal pins. Also consider having the crank turned with 1/8" fillet radii to further increase journal strength which will require the use of special bearings that are clearanced for those wide fillets. For Clevite 77 bearings, rod bearings (part number CB663H) and main bearings (part number MS909H). In addition, to possibly cut down on your costs, you could use a SCAT or Eagle stroker crank and just turn down the mains and the thrust plate to fit the 327 block instead of having George at Speed-O-Motive have one turned for you.

 

Thanks for the detailed reply, Tom.

First three answers are Yes, Yes, and Maybe. Maybe because IF I decide to go this route, I will probably use a roller cam. Certain that it won't be a small base circle cam.
No, I am not familiar with any special considerations in building a 383.
I understand your comment about main cap studs, for strength, instead of bolts. I am very concerned about whether the small journal crank will be strong enough to support the long stroke! Don't know whether any "band aids" will make up for the poor rod/stroke ratio which would result from the buildup.
I want to use the stock harmonic damper from the SHP 327/365, and never heard of any balance issues with the 383. I DO know, that the 400 is "externally balanced", and the 302/327/350 is "internally balanced". Assumed that the 383 is "internally balanced" too. I already own a service replacement LT1/Z28 intake, and the MAIN CONSIDERATION will be using my 7 finned Corvette valve covers with Z28 intake configured as per 1967 (small journal 302/350 block) oil fill tube in front.....................just like my L76.

 

Scott,

I don't like the stroke/journal ratio inherent with the small journal crank, either. See my reply to Tom Parsons for more.
My block is a non original, "numbers matching" block! Original engine is long gone. If I can't build a strong, reliable stroker for RACE duty, then I'll revert to plan "A", and use this block to build the original 327 with 30-30 or LT1.
If I was not concerned with an "original appearing" external config for a hypothetical stroker, then I'd go "all the way" and use an aftermarket 400 block, with aftermarket heads, like Brodix/Dart/Edelbrock aluminum, with solid roller, etc.
The second scenario just might have to be a separate, second engine project.

 

FWIW, you can have anything internally balanced so that the regular flywheel and balancer can be used.

My 427 SB is internally balanced and uses a neutral flywheel and balancer (I also had the 15 pound flywheel micro balanced to neutral).

Doug

 

Joe,
First of all, FROM THE FACTORY, ALLLLL SB400s and 454BBs are externally balanced. This means they have BOTH a flywheel (or flexplate) and harmonic balancer which are UNbalanced. ALLLLLLLLLLLLLLLLLL other Chevy V8 engines are internally balanced and have NEUTRAL balance flywheels/balancers.
A 383 is essentially a SB400 with a smaller bore (350 bore-400 stroke), thus, a 383-----------------------WHEN USING A 400 CRANK----------------will also be externally balanced and will require the balancer and flywheel from a 400. As an alternative to an UNbalanced flywheel, there is an aftermarket balance plate available which is attached to the rear of the crank between the flange and flywheel. This allows the use of a neutral balance flywheel.
Now, there are aftermarket crankshafts as well as rods and pistons which can be internally balanced, thus allowing the factory neutral balance balancer (such as your 365hp balancer) and flywheel.
Last, if you use a crank/rod/piston combination that requires the rotating assembly to be EXternally balanced at the balancer and flywheel, then you can pay EXTRA to your machinist to have it all balanced internally. This is done by drilling holes in the crankshaft counterweights and adding "heavy" Mallory metal. Thus, increasing the weight of the counter weights, thus, accomplishing an internal balance, thus, you get to keep your original balancer (I assume it is the finned balancer) and flywheel.
OK, with all of that said, that finally brings us to the crankshaft itself. If you are going to buy an aftermarket 3.75in stroke small journal crank, THERE ARE CRANKS AVAILABLE THAT WILL ALLOW AN INTERNALLY BALANCED 383 TO BE BUILT! That would be my primary recommendation for your needs.
The (better) aftermarket cranks with small journals are just fine for your purposes. I wouldn't hesitate to build a small journal 383 from a 327 block with an aftermarket crank. AFTER ALL MACHINE WORK AND CLEARANCING IS COMPLETED, YOU WILL STILL HAVE TO HAVE THE FINAL ROTATING ASSEMBLY BALANCED!!! This will include: crank, rods, pistons, one set of rod bearings, one set of rings, flywheel and balancer (BOTH the balancer and flywheel should have a perfectly neutral balance!!!!!!!!).
Last, I cannot stress enough my recommendation to use studs instead of bolts for the main caps with this much stroke in a hi-perf small journal block!!!!

I have a SB400 in the 56 and I wanted to retain a sort of stock FI 283 appearance. The UNbalancedd 400 balancer would be a dead giveaway that it was either a 383 or 400. So I paid extra to have it internally balanced with heavy metal in the crank and that allowed me to install the big, finned balancer.

 

Oh ya, your 7-fin valve covers will work just fine with an early LT-1/Z28 intake.

 

Thanks again Tom.
I intend to have my block bored/honed from .030 to .040..............primarily so that we can use a deck plate..................so new pistons are already in the "mix". Since it is not the original engine, but "numbers matching", I want to check the decks for evenness. Decks were already milled (about) .015 to wipe old numbers, fake broached and restamped. My intention is to design for minimal quench (no matter which stroke I eventually settle on). Probably will mill decks to zero, and adjust C/R with head gasket config.
If I go with the stroker, I'll use a moderate duration roller. Preferably a solid, to "try" to emulate the sound of the 30-30. The problem is, that in order to get same overlap as the 30-30, and replicate the 9.5 inch idle vacuum, and distinct lope, probably would necessitate a radical, full race solid roller..................which I definately DO NOT want. Most streetable rollers that I have seen, are hydraulics, with durations in the 235-245 degree range, but fast ramps with high lifts in the .500-.550 range. Maybe I can specify close LSA to get the "lope". Me and my engine builder (who respects my attention to detail, and will work closely with me) will have to put our heads together and design a cam that will be suitable.
Cost will be a factor, and plan "A", build: 331 with 30-30 or LT1 flat solid are still in play.
You can see that there is basically identical machine work involved with either build! Internal balance with aftermarket stroker crank, then, would be identical for either, also.

Additional costs for the stroker would be:

New forged crank-small journal, tufftrided
Roller cam/tappets/springs/pushrods.
Block machined for roller tappets.
Aluminum heads, such as AFR, professionally CNC ported.
Flat KB hypereutectics, rather than forged popups. (need pistons, in either case........price difference within about 100.00)
Holley 0-80528-1 carburetor for the Z28 intake manifold.

The large cost difference (mainly for the heads and porting) must justify the difference between a relatively torque shy 327 (whether with 30-30 or LT1) with peak power of (about) 290-300 RWHP @ 6500, versus a torque monster 383 with peak RWHP of (about) 430 @ about 5500.

 

You ain't gonna see anywhere near 450 RWHP out of that motor unless you get a tall enough/big enough intake manifold. Anything that fits under a stock hood, won't get you the torque at the RPM you need for that HP. Your cam is going to have to be lumpier than 235 degrees @.050"/.560" lift also. Also 11.5-12:1 compression/racing gas would help quite a bit.

450 RWHP is about 540 SAE gross (lab dyno) HP for reference. That is what an original L88 put out.

Now the new model heads and roller cam will give you a much wider torque curve that an L88 ever had,a nd it will be much more drivable on the street and your average torque will probably be higher, which makes for a faster car.

Doug

 

If you purchase a Scat or Eagle crank that does not have a 1/8 inch radius already ground in, you can't add it unless you widen the the rod pin.

I ground cranks, even made some SB and BB forged cranks from raw forgings, and learned what is possible and what is not.

It is also better to use a crank made for the application due to the location of the oil holes. Unless the crank has the oil system custom drilled, crossed drilled both rods and mains, you can expose the edge of the oil holes in extreme undercuts and cause rod pin oil bleed. Stock cranks and the cheaper after market cranks have the oil holes drilled on an angle, not straight through.

GM cross drilled some cranks, only the mains.

The smaller journal cranks have better bearing life, less bearing speed.

Cup cars use a Honda size journal, 1.880, that may be even smaller now. Seems to work, 9500 to 10K for however long they need it.

 

Sounds like you have a plan.
I don't know your situation for fuel consumption, but at our house, fuel economy is ALWAYS an issue. Sooooooooooooo, I compromised with all the cars and now have rather high rear gears, wide ration 4sp (M20) and engines that make plenty of lo-mid torque. Generally, that translates to long stroke, lo range cammed engines. This doesn't give me hard core, off the line starts, but after 15-20mph, they're gone. Plus, Interstate rpm is kept reasonable (about 76mph at 3000rpm). The 400 in the 56 will make 6000rpm fairly easily, and at ~6000rpm in 1st gear, I'm at Interstate speed, then 2nd gear, and I'm gone (90-100mph easy in 2nd gear).
Yes, I truly miss the old days of spinning a short stroke engine with a 4.11 rear, but since the old days of $.25/gal for gas is long gone, I gotta compromise!!
Now, if you're one of those financially independant guys that can afford gas at whatever the price, that's great! I can't. So I see lo-mid torque, long stroke engines as the optimal way to go. Built right, 6000+rpm is still easily attainable.

 

What about ALLLLLLLLLLLLLLLL the one peice seal 350-1986 up aren't the extrenally balanced on the rear only. At least the last 50 or so I have balanced have been that way or maybe I am getting the junk ones

 

OK, OK, OK, OK, OK, OK, OK!!!!!!!!!!!!!!!!!!!!!!!
I should have been more specific and clarified EVERYTHING by mentioning 2-piece rear seal engines. BUUUUUUUUUUUUUUT, since the discussion was specifically directed at the EARLY, small journal blcoks, and a crank and parts and related hardware for 2-piece rear seal engines, I ASSUMED (BAD MISTAKE ON MY PART) that everyone would recoginze that all discussions pertaining to the engine, and engine parts being referenced, would be for the PRE 1-piece seal engines. JEESE!!!!!

So now, do we need to open a completely new discussion on 1-piece seal engines and the parts/machining processes/assembly methods for them.
Then, after that, do we need to go into the current generation of engines? Maybe we also need to get into the variations of 6cyl engines, since Corvettes also had 6cyl engines. And then after that, maybe we could get into the differences between early-late T10 4spds and early-late posi rears for the 57-62 cars!

 

[QUOTE=muncieman;1567161244]If you purchase a Scat or Eagle crank that does not have a 1/8 inch radius already ground in, you can't add it unless you widen the the rod pin.

I ground cranks, even made some SB and BB forged cranks from raw forgings, and learned what is possible and what is not.


That was in response to Joe talking to Speed-O-Motive about having a crank turned from a forging.

 

But didn't you say ALL IS ALL isn't it

 

Mr Blockman,
How much weaker are the 327 blocks with their narrower webs and main caps. I've seen cracked webs in 327 blocks so that is why I'm asking. There are quite a few of these SJ strokers running around, most don't spin over 5,000RPMs in stock trim anyway.
Wes has the programma 4 bolt caps installed, do you think this is required as opposed to just using the ARP studs.

 

Yes splayed caps are the way to go with that much stroke as have done quite a few of those small journal blocks for circle track guy that run 283 mains and honda rod cranks and 3.480 or 3.500 strokes up to 550 horse. On these blocks we did use a front billet cap and straped the rear main cap.

The webbing of those old blocks are not very strong and they need all the help they can get.

Remember studs don't make the cap any stronger as its just a grey cast iron cap with better haredware.

Before you spend any money on that block have the cylinder sonic tested for thickness as we have seen thin walls from time.


Good luck with your build Carl

 

I use a SJ rod pin in my 3.562 stroke SB. You offset grind a 350 steel crank to 3 9/16 stroke and use a 6 inch rod with custom pistons. Motor makes a ton of torque and it will spin over 7K and live.

It will make in the range of 400 rwh with a mild roller and good heads.

Made a lot of rat motors look very bad