[travis]

On one of my recent trips to/from OK from Missouri, where I have way too much time to think about stuff like this, I came up with a few ideas for a low budget mini stroker. A basic 350 block, offset grinding the stock cast crank either .050 to standard small journal 5.7" rod size (.100" extra stroke), or even .080 to .030 under small journal rod size (.160" extra stroke). This would give anywhere from 360" (4" bore, 3.58" stroke) to 377" (4.060" bore, 3.64" stroke).
Using a set of dirt cheap rebuilder type dished or flat top pistons, either cast or hyper's that have a 1.54" compression height, and the deck height can work. 2 examples...the 350 in my 3/4 ton has a stock stroke, 5.7" rods, and cast federal-mogul flat top pistons. With an undecked block, they end up at .048" in the hole. I had a bare minimum decked off the block to correct a slight warpage issue (.008"), leaving me with the pistons .040" in the hole. By offset grinding the crank to standard small journal size (2.000"), this gives an extra .100" stroke, and moves the pistons up in the bore an extra .050", leaving the pistons .010" out of the hole. With a set of commonly available .050" or .051" head gaskets, quench still comes in around .040". I have another engine that also has some unknown .030 over cast flat tops in it that ended up .051-.053" in the hole with what I assumed to be a undecked factory block. Offset grinding the crank to small journal size gives an almost perfect 0 deck height...a .080" offset grind puts the pistons .015" out of the hole. With a .051" thick head gasket, there is still .036" quench. A setup like this, with my other spare 350 block which needs to go to .060" over, yields 377".

Now...my questions are...

1) where is a good source of rebuilt small journal sbc rods?

2) is it safe to offset grind a stock cast iron crank this far?

3) Silvolite, among others, lists "non performance" hypereutectic stock replacement type pistons. What is the advantage to a piston like this, compared to a regular cast piston? Do they use less silicon than the "performance" hypers?

4) am I completely crazy?


I have been playing around with this idea for a few days. The applications would be typical of what I mostly build...under 5500 rpm, pump gas grunt motors...not any serious performance application, in which case a Scat or Eagle stroker crank would make a lot more sense.

 

[onovakind67]

I'll go with #4. You'll spend a whole lot more money with special ground cranks and special pistons than you would with an off-the-shelf stroker crank setup.

 

[novaderrik]

as soon as i can get my hands on a 4.3 out of a 94-96 Caprice, i'm going to build the LT1 out of my 94 cop car into a 302 and put that in my Monte.
i know- it's like going backwards, but it will still have plenty of power and should get me some great mpg. until i put the junkyard twin turbo setup on it..
and will it ever rev...

 

[travis]

I'll go with #4. You'll spend a whole lot more money with special ground cranks and special pistons than you would with an off-the-shelf stroker crank setup.

Theres nothing special about the pistons...just cheap, rebuilder type cast or hypers with the reduced compression height. They can usually be found for well under $100.

The most expensive part about this would be the machine work. I have no idea what it costs to get a crank offset ground. That in itself could make this idea not so economical.

Novaderrick, take a look at speedomotives website. They list stroker setups for the 4.3 V-8's. I think that would be a pretty neat little engine.

 

[novaderrik]

i don't want a stroker setup for the 4.3- i want the 3" stroke crank and 5.94 rods out of the 4.3 to put in the 5.7 LT1 block i have with an off the shelf set of 350 pistons to build me an LT1 302..
then maybe stick the LT1's crank and rods with a set of 305 pistons to have an LT1 305..

 

[rojo]

I've got a offset grind stroker on the stand right now. It's an old forged 350 crank using 327 rods. The stroke is 3.562 and the bore is .060 which should net 369ci. I used the cheap 1.54 pistons but the block had already been decked to ??? which makes the pistons .003 in the hole. I came by this engine with crank and the rods so I have little invested. Not sure what all this would cost to have done but I'm guessing a 383 would be cheaper per c.i.

 

[SY1]

Be careful going cheap on the pistons. The death rattle is expensive when one breaks, I found out last fall.

There are only a few years of mid 60s small journal rods that you can run. The 283 rod is not an option, thin cross section, very weak in the thrust areas on the big end. The later 64-67 SJ 327 rod had beefed up thrust area and thicker beam. You need ARP Pro Series wave loc bolts because they are the best you can buy and the SJ rod bolts are already tiny.

 

[rojo]

Be careful going cheap on the pistons........

I agree, mine's just a temp/have fun/experimental engine. It will have good heads on it though. I hope they'll be safe. :yes:

 

[pdq67]

Travis,

You can only offset grind a crank .090" b/c at .100" under you end up w/ a "tangent flat"...

Go for it guy!!

pdq67

PS., rebuilt rods, try Comp. Products??

 

[67 Plum]

SJ rods $179 from Competition Products.The H344NP Speedpro hypereutectic flat top 4 valve relief pistons can be bought off Ebay http://cgi.ebay.com/ebaymotors/Chevy-Small-Block-350-SPEED-PRO-Pistons-H345NP-30-SBC_W0QQitemZ110095814933QQihZ001QQcategoryZ33623QQrdZ1QQcmdZViewItem .Sounds like a good idea to me.I would think around $150 to grind the crank.

 

[67 Plum]

novaderrik the local Pick and Pull has 4 of those 4.3 Caprices.Thought abought pulling one myself.I would like having a set of the rods out of one.

 

[novaderrik]

i'm hoping to find a complete 9C1 with the 4.3.
my 86 Caprice needs a better suspension..

 

[rojo]

Be careful with the Speedpro hypers in terms of the comp height in the 1.54 range. I ordered a set from Summit and they were .020 off. Ordered a set of (the other 3 or 4 cousin brands) from Napa and got the same result. Finally my Napa guy got in touch with whoever to decide that the hypers weren't as advertised but the cast were. Just a heads up.