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poop head bucket list engine

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poop head bucket list engine

duffer duffer
I love my Chevy Chevette! | Posts: 8 | Joined: 12/10
Posted: 10/14/13
12:48 PM

The present engine (or the short block thereof) in my 1955 Willys CJ 3B was installed in 1980.  It is 381 cid running 10.5:1 with aluminum heads and EFI.  As one might expect, after 33 years, that short block is tired and in need of a rebuild or, preferably, replacement.  Being everything is set up for Gen I, I can't think of a strong compelling reason not to stick with it.  Besides, that is where my experience is.  Over the last 40 something years, I have probably built several dozen small blocks, just none of them with entirely after market parts and the 3.75 stroke was the maximum I have used.

So what is desired is a light weight, compact package with some stump pulling low end torque.  I'm thinking a nice square 4.125 x 4.125 bore/stroke and aluminum block/heads.  While this may never rev higher than someplace around 5500, it has to be bullet proof.

Here are my present thoughts: Callies SAU21A-MG crank, Callies U14143 6.125 I beam light weight rods, Dart 31712222 block (9.325 deck, .391 raised cam), and Dart 220 23 degree aluminum heads.  With that block height/crank stroke/rod length, the oil ring is still going to be in the pin bore.  Pistons will be custom and leaning toward Ross.  Also thinking a standard 5/64, 5/64, 3/16's chrome molly ring set with factoy spec top ring position.  The cam selection has not been made but I am using a Comp Cams 12-466-8 in the 381 and it works pretty well with the ProFlo2.  I had to use 1.5:1 rocker arms on it in the 381 rather than the 1.6:1 because I didn't have sufficient piston clearence but with custom pistons, that shouldn't be a problem in the new mill.

Here is the present set up:
9671173973 153Bf5954f B
9671181465 2F8df4290b B

Ok, now the questions.

How big a problem is having the oil ring in the piston pin bore for endurance?  Use inserts?  Favorite pin locks?

Is it worth all the problems to go with a 9.500" deck to keep the ring pack above the piston pin?

Is the .391" raised cam sufficent to clear the proposed crank/rods?  Will one still have to use a small base circle cam?  I would prefer not to do that because it will still be wet sump running a big block pump.

Am I full of crap?

Oh, and absolutely NO CHINESE!!!!!!!  

pepsi1 pepsi1
Big Block power for the win | Posts: 940 | Joined: 03/11
Posted: 10/14/13
06:26 PM

Why not purchase a Hi-Horse power Gen.1 crate engine. It will save you money in the long run. Only my 2 cents.



duffer duffer
I love my Chevy Chevette! | Posts: 8 | Joined: 12/10
Posted: 10/15/13
06:11 AM

double post  

duffer duffer
I love my Chevy Chevette! | Posts: 8 | Joined: 12/10
Posted: 10/15/13
06:30 AM

"Why not purchase a Hi-Horse power Gen.1 crate engine"

First, horse power is a contrived term and has no real bearing on this discussion where high torque right off idle is the goal.

Second, the only high displacement crate engine I know that is commonly available is the World Products version.  Their 454 uses a 4" crank and 4.250" bore (same dimensions as a big block) in a standard 9.035" deck block.  If you think about that, it leaves the materal between adjacent cylinders slightly north of 1/8".  I also could find no definative source for their crank/rods/pistons which leads me the believe they are all chinese.  Using one of those on the street may be ok because AAA can quickly give your ride a ride home.  In a Jeep, deep in the boonies, that isn't going to be the case and any sort of tow can be highly problematic.

Third, most of the high horsepower crate engines are just that.  They have no bottom end with the torque peak usually someplace between 4500 and 5500 rpm and a peaky torque curve.  A cam change can usually fix part of that but it's just wasted money.

Am I going to spend more?  Certainly, but I fully intend to get exactly what I want.  I am commited now anyway as I pulled the trigger on the crank and rods (Callies Magnum) yesterday.  I will get the block/pistons sorted out this week with a little more research.  Buttons may be a good solution.  

duffer duffer
I love my Chevy Chevette! | Posts: 8 | Joined: 12/10
Posted: 12/04/13
09:17 AM

As usual, there have been a few kinks along the path to this build, but there is some progress on this stroker.  I have received the JE custom pistons that are based on their 4.125" blower pistons, but with 1.137 compression height and 21 cc dish (and they do use oil rail supports).  These will zero deck in the 9.325" deck block.  Sourcing issues ended up with Oliver getting the nod on the 6.125" rods.  The weights on both rods and pistons exhibited about a 2 gm spread so we will be removing some metal for the balance job.  The Callies 4.125" cranks are apparently built on order and that is supposed to arrive mid January.  I should have the Air Flow Research full CNC 1095 heads this week also (decided the Dart 220's would likely have a more negative effect on bottom end torque than would be acceptable).

Comp Cams will be grinding a steel billet cam for this specific application which I think is going to work exceptionally well (218/226 degrees at 0.050, 0.571/0.531 lift on intakes and exhaust respectively, 110 degrees LSA, 106 degrees intake centerline, and using 1.6:1 rockers on the intakes, 1.5:1 rockers on the exhaust).

Most of the other misc pieces are on the way and should have the block ordered this week.  Going to get the block fully preped as I don't think any of the local machine shops can come close to Dart on the final bore finish that is done with the deck plate and at operating temp.

The deck clearence will be the 0.041" compressed gasket thickness as I wanted this at close to the minimum to reduce potential problems with pre-ignition at low rpms.  Piston clearence is 0.005" and I fully expect a little piston rattle until they are warmed up.  I still need to address the wet sump oiling system and the pan.  I may just TIG up a pan as this application definately needs a skid plate, has no clearence on the right side due to a front drive shaft, and can't be any deeper than the stock pan due to skid protection on the bell housing/transmission/transfercase.

Definately starting to get a little of that "new car" feeling and a big dose of curiosity.  

dond1965 dond1965
V-6 Camaros rule! | Posts: 33 | Joined: 12/13
Posted: 12/13/13
08:09 AM

since money was not an issue for you , there was something you could have spent it on to get better results. namely a different piston/ring set up. if you had elected to use a 2 ring piston design and 0.043 dykes top ring combined with a 3mm oil control ring set, you could move the oil ring up on the piston! personally i would have combined that with a 4 inch stroke crank myself, and called it a done deal. its yours, enjoy it!