Lefora Free Forum
login join
Loading
453 views

chevy 350 engine build-sleeper small block combo,part-1

Categories > Tech Articles
Page 1
1–4
ledhead
fanatic - founder
658 posts
0 permalink

Chevy 350 Engine Build - Sleeper Small-Block Combo

Sneak Up And Put 'Em Away With This Sleeper Small-Block Combo
By Douglas R. Glad
Photography by Douglas R. Glad



Small Block Chevy Engine Build
This thing looks like a 350 but has a 4.00-inch crank. The extra 1/2-inch stroke is guaranteed to add some torque and horsepower.

This is the perfect short-block for your sleeper. It looks like an ordinary Chevy 350, but underneath is a 4.00-inch stroke crank and a sturdy bottom end that is ready to handle dragstrip time, street miles, and some hits from our friend the nitrous bottle. This is intended to be an engine you can do yourself with a common block and would be perfect for a four-door Nova, C10 truck, or wrong-year Chevy wagon. It will look stock and make grunt for some serious street fun.

In this issue, we are going to show you how to assemble the short-block and get it ready for street action. Just for grins, and to get a baseline for future tinkering, we added some iron 2.02 heads and a throwaway manifold and gave it a quick pull on the dyno. We figure there is at least another 100 hp to be had with an intake, carb, and cylinder head swap. We'll show you those parts in future issues. For now, crack a cold one and discover how to massage a 4-inch crank into a 3.48-inch hole.

Small Block Chevy Engine Build
The problem with running a 4.00-inch stroke crank in a 350 block is the 6-inch rod required to clear the counterweights on the crankshaft. The long rod will put the piston pin up into the ring pack. It's been done before on race engines, but on the street you might end up with oil consumption and other issues. The crank on the right is from RPM and retails for about $500. It was smoothed with a Makita 4-inch disc grinder by Ted Toki at Westside Performance. He took a small amount of metal off of the end of the counterweights to get them to clear the pistons.
Small Block Chevy Engine Build
The trick with this combo is to use 5.850-inch Chevy rods with 0.927 pin diameters that are already clearanced from Eagle. The rods work with a short, off-the-shelf piston with a pin that just clears the ring pack.
Small Block Chevy Engine Build
The 5.850 rod just clears the throw on the 4.00-inch crank. A 6-inch rod also clears but forces the piston pin high into the block. A stock 5.700-inch Chevy rod will crash the pin into the counterweight.
Small Block Chevy Engine Build
These forged pistons are made for a Ford 331 (302 stroker), so they are easy to get and cheap. The Ford 5.0L 1/16, 1/16, 3mm ring pack makes this whole thing work. The pistons have a part number for a 0.927 floating pin that can be used with the Eagle rods.
Small Block Chevy Engine Build
After the engine was cleaned, Toki made some preliminary cuts on the oil pan rail to clear the big end of the rods. This grinding would have been standard on 383s before the advent of the aftermarket rods with a smaller capscrew. Now it needs to be done only for a 4-inch crank.
Small Block Chevy Engine Build
Toki has what are called sacrificial bearings along with a cap that slides on and off with ease to mock up the crank and rods for clearancing. When there is a clearance issue, it is marked with a Sharpie, ground, then tried again until everything fits.
Small Block Chevy Engine Build
This is a close-up shot of the cap bolt clearing the pan rail. This is a trial-and-error deal, so if you have more time than money, it is a perfect summer project.
Small Block Chevy Engine Build
Toki uses partial Hard Blok to compensate for GM core shift in case you get into the water jacket. But he says it is not necessary. He clearances many blocks, and it is a matter of safe business practice. The areas at the base of the cylinder near the pan rail (arrows) are where you might hit water.
Small Block Chevy Engine Build
Once the rotator is completely clearanced, the engine is disassembled, bored, machined, and painted for final assembly.

__________________
rev it on the red line
reply
quote
31 August 2009 08:54 PM
ledhead
fanatic - founder
658 posts
0 permalink

part-2

Chevy 350 Engine Build - Sleeper Small-Block Combo




Small Block Chevy Engine Build

On The DynoThe intake and heads are the big cork in this combo, but ultimate power wasn't the point. With this big bottom end, the torque is steady and we should be able to add another 100 to 250 hp with heads, an intake, and a little hidden nitrous system. Check the numbers.*


RPMLB-FTHP
2,500409195
2,600406201
2,700404208
2,800404215
2,900404223
3,000407233
3,100410242
3,200414252
3,300415261
3,400417270
3,500421280
3,600426292
3,700429302
3,800430311
3,900429318
4,000426325
4,100423330
4,200418335
4,300414339
4,400410343
4,500405347
4,600400350
4,700394353
4,800387354
4,900381355
5,000373355
5,100366355
5,200358355
5,300350353
5,400341351
5,500332347
*Rounded to the nearest decimal



Small Block Chevy Engine Build
Because the pistons are intended for a Ford cylinder head, the Chevy valve relief notches need to be cut into the piston. This piston can take up to a 2.10-inch valve if we were to step up to a set of aluminum heads.

The HeadsAlthough this article is primarily about wedging the biggest crank possible into a 350 block, we couldn't resist running it on the dyno. We also wanted to keep this engine as low-buck as possible, so we used a set of iron 882 heads for the baseline. Toki tuned them up with a set of 2.02 intake valves and added a set of what he calls Z28 springs that can handle up to 0.550 lift. Besides being cheap, the springs fit into a standard seat, allowing you to use the factory oil shield and valve seals. Toki thinks it is the best way to control oil.

"You can have a guy with totally shot valveguides and it won't burn oil because the shields are still in place. It is an inexpensive way to control oil without cutting the tip of the valveguide to install Teflon seals." Toki says. For the ignition, we tried the MSD Street Fire HEI. It is basically a good distributor that you don't have to rebuild before use. It comes with vacuum and mechanical advance, adjustable curves, and is pretty with a polished housing and red cap. It already has a built-in coil, so all you have to do is stab it in and connect it to 12 volts.



Small Block Chevy Engine Build
With a 0.030 overbore and a 9.025-inch deck, the combination of 4.00-inch stroke, a 5.850 rod, and a 1.175-inch piston height, you get a zero deck and 408 inches. If you deck the block between 0.005 and 0.008, you can be creative with head gaskets to get the compression ratio you want based on your cylinder head choice. With a 76cc chamber, this engine has about 10.5:1 compression.

Cam and ValvetrainThis combo doesn't need anything too crazy in the cam grind to make torque. The grind Toki chose was a mild Comp Cams circle track cam designed for a small, low-compression engine with an iron intake and manifolds. It has 236/238 duration at 0.050 with 0.501/0.501 lift on a 108 LSA. Toki wanted something with less than 240 degrees of intake duration to keep some air velocity and a short lift to use the Z28 valvesprings.

The Potential DownsideWhen you add Hard Blok to short-fill the water jacket, you get controversy. Jack McInnis from Dart Machinery (which sells aftermarket blocks) says it will overheat, Ted Toki from Westside (which sells parts) says it won't. It is important to understand that there are gambles and payoffs here. For a mild street engine, this works. On a radical race engine that you try to put on the street, you will run into oil cooling issues. We would add an oil temp guage to make sure oil stays below 230 degrees and run a synthetic oil like Mobil 1 to be safe.

If you plan on using this as a mild combo like we are, it should run forever.

Budget Big-Inch Stroker SpecsBore: 4.030Stroke: 4.00Deck: 9.025Rod: 5.850Compression height: 1.175

__________________
rev it on the red line
reply
quote
31 August 2009 08:57 PM
ledhead
fanatic - founder
658 posts
0 permalink

part-3

Chevy 350 Engine Build - Sleeper Small-Block Combo



Parts And Prices*
Short-Block
PartPNSourcePrice
350 blockN/AWestside Performance$125.00
Pistons12347-0.030Probe$452.17
RodsCRS5850BSTEagle$475.00
Crankshaft4.00RPM$495.00
Rod bearingsCB663-HKing$60.00
Main bearingsMS909-HKing$105.00
Rings9901-30Akerley and Childs$89.90
Total$1,802.07
*Prices are quoted from Westside Performance.


Machine Work
JobPrice
Bore and hone block$160.00
Deck block$150.00
Add Hard Blok$80.00
Block prep (clearancing block and pistons)$350.00
Balance rotator$125.00
Total$865.00
Assembled two-bolt block parts and labor$2,583.57
Assembled four-bolt block parts and labor$2,808.57


Other Parts**
PartPNSourcePrice
Camshaft12-647-5Comp Cams$176.39
Complete cylinder heads882Westside Performance$800.00
Iron IntakeN/APick Your Part$29.99
Q-Jet carbN/APick Your Part$33.99
Distributor8362MSD$143.95
Timing chain3200Comp Cams$27.95
Cam lock plate4605Comp Cams$2.50
Lifters812-16Comp Cams$72.95
Stamp steel rockers1212-16Comp Cams$81.95
Pushrods 7.800-inch7372-16Comp Cams$92.88
Assembly lube104Comp Cams$6.95
Cam and lifter lube152Comp Cams$6.95
Oil pumpMSSHVMelling$27.95
Z28 valvesprings***98214Competition Products$29.95
**Prices are from Summit Racing.
***Price from Competitionproducts.com

Summit Racing Akron OH 800/230-3030 Summitracing.ComWestside Performance Los Angeles CA
Comp Cams 901.795.2400 comp.com

__________________
rev it on the red line
reply
quote
31 August 2009 08:59 PM
ledhead
fanatic - founder
658 posts
0 permalink

sorry for the inconsistencies in the transfer on part-2.bob

__________________
rev it on the red line
reply
quote
31 August 2009 09:00 PM
Categories > Tech Articles
Page 1
1–4

Locked Topic


You must be a member to post in this forum

Join Now!