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  #1  
Old 11-02-2001, 07:07 PM
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Default 400 small block crank in a newer 350 block.

Does any body know if you can use a 400 small block crank, in the newer 350 block with the 1 piece main bearing seals?

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Old 11-02-2001, 10:21 PM
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Default Re: 400 small block crank in a newer 350 block.



10051118 - Crankshaft Seal Adapter Pace Price $97.04

This adapter kit allows you to install an early style crankshaft designed for a two-piece seal in a block which is machines for a one-piece rear seal. This seal adapter can also be used when installing a heavy-duty crankshaft in a cast iron Bow Tie small-block or Bow Tie V6/90degree block machined for a one-piece seal.

Technical Notes: The crankshaft seal adapter kit includes a two-piece aluminum seal retainer and related hardware. It does not include a gasket and two-piece seal; use pre-1986 two-piece rear seal GM#10121044, retainer gasket GM#12337823, and dowel pin GM#9441003. The large outside diameter of the seal adapter requires a 1986 or later oil pan and gasket set. See the Chevy Power Manual for installation instructions. Hex bolt GM#10051121 and washer are used to hold the two halves of the adapter together. Bolt GM#10051123 is used to hold adapter to cylinder case.




Tech Tip

One-Piece or Two-Piece Rear Seals ???

Production small-block V8 and V6/90degree Chevrolet crankshafts were redesigned in 1986 to use a leak-resistant one-piece rear seal. The diameter of the crankshaft flywheel flange was reduced to fit this new seal. The engine block, oil pan, pan gaskets, and flywheel were also redesigned to accommodate this one-piece seal.

Crankshafts designed for one-piece seals have a smaller flywheel bolt pattern than pre-1986 production cranks. All small block and V6/90degree cranks which use a one-piece seal require a counterweighted flywheel for proper engine balance.

Unmachined crankshaft forgings and most heavy-duty crankshafts (except GM#14096036) use pre-1986 two-piece rear seals. These cranks can be installed in late-model blocks which are machined for one-piece seals by using crankshaft seal adapter GM#10051118 (bottom of page).
dave




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Old 11-02-2001, 10:22 PM
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Default Re: 400 small block crank in a newer 350 block.

Chevrolet never made a 400 with the flange on the back of the crank to accept the one piece seal. If you are wanting to build a 383 stroker, get the 350 block from an older vehicle and use the newer model heads and accesories. These blocks are common and cheap in the paper(at least around here-complete 350's for about $100)The only difference between the older blocks and the newer one piece rear main blocks is the on piece rear main. This means anything else will bolt up the same! Gotta love Bowtie interchangeability!

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Old 11-03-2001, 06:26 AM
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Default Re: 400 small block crank in a newer 350 block.

Dave is correct, I have one in my shop set up this way.

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Old 11-03-2001, 08:16 AM
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Default Re: 400 small block crank in a newer 350 block.

I made an assumption, I figured the main journal size difference was known by the orginal poster. I figured the original poster did not know about the crankshaft adapter.

I just copied and pasted the crankshaft adapter information from Pace Parts.

I've included some copied and pasted information from Sallee Chevrolet on SCAT Cranks. SCAT offers a 350 crank with 3.750 stroke (SBC 400 stroke), one piece rear main seal, with 5.7" center to center connecting rods. SCAT Part # 9-350-3750-5700-L. Price $239


Series 9000 Chevy Cast Stroker Crankshafts
The Only Profiled & Neutral Balanced Cast Crank

Available in 350 and 400 main sizes with Two piece Rear Main Seal and in 3.750" or 3.800" Strokes
Only 47 lbs. to 50 lbs. - Lighter Than the Old Style 383
Clearanced for 5.560", 5.700", and 6.000" Rods
YES! You Can Use TRW Forged Pistions
Knife Edged Counterweights
Lightening Holes in All Rod Throws
Scat Cast Stroker Cranks Require Balancing Prior To Assembly
Patterned after Scat's $2000 Custom Billet Crankshafts
Series 9000 350 Main Chevy Cast Crankshafts

New P/N
Old P/N
Crank Model
Price

9-350-3750-5700
935037557
3.750" Stroke x 5.700" Length Rod, 2.100" Rod Pins
$219.00

9-350-3750-5700-2
935037557P
3.750" Stroke x 5.700" Length Rod, 2.100" Rod Pins, Lightweight
$269.00

9-350-3750-6000-2
935037560P
3.750" Stroke x 6.000" Length Rod, 2.100" Rod Pins, Lightweight, Int. Bal.
$279.00

9-350-3750-5700-L
93503755L
3.750" Stroke x 5.700" Length Rod, 2.100" Rod Pins, One Piece Rear Seal
$239.00

9-350-3750-6000-L
New!
3.750" Stroke x 6.000" Length Rod, 2.100" Rod Pins, One Piece Rear Seal
$239.00

9-350-3800-5700
935038057
3.750" Stroke x 5.700" Length Rod, 2.100" Rod Pins
$259.00

Series 9000 400 Main Chevy Cast Crankshafts

New P/N
Old P/N
Crank Model
Price

9-400-3500-6000
940035060
3.500" Stroke x 6.000" Length Rod, 2.100" Rod Pins, Lightweight
$259.00

9-400-3750-5700
94003755
3.750" Stroke x 5.565" Length Rod, 2.100" Rod Pins
$219.50

9-400-3750-5700-2
94003755P
3.750" Stroke x 5.565" Length Rod, 2.100" Rod Pins, Lightweight
$269.00

9-400-3750-6000-2
94003755P
3.750" Stroke x 6.000" Length Rod, 2.100" Rod Pins, Lightweight, Int. Bal.
$279.00

dave



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Old 11-03-2001, 11:24 AM
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Default Re: 400 small block crank in a newer 350 block.

Dave, this Forum would really be lost with out you! Thanks a bunch!!!! Which would be the better route to go, use the older block & the newer FI heads, or use the newer block with the old crank?

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Old 11-03-2001, 01:15 PM
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Default Re: 400 small block crank in a newer 350 block.

Thanks for the kind words. It's just a matter of budget on what would work out best for a 383. I personally like the the Chevy SBC 400 crank, but finding a virgin SBC 400 crank is not easy. There is an additional cost to machining a SBC 400 to fit a SBC 350. It's also an additional expense to use the crankshaft adapter.

I've never used a SCAT crank, so I'm not going to be a very good judge on the quality of there 9000 Series cranks. For the price, the SCAT 383 one piece crank can be a very affordable option. All things considered, it's really going to depend on the quality of the machine shop you decide on to help with your 383 engine plans. The best parts ever made will not last if the machine shop is not correct with there measurements!

I built a SBC 400 using Vortec heads about 18 months ago. It's a very strong motor, and uses 87 Octane unleaded gas. The engine is using an Edelbrock PERFORMER intake manifold. The SBC Vortec 400 I built is used around Portland Oregon which is not the hottest climate in the United States. Gas varies between state lines, so not all 9:1 compression engines can run on 87 Octane unleaded gas. Hot weather can also effect a 9:1 compression engine using 87 Octane gas.

All things considered, if I was to build a 383 today, I'd start with a phone call to Engine Rebuilders Supply (ERS) and get a one piece rear main seal 350 4 bolt main block with factory roller camshaft. I'd most likely get a set of used Vortec heads while I was there. I could hope to find a virgin SBC 400 crank at ERS, but would most likely get a 383 SCAT crank from Sallee Chevrolet. Then I'd get into the machine shop and get to work and make a nice 383, balanced using hypereutictic pistons and a new harmonic balancer. I'd keep the compression close to 9:1 and use a RV grind type camshaft.

Then again, I might just get an HT383 from Sallee Chevrolet, and be finished with the project on a long weekend.
dave

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