That Junk Engine Won't Last!

G

Gene K

Joined
Jan 25, 2003
Messages
5,347
Location
Decatur AL USA
Bracket Race Engine

Had a friend put together a temporary junk motor out of cheap and old parts he had laying around. Lots of Naysayers.

377" Small Block Chevy (4.125" x 3.75")
Stock 350 2-Bolt Block with hone job.
Stock 400 Crank unturned and unbalanced.
Stock 400 5.565" Rods with stock bolts.
Stock Replacement Bearings (NAPA)
Stock Oil Pump
NOS GM Pistons TRW 11:1 LT1 350 Forged (PAW used to get $99.99 for these).
Iron Rebuilder Rings (NAPA)
Dart Iron Sportsman with home pocket and good valve job (These were $599 a pair in the old days).
Ultradyne Flat Tappet Claimer Cam ($60) with OEM GM Lifters ($20).
Weiand Team G Intake
Old 750 DP Holley Race Carb

6.70 at 100 mph (1.76 Powerglide) at 3,000 lb (1/8 mi).

500 bhp based on trap which is likely a low estimate due to the converter losses.

It spun a bearing last weekend.
It needed oil changes, plugs and several sets of cheap Z28 valve springs over 17 years. Those were the original bearings from 17 years ago.

We go WAY faster now but sometimes I think it's lots less fun.

Edit: Got curious and went diving in my old references.
Camshaft Specs -
Solid Flat Tappet 285/295(0.020) 252/261(0.050) 0.525/0.525 106LSA.
If anybody wants one I think Bullet Cams could set you up as they have all Harold's old (Ultradyne) masters. Better cams today but that one would run on cheap springs and made good power.
 
Last edited:
For me, this is more of a testament to the design and quality of construction of the "old" Chevrolet engines. While we may have made major changes through the years for computer aided design and materials, these examples speak to the ingenuity of the designers and builders of yesteryear.
 
Gene K said:
Bracket Race Engine

Had a friend put together a temporary junk motor out of cheap and old parts he had laying around. Lots of Naysayers.

377" Small Block Chevy (4.125" x 3.75")
Stock 350 2-Bolt Block with hone job.
Stock 400 Crank unturned and unbalanced.
Stock 400 5.565" Rods with stock bolts.
Stock Replacement Bearings (NAPA)
Stock Oil Pump
NOS GM Pistons TRW 11:1 LT1 350 Forged (PAW used to get $99.99 for these).
Iron Rebuilder Rings (NAPA)
Dart Iron Sportsman with home pocket and good valve job (These were $599 a pair in the old days).
Ultradyne Flat Tappet Claimer Cam ($60) with OEM GM Lifters ($20).
Weiand Team G Intake
Old 750 DP Holley Race Carb

6.70 at 100 mph (1.76 Powerglide) at 3,000 lb (1/8 mi).

500 bhp based on trap which is likely a low estimate due to the converter losses.

It spun a bearing last weekend.
It needed oil changes, plugs and several sets of cheap Z28 valve springs over 17 years. Those were the original bearings from 17 years ago.

We go WAY faster now but sometimes I think it's lots less fun.

Edit: Got curious and went diving in my old references.
Camshaft Specs -
Solid Flat Tappet 285/295(0.020) 252/261(0.050) 0.525/0.525 106LSA.
If anybody wants one I think Bullet Cams could set you up as they have all Harold's old (Ultradyne) masters. Better cams today but that one would run on cheap springs and made good power.
Click to expand...



A couple of things are wrong here. The stated stock bore of a SBC 350 is 4.00", not 4.125".
Installing a stock SBC 400 crank in a 327 or a 350 block requires the main journals of the crank to be turned.
 
skyactiv said:
A couple of things are wrong here. The stated stock bore of a SBC 350 is 4.00", not 4.125".
Installing a stock SBC 400 crank in a 327 or a 350 block requires the main journals of the crank to be turned.
Click to expand...
Maybe it was a .030-over 400 destroked with a 350 crank?
 
The OP said " Stock 350 2-Bolt Block with hone job."
He made a mistake somewhere, no biggie.

A 377 can be made from a SBC with a 4.00" bore and a SBC 400 crank.
The classic SBC displacement mod is to bore a 350 .030" over, install a 400 crank which makes it a 383.

A .030" over 400 block with a 3.48" SBC crank does equal 377 C.I.
Calculator by Spicer: https://spicerparts.com/calculators/engine-displacement-calculator
 
When I was a kid I had the the opportunity to work in a big marina that had a big engine building shop with a machine shop on premises . I came in with all my car magazine know how and was shocked when I saw lots of performance builds getting done with two bolt main blocks and cast cranks .
I dont mean full race stuff but certainly stuff that lotsa guys would buy four bolt blocks and steel cranks . This was in the eighties so H beam rods were silly money for most people . We put em in stroker big blocks but that was about it .
Anyway, what I learned there was meticulous attention to detail, straight and round machine work and clean engine assembly . Ive seen plenty of two bolt, factory rod short blocks stay together just fine .
OPs post didnt surprise me at all . Thats the way it was for lots of guys . It was the mutts who threw together questionable parts in a dirty garage that had problems .
 
skyactiv said:
A couple of things are wrong here. The stated stock bore of a SBC 350 is 4.00", not 4.125".
Installing a stock SBC 400 crank in a 327 or a 350 block requires the main journals of the crank to be turned.
Click to expand...

It was a 4.00 Block (Don't know why I entered the 400 SBC Bore).

The crank was from a previous project so had already been turned to 350 Main diameter. I simply meant it was an OEM 400 Crank and wasn't turned before going into the race motor or rebalanced for the pistons. Clearances were within spec but not optimised.
 
Last edited:
As someone who built his fair share of chevys small and big block its certainly not a hard job to DIY
but throwing junk together on a budget is an American tradition LOL . 377s with the right heads run fast
unfortunately 400 blocks crack easily but hey it didnt cost much ....Today the age of the LS is here,a healthy
5.3 with the right mods will run circles around a 377 and last forever ..
 
Gene K said:
It was a 4.00 Block (Don't know why I entered the 400 SBC Bore).

The crank was from a previous project so had already been turned to 350 Main diameter. I simply meant it was an OEM 400 Crank and wasn't turned before going into the race motor or rebalanced for the pistons. Clearances were within spec but not optimised.
Click to expand...
You are forgiven being a FORD guy :)

Typical Pass car 2 -bolt chevy blocks and cast crank could support 325 HP all day. Anything much over 375HP they are grenades.
But as kids or young adults we didn't care, the boneyard was full of cheap parts. A weekend out on the street could equal a 1/2 season of drag racing.
 
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