Build Engine For Long Term Durability

Grumpy

The Grumpy Grease Monkey mechanical engineer.
Staff member
STINKY HERE<
I am opening a can of worms here, and boys, you keep it civil.

What is the best SBC? I am not talking about the one the will put out the most TQ and HP...which one will last for 300K, or more, in a PU, or in your wife's car. Which one lasts the longest, and won't mysteriously just blow up on you.

The LSs finally have enough time in them to have a track record. Everybody thinks that they are the Cat's Meaw (SP?), but how are they after 250K?

The Vortecs...prone to swallowing antifreeze on the intake...drove one at work...they sold it at about 125K. IT still ran fine, but twas leaking antifreeze and they wouldn't put $500 in to it (and I am sure that it had coolant in the oil).

Now, for my money, a TBI 350 is the best. My company used to drive them and at 150K, no oil usage and they still ran strong. We ran the snot outa them. They would cruise above 85...it would take about 10 secs for the speedo to start dropping off of 85, where it pegged. They would run at 85, when it was 115 out. A '93 Caprice would overheat about 90 (hit a Jackrabbit at 107 in one...what a mess).

As a side point, the Fords ran fine, same mileage outa them, but there were other issues. A TBI 350 in a Suburban, w/150K on it would outrun a brand new '97 Expedition.



If the goals max mileage with few maintenance related failure issues,
if the goal is max durability and power is not the only or even the main consideration, you make choices based on increased durability,
a few factors in the component design do increase durability and the use of better quality aftermarket components will add considerably to the engines life span.
stress and heat must be minimized ,controlled and consistent, and lubrication maximized,
and Id suggest a multi spark ignition, and Id use a multi coil coil on plug ignition,
and limiting the rpms to about 5700-5800 rpm and keep the compression down near 10:1 so you could use pump octane gas.
Id like to use an over drive transmission, a 2500 stall converter and a 3.54:1 rear gear.
Id use stainless 1,3/4" full length headers and a full 3" dual exhaust with an (X) pipe.
Id use bosch platinum spark plugs
Id suggest due to what Ive seen over decades that almost all OEM parts are built to be the lower price bidder components,
and as such Id damn sure use aftermarket parts in most areas thus they are not nearly as strong or durable as the better aftermarket clones, Id specify clevite H bearings and I use a standard capacity standard pressure BBC oil pump,
if I was building a SBC engine to make reasonably good power but with long term durability as the main goal,
Id select a forged two piece rear piece DART block,
https://www.summitracing.com/parts/drt-31161111#overview
https://www.summitracing.com/parts/sca-1-40570#overview
use 6" rods with 7/16" ARP rod bolts and a 3.5" forged crank with forged pistons,
https://www.summitracing.com/parts/sca-1-40570#overview
Id select a hydraulic roller cam with a bit less than .520 lift and about 215-220 duration at .050 lift on a billet cam core,
Id install steel roller rockers with a 1.5:1 ratio,
https://www.chevydiy.com/wp-content/uploads/2017/01/17-6.jpg
https://www.hardin-marine.com/p-100245-sb-chevy-valve-spring-oiling-system.aspx
Id use a 7-8 quart oil pan
http://www.grumpysperformance.com/wpan3.jpg
and wix extra long oil filters, and a few ceramic high temp magnets to trap metallic debris
http://www.grumpysperformance.com/51800.jpg
and change oil every 5K miles and use a mix of 6 quarts of mobile 1 synthetic 10w30 and a quart of MMO,
id use direct port injection with 22 lb injectors
my goal would be something like a 350hp/380 ft lbs power band,
Id use heads with bronze valve guides and hardened steel valve seats, with about a 190cc-200cc , port size probably brodix IK heads
Id select the (FIRST tuned port INTAKE)
https://firstfuelinjection.com/
keep in mind direct port injection limits wasted fuel and allowing fuel to wash lube from bore walls rings etc.
Id specify use of an oil cooler and a larger than average radiator with at least a 60% antifreeze mix that gets changed every year.


every part you choose is a compromise , and may require changes,
that cost you in time, money or performance to some degree,
and almost every part will require a bit of fitting or clearance work,
or adjustment to fit and function to get the best results
if it drops out of the package and bolts together as it drops out of the package,
its almost certain its not functional to nearly its full potential

your job is to think things through carefully and make sure parts fit and function to their full potential,
little things like checking piston ring end gap, verifying bearing clearances, and ccing the heads and checking piston to valve clearance, degreeing in the cam and verifying the valve train geometry, polishing combustion chambers, getting a decent 3 angle valve job, MATTER!

as always it really pays to think things through carefully,

use a build sheet documenting all parts used, machine work done or scheduled and the costs and time required.
this will inevetably result in your having to do some research and ideally not skip over important steps like checking clearances, valve train geometry , parts selection and compatibility issues or lubrication and ignition system issues
break the build down into sections like the block and required machine work, the rotating assembly, heads and valve train, lube and cooling systems, matching the injection, carbs or intake manifolds selected, matching the headers and exhaust system, and of course matching the drive train gearing, differential gearing, tires and brakes to the intended usage.
all of these steps require some research to get the ideal results
 
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Better Jump on a Dart Block if you find one and need it.
Report few months back no more.
Going to be casted in China.
13 months to receive shipped from China on a boat .
Then Chevy Guys Revolted.
Don't want a China Dart Block.
Looking for a USA Foundry last I knew.
 
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