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4.3 L TBI VIN LB4 Engine tuning

  #1  
Old 02-26-2013, 05:37 AM
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Default 4.3 L TBI VIN LB4 Engine tuning

Hi all,

I'm coming closer to rebuild one of the engines of my two 1994 BLAZER S10's.
One has a lot of rust and sits on a friends place (sheet metal shop) becaus it cannot pass our very strict rules on safety of cars in Europe (especially my place).

The other one is my daily ride, mostly short trips up to 12 km (about 7 miles) and some longer rides.
As my daily has over 280'000 km (170'000 miles) on the odo and the trans started whining a bit it's time to think - rebuild.

S10 #1 (my daily ride)
280'000 km (170'000 miles)
11.5 l/100 km (20.3 mpg)

S10 #2 (the rusty one)
175'000 km (110'000 miles)
unknown but to judge from the few rides about the same as #1.

When it comes to engine rebuilds I'll do it myself, being associated with some garages I have the opportunity to work with some of the best mechanics and engine shops in my area. (Ferrari and vintage car restoration).

When it comes to tuning I have to keep EVERYTING street legal including emissions which means no cams and stuff. Nevertheless I'm thinking of properly blueprinting the engine and was wondering what your rebuilds were and how they turned out. I'm also interested in those using performance parts.

Let's use this thread to do some shop talk about what we do and did to this type of naturally aspired engine and how it turned out. BTW those builds gone awry are of the greatest interest to learn from. Especially what gave in.

What do you think are the best pieces such as for pistons, gaskets, etc.?
Where is a good place to shop internet wise? (Such as rockauto or summit?) Experiences?

GOAL:
Blueprint the engine and mod to get better torque at same rpm (including mor hp at same rpm) with the goal to reduce fuel consumption and getting better mpg.

IN DETAIL:
Dyno test if possible and within budget
Tear apart and clean
Measure all specs to determine material needed. (Me thinks mostly all)
Order the pieces
Dyno test if possible and within budget

BLOCK
- sand away all ridges, edges etc. from the casting.
- open up all passages for cooling agent etc. to match counterparts including gaskets
- bore and hone
- main bearings and all seals replaced
- paint (which colour? don't know yet - but most probably black)

CRANKSHAFT
- clean, have it crack tested (if budget permits)
- rework if needed
- open up all internal bores, clean internally, check, rebore if needed, close bores again
- balance (with pistons and rods and flywheel)

CAMSHAFT TO VALVE ASSY (ALL MOVING PARTS)
- clean, check, reuse if possible
- valves check, reuse or change, if changing, I'll exchange all as a set
- remaining parts, check, reuse or exchange
- springs measure, tension checking
- rockers, check for wear, eventually replace
- studs, check for wear, eventually replace
- polish all exhaust valves

OIL PUMP
- check, replace if needed
- plumbing - modify for acessibility (separate project if feasible ****ty thing to get to the oil lines running along block)

VALVE, BALANCER SHAFT DRIVETRAIN
- check replace if needed

RODS
- check and reuse rods if possible
- statically balance (top - bottom end weight matching the set)
- eventually polish?
- new bearings

PISTONS AND RINGS
- check eventually reuse with new rings
- statically balance and match weights of the set
- replace pins and safeties

CYLINDER HEADS
- clean, disassemble, crack checking
- valve guides, replace (if not in perfect condition) eventually only after the porting job
- valve seats, replace (if not in perfect condition) eventually only after the porting job
- sand away all ridges, edges etc. from the casting
- open up all passages for cooling agent etc. to match counterparts including gaskets
- match all ports to gasket and counterpart
- porting job? (still investigating what has to be done - I'll need to see the head first)
- polish all exhaust ports
- shave it to properly seat the gasket eventually a bit more to rise compression from 9.05:1 to 9.1:1
- paint it - most probably black as the block

INTAKE MANIFOLD
- clean, disassemble, crack checking
- sand away all ridges, edges etc. from the casting
- open up all passages for cooling agent etc. to match counterparts including gaskets
- porting to head with consideration to the gasket to get the best match possible
- inside job, to be detailed once I see it
- match to TBI with gaskets etc.

WIRING
- rewire everything to RH side of engine to connectors close to the firewall
- hoses, reroute and employ connectors at firewall
- new distributor
- new ignition cables and spark plugs

Would that do the job in bringing a couple miles more on the gallon and make it last another 200'000 miles?

Comments please - but keep replies strictly to the V6 TBI - no talk about V8 swaps, turbo's, compressors as they can never be street legal and will venture way too far. I'll enlighten a bit on a separte thread about our rules.
 

Last edited by error_401; 02-26-2013 at 06:42 AM.
  #2  
Old 02-26-2013, 10:20 AM
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Well,i like what you have planned. You said something about not wanting to swap cams. The cam is tiny on these things. This cam is a mild improvement for the stock one. the comp cams 260hr. works with stock converter, and stock gear ratios. It should still pass emissions. do that,the ultimate tbi mod. and bump the fuel pressure a few pounds and you should have what you want.
 
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Old 02-28-2013, 10:04 AM
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Thanks for the input.

Had a look at these cams. Trouble is with these cams you have to change the whole on moving parts in the valve train. They are for flat tappet without hydraulic lifters. It also says on the specs for non computer controlled vehicles which is not the case.

Anybody ever tried one of these cams on the above engine?

The 260
http://www.compperformancegroupstore...e=CHEV466Cam43

Or the 240H
http://www.compperformancegroupstore...e=CHEV466Cam43
 

Last edited by error_401; 03-01-2013 at 05:00 AM.
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