I was thinking it would be cool to hear from the group on the best things you have done on your C3 AND the worst. Please list them and if you have pics, share.
I will kick it off.

BEST: Suspension upgrade. Bilstein Shocks, VB&P front springs and rear composite and spreader bar. Really improved the ride and handling.
Close second is the MSD Programmable ignition.

WORST: This one is hard. I would have to say it was toying with the HEI distributor and adding parts to it. It was a cheap Ebay one and I never was satisfied with the results.

How about all of you?

 

I've pretty much been through everything on my car over the years, including a frame-off, but here are the two that stick out to me.

BEST: Hands down it was replacing the four-speed with a TKO600 5-speed. Yeah, this can be an expensive mod, but the moment you first shift into 5th on the Interstate, you feel like you just bought a completely different car. Truly transformational mod.

WORST: A high volume water pump. Not knocking the component, it's a great pump (made in USA) and performs flawlessly. However, the combination of this pump (which required a balanced thermostat with two small bypass holes), a DeWitt's aluminum radiator, well functioning radiator shroud and hood seals, and the Pace Car style front spoiler just do too good a job at cooling the car. This is with thermostaticaly controlled electric fans. Car takes a long time to warm up due to bypass holes, and doesn't stay there when the weather is cooler. This ties in a bit with the above actually as when you are on the highway in 5th, the motor is turning slow and the air is just ramming through the radiator. If the ambient temp is in the 50s or below, the engine actually cools down enough to close the thermostat. To combat this I have to insert a piece of cardboard to block part of the radiator in the cooler temps. I'll go back to stock volume pump at some point which will let me use a thermostat with no holes.

 

Best: AFR 195 heads and retro roller cam. Worth every penny!

Worst: Can't think of anything. All my mods have been positive thus far.

 

Best mods - I have done, EFI electric head light motors and exhaust that doesn't drone.

Worst - open element air cleaner without cold air access, ECM see IAT over 140*

 

What suspension were you coming from and what Bilsteins did you go with? Heavy duty or Sport? (What weight springs?)


Adam

 

Ignoring my recent total makeover and listing just the simple stuff (69-SBC)

Best: Headers, Aluminum Heads, MSD ignition, Holley carb
Worst: Hi volume oil pump, Mallory ignition

 

Nice thread.
It made me think; if I had to undo all the things I've done, what would I leave to last.

Best thing:
Got to say, it would be the manual transmission (a TKO-600 that replaced a TH700R4).
I would rather have less power and a manual than bags of power and an auto.

Worst thing:
In the mid 90's for about a month I fitted one of those black vinyl "bra" nose protectors.
I was young, I didn't know better, I feel ashamed

 

Omg so many to list over the last 35 years...

Best:

VBP 360 monospring (1985), Spreader bar, Holley 4175 instead of the Qjet, Poly upper and lower control arm bushings, Gary Ramadei custom blueprinted/rebuilt OEM steering box, Hella European Halogen Headlights in 1983 (100 watt highbeams, 55/60 watt lows), 255/45/17 ZR Ultra High performance summer only tires, Bilstein HDs front/Sports rear, 2.5 True dual exhaust with Long Tube Headers (headers added 1 month ago) on the upgraded/complete rebuilt L-82 with AFR heads, 10.2:1 compression, Howards Roller cam, competition adjustable strut rods with Heim joints, poly sway bar bushings, 1979 GM front spoiler extension, Performance Friction Brake pads with SS flex lines, 81/82 oil temp gauge in place of the clock (1986), complete lining of the interior with sound deadening/heat insulation under the carpeting to block heat intrusion/road noise, 3/4 inch OEM/GM style rear sway bar to balance the handling in place of the 7/16 GM rear sway bar and there is more...

Not exactly worst BUT:

Same issue with cooling as SLVRSHRK, Dewitts radiator and Stewart Stage 2 aluminum water pump...car runs too cool especially on cooler days...never gets up to proper operating temp...went from running HOT as a stock L-82 in the 80's to too cool today...talk about going around full circle....

Flex Fan in the 80's..ridiculously noisy and did NOT improve the cooling...

My 78 L-82 4 speed Gymkhana suspended C3 looks fairly stock with the exception of the wheels and the engine that looks like an L-82 minus the AFR heads but runs and handles like a modern sportscar with serious power...Not exactly like my 10 C6Z06 but not too far behind....

 

Best,1987 Gale Banks Twin Turbo Set up.

Worst, Ever Since, Gale Banks Twin Turbo Set up as it has prompted 4 Transmission swaps, 3 rear end swaps, Numerous suspension changes, body work changes, 3-4 Wheel and Tire changes, 2 Engines. And who knows what will lie in the future.

 

Best Mod - AFR cylinder heads and Borgeson steering setup.

Worst Mod - I really don't have any except for the Stewart stage two pump that I just learned was a problem.

 

Best: Pull all of the pollution control and re-route vacuum lines to start. True Dual Exhaust.

Worst: putting 255 60 15's on the front wheels, too big for stock suspension. Should have stuck with 245 60 15's on the front. But there great on the rear.

 

On the positive side, you guys with the multi row aluminum radiators and Stewart Stage 2 aluminum water pumps- if you ever do the bottom-end you can go with a 383 stroker rotating assembly and combine it with good 64cc chamber heads and get away with 11:1 compression given your low temps if you feed it good gas.... -Silver lining?


Adam

 

Well considering that I've only got a couple mods installed so far this will be easy for me:

Best mods:
1. Monster 4L60e Transmission -torquey, fun 1st gear, 0.70 OD makes for low cruise RPMs and good fuel economy- computer control enables toggle switches for "eco mode/perf mode" and "dyno mode" -Locks up TC in 3rd full time so the dyno results aren't thrown off by TC slipping. Supports 500hp and 450 ft lbs. Also supports paddle shifters.
2. New Exhaust (coated full length headers, true duals, high flow mufflers, no cats)

Worst mod: Chinese Chrome wheels- impossible to balance, weight a metric ton, and I'm just waiting for them to start looking crappy. I should've spent 30% more on polished or PVD-coated aluminum TT2s...


Unknown: Steeroids Rack and Pinion- right now the steering isn't great at low RPMs but I need to check for binding and I know the 79 power steering pump's pressure is low for these things (they like 1100 PSI -79 puts out only 850 or 950 PSI). Not sure whether to go with a smaller pulley or tear the pump apart and modify it for higher pressure. Might try a smaller pulley and if I don't like it just buy a replacement pump that comes with 1100 psi.


Adam

 

Where'd you get the spoiler extension? -You already had the L82 front spoiler and this just extends it down further, right?

Is this the Doc Rebuild one or something you made?


Adam

 

I have the Stewart stage 3, Dewitt's and electric fans. I guess it runs pretty cool down the highway, but a little hot in traffic until the fans turn on. I haven't noticed anything bad, yet.

Good thread.

 

For those of you with "too cool" running C3s, I have to ask whether you have automatics or manuals and if automatics whether you have dedicated trans coolers or not. (I've heard switching to a dedicated trans cooler can take a significant load off of the radiator.)

 

Pulley changes won't do a thing. The pressure is set by a pressure relief/bypass valve in the outlet fitting.

 

1979 GM spoiler extension for 79 L82 with heavy duty cooling...Bought from local Chev dealer in 1990. Attaches to my 78 chin spoiler

 

I have the Stewarts Stage 2 pump. It doesn't have a bypass hence the need for a thermostat with holes in the housing to allow a flow of coolant otherwise the pump would cavitate. It does take a while longer to reach operating temps but it does get there. I'm also using a stock recored rad.

 

Best....
-406 sbc and tko 5 speed

Worst....
-AFR heads that aren't installed yet
-$4000 interior package that sits up in the loft not installed yet
-first dual exhaust system that I had installed.....the guy had no clue what he was doing, I went elsewhere and had it redone.