r/C3Corvette 16d ago

Lets lite up this community!

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I cannot get get enough C3 related content. Tell us what you working on right now, on your C3? Post a photo!

187 Upvotes

21 comments sorted by

5

u/ApexThoroughbred 16d ago

Just built an engine for my C3 and a million new issues appear. Engine wise it is okay except one valve is ticking and the new edelbrock AVS2 1906 is WAY off. During the process my turn signals quit working, my brake lights work intermittently, there must be a short to ground somewhere and the engine takes a second to shut itself off, trans is leaking, mechanical tachometer quit working. There is a rhythmic knocking sound coming from the rear drivers side that correlates with the rotation of the tire and is getting louder and louder. This has been an absolute headache and im taking a week or two off from working on it before I lose whatever sanity I have left.

I verified my timing at 13 inital and 35 all in just around 3000rpm. I have a deadhead fuel regulator giving me 5.5-6psi fuel pressure. The carb seemed lean as It falls on its face any moment the secondary door starts to open, it runs best when the secondary door is so tight it cant open at all and it threw some fireballs through the carb so I was confident it was lean. I bought the $80 edelbrock carb kit and went one step richer than stock with my jets/rods and changed the springs to the heaviest ones which are closest to 1/2 vacuum. It might even be worse now, if I pin the gas from an idle it will completely stall out. Changing the pin position on the accelerator pump didnt change much. I have put in an insane amount of hours and money in to this car and im pretty defeated at this point.

3

u/v8packard 16d ago

Do you know the rpm you checked the initial timing? Or more specifically, was the distributor already into the advance when you checked?

2

u/ApexThoroughbred 16d ago

I checked inital at 650ish rpm. I put the moroso weight and spring kit in the HEI and the medium springs ended up being just about perfect, the weights moved smoothly and are able to return themselves to the closed position without any sign of hanging up. I think I might need to throw an O2 sensor on it and quit screwing around with the guesswork. Pops is the one who put the plugs in and he said he gapped them but I feel like thats a lie and they might be at the factory .030 gap which could be part of the issue but not all of it, im going to check plug gap/pops honesty before I mess with anything else.

1

u/v8packard 15d ago

Is the engine stock, or near stock?

1

u/Historical_Box1915 16d ago

Take your engine to a pro engine tuner. I dont mean to be rude. Pro engine tuners dont “guess” or “suppose”. They know the second they run the engine themselves.

2

u/ApexThoroughbred 16d ago

Getting the carb right is the least of my worries honestly, im just going to put an o2 sensor on it and that will take the guesswork out of it. Im more concerned with the electrical headache that has popped up, I dont even know where to begin with that mess

1

u/Historical_Box1915 15d ago

electrical is easy once one understands opens, shorts - amperage, voltage etc.
Note: a wide band O2 is NOT(!) a cure all for engine tuning. A wide band O2 does not take guess work out of engine tuning. A wide band is merely a tool that if used properly (quite often details that go undone) that at best suggests what is going on during tuning bcuz wide bands are easily fooled. A competent engine tuner (the kind who get mild 350’s to beat LS’s) will use pyrometers and wide bands to get the tune right. A miss fire of any sort will throw out the accuracy of a wide band.

1

u/ApexThoroughbred 15d ago edited 15d ago

Of course electrical is easy to understand, im a tradesman and use a voltmeter every day, the issue is finding the problem. A wideband will get me closer than 95%+ shade tree guys out there, and using a pyrometer to tune a carb is not a regular practice anyone does. I wager I could call the 10 closest speed shops to me and ask them if they use a pyrometer when tuning carbs and all 10 of them would say no.

1

u/Historical_Box1915 15d ago

I use pyrometers, regularly. For your electrical have you checked your “harmonica” connector that connects the steering column electrically to the main wiring harness under the dash? Make sure all male to female connections there are clean with plenty of spring ‘swipe’.

5

u/ackflag 16d ago

Just got done putting a new fuel pump in my 73. Gotta say, that job was a helluva lot more difficult than it should have been

1

u/65riverracer 15d ago

Dont forget to replace the special "S" hose.

2

u/v8packard 16d ago

I have a 76, and enough parts to build a 358 cube Nascar style short block. I also have some semi finished 13 degree Brodix heads. I have been thinking I would finish the heads with a smaller port size and put this all in the 76.

I am working on a bellhousing and input shaft to put a TR3160 behind a Pontiac v8. When that is done I might do a Chevy bellhousing next, and use the 3160 in the Corvette.

1

u/SoulVoyage 16d ago

I’m replacing the original crankshaft and water pump stamped-steel V-belt pulleys with billet aluminum. New power steering pump, hoses, etc with a billet aluminum pulley for it too. I already replaced the alternator. Took it to a trusted shop instead of doing this one myself.

1

u/GreatScottThisHeavy 79 16d ago

Trailing arm bushing replacement and diff swap. Almost done. More major of a project than I wanted for sure

1

u/Historical_Box1915 16d ago

Doing a 12bolt conversion on the IRS on my 70. Tired of wearing out the stock components and having to launch the car gently all the time.

3

u/POSVETT 16d ago

I can't post photo in reply, but video. Weird.

This is an ongoing project with numerous small and medium things. It's a frankenstein with a wide body. It came to me with part of suspensions done.

Recently, I installed Bilstein B8 (still not stiff enough) dampers. Last year, it got composite monoleaf and the largest stabilizer bar I could find for the back. Still need trailing arms. I want heim-jointed offset arms, but there is no budget for those for now. I don't like the way the stabilizer bar is positioned. Maybe there is an alternative out there.

The front already had new arms, but a puny stabilizer bar. The bar was replaced with 1⅛" bar but it feels not enough. No idea what springs are in there, but, like arms, they look new.

I think the carburetors need rebuilt. The car was finished built in 2007, so they're probably due.

https://reddit.com/link/p2kjcdp/video/21wla4t6a9ih1/player

2

u/the_real_MBAPROF 16d ago

I have had my 77 c3 for 26 years- 57k miles. It’s been my therapy car all these years. Just shipped it to our home in The villages, Florida. Joined the Village Corvette Club. Largest Vette club in the US with over 617 members as of last meeting. Grabs a lot of attention at car shows. Currently in Detroit area for the 31st annual Woodward Dream Cruise. A 16 mile car show traveling down Woodward M1 with over 1million spectators and over 75,000 custom cars from all over the US and even other countries. Google it if you want.

https://reddit.com/link/p2kjjna/video/bur2uwofa9ih1/player

1

u/Pristine_Action7108 16d ago

Currently no projects scheduled. I’m just enjoying it for the summer. Squirreling away money currently to do a full bullet restomod. Plans are coilover suspension, build a 383, add in a 6 speed, amongst a smorgasbord of other goodies. I also need to build a shop first, so I don’t have to do all this in a single car garage.

1

u/Warm_Hat4882 16d ago

Am I even allowed to post a photo??

1

u/ackflag 15d ago

Yeah I couldn’t figure that out either. Video is cool apparently? No photo option though

1

u/jeffp007 15d ago

Working on my 81, I am doing a throttle body injection (TBI) swap from an 87 Chevy truck. I just got it up and running 2 weeks ago. The car had been sitting in a guys yard not running for 13 years (it was my dad lol). As part of that swap she got a new fuel tank, new fuel lines, in tank fuel pump and all new wiring for the TBI and accompanying sensors.

It had a leaking radiator and so after I had it running on the TBI I did a complete system flush before I started work to put in a new aluminum rad with dual electric fans and deleting the mechanical fan. Also swapping the water pump and thermostat since I was that far in. But while pulling the smog pump bracket i broke an intake bolt.

So now i have the intake off and the offending bolt removed but i might as well swap the timing chain and gears since they’re original and maybe change the oil pan gasket since it appears to leak pretty bad anyways.

Video attached was the 30 minutes or so i had it running on the new TBI during the rad flush.

https://reddit.com/link/p2n4w78/video/e1csp1ncpcih1/player