C3 Tech/Performance V8 Technical Info, Internal Engine, External Engine, Basic Tech and Maintenance for the C3 Corvette
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Old Feb 6, 2026 | 04:59 PM
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Got the valve covers off and one side looked like it might have the correct fasteners the other side had hardware store bolts. Doesn't look too bad in there so far just a few bits of gasket laying around.



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Old Feb 6, 2026 | 05:02 PM
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This is where I'm at today, my plan is to plug all the hole that go to the sump with some rags and clean off the gasket and gunk. Then it looks like I need to take the fan and fan clutch off at the minimum to be able to turn the motor over by hand.



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Old Feb 6, 2026 | 05:05 PM
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And I forgot to show how I sucked the coolant out of the manifold and some out of the radiator. The thing on the fender is a vacuum generator and the glass carboy is for making wine and the orange cap with another part is how you siphon the wine out of the carboy.




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Old Feb 6, 2026 | 08:24 PM
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where the Mr G breather is now, was probably an OE hose-pipe from base of air cleaner assembly >>> supplying air thru Pass head and into crankcase >>> then evacuating thru Driver head and out the PCV to carb base>>> drawn into intake plenum and into chambers then burned.

* have virtually same tires on mine. Both your Mastercraft Avenger and Jetzon Revenger manufactured same company. I've compared them long ago and they're in all ways identical.
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Old Feb 7, 2026 | 11:49 AM
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I'm thinking at this point that I'd be better off just pulling the exhaust manifolds off then pulling the heads off. This way I can work on them on the bench and get more information about what I have for pistons and measure the deck height.

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Old Feb 7, 2026 | 06:49 PM
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Originally Posted by jthornton
If I get the valve springs off using the rope method and I feel any slop in the valve guide I'll stop right there and pull the heads off and decide if I want to have them rebuilt or just replace them with some aluminum heads. It's surprising how small of a movement you can feel with your hands and being a machinist among other trades you learn to feel clearances.

I feel much better about the lower end after the compression test... and the inside is looking much better not to mention the under side too.
JT
^^^THIS^^^
When checking for stem wobble, let valve drop a little off seat first; most-recent Gen 1 sbc GM Powertrain repair manual actually specifies about 0.063" off the seat. No bs.
Then measure side-to-side: same ref "service" specs = 0.0010" - 0.0037"
If ya recondition-service heads; don't forget the K-Liner option.
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Old Feb 8, 2026 | 06:56 PM
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Ok I got the drivers side head off and the bore is 4.030" and the piston is 0.025" below the deck at TDC.




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Old Feb 8, 2026 | 08:06 PM
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Why not just pull the engine at this point, put it on an engine stand, clean and paint it along with new front/rear seals, core plugs, etc. detail the engine compartment. It's a pita to do heads while the engine is still in the car.
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Old Feb 8, 2026 | 08:28 PM
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Oh yeah, put those Flotek heads on there. You'll save about 40-50 pounds. With the L83 cam you'll have a easy 14 second (educated guess) cruiser.
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Old Feb 9, 2026 | 06:15 AM
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guessing bottom end had been freshened as well.
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Old Feb 9, 2026 | 06:39 AM
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Originally Posted by Fly skids up!
Why not just pull the engine at this point, put it on an engine stand, clean and paint it along with new front/rear seals, core plugs, etc. detail the engine compartment. It's a pita to do heads while the engine is still in the car.
I was thinking the same thing last night. I need to get access to the starter wires and see why Bubba cut that one wire off. And I want to put some better plug wires on with cable organizers.

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Old Feb 9, 2026 | 11:53 AM
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Originally Posted by jthornton
I don't have any oil on the outside of the heads so the valve cover gaskets are doing their job. It does leak from the rear main seal but that's another project.

JT
I have to take that back, the heads now that I have enough stuff out of the way and pulled one have oil on the outsides.

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Old Feb 9, 2026 | 11:58 AM
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I'm glad I decided to pull the motor out as the deeper I look the more stuff needs replacing like the lower radiator hose, the heater hose from the water pump, the heater control valve, the dip stick tube is loose and wobbles all over. It will be a lot easier to fix Bubba's wiring modifications with the engine out.

Are there any heads up I need to know about pulling the engine and leaving the 700R4 in the car?

JT
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Old Feb 9, 2026 | 03:38 PM
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The dipstick is pressed into the block but should have an additional support tab securing it to the block.
I supported the transmission with a scissors Jack with a block of wood on the transmission oil pan while the car is on Jack stands. You don't need to remove the hood but I disconnected the hood support to get the hood to open wider using a ratchet strap tied to some shelving in my garage. Removing the water pump gives you some extra room to work with. But the one thing that I would strongly recommend is a load leveler. Makes the job much easier.

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Old Feb 9, 2026 | 04:31 PM
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Originally Posted by jthornton
I'm glad I decided to pull the motor out as the deeper I look the more stuff needs replacing like the lower radiator hose, the heater hose from the water pump, the heater control valve, the dip stick tube is loose and wobbles all over. It will be a lot easier to fix Bubba's wiring modifications with the engine out.

Are there any heads up I need to know about pulling the engine and leaving the 700R4 in the car?

JT
I recall that I'd used a length of either 2x4 or 2x2 to bridge across C3 frame rails and supported front of TH400; simply jammed it in; where it remained for many weeks while car was on about six or eight jackstands. Seems, I may have pulled converter and that bellhousing's lower angle rested on bridge. This job was in a buddy's large quonset hangar and had use of Very large rolling crane (way more than a cherry picker).That's been quite a while back +20yrs. Sorry, no pic.

Remember lowering car onto wheels, (motor out but trans still in) and we towed it along strip to another buddy's hangar; where I built motor and dynoed it in his cell. Soon sold it and bought a roadster.
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Old Feb 9, 2026 | 04:36 PM
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@Fly skids up! Thanks, I have a jack tray on the 4 post that I can use to hold the transmission up with. I'm going to get or make a load leveler I have the stock and machines to make one and I have a piece of acme thread rod that needs a home so why not. I was looking at the water pump and thinking it would be better off the engine. I hope to find a set of those wheels one day for my C3...

Both heads are off and oddly the passenger head bolts smelled like an old farm shop to me. My grandparents had a dairy farm and that's the smell I remember.

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Old Feb 9, 2026 | 05:59 PM
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This is where I'm at today.



@Rebelyell Interesting you mentioned Quonset hut, I was born in one on King Salmon Island in the territory of Alaska (not a state yet). They had to fly the doctor in from Anchorage and my Dad administered the ether as there was no one else around to do it.

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Old Feb 9, 2026 | 06:13 PM
  #38  
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Unbolt the 3 fasteners that hold the converter to the flexplate and slide it back as far as it will go. Once you support the transmission at the front you can pull the engine. Be very careful to prevent the converter from sliding forward and falling out. They make a big mess all over the floor when they slip off. Rope and a block of wood to press across the converter at a minimum.
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Old Feb 9, 2026 | 07:51 PM
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Originally Posted by jthornton
@Fly skids up! Thanks, I have a jack tray on the 4 post that I can use to hold the transmission up with. I'm going to get or make a load leveler I have the stock and machines to make one and I have a piece of acme thread rod that needs a home so why not. I was looking at the water pump and thinking it would be better off the engine. I hope to find a set of those wheels one day for my C3...

Both heads are off and oddly the passenger head bolts smelled like an old farm shop to me. My grandparents had a dairy farm and that's the smell I remember.

JT
well, may be good reason for that smell.
Radiator Specialties Company, is a century old & HQ'd at Charlotte NC USA
RSC still around and making all sorts of automotive chemicals/remedies; most sold at car dealer parts counters, parts stores and used to sell at full-service gas stations.
Dunno if they still make it, but RSC used to market a pasteboard "tin" of radiator stop leak that was filled with a dry, powdery, granular stuff that was simply, mostly Manure.
It's an old, old farm remedy that works: put a handful of horse or cow dung IN the radiator; it circulates, and settles into leaking spots. RSC simply figured out how to package and market what farmers had long known of. Similarly, some remedies include ground black pepper.
Yes, the tinned stuff from RSC aka SolderSeal does smell of just what's in it: Manure. And, once wetted and warmed by motor, that 'cachet' becomes that much heavier.
Nope, this ain't just some of andy's mayberry, it's for true. Perhaps your motor has had the farm treatment during its long tenure ?
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Old Feb 9, 2026 | 08:46 PM
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Originally Posted by jthornton
This is where I'm at today.



@Rebelyell Interesting you mentioned Quonset hut, I was born in one on King Salmon Island in the territory of Alaska (not a state yet). They had to fly the doctor in from Anchorage and my Dad administered the ether as there was no one else around to do it.

JT
JT
Seems both Alaska and Hawaii gained statehood 1959.
Wasn't born Hawaii, but as a small dependent and while it was still a territory, we resided off-base near Pearl. We lived in a Filipino section; none of us spoke the language. But I recall playmates nonetheless. I can't remember where I laid my phone down, but I recall their names; go figure.
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