SBG's C3

[SuperBuickGuy]

I'm more concerned with getting the fenders on square.. but I know the driver's side is down compared to the passenger side - so that will be fixed

oil leak fix


I didn't notice the other times I pulled/put this together, but steel crank


and fixed (I hope)

 

[denpo]

 

[SuperBuickGuy]

 

[bobs77vet]

the sump pan on a 700r4 gets torqued to like 100 inch lbs and anything more ruins the gasket and it leaks....the oil pan on the mga is 6-9 ft lbs.....i felt like a numb nut using a torque wrench to 84 inch lbs. looks like you picked a nice gasket.

 

[SuperBuickGuy]

you want irony? the prior pan I had put on with mult-part gaskets... and they didn't leak (I was originally planning on selling this car, so I used what I had laying about)

the one-piece leaked... and after pulling it off and looking at it, honestly it shouldn't have.

this one-piece.... another leak, but I think it's because I need to put a washer on one of the pan rail bolts - so I'm not exactly turning into a fan of the one-piece.... with that said, it may cure itself because the motor hasn't been fully heat cycled - but why risk it? I'll get shoulder bolts today.

 

[GoVetteGo]

There has to be something touchy with the one piece gaskets. I have installed 2 and both leaked, Never had the 4 piece gasket leak!! And H have been playing with SBCs since the sixties!!!

What is the secret??? Not tightened enough??? Tightened too much!!!

 

[SuperBuickGuy]

silicone, lots and lots of silicone... oh yeah, and oil pan rail studs...

it's not leaking now, but good gracious that was tough


and I agree - the one-piece sounds like such a good idea. I won't be fooled again.

 

[GoVetteGo]

silicone, lots and lots of silicone... oh yeah, and oil pan rail studs...

it's not leaking now, but good gracious that was tough


and I agree - the one-piece sounds like such a good idea. I won't be fooled again.

:thumbs::thumbs:

Yeah - I have the pan off my 78 so I can powder coat it - I'll stick to the 4 piece when it goes back together!

I hate oil leaks :beer:

John

 

[SuperBuickGuy]

I've never liked how the belt tensions on this car, so I'm fixing it - also, when I replaced the water pump, it was used.... because that's what I had... time to fix both




as with all things.... it doesn't fit



so I welded an aluminum extension on it


and fixed


I had aspirations of making it flat-sided; but then I realized my belt sander needs a belt - so it's a bit more modern art than machined (used a side grinder)

​

 

[bobs77vet]

looks good! that tube would look cool cross hatched like a nail punch body

 

[SuperBuickGuy]

knurling requires a lathe.... with the hood closed; it looks perfect.

 

[bobs77vet]

i think the project looks great with the hood open!

 

[SuperBuickGuy]

i think the project looks great with the hood open!

thanks man

 

[mrvette]

i think the project looks great with the hood open!

i think the project looks great with the hood open!

thanks man

I agree, and especially mine being driven almost daily.....I look at cars with a slightly jealous eye....:clobbered:

 

[SuperBuickGuy]

i think the project looks great with the hood open!

i think the project looks great with the hood open!

thanks man

I agree, and especially mine being driven almost daily.....I look at cars with a slightly jealous eye....:clobbered:

I think that my cars photograph well, but IRL, they're certainly not show or race.

 

[SuperBuickGuy]

so, time to fix yet another issue - the brakes. I'm tired of the "will I have enough vacuum or not" issue with the motor; so I'm putting manual brakes on the car



so I have to clear a hole


now is the time I mention I'm really getting tired of trying to fit my 210 lb chassis in the footwell

anyway

here's where I stopped

an adapter to eliminate the booster.... tomorrow, brake lines

 

[bobs77vet]

interesting, it seems like we talked about this before... so how do you size the master cylinder piston and piston travel to get the full compression with the correct pedal travel? are there sizing guidelines or something similar?
thks bob

 

[SuperBuickGuy]

Yes there are - I have a spreadsheet on my other computer that I'll post up here tonight.

Though I have a question about the C3 system. It is beyond my pay grade to understand why the front (which operates the front brakes) brake line from the booster to the proportioning valve is smaller to the front wheels than it is to the rear. I intend (unless some explains to me prior) to change the lines to the proportioning valve to same size (and let the valve, not the pipe size change the amount of fluid the front brakes get).

I think someone made a mistake at SS brakes because the front line/rear line orientation on a C3 is reversed of what is "normal." Normally, the front reservoir feeds the front brakes, and the rear the rear brakes; but on a true C3 Master cylinder the line from the front then crosses to the back of the proportioning valve.... however, as the fitting size is different front/rear, it's impossible to screw up from my end. What is odd, in all of that, is the smaller line feeding the front calipers since there are more pistons in the front than in the rear.

Or I could be complete full of ****.... but everything I've read points to what I just described.

 

[MYBAD79]

Yes there are - I have a spreadsheet on my other computer that I'll post up here tonight.

Though I have a question about the C3 system. It is beyond my pay grade to understand why the front (which operates the front brakes) brake line from the booster to the proportioning valve is smaller to the front wheels than it is to the rear. I intend (unless some explains to me prior) to change the lines to the proportioning valve to same size (and let the valve, not the pipe size change the amount of fluid the front brakes get).

I think someone made a mistake at SS brakes because the front line/rear line orientation on a C3 is reversed of what is "normal." Normally, the front reservoir feeds the front brakes, and the rear the rear brakes; but on a true C3 Master cylinder the line from the front then crosses to the back of the proportioning valve.... however, as the fitting size is different front/rear, it's impossible to screw up from my end. What is odd, in all of that, is the smaller line feeding the front calipers since there are more pistons in the front than in the rear.

Or I could be complete full of ****.... but everything I've read points to what I just described.

In almost 10 years of owning this C3 I never paid attention and I never noticed the front brake line is smaller than the rear.... I just went out to the garage to have a look.... Damn sure the rear line is bigger..... This assumes the rear reservoir is for the rear and the front for the front..... I did not look that closely :smash::smash:

 

[SuperBuickGuy]

I don't know how to attach an .xls file to vettemod.... this is a pretty useful tool; so maybe it can get posted up in downloads?

 

[bobs77vet]

i sent you my email address for that file, i would like to see that.


I bet the line size has more to due with how fluid moves over distances and the bigger pipe going to the back has less residual pressure loss so the "pressure signal" front to back is more even, and the proportioning valve is controlling volume as opposed to pressure

 

[SuperBuickGuy]

i sent you my email address for that file, i would like to see that.


I bet the line size has more to due with how fluid moves over distances and the bigger pipe going to the back has less residual pressure loss so the "pressure signal" front to back is more even, and the proportioning valve is controlling volume as opposed to pressure

I agree with that analysis, but at some point the pipe size gets too small to effectively transfer the signal - with electrical wires, the light doesn't light and the wire burns up like a fuse.... in this case, I think the brakes just don't work.

 

[bobs77vet]

I got the file thanks, maybe GM being cheap skates was trying to save a few pennies on each car every where they could hence the smaller tubing

 

[SuperBuickGuy]

I got the file thanks, maybe GM being cheap skates was trying to save a few pennies on each car every where they could hence the smaller tubing

I don't know - the more I learn about cars and their systems, the more I realize I don't know.

 

[bobs77vet]

well what we don't know is how their penny pinching ways leads to design decisions.....and seeing now about the key cylinder issues being ignored because it was too costly to change tooling is a real eye opener.....its all about dollars and cents to the corporate folks

 

[SuperBuickGuy]

so a bit more work done before small group this Friday night

the adapter installed


bench bleeding


it's actually bolted to the firewall, just no picture of that yet...

 

[rtj]

A vacuum reservoir works. But, my 68 had manual brakes and those worked great.

 

[mrvette]

so a bit more work done before small group this Friday night

the adapter installed


bench bleeding


it's actually bolted to the firewall, just no picture of that yet...

Methinks you going to have to do your input rod length, just like I had to shorten the input rod on my Hydroboost in the '72.....PIA....


:surrender:

 

[SuperBuickGuy]

apparently I didn't take a picture, but that rod is the same length as the input rod to the dual diaphragm booster that I removed.

 

[SuperBuickGuy]

So I got the brake lines connected - but not bled, I'll have to have a friend come by tomorrow to finish that task....

first... length of the rod on the booster


I should probably hold the camera steadier... but everyone's seen a non-power master cylinder