Hi 77nomad, thank you as well. I will gather all the details that you mentioned and give a call to Coan. Will see what they recommend as well and compare.

How much will a 78 camaro weights? It is not easy to calculate. At least I need to know the standard weight of the car.

 

Not sure I'd go as low as 2500 for what sounds like a pretty high HP 572. If the builder thought a 3000 was right, I wouldn't go lower than the 2800, or as I said before, risk having the trans trying to pull you through stop lights.
You're looking at around 3600 lbs for a stock 2nd gen Camaro with a BBC. Weight doesn't have to be exact, and that should be close.

 

Hi BB427, yes I stay with his recommendations. How did you ended up with the calculation 65 mph will be around 2875 rpm, and at 35mhp it will be 1550 rpm when using TH400?

What gear ratios do I need for TH400. Transmission ratios are a black box for me!!

 

You can't change the ratio on a TH400. The output end of a TH400 is 1 to 1 final drive, so it will be the same as engine speed in 3rd gear. OD trans will run slower than engine speed in their OD gears. There are rpm calculators on the web to calculate engine rpm based on known tire diameter, mph, and rear end gears.

 

Wallaceracing.com has about the most comprehensive site when it comes to aotomotive related calculators.

 

So all the TH400 have the same gear ratios on the 1st, 2nd and 3rd gears and could not be changed. So the only gear ratio which can be changed on a camaro is the rear end. is this correct?

What is when they say fully manual valve body? This is in TCI transmissions.

 

Ratios for TH400 are 2.48, 1.48, 1:1 I don't know of any choices other than this, unless it was custom. A manual valve body makes your automatic shift manually only. I like my hotrods with manual valve bodies, but not my drivers. I don't mind up/down shifting my hotrods.
Some manual valve bodies also reverse the shift pattern, and some don't have compression when you let off the gas. The forward or reverse pattern is the user's choice, but I'd want to make sure the trans will have compression on downshifts.

 

So with a manual valve body, the transmission does not shifts automatically any more? You have to select the gears by moving the lever? Never had automatic transmission in my life.

What do you mean by 'some don't have compression when you let off the gas'

What is compression on down shift?

 

That's correct. Whatever gear you put it in is the gear it will stay in, so you have to shift as you would with a manual trans, just no clutch.
Compression is what slows your car down when you down shift. If you have no compression, it's like putting your trans in neutral when you downshift, or whenever you let off the gas pedal. It simply coasts without slowing down from engine compression.

Are you sure you really want to have a car that is so exotic in it's power train that you can't work on it, or don't understand how it functions? Not trying to be rude, so please excuse me for asking. It's just that I've owned cars like what you're looking at building, and they need constant tinkering, and adjustment to keep running in tip top shape, and that requires a good understanding of all the components.

 

Hi, sorry for my silence. Was on a short break with my family for Christmas.

No I do not have a clue on how it works. I know some basics that I Google from the internet for my own interest but I am not a mechanic, never studied these things. So I excuse my self for asking questions that seems to be silly but for me will be useful information. I work as an avionics engineer on aircraft and cars are my hobby and not my work.

If a manual valve body needs continuous adjustments and are mostly used for racing, then I will not even think about it. It is not my intention for drag racing with this car although I need a big engine and a good transmission and rear end. I thank all of the people like you which share their knowledge and past experience with me