1970 bb coupe engine restoration

[Randy C.]

I am working with a restorer on a '70 bb coupe and our goal is to have a finished product that looks and operates as original. We are in the process of putting the engine together and we are a bit stumped with the TCS system. Does anyone have a pic, or pics, they can post for me, of what an original TCS system looks like? We are having trouble reading the assembly manual as to what it is supposed to look like, and all we have now is a lot of bent tubing - it appears that some of the system was removed, and the rest disabled, sometime in the car's past. It's a '70 big block THM w/o A/C. Thank you! Randy C.

[Terry M.]

Re: 1970 bb coupe engine restoration

I am working with a restorer on a '70 bb coupe and our goal is to have a finished product that looks and operates as original. We are in the process of putting the engine together and we are a bit stumped with the TCS system. Does anyone have a pic, or pics, they can post for me, of what an original TCS system looks like? We are having trouble reading the assembly manual as to what it is supposed to look like, and all we have now is a lot of bent tubing - it appears that some of the system was removed, and the rest disabled, sometime in the car's past. It's a '70 big block THM w/o A/C. Thank you! Randy C.

Here you go:

[Mike E.]

Re: 1970 bb coupe engine restoration

Nice pics. I like the orange R on the carb!

[Terry M.]

Re: 1970 bb coupe engine restoration

Nice pics. I like the orange R on the carb!

Even though I know it is not your thing - I confess. I had malice a fore thought in adding that picture as it barely filled Randy's request.

I am pleased you caught it so soon Mike. We have to get together once the Spring thaw comes.

[Alan S.]

Re: 1970 bb coupe engine restoration

Hi Terry,
I'd think Mike can be confessed to, he just wouldn't typically offer absolution.
He may clarify that, but I believe that's what I learned in my Calvinist upbringing.
Regards,
Alan

[Patrick H.]

Re: 1970 bb coupe engine restoration

Hi Terry,
I'd think Mike can be confessed to, he just wouldn't typically offer absolution.
He may clarify that, but I believe that's what I learned in my Calvinistic upbringing.
Regards,
Alan

LOL. I think Mike's the wrong "flavor" to offer absolution.

[Mike E.]

Re: 1970 bb coupe engine restoration

I'm flavorful enough to hear someone confess, and also to offer absolution. Wrong flavor to impose penance. As an aside, I'm doing the funeral of a long-time new car dealer(Don Jacobs) here in Milwaukee tonight. Buick, Toyota, etc. over the years. Never Chevrolet.

[Terry M.]

Re: 1970 bb coupe engine restoration

I am glad to hear you are not 100% retired. As you know, I am counting on you.

[Patrick H.]

Re: 1970 bb coupe engine restoration

I am glad to hear you are not 100% retired. As you know, I am counting on you.

Now THAT should be an interesting one.... ... which is hopefully many, many years away.

[David K.]

Re: 1970 bb coupe engine restoration

Terry,

It's me again but with a different question and hope I am not hijacking the thread. Is there a way to defeat/disable the TCS system and still keep the appearance and looks as the factory installed it? I have an original/unrestored 70 Z-28 Camaro with the TCS untouched and still in place. I suppose a problem might arise in the fact that the rubber hose from the VAC goes to the solenoid mounted on the intake rather than directly to the carb itself. I notice when sitting still at an idle if I shift into 3rd gear the rpms increase noticeably. I can imagine the TCS system was emmisions related as prior year cars were not so equipped. Do I even want to defeat or disable the system? Thanks for your thoughts.

Dave

[Terry M.]

Re: 1970 bb coupe engine restoration

Terry,

It's me again but with a different question and hope I am not hijacking the thread. Is there a way to defeat/disable the TCS system and still keep the appearance and looks as the factory installed it? I have an original/unrestored 70 Z-28 Camaro with the TCS untouched and still in place. I suppose a problem might arise in the fact that the rubber hose from the VAC goes to the solenoid mounted on the intake rather than directly to the carb itself. I notice when sitting still at an idle if I shift into 3rd gear the rpms increase noticeably. I can imagine the TCS system was emmisions related as prior year cars were not so equipped. Do I even want to defeat or disable the system? Thanks for your thoughts.

Dave

[Mike F.]

Re: 1970 bb coupe engine restoration

My 70 L-46 has the TCS in place and fortunately for me the TCS solenoid broke in the open position. So with everything hooked up and looking correct I have manifold vacuum going to the distributor all of the time. You could get a spare TCS solenoid and core it or break it in the open position.

[David K.]

Re: 1970 bb coupe engine restoration

Terry,
Thanks for the reply. No, I do not want to eliminate the vacuum advance at all. Just looking for way to go around the TCS and still have all the hardware mounted on the engine and looking functional when it really isn't. I assume for emmisions purposes the TCS limits advance in the lower gears until reaching 3rd gear and then it allows advance to take place. I think I'll play with it and see if I can figure something out.

Dave

[David K.]

Re: 1970 bb coupe engine restoration

My 70 L-46 has the TCS in place and fortunately for me the TCS solenoid broke in the open position. So with everything hooked up and looking correct I have manifold vacuum going to the distributor all of the time. You could get a spare TCS solenoid and core it or break it in the open position.

Mike,

Great suggestion! Why didn't I think of that? I think I'll remove my original solenoid and pack it away and then get a repro and break it to the open position and then throw it out in the yard for a week or so to get used and weathered looking and then put it on my survivor Z-28. LOL.
Thanks for the help Mike.

Dave

[Terry M.]

Re: 1970 bb coupe engine restoration

Terry,
Thanks for the reply. No, I do not want to eliminate the vacuum advance at all. Just looking for way to go around the TCS and still have all the hardware mounted on the engine and looking functional when it really isn't. I assume for emmisions purposes the TCS limits advance in the lower gears until reaching 3rd gear and then it allows advance to take place. I think I'll play with it and see if I can figure something out.

Dave

Your thumb nail description of the operation of the CS is correct, except I believe it uses ported vacuum rather than manifold (or full time) vacuum. One can keep the solenoid open all the time by grounding either the wire going to the transmission or the temperature sensor wires -- the green wire on the passenger side head. owever one can gain more performance by routing the distributor vacuum to full time.

How much use are you going to give your Corvette? IMO if you will drive it only the typical 1000 or so miles a year it is not worth the trouble to disable the TCS system.