'78 big block cruise in my '80 small block?

[Boostaddict]

I'm thinking of adding cruise to my '80 400/th350c truck. Looking for a donor truck for parts and found a '78 454/400 truck. Other than needing to find a servo bracket for a small block or modding it to work (and probably a 1484 cruise control kit since I have an edelbrock) is there any reason this wouldn't work? Any differences in speedo cable, wiring, etc? I read that newer cruise setups have wiring to disable the torque converter lockup, and this setup would be missing that I assume… but I'd guess that shouldn't be a problem since the th350c TC should unlock automatically? Thanks!

Wayne

[gchemist]

I ditched the stock system in my truck. I even have a brand new servo sitting my garage that I didn't use. I had hard time trouble shooting it. I installed a unit from www.rostra.com. Units from Rostra are popular with hot rodders. At the time, they only had vacuum units. Now they have electronic versions. They are easy to install. They are worth every dime.

[Firebirdjones]

I still have the OEM setup on my 79 454 and it works perfectly.

The only real difference between the big block and small block setup is the bracket that mounts behind the driver side cylinder head and holds that huge vacuum pod.

Obviously the small block and big block use different brackets here,,,but the rest of the system is a direct swap. There will be a 2 piece speedo cable that splits at the control box on the driver side inner fender. I did have to rebuild my control box many years ago,,,a service that GM offered at that time. It's just a simple magnet setup inside there.
The switch is a simple single button on the turn signal lever, pressing halfway sets it,,,push in all the way for coast and resume.

My 79 (being a 454/400 turbo) doesn't have the lockup converter so I can't answer that question,,,,but they were very primitive back then with a simple vacuum switch mounted on the firewall by the brake booster.

If you need pics I could probably shoot a couple.

[Boostaddict]

Thanks. I'd prefer to run a stock cruise setup rather than a more modern setup, even if troubleshooting could be more of a PITA. There is just something about "trying" to keep the truck running OEM parts that I strive for (I had no choice with the carb on my truck).

[Firebirdjones]

Originally Posted by Boostaddict

Thanks. I'd prefer to run a stock cruise setup rather than a more modern setup, even if troubleshooting could be more of a PITA. There is just something about "trying" to keep the truck running OEM parts that I strive for (I had no choice with the carb on my truck).

You sound like me

It's really easy to trouble shoot. A few vacuum lines and a couple wires, that's really all there is to it. Out of all of the factory setups I've had, the only thing I've ever had a problem with is the unit mounted on the inner fender.

They wear out over time (I'm talking many years of use) and generally what you get is a unit that hunts for speed all the time.

Very easy to rebuild, all the parts are still available. It basically mimics the design GM has used since the 50's and 60's. If I'm not mistaken,,,,GM probably still offers the rebuilt unit's in exchange for your old one. I did this a few years ago. Probably many aftermarket companies out there rebuilding them too if you search around.