70 Chevelle with new Aces TBI sytem problems

[Bart_3500]

During a restoration of my parents (now mine) Malibu sport coupe I decided to go with an after market EFI system. I further complicated things by going with Vortec heads (aka VH) and an Air Gap intake manifold. The VH have a completely different bolt pattern which is most of the problem. The throttle linkage brackets don't fit or land where the old intake (oem 2 barrel) had them. I've purchased two different aftermarket bracket assemblies and with bending and modifying have it mostly lined up with the TB and the throttle cable should work. Now the kick down for the TH350 trans is too short and pretty tight in it's run from the trans. I mock-uped the oem intake and carb and found the distance between the bracket and the old carb is 7 7/16". I know there's some adjustment in the end of the cable but not sure if it's enough. I'm wondering if a larger vehicle (Impala or Pickup) would have a longer cable (recommendations needed here) and where in the loop at the of the cable be at while at rest?

[dave w]

I wonder if Lokar has a cable that will work for Malibu Sport Coupe: https://www.lokar.com/throt-cable-kickdowns.html

[Bart_3500]

I wonder if Lokar has a cable that will work for Malibu Sport Coupe: https://www.lokar.com/throt-cable-kickdowns.html

Good thought! I'll keep that in mind. Thanks

[1project2many]

During a restoration of my parents (now mine) Malibu sport coupe I decided to go with an after market EFI system. I further complicated things by going with Vortec heads (aka VH) and an Air Gap intake manifold. The VH have a completely different bolt pattern which is most of the problem. The throttle linkage brackets don't fit or land where the old intake (oem 2 barrel) had them. I've purchased two different aftermarket bracket assemblies and with bending and modifying have it mostly lined up with the TB and the throttle cable should work. Now the kick down for the TH350 trans is too short and pretty tight in it's run from the trans. I mock-uped the oem intake and carb and found the distance between the bracket and the old carb is 7 7/16". I know there's some adjustment in the end of the cable but not sure if it's enough. I'm wondering if a larger vehicle (Impala or Pickup) would have a longer cable (recommendations needed here) and where in the loop at the of the cable be at while at rest?

There used to be throttle cable (and detent cable) brackets that bolted to the base of the carburetor. The detent cable portion was adjustable by loosening two machine screws and sliding the bracket pieces. They were sometimes problematic for loosening up with but if you set it up correctly then welded it together it worked well. Here is one example:


I'm guessing the combination of Vortec heads and air gap intake puts the TB base farther away from the crankshaft centerline creating a need for a longer cable. ATP is a large supplier of aftermarket cables and years ago I was able to use dimensions listed in the back of their parts catalog to find a throttle cable for a custom smallblock EFI installation. It looks like they have detent cable dimensions and pictures online. https://atpautomotive.com/cables?subcategory=705 ATP Y-101 is 44" long and is listed as fitting mid '70 Pontiac and Buick cars.

If you're searching wrecking yards or used part sources, you may have a little more work ahead of you. It looks like Chevrolet went through a few different "eras" of detent cable as demonstated by this picture of THM350 smallblock detent cable brackets: https://67-72chevytrucks.com/vboard/...6&postcount=25

For vehicles with longer cables I would use engine options as a key. Anything with a straight six is a good start. A 1979 C1500 with 250 six and THM 350 may have a longer cable. I believe the distance from carb to back of block is longer and the engine is slightly taller than SBC. Olds / Buick engines may also have longer cables. A '75 Delta 88 w/ 350 or a '75 455 Electra w/ 350 might work. In the late '70s GM was pairing an Olds 307 with a THM350 so you might find a longer cable in a '79 Electra. Full size vans typically had longer cables but we're often talking feet, not inches.


Good luck! I'm genuinely curious as to what you end up doing. Please keep us updated.