MSD Atomic EFI on '79 K30 in Cali

[Apache'71]

Never mind regarding the EGR valve. Got that mixed up with something else.

My truck doesn't have an EGR valve (probably cause it's a K30)!

One less thing to worry about...

[donw1986]

Yes used edelbrock adapter on intake and yes have an egr and yours should be basicly same it will fit with the adapter, at least it did on mine if that is what your were asking

[Apache'71]

Thought I'd add an update for anybody following or who may be thinking of doing this to a rig requiring CARB compliance.

I got everything installed about two weeks ago and it fired up on the first try! It ran great (despite me plumbing the fuel pressure regulator backwards)! I re-plumbed the regulator, revisited all the MSD settings and can't believe how well it's running. It fires up nearly instantly, it idles pretty well (better than before but I think I could further improve it if I was controlling timing), and the throttle response is almost like a new, ok maybe newer, rig. I could never break the rear tires loose before but now I have to be careful to keep from doing it. There must be at least a 20hp increase on the bottom and mid end.

I have a more noticeable knocking sound (valves?) at low rpms in 2nd gear under load and a slight backfire when coasting in gear when cold and warm, but these issues were present before the Atomic install. The engine probably has some bad valve guides (blue smoke on startup) and could probably use a valve adjustment I suppose. Maybe the vacuum advance on the distributor is defective too. All things to run down in time...

The factory air injection system is still installed on the rig and to the best of my knowledge is functional, but it doesn't seem to be throwing off the O2 sensor as MSD told me it would. Probably the only thing that could pose a problem for emission re-inspection is the fact that the old carb had a TRC actuator mounted to it and there is no provision or way to remount it to the MSD to my knowledge. I just left the vacuum valve that's mounted on the manifold there and capped off the vacuum line since there is no actuator anyways. I guess I'll cross that bridge in two years when it's up for re-inspection...

The only things left to do is to remove, cap off or just ignore the old hard fuel line along the frame rail, remove the mechanical fuel pump and blank off and figure out why my fuel gauge isn't working now after installing the new sending unit.

Hopefully this will give some other folks on the fence a little more piece of mind where CARB compliance needs to be maintained.

Let me know if anyone wants more details on parts used, install, MSD settings, etc.

[donw1986]

Glad it works good for you, just wondering what is a TRC, my carb had a throttle position sensor and mixture control solenoid

[Apache'71]

Originally Posted by donw1986

Glad it works good for you, just wondering what is a TRC, my carb had a throttle position sensor and mixture control solenoid

It's the Throttle Return Control Valve/Actuator. The valve is a vacuum canister on the manifold that operates a the actuator that's mounted on the factory carb.

Here's what I found it does:

Two different throttle return control systems are used. The first is used from 1975 to 1978. It consists of a control valve and a throttle lever actuator. When the truck is coasting against the engine, the control valve is open to allow vacuum to operate the throttle lever actuator. The throttle lever actuator then pushes the throttle lever slightly open reducing the HC (hydrocarbon) emission level during coasting. When manifold vacuum drops below a predetermined level, the control valve closes, the throttle lever retracts, and the throttle lever closes to the idle position.

The second TRC system is used in 1979. It consists of a throttle lever actuator, a solenoid vacuum control valve, and an electronic speed sensor. The throttle lever actuator, mounted on the carburetor, opens the primary throttle plates a preset amount, above normal engine idle speed in response to a signal from the solenoid vacuum control valve. The valve, mounted at the left rear of the engine above the intake manifold on the 6-cylinder, or on the thermostat housing mounting stud on the V8, is held open in response to a signal from the electronic speed sensor. When open, the valve allows a vacuum signal to be sent to the throttle lever actuator. The speed sensor monitors engine speed at the distributor. It supplies an electrical signal to the solenoid valve, as long as a preset engine speed is exceeded. The object of this system is the same as that of the earlier system.

Even though CARB compliance probably requires that I maintain this, it's probably redundant with all the things the Atomic is doing electronically.

[donw1986]

I think you will be ok with carb, by the way i did just take mine to the local smog guy near me, i did not go to the smog ref

[ZacharyDouglas1992]

I can't believe I haven't stumbled across this post sooner. I have an '83 GMC K3500 that is just a smog nightmare. The original Rottenchester was ruined in the body shop as it it was just totally contaminated with bondo dust. I ordered a replacement carb and I cannot seem to get the truck to do everything right at stock timing. I can get it to idle like a dream, or perform under throttle, but definitely not both. I can get it to run fantastic with enough timing (16 deg) but I have to be at 4 deg BTDC for smog purposes. I have toyed with the MSD atomic idea since it was more than twice the price it is now. The only thing that has been scaring me lately is the addendum that speaks to the AIR system. (mine has 1 ton CA emissions for 83, so the AIR tubes go straight into the manifolds, and the truck has true dual exhaust with no catalytic converter.) Your post gives me a little more hope that I can make this work.

I would like to keep the dual tank functionality too, as I would imagine even with the FI my mileage will be 11-12 on the 454. Maybe that can be accomplished with an external pump after the valve, but I am not sure what that would mean as far as running a return line.

Any of your feedback is appreciated. I am nearly frustrated enough, and encouraged enough by the posts here, to try it.

[buffydores]

God bless anyone who has to deal with CARB. I'm so thankful I don't live in California. Wonderful place to visit though.

[donw1986]

You can maintain the dual tanks, i did , there are 2 types of tank switching valves the earlier years it wont work not sure exactly what year they changed them but the valve in my 86 is rated for 65 psi, works fine, you will need to change the switch on dash to an 87, the 87s came with factory throttle body so the switch appears the same but keeps power running through it to power the fuel pump i installed a pump in each tank, when you flip the tank switch it reroutes the power to the punp on the tank you select