Calling Spica Gurus

genericwood · #1 (**permalink**) 12-21-2003, 09:18 PM

Just reassembled my GTV this weekend with a new 164hp Ingram pump, 40mm throttle bodies, big intake valves, 12mm intake cam and 11 mm exhaust cam. Now I have a poor running condition I can't quite narrow down. Here is what it does. After being warmed up properly, the engine has a hesitation when you feed in moret throttle. If you keep your adding throttle it will clean up, but continues to have a random miss as you accelerate through higher rpms.

My first guess was that it was running lean, but the mixture was set using Ingram's method of running the engine at 2500rpm and finding the middle point between poor running on the rich and the lean sides. It took about a turn and a half to find either side of the mixture setting. Does this sound right? The car has a new Bosch pump and the fuel pressure light works properly. It also has an MSD that seems to be working properly.

I'd appreciate any recommendations regarding things I may not have thought of yet. Tomorrow morning I may try enrichening the mixture and see if that helps.

Erik

**Roadtrip** · #2 (**permalink**) 12-21-2003, 09:58 PM

1. Use your induction timing light to check spark consistency at all rpms.
2. Check the throttle butterfies to SPICA pump throttle arm (long & short rods) for correct relationship.
3. Are you sure the cam timing is right?
4. Try disconnecting the wire to the fuel cutoff solenoid. Tape it so it won't short out against anything.
5. Did you set the pump gap with a dummy actuator to the correct throttle arm-to-reference screw gap? That is the only way to easily and correctly set the pump gap. If you need a dummy actuator, I can send you one. I would assume that Wes would have sent it already adjusted.

genericwood · #3 (**permalink**) 12-21-2003, 10:57 PM

Thanks RoadTrip. I did check spark consistency. It looks good. I adjusted the short rod on the bench before installing the head. After settiing the .019" gap, I adjusted the length of the long rod. The cam timing is spot on. I haven't tried to disconnect the fuel-cutoff solenoid, but will tomorrow. I suspect that Wes did have the mixture close when he sent it. But he didn't supply a TA, so he couldn't have set the reference gap.

Guess I will just have to go back through everything one at a time.

genericwood · #4 (**permalink**) 12-26-2003, 06:33 PM

John S. and other Spica gurus, please chime in. I still haven't figured out the problem with my new Spica pump. And since Wes won't be in his shop this weekend, I thought I'd give the BB a try.

I have now rechecked cam timing and valve lash, unhooked the MSD, and replaced the plugs, coil, points, condensor, cap and rotor. I am now 100% sure the poor running condition I am having is mixture. The pump arm gap is .020" with engine at 175 degrees. The long arm is adjusted to not change the gap when attached. The butterflies and short arm are adjusted properly. The pump timing has been triple-checked.

When setting the mixture with the fuel cut-off solenoid at 2500, I can screw in the solenoid and find reduced rpm's due to a lean condition. But unscrewing the solenoid past this point, the revs never change. I can attempt to richen the mixture by several turns and never get a drop in revs. Furthermore, with the mixture set about 3/4 turn out from the point that I get a lean drop in revs, I do not get any change in revs when I activate the cold-start solenoid. It clicks, but revs don't change. I believe you should be just about able to kill the motor due to a rich condition when you do this.

At Wes' recommendation, I removed the altitude compensator and observed the fuel rack moving with the throttle. But apparently something is keeping it from moving far enough rich.

Any ideas?

Erik

**Roadtrip** · #5 (**permalink**) 12-26-2003, 10:03 PM

Quote:

I believe you should be just about able to kill the motor due to a rich condition when you do this.

genericwood · #6 (**permalink**) 12-26-2003, 10:41 PM

Thanks John. I really haven't considered a fuel pressure problem, until now. Each time I've talked to Wes he has dismissed that as the source of the problem due to the functioning light. But it is something that I will check tomorrow. I have run the engine in the dark to look for sparks. But, unfortunately, the problem I have only seems to show up under load. All the wires look good in the garage.

Tomorrow, I will see how much fuel pressure I can measure. But I still can't imagine that would keep me from being able to find a "too rich" point when setting the mixture????

Thanks for your ideas. You've given me a couple more things to check!

Erik

**Roadtrip** · #7 (**permalink**) 12-26-2003, 11:08 PM

The only things I can think of that would cause a too lean condition would be a broken compensator retaining spring or a baro compensator that was out of spec. Both of these things would allow or force the compensator link to a lower setting on the vertical toothed link, thus a shorter radius throw and leaner condition. I don't suppose you opened the rear inspection plate to see what tooth the spring clip was set on before you installed the pump. There really wouldn't be any reason to.

You can get the pump to reset itself automatically if you rev the engine up to about 4000 rpm, then let of the throttle off completely. Do this a couple of times. What this does is forces the cam follower to the "reset" postion on the 3D cam and temporarily disengages the vertical link from the compensator link. When that happens, the compensator link retaining spring is free to pull the compensator link up to the bottom pin on the baro compensator.

genericwood · #8 (**permalink**) 12-26-2003, 11:16 PM

Thanks again John. I didn't check to see the which tooth the spring clip was in. But I am confident it is in place. The rod on which the barometric pressure compensator acts has resistance to movement. I assume due to the spring clip being on a tooth. I haven't measured the barometric capsule itself, but it looked similar to the ones in a couple of spare pumps I have. I'm sure Wes checks them during a rebuild.

I will reset the position of the clip as you described when I get to work on it tomorrow. I will be crossing my fingers that it is a fuel delivery problem that just isn't bad enough to actuate the light!

Erik

**Roadtrip** · #9 (**permalink**) 12-26-2003, 11:24 PM

If the spring clip breaks, it releases the compesator link completely which allows the rack full forward and shuts off fuel delivery altogether. I'm sure your baro compensator is ok. It should be about 27mm from the bottom of the flange.

Alfapaulic · #10 (**permalink**) 12-27-2003, 05:08 AM

Make sure the ignition coil mounting bracket is secure, the original equipment sheet metal screws get barely loose and can cause a similar condition!!