Still working on my neighbor's 97 Challenger (sgl 787).
Having issues...as in after all my work, it is still doing the exact same thing it did before.
Questions at end, background first.
Original symptoms: slow acceleration to top speed, but was able to plane up to about 40mph eventually, with two ~150# adults.
Finished rebuilding the carbs, replacing the oil lines, adjusting the cables, etc. The only things that looked bad in the carbs were parts in the fuel pump on the MAG carb, which were replaced with the full rebuilds. Three little holes (2 tiny, one small) all flow good in both carbs. Oiling pump synchronized to factory spec.
The carb adjustments were set to 1 turn out for the low speed adjustment and 0 for the high speed adjustment. I set the idle to 1500, then we put it in the river for better tuning.
Our first run was not right. It would stall if we gave it gas slowly, so we had to push the throttle past half, then it would go pretty well. It took a long time to come up into a plane, but we did hit 38 mph GPS upstream and 42 downstream.
We stopped and I turned the low speed adjuster out to 1-1/4 on both carbs, tested, then 1-3/8, test, adjust, test, finally settling on 1-5/8 turns out.
Does 1-5/8 turns out seem excessive? It practically JUMPS out of the water now, then falls on it's face and won't plane.
This is where we noticed the exhaust hose between the cone and water box had split wide open, eliminating any chance of tuning further.
I have to get the cone and the water box to align properly with shims under the cone mounts, then replace the hose that connects then.
I'm going to take the water valve (RAVE looking thing) on the exhaust off and inspect it. I had set it to factory specs. Also cleaned the RAVE valve knives on a wire wheel. They polished up really nice. RAVE valves were also reset to X clicks from level, per factory setting.
Now, what I didn't do. I couldn't check the pop off pressure or do any of the leak tests because I don't have the tooling for that. It's going to be about a week for parts, so I plan to assemble a gauge on a tee with a Schrader valve to accomplish those tests.
Can a bad water valve cause the original symptoms?
I totally blame the lack of top end late in the day on the exhaust leak.
What else should I be looking at?
I'm suspecting that the popoff may wrong, making low speed tuning difficult and the water valve is bad, making high speed tuning difficult, but it DID get up to speed at the start of our lake test, then would not later.
Enriching the low speed adjuster made I scream out of the hole, but 1-5/8 out send like a lot, 5 steps from the factory setting!?! What settings are you guys running? Michigan is about 500 above sea level, so it shouldn't take that much.
Anyway, been editing this for a while, trying to organize my thoughts into questions. It's in the 80's here in Michigan and he can't go into the river, unless he uses his larger inboard/outboard (jet boats are better for changing river waters due to the shallow draft).
Best advice I've found so far: when the engine bogs from a bad carb adjustment, pull up the choke a little. If it gets better, it was too lean. Turn the adjuster out 1/8 turn more. If it stalls, it was too rich. Turn them in 1/8 turn.
Best advice I can give?
Paint your carb adjusters, so they are easier to find. I used paint markers. Idle is yellow, low is orange, high is red.
Having issues...as in after all my work, it is still doing the exact same thing it did before.
Questions at end, background first.
Original symptoms: slow acceleration to top speed, but was able to plane up to about 40mph eventually, with two ~150# adults.
Finished rebuilding the carbs, replacing the oil lines, adjusting the cables, etc. The only things that looked bad in the carbs were parts in the fuel pump on the MAG carb, which were replaced with the full rebuilds. Three little holes (2 tiny, one small) all flow good in both carbs. Oiling pump synchronized to factory spec.
The carb adjustments were set to 1 turn out for the low speed adjustment and 0 for the high speed adjustment. I set the idle to 1500, then we put it in the river for better tuning.
Our first run was not right. It would stall if we gave it gas slowly, so we had to push the throttle past half, then it would go pretty well. It took a long time to come up into a plane, but we did hit 38 mph GPS upstream and 42 downstream.
We stopped and I turned the low speed adjuster out to 1-1/4 on both carbs, tested, then 1-3/8, test, adjust, test, finally settling on 1-5/8 turns out.
Does 1-5/8 turns out seem excessive? It practically JUMPS out of the water now, then falls on it's face and won't plane.
This is where we noticed the exhaust hose between the cone and water box had split wide open, eliminating any chance of tuning further.
I have to get the cone and the water box to align properly with shims under the cone mounts, then replace the hose that connects then.
I'm going to take the water valve (RAVE looking thing) on the exhaust off and inspect it. I had set it to factory specs. Also cleaned the RAVE valve knives on a wire wheel. They polished up really nice. RAVE valves were also reset to X clicks from level, per factory setting.
Now, what I didn't do. I couldn't check the pop off pressure or do any of the leak tests because I don't have the tooling for that. It's going to be about a week for parts, so I plan to assemble a gauge on a tee with a Schrader valve to accomplish those tests.
Can a bad water valve cause the original symptoms?
I totally blame the lack of top end late in the day on the exhaust leak.
What else should I be looking at?
I'm suspecting that the popoff may wrong, making low speed tuning difficult and the water valve is bad, making high speed tuning difficult, but it DID get up to speed at the start of our lake test, then would not later.
Enriching the low speed adjuster made I scream out of the hole, but 1-5/8 out send like a lot, 5 steps from the factory setting!?! What settings are you guys running? Michigan is about 500 above sea level, so it shouldn't take that much.
Anyway, been editing this for a while, trying to organize my thoughts into questions. It's in the 80's here in Michigan and he can't go into the river, unless he uses his larger inboard/outboard (jet boats are better for changing river waters due to the shallow draft).
Best advice I've found so far: when the engine bogs from a bad carb adjustment, pull up the choke a little. If it gets better, it was too lean. Turn the adjuster out 1/8 turn more. If it stalls, it was too rich. Turn them in 1/8 turn.
Best advice I can give?
Paint your carb adjusters, so they are easier to find. I used paint markers. Idle is yellow, low is orange, high is red.
