351w Timing, Igntion & Overheat - Q&A

So I've searched high and low and yet still have some questions about timing my 351w.

All other stories aside I had initially set the timing at 6 deg @ 600 RPM on the trailer. My mechanic said it would probably have to be adjusted once in the water and under load. I took the boat to the lake this past weekend; it started fine, but would cough / backfire under load and wouldn't get above 1500 rpm. I had my timing light with me, but couldn't get a good reading in the midday sun so I ended up timing it by ear. This got it running good enough to make a bunch of ski runs & drive around for the day. Since then I discovered I had plugs 2 & 3 were flip-flopped, I fixed that and now the boat fires right up an runs great. No pinging, no backfiring / coughing, just runs great.

Questions:

1.) If I had it timed to 6 deg @ 600, why was it a dog on the water? Do you have to time it in gear like you set the idle?

2.) Other than the Skidim Plug Wires are there any other suggested / off the shelf plug wires for my Malloy equipped 351w?

3.) Once everything is up and running I could stand to replace the points, or go with the electric ignition conversion. Any recommendations on this?

What should I be looking for at 3000 rpm?

6 deg is pretty conservative, and can cause it to run like a pig at low RPMs. I run 10 in mine and it still runs good on 87, it could probably go 12-14 with premium but I'm cheap. As gun-driver said, check the advance, I believe it should be 34-36 total by 3000. You'll need a timing light with an advance dial or some timing tape on the balancer.

The 600 RPM figure would be in gear, you shouldn't have the idle set that low in neutral. Idle is typically set for 600-650 in gear. 600 in neutral would be 450-550 in gear, way too low. It'll chug and you can run into oil pressure issues if it gets any lower..

You'll probably have to mess with the mixture screws a bit while you get all this adjusted. If you don't already have one, a vacuum gauge makes all of this much easier because you can dial it in for the highest vacuum reading after you get the timing and idle RPM set.

Your mechanic gave you some bad information. “My mechanic said it would probably have to be adjusted once in the water and under”

The advance works on centrifugal force. Under load or in the water is not important. You can set the initial timing on the trailer if you want. Typically they won’t start advancing until you get to 1000RPM (enough centrifugal force to overcome the springs). Just make sure to set the initial timing (10 to 12 BTDC) at an RPM low enough (600 RPM would be great) so the distributor is not advancing.

Andy,
Find a new mechanic. I concur with the others he doesn't know what he's talking about. Sounds like a back yard hack that doesn't know the difference between vacuum and mechanical advance. I would not let him touch my boats.

Boy Pete that seems a little harsh for someone you've never met. It may be hard to believe, but we all didn't come out of the womb with total inboard knowledge like yourself. At no time did I say he was a paid professional, just someone who knows more about V-8's then I do. That being said we're both learning here so I'd appreciate it if we'd keep the focus on the problem.

As for my timing: I fired it up in the driveway and it seems my "by ear" tune landed at 12-13 deg @ 600 rpm. I dialed it back to 10-11 (hard to see in the sun still) and plan on rechecking & resetting in the lake tomorrow AM.

As for the electronic ignition I saw them wile perusing Skidim and figured I'd ask.

LeftFieldEngineering wrote: Boy Pete that seems a little harsh for someone you've never met. It may be hard to believe, but we all didn't come out of the womb with total inboard knowledge like yourself. At no time did I say he was a paid professional, just someone who knows more about V-8's then I do. .

Andy,
Sorry that You feel I was harsh but you said he was your "mechanic" and didn't add any other description. A better description other than just mechanic would have been helpful to myself as well as others.

Hose connections aren't your problem anymore. You have a blockage or a marginal impeller. Check the condition of the impeller or blockage in the cooler. If that's OK you could have had an impeller frag on you and now pieces are lodged downstream from the RWP. Usually the thermostat housing.

I pulled the RWP last night, impeller looks like the day I put it in there. The strainer also looks good. I plan on pulling the cooler hose later, but I'm not holding my breath. It's a new motor, new hoses and the assembly has only seen 1 impeller which is perfectly intact. Like all my other problems I'm sure it's going to be a hard find.

I know you said you took the pump off and the impellor looked fine. Did you look on the suction side where the water enters the housing.

I had the same symptoms you had, found a bunch of small fragments of the previous impellor lodged there.

Still your finger up there and see if its partially plugged with debris. Or if it still off give it a visual inspection.            

you say it gets hot as your get into the higher rpms, I have to ask, what oil are you running? and are you running an oil cooler?

also i read someone mention accel for ignition parts. In my opinion, they make a decent internally resisted coil, i have not used their distributors but do not use accel wires. they are rubbish. I have watched brand new sets leak while on the dyno. We would always send customers home with them still in the box and suggest they get some msd or OEM.
-Tony

Overheat at speed is a pump or impeller problem (if not a blockage). Order the proper Sherwood and I bet the problem goes away.

this is the first i've read of the sherwood pumps being bad. but yes, i would start there if that is the case.

I'd say 25% footin, 35% wakeboard / ski, 40% idle (evening cruising).

Since I'm still running the old carb there's a possibility its leaning out at some point. The reman carb will be here and installed tomorrow.

Another thing I should add. This past weekend we made 2 barefoot runs, the first was 1.8 miles and the boat didn't heat up that much (relatively) apx 180 deg on the dash. Knowing I wanted to measure temps I pulled out the IR thermometer and checked the intake next to the sensor pickup and it was 175 deg and the T-stat outlet (going to the U bend) and it was 119 deg (coldest I've ever measured it at the t-stat outlet). It had cooled down to 145-150 by the time we idled over to the kick-skis.

The 2nd run was almost 2x as long at 3.5 miles and that one heated up to apx 230 on the dash, and 180-200 on the intake. It also returned to 145-150 within a min.

While searching I came across this thread Engine Temp Fluctuation post 8 by TX Foilhead said the PCM thermostat opens all at once and the NAPA variant opens slowly. I did install the NAPA thermostat a week or so ago. It says it's "Replaces OEM Name & # : Crusader 97631, Pleasurecraft RP026002E" Which is the Pleasurecraft part number listed at NautiqueParts.com. Could this have anything to do with the problem?