Nola Mike's 3.7/470 --> 4.3L swap thread

[Scott Danforth]

All you can do is fix things as you find them. Nothing like a rebuild to find every little problem.

Its called ship-fitters disease.....Next thing nola mike will look at the gel and think..... I need to restore that...

and 4.5 years later...... oh wait..... that was me....

 

[nola mike]

Alright! Splashed! About 5-10 miles of driving.
,
Alternator still funny. Initially wasn't charging, then started overcharging, then settled in. Stayed where it was supposed to rest of the time.

Temp was rock solid at 140-150 on my gauge the whole time, except when I did my plug chop and saw the gauge over 160. Didn't do it again though, so I'll keep an eye on it.

The shift issue (I think) was that the slide came out of engagement with the shift lever ball when I was installing it. Timed myself on this one today-- 25 minutes to remove drive, ID and fix issue, and replace drive

Big scare when I first shut down, and heard water pouring into the bilge right as I cut the engine, and then stopped. Thought about that y pipe, but then noticed I hadn't tightened the clamps on that exhaust boot. Seemed like a big leak, but didn't recur. Another thing to keep an eye on.

OK, the biggest issue is it's running lean. Runs great below 2500 RPM, but starts surging after that and eventually starts backfiring if I push it. No pinging at least. Doesn't matter if I ramp up slow or fast. Interestingly, it gets on plane without stumbling badly. Doesn't do it smoothly, but doesn't backfire either. Again, I can hammer it or go slowly, and it planes ok.
Problem is i have NO idea where the issue is. It can literally be anywhere in the fuel system. I'm going to start a new thread with this issue, since it's now a general issue and not really specific to the swap. I'll throw my plug pic onto both threads though. This is #5 plug. No surprise. These things are damn near impossible to get at, and I have the burns now on my hands to prove it.

scott danforth: Yeah, I've been eyeing my gel coat. The cleanliness of my boat is directly proportional to how it's running.

EDIT: Do I get to update my sig now?

 

[Scott Danforth]

look at float setting and fuel pressure for your lean

I know the flow rate of the carter pump will flow at a rate of well over 30GPH in-situ :facepalm: and 72 GPH without re-striction (per spec). so my guess is your float level is set low or your carb has an inlet filter in the fitting that may be plugged.

 

[nola mike]

look at float setting and fuel pressure for your lean

I know the flow rate of the carter pump will flow at a rate of well over 30GPH in-situ :facepalm: and 72 GPH without re-striction (per spec). so my guess is your float level is set low or your carb has an inlet filter in the fitting that may be plugged.

No, I quintiple checked the float when I was running rich. I'm 100% sure it's correct. There is no inline filter. My original carter was putting out 8 psi (and flooding the carb). This one was 2.5-3. It's supposed to be 6 psi. But I don't know the relation between pressure and volume in the case of the pump.

 

[Scott Danforth]

your pump should be putting out 6psi. what is the voltage feeding it?

 

[nola mike]

your pump should be putting out 6psi. what is the voltage feeding it?

Trick question? Batt voltage. Good positive, off the slave iirc. Yeah, I know the specs. Like I said though, I don't know if low psi equates to low volume. I may just keep ordering pumps until I get one that's right. I shouldn't have to guess.

 

[Scott Danforth]

New pumps have a warranty

 

[nola mike]

Jeez, another new pump, again only putting out 2 psi. I'm very unimpressed with this Carter pump. In addition, the wires are fastened to the pump with these cheesy friction fittings...

So had 8 out on the boat today, a solid 50 mile cruise. Ran great, only mishap was when said wire popped off of fuel pump and engine died. There were some very concerned passengers until I was able to figure out what happened...

I still haven't opened it up (want to get my carb set up correctly in the lower end first) so I don't know what my wot rpms are. But I noticed that I'm doing 32mph @ 2600 rpm, and 40 mph 3K. Same 1.84 ratio and 23p prop as on my 470, but that would hit 32 mph at about 3300 rpm and 40 mph@ 4k. Shouldn't this 4.3 be over revving?

 

[Scott Danforth]

did you adjust the tach from 4 cylinder to 6 cylinder?

 

[nola mike]

did you adjust the tach from 4 cylinder to 6 cylinder?

Yeah, tach is in synch with my dwell meter until 2500k (max of the dwell meter) within 50-100 rpm.

 

[Rick Stephens]

Jeez, another new pump, again only putting out 2 psi. I'm very unimpressed with this Carter pump. In addition, the wires are fastened to the pump with these cheesy friction fittings...

So had 8 out on the boat today, a solid 50 mile cruise. Ran great, only mishap was when said wire popped off of fuel pump and engine died. There were some very concerned passengers until I was able to figure out what happened...

I still haven't opened it up (want to get my carb set up correctly in the lower end first) so I don't know what my wot rpms are. But I noticed that I'm doing 32mph @ 2600 rpm, and 40 mph 3K. Same 1.84 ratio and 23p prop as on my 470, but that would hit 32 mph at about 3300 rpm and 40 mph@ 4k. Shouldn't this 4.3 be over revving?

Same outdrive, same prop, same hull and you are spinning the prop same RPM but getting 10 MPH more. Not possible.

 

[nola mike]

Rick Stephens ,@scott danforth, you're both right. That doesn't make a damn bit of sense. Even if my tach was on 4cyl mode, that would be 3750 rpm 32 mph, which is too high but closer in a loaded boat. I'm going to have to investigate more...

 

[Scott Danforth]

is your speed vs the GPS or the pitot tube speedo?

 

[nola mike]

is your speed vs the GPS or the pitot tube speedo?

Gps. Pitot had rot around the screw holes. Filled and was going to remount, but decided I'm going to replace the speedo with a gps unit instead and limit the holes...

 

[Scott Danforth]

was the old speed off the old speedo ? if so, it could have been reading off.

 

[nola mike]

was the old speed off the old speedo ? if so, it could have been reading off.

Gps and old speedo agreed to within 1 mph at those speeds...

 

[nola mike]

A little more testing today. The digital tach i ordered didn't work, so used the dwell meter again. Up until about 1800k they were identical, and then the boat tach started lagging. It was reading 2-300 rpm lower than the dwell meter by 2500 rpm (limit of the dwell meter). By the boat tach I was at 30 mph 2500 rpm, but 40 mph at 3100, and 45 mph @wot, which showed 35-3600 rpm. I'm thinking I'm probably getting more of an error the faster I go. Strange because it seemed accurate when measuring 4 cyl (last year 46 mph @ 4500 rpm)

 

[Rick Stephens]

That's pretty close to the neighborhood of what I get on a similar size boat - 1 MPH per hundred RPMs. Of course not quite that consistent throughout the RPM range, but close. I've taken my good electronic advance timing light out on the water to verify tachometer readings from the dash mount tach. The timing light readings seem correct anyway.

 

[nola mike]

A little more testing today. The digital tach i ordered didn't work, so used the dwell meter again. Up until about 1800k they were identical, and then the boat tach started lagging. It was reading 2-300 rpm lower than the dwell meter by 2500 rpm (limit of the dwell meter). By the boat tach I was at 30 mph 2500 rpm, but 40 mph at 3100, and 45 mph @wot, which showed 35-3600 rpm. I'm thinking I'm probably getting more of an error the faster I go. Strange because it seemed accurate when measuring 4 cyl (last year 46 mph @ 4500 rpm)

Got my induction cheapo tach to work (I also got a slick bluetooth dvm that can measure hz, so I'm going to see if I can get some reliable readings from that). my boat tach does indeed seem to get worse with increasing rpms. Now speeds are looking just like they were with the old motor, 1 mph/100 rpm. WOT got me 47mph @4500 rpm. Wasn't sure if I heard it ping a couple of times, so backed off. I still should be over revving with the increased power. Probably won't get to try much more this season.

 

[nola mike]

Alright, boating season not quite done yet! I think my tach wasn't adjusted correctly. I think it was set for v8, but the v6 setting was between clicks on the adjustment, if that makes sense. Got it so that it now reads consistently 150 rpm higher than the digital tach. Today I hit wot at 4750 rpm and 48 mph, closer to what I've been expecting, and more powerful than the 3.7. if I went up 2" I'm pretty sure I'd hit 50. My buddy with his 20' chaparral that weighs almost 2x says he can hit 50 with a 4.3 efi vp. Dunno if I buy it. But we're getting closer. Hopefully next season we'll be looking at minor carb tweaking, cosmetics, and stereo (no electronics hooked up yet).