Ignition and Timing Questions

[captainblye]

I have a 1988 Carrera Caliente with a mostly stock Hardin Marine 454 (330 hp) with log manifolds and I think the size of the 4 barrel carb is a 850 cfm. I am still running the mallory distributor that has points. The boat has 150 hours on it and I don't think the point have never been set or replaced. I have had the berkley pump done by MPD (stage 2.5). The engine doesn't labor at all and engine never revs above 4200 rpm. I am running the stock aluminum impeller that MPD has reworked. At 4200 RPM I am neck to neck with 60+ mile per hour PWC. Sounds too good to be true. I know there is more rpm to be had out of the motor.
I am considering installing a DUI distributor, increasing the spark plug gap, and possibly increasing the advance on the ignition timing.
Will these mods help with getting the rpm up?

[lilrick]

be careful! If it starts pinging, back the timing down. It would definitely be worth the distributor change though.

[455Rocket]

Just one unrelated point... the stock carb. for your motor was a 650 CFM Marine Holley

[probablecause]

Never above 4200 RPM AND running at 60+ MPH AND a stock motor - :argue:

[bighead]

I have a similar setup, 87 Commander 21 footer open bow 454 hardin marine 325 hp, AT AA imp, inducer and stuffer, edelbrock rpm airgap holley 750 4160 carb with spacer dual points with super coil and just did 58.8 GPSed with half load of fuel, anchors, dual batteries and 60lbs of tools turning 4200rpm and it has the peanut smog heads.Not too bad for a big heavy.Timing is 32 deg total at 3000 rpm. Let me know if you do the ignition and see improvment but use a gps to verify actual speed before and after so you can see the actual increase or decrease.

[captainblye]

be careful! If it starts pinging, back the timing down. It would definitely be worth the distributor change though.
Thanks lilrick I'll keep that in mind. Any idea of how much I can advance the timing without encountering any problems?

[captainblye]

Never above 4200 RPM AND running at 60+ MPH AND a stock motor - :argue:
Probablecause - I probably should confirm that with GPS. If I'm not over 60, I'm close to it.

[captainblye]

I have a similar setup, 87 Commander 21 footer open bow 454 hardin marine 325 hp, AT AA imp, inducer and stuffer, edelbrock rpm airgap holley 750 4160 carb with spacer dual points with super coil and just did 58.8 GPSed with half load of fuel, anchors, dual batteries and 60lbs of tools turning 4200rpm and it has the peanut smog heads.Not too bad for a big heavy.Timing is 32 deg total at 3000 rpm. Let me know if you do the ignition and see improvment but use a gps to verify actual speed before and after so you can see the actual increase or decrease.
Bighead - I'll keep you posted on what type of results I get from the hei distributor. I just need to get my hands on a good hand held GPS. Can you recommend a good one?

[captainblye]

This past weekend I was towing skiers. When I'd jump on it to get them out of the water, sometimes, I'd get a pop coming from the carb. I'm thinking its just an ignition problem. Does that diagnosis sound right to any of you?

[bighead]

I have a Garmin handheld one and it does work fine, I think you can pick up a handheld these days for under 200 bucks at just about any electronics or sporting goods store.You will be suprised at what it will tell you and anyone else who will make a couple of runs with it, it is a humbler for sure.

[captainblye]

I have a Garmin handheld one and it does work fine, I think you can pick up a handheld these days for under 200 bucks at just about any electronics or sporting goods store.You will be suprised at what it will tell you and anyone else who will make a couple of runs with it, it is a humbler for sure.
I picked up a garmin etrex (yellow) from circuit city for $83. They matched Walmart's online price.
I think I might also have an issue with the vacuum secondaries on the carb opening. I need to resolve that before I drop the HEI distributor in. Hopefully I'll have the carb issue resolved and the distributor dropped in this weekend.
I'm going out to ehrenberg (near blyth on the river) the weekend of the 23rd and I need to get this stuff done pretty quick.

[bighead]

What a score on the gps, they are a lot of fun to play with and a great way to gauge any increase in speed with mods. I use mine a lot and try to keep everything consistent when making runs like same fuel load and octane, load in boat I usually just empty all the gear like anchors, shade, chairs,coolers etc to have the highest top speed numbers. I had the original 750 vac sec marine carb on it and the secondarys were not operating properly or fully opening until the throttle was pinned for a few seconds, a friend had the same carb but new and I threw it on and there is a big differrence in when the secondarys open and it is considerably quicker but I gained nothing on the top.I would have said it was way faster by seat of the pants b ut the gps showed the truth. I will be doing some upgrades to my motor like roller rockers first then change the heads from smog to 049, it sounds backwards to do the rockers first but I just wanna see what if any gain I will get. We have similar powerplants mine is a 1987 Hardin Marine 454 with dual points, performer RPM airgap and logs. I will let you know what if any gains I see with the mods. Let me know how the distributor works for you.

[captainblye]

I used the white spring for the vacuum secondaries and now they work fine. I also dropped in the DUI HEI distributor, MSD Plug Wires, and a new set of plugs. Now she accelerates like a bat out hell. But I am disappointed with the top end speed of 53.5 miles per hour (gps) spinning 4400 rpm. The boat feels faster on a lake then on the river.
I have no idea of how much mph the boat gained by adding the distributor. I was pressed for time and didn't have a chance to do a before and after run. But wat I do know all hesitation is gone and the boat seems alot quicker.
Its time to make some mods. I'm considering replacing the stock hardin intake manifold for an edelbrock. I'm also considering replacing the log manifolds with a set of lighting headers. What should be my next mod?
What mod will provide the most bang for the buck?

[probablecause]

Supercharger/blower!

[lilrick]

I used the white spring for the vacuum secondaries and now they work fine. I also dropped in the DUI HEI distributor, MSD Plug Wires, and a new set of plugs. Now she accelerates like a bat out hell. But I am disappointed with the top end speed of 53.5 miles per hour (gps) spinning 4400 rpm. The boat feels faster on a lake then on the river.
I have no idea of how much mph the boat gained by adding the distributor. I was pressed for time and didn't have a chance to do a before and after run. But wat I do know all hesitation is gone and the boat seems alot quicker.
Its time to make some mods. I'm considering replacing the stock hardin intake manifold for an edelbrock. I'm also considering replacing the log manifolds with a set of lighting headers. What should be my next mod?
What mod will provide the most bang for the buck?
did you mention what your timing was set at? I wouldn't run anything above 36 deg full advance. and i would run the premium fuel. Buy the lightning headers TOO! Then when you're ready to rebuild your motor, you've already done the necessary upgrades to accomodate more HP!!!

[lilrick]

Just one unrelated point... the stock carb. for your motor was a 650 CFM Marine Holley
I would definitely investigate a carburetor upgrade as well.

[jbone]

The Air Gap would be a good upgrade with carb spacer. See the link for the Super Sucker carb spacer.
http://www.cfm-tech.com/
No more than 36 deg advance. Try going down 1 deg at a time to check performance with the gps.
Do you have a diverter? If not, that is a very good upgrade for speed and performance. As well as a droop and ride plate.
Then headers.
That gps was humbling wasn't it. You thought 60 +/- and you got almost 54 mph.
J

[captainblye]

Full timing advance is set at 36 degrees. During tuning I was had it at 48 degree with no pinging and the motor didn't even run hot. But I sacificed performace for reliability and set the timing at what DUI recommended (36 degrees total advance.) I was running premium fuel.
I have a place diverter and a droop snoot. I don't have a shoe and ride plate yet. The guys that built my pump told me to spend my money on more motor.
I want a set of lightning headers but I'm not sure if they'll fit under the motor box. The overall width of the motor with the headers installed is 33". The motor box width is around 31-32". It would be a tight squeeze. I'd also need some special plumbing to connect the headers to the exhaust tips in the transom..