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Topic Review (Newest First)

  • 03-02-2015, 03:50 PM
    H20MOFO
    I personally dont know anyone who runs a vac. advance.....not saying your boat wont run with one...just sayin.
    The way it was explained to me......if it only takes 100 hp to get to 2500-3000 rpm...and you have a 450 plus inch motor...why worry about tuning for the motor could do with 3 cyl. at that hp/rpm level.
    Sure cars benefit from a vac advance....they also have 3-5 fwd gears....apples to oranges.
    My boat starts....idles....and has way better throttle response locked. To each his own I guess
  • 03-01-2015, 06:27 PM
    ICECREAMAN
    Man sneaky you're thick between the ears brother. What info I've shared is from 40 years of experience. I don't regurgitate internet info. I've been removing advance mechanisms from distributors since the late 70's. As I stated before, it's been a common practice for performance tuning for years. If you couldn't figure out how to make it work, that says quite a bit about your abilities or lack there of. I did my first major jet boat resto in 1979. I've made my living working on cars since my parents opened a repair shop in the early 70's. I pass on what I've learned by building and running what I build not watching "how to" videos on You tube. I've personally owned at least 14 boats, most being resto's. Plus I've help several friends and family with theirs. How many boats have you built? From reading a couple of your posts, and from what I saw in your picture, I'd say you're still on you 1st.

    This little bickering match has run it's course so I'll leave you with something to spend a few minutes looking at. It was a boat I built with some help from a friend a couple years ago. Or maybe I just built it "in theory."
    Anyway, give it a look before you accuse me again of being only theorist and not a builder.

    http://www.performanceboats.com/jet-...ck-pickle.html
  • 03-01-2015, 11:22 AM
    sneakyneon
    Here is the difference between our posts, I'm speaking from experience your speaking from theory, I give advise on things I have seen first hand, not the stuff I read about on the internet. I have seen how much vacuum my engine(mild 460) made at part throttle on a plane, and the effects vacuum advance made on a WIDE BAND 02 sensor. I have no data on fuel consumption but felt after switching to a billet mechanical distributor that it was noticeably worse. Not that I care about fuel consumption but I do like running it as clean and efficient as possible. So if you have data or you have tried and failed to make a vacuum advance distributor work by all means call me a liar. I said from the beginning if you if you want simple and don't like getting the most out of it stick with what everyone else is doing, but.... there are a few of us that like to experiment and see what works and what doesn't. If my timing recommendations is confusing and you cant fallow that then I suggest you let someone else work on your boat.
  • 03-01-2015, 09:38 AM
    ICECREAMAN
    Quote Originally Posted by sneakyneon View Post
    A stock 454 at 3k with a proper pump will be at light enough throttle with high enough vacuum to run vacuum advance and see benefit from it.
    16-18 initial
    36-38 total mechanical
    40-45 vacuum (ported vacuum source.

    Anytime you transition into the throttle the vacuum drops and engine goes back to mechanical advance. Anytime your at light throttle you get get better economy and cleaner burn. Its pretty simple.

    Here's my boat, obviously I know nothing about tuning (Ya, I would have to agree with you!)
    Attachment 693601
    I was going to just let it go but I can't help myself. With each new post, you dig yourself a deeper hole. You may want to quit digging.

    Initial+ total mechanical+ vacuum = 44-45* ?????

    This is wrong on many levels. Total= total= total. No matter how you get there, it's total, as in complete, that's it, no more, all shes got!
    When you get total mechanical, you don't get 7* more from the vacuum advance. Why? Because you've reached TOTAL advance.
    There's also too much timing. If my optimum timing is 36* I would hate to have my dizzy pull in another 7* from the vacuum advance while I'm cruising along so now my motor is detonating like crazy. And since we both agree (I think) that the vacuum signal changes fairly erratically with changes in throttle input, why would constantly changing timing be more efficient or beneficial??

    Try this; it's called Vacuum advance. It's purpose is to advance your timing by using vacuum.

    Mechanical aka centrifugal advance. It advances your timing using inertia. You can control how much or soon it adds timing by the use of weights and springs.

    Initial aka static timing. This is where the distributor is set in relation to a pistons relation to TDC.

    In most performance jet boat applications (even stock motors) people are tuning for a fairly narrow window, 1/2 to full throttle. That's where the majority of your run time is spent. At this RPM range most motors work best at total advance. So if your distributor is locked and set initially at total advance, there is nothing to gain by having a vacuum advance installed because we're at full advance already!

    So, if you personally like 80 year old technology, on your engine, run it! But by your picture of your EFI set up you don't.
    So please don't try and tell me that there's any benefits in economy or performance by using one! Otherwise builders/tuners wouldn't have been pulling them off their distributors for centuries, and you'd see them on every hot rod out there!

    P.S. You may want to clean up your plug wires. It looks like you alternator is about to eat one.
  • 03-01-2015, 08:53 AM
    motorhead
    GM HEI distributors are a great set up for a jet boat. The reason you read that they shouldn't use one for a marine application is that they are not USCG Approved for marine applications. That marine rating only applies where the engine(s) are in a covered engine compartment where gasoline vapors can accumulate and be ignited by a spark. This is obviously not a problem in a boat with an engine mounted out in the open. Contact a speed shop that can lock out your vacuum advance and set the advance curve for you to match the level of performance of your particular engine. I have been running an HEI ignition on my '73 Rogers Super Cyclone with 463ci full roller Olds for many years. It runs great. Never any problems. Another benefit to running the HEI distributor is that you can walk into ANY parts store and find coils, caps, rotors, and pick-ups should any of those fail. That is not something you can do if you have a Pertronix or MSD distributor.
  • 02-28-2015, 10:04 AM
    sneakyneon
    A stock 454 at 3k with a proper pump will be at light enough throttle with high enough vacuum to run vacuum advance and see benefit from it.
    16-18 initial
    36-38 total mechanical
    40-45 vacuum (ported vacuum source.

    Anytime you transition into the throttle the vacuum drops and engine goes back to mechanical advance. Anytime your at light throttle you get get better economy and cleaner burn. Its pretty simple.

    Here's my boat, obviously I know nothing about tuning
    Attachment 693601
  • 02-28-2015, 09:00 AM
    1320
    Quote Originally Posted by ICECREAMAN View Post
    Well sneaky, in you're first post I thought you ignorant (lacking in knowledge) and a bit arrogant, especially since you didn't know what you were talking about. Your second post was just stupid! I don't really want to get drug into a pissing contest, especially with someone whose knowledge in basic mechanical ignition is minimal at best, but since you asked, I'll take one stab at it.

    Just because a motor is stock doesn't mean you don't want to tune it for optimal performance. Better fuel mileage is good! But a vacuum advance doesn't work in a jet boat, so it won't help in that department. The only time vacuum advance works is with a high vacuum signal like when a car is cruising the freeway at a low rpm and minimum throttle. Most all jet boats idle around 1000 rpm. They don't even normally plain until around 2500 rpm. Once the motor reaches about 2000 rpm or so, the mechanical advance would have kicked in and the distributor would be at or close to full advance anyway. Anytime you accelerate the vacuum signal drops down to a minimum, maybe 2 to 6 inches Hg. This eliminates any effect a vacuum advance has on a distributor, so now your back to mechanical advance. Most jet boats cruise around 3000 rpm and above, and are under constant load unlike a car with a transmission and a differential which greatly reduce engine load. So, again, were back to full mechanical advance. As I stated earlier, the main reason for lower initial timing is to help the engine start easier. It also helps the engine to idle a little smother (lower) and reduces emissions AT IDLE. Most guys with performance engines, no matter how stock, are not all that worried about the Hydrocarbons that are being emitted at idle unless they're trying to pass a smog test. BUT, a properly tuned engine is normally a very clean burning engine! Most knowledgeable people tune their engine so they burn clean by using the right size carburetor, adjusting the carburetor and jetting for proper A/F ratio, setting the timing for complete cylinder combustion with out detonation, running the proper plugs, using the proper fuel, things like that. I personally feel that since most jet boats mainly cruise higher than 2000 rpm, and are under constant load, a vacuum advance is totally worthless. And by eliminating the mechanical advance and locking the advance plate, I have one less thing to fail and one less variable in my tune up equation. I can set it for total advance and forget it!! Hopefully this will help you understand tuning a jet boat a little better. If not oh well, I think the op got the information he was looking for. Feel free to insult my minimal knowledge and intelligence in the performance boat arena and make yourself feel better.

    Op sorry to have cluttered your thread with stupid BS. hope you've got your answer.
    This is good clutter!
  • 02-28-2015, 12:00 AM
    ICECREAMAN
    Quote Originally Posted by sneakyneon View Post
    Your superior knowledge of the internal combustion engine shines through your knowledgeable words.

    Its a STOCK 454.... Why would better fuel mileage be a bad thing? This thing you call "emissions" ummmm you mean a engine that runs clean at part throttle, yeah that sounds horrible. How would it hurt? do you even understand what your talking about?
    I agree, for people that don't get it and don't want to get stick with the simple.

    Well sneaky, in you're first post I thought you ignorant (lacking in knowledge) and a bit arrogant, especially since you didn't know what you were talking about. Your second post was just stupid! I don't really want to get drug into a pissing contest, especially with someone whose knowledge in basic mechanical ignition is minimal at best, but since you asked, I'll take one stab at it.

    Just because a motor is stock doesn't mean you don't want to tune it for optimal performance. Better fuel mileage is good! But a vacuum advance doesn't work in a jet boat, so it won't help in that department. The only time vacuum advance works is with a high vacuum signal like when a car is cruising the freeway at a low rpm and minimum throttle. Most all jet boats idle around 1000 rpm. They don't even normally plain until around 2500 rpm. Once the motor reaches about 2000 rpm or so, the mechanical advance would have kicked in and the distributor would be at or close to full advance anyway. Anytime you accelerate the vacuum signal drops down to a minimum, maybe 2 to 6 inches Hg. This eliminates any effect a vacuum advance has on a distributor, so now your back to mechanical advance. Most jet boats cruise around 3000 rpm and above, and are under constant load unlike a car with a transmission and a differential which greatly reduce engine load. So, again, were back to full mechanical advance. As I stated earlier, the main reason for lower initial timing is to help the engine start easier. It also helps the engine to idle a little smother (lower) and reduces emissions AT IDLE. Most guys with performance engines, no matter how stock, are not all that worried about the Hydrocarbons that are being emitted at idle unless they're trying to pass a smog test. BUT, a properly tuned engine is normally a very clean burning engine! Most knowledgeable people tune their engine so they burn clean by using the right size carburetor, adjusting the carburetor and jetting for proper A/F ratio, setting the timing for complete cylinder combustion with out detonation, running the proper plugs, using the proper fuel, things like that. I personally feel that since most jet boats mainly cruise higher than 2000 rpm, and are under constant load, a vacuum advance is totally worthless. And by eliminating the mechanical advance and locking the advance plate, I have one less thing to fail and one less variable in my tune up equation. I can set it for total advance and forget it!! Hopefully this will help you understand tuning a jet boat a little better. If not oh well, I think the op got the information he was looking for. Feel free to insult my minimal knowledge and intelligence in the performance boat arena and make yourself feel better.

    Op sorry to have cluttered your thread with stupid BS. hope you've got your answer.
  • 02-27-2015, 07:35 PM
    sneakyneon
    Quote Originally Posted by ICECREAMAN View Post
    Wrong! Vacuum advance distributor is totally worthless in a jet boat. Vacuum advance is for fuel economy and emissions in a car. Neither are applicable on a jet boat, especially with a BBC. Mechanical advance is to assist in starting. Low initial timing helps the engine start, especially if you have a higher compression motor. It allows you to set your timing at 8-10* initial and then advance to total timing once you've accelerated. Once the motor is started and you've exceeded 2000 rpm, you want total advance for best performance. I've never seen any true performance motor builders recommend a vacuum advance distributor, especially in a boat.
    Your superior knowledge of the internal combustion engine shines through your knowledgeable words.

    Its a STOCK 454.... Why would better fuel mileage be a bad thing? This thing you call "emissions" ummmm you mean a engine that runs clean at part throttle, yeah that sounds horrible. How would it hurt? do you even understand what your talking about?
    I agree, for people that don't get it and don't want to get stick with the simple.
  • 02-27-2015, 01:48 PM
    H20MOFO
    I run an automotive hei....locked at 40*+. I think if I were going to purchase a new one....I would take a good look at a D.U.I (DAVIS UNIFIED IGNITION I BELIEVE)
    I am fairly certain they have a "marine" unit.
  • 02-27-2015, 09:30 AM
    1320
    I appreciate the input. I raped the search feature for a couple hours before throwing this post up, the majority seem to agree with eliminating the VA. I couldn't find a consensus for specific brands and I had no idea that MSD had a budget minded HEI. I guess this distributor is MSD's answer to the Pro Comp line? Think I'll go ahead and pull the trigger on it. Many thanks.
  • 02-27-2015, 08:49 AM
    ICECREAMAN
    Quote Originally Posted by sneakyneon View Post
    Stock 454 will benefit from a Vacuum advance no matter what the application, when your on plane and light throttle, you will keep the plugs cleaner and improve efficiency. Regardless you need the distributor setup properly, you will need to tailor the RATE of mechanical advance and have adjustable vacuum advance. No distributor will be perfect out of the box without setting it up for your application. The flip side to that is, if you don't care about getting the most out of your boat and just want to turn the key and go then fallow the advice above.

    Wrong! Vacuum advance distributor is totally worthless in a jet boat. Vacuum advance is for fuel economy and emissions in a car. Neither are applicable on a jet boat, especially with a BBC. Mechanical advance is to assist in starting. Low initial timing helps the engine start, especially if you have a higher compression motor. It allows you to set your timing at 8-10* initial and then advance to total timing once you've accelerated. Once the motor is started and you've exceeded 2000 rpm, you want total advance for best performance. I've never seen any true performance motor builders recommend a vacuum advance distributor, especially in a boat.
  • 02-27-2015, 06:24 AM
    sneakyneon
    Stock 454 will benefit from a Vacuum advance no matter what the application, when your on plane and light throttle, you will keep the plugs cleaner and improve efficiency. Regardless you need the distributor setup properly, you will need to tailor the RATE of mechanical advance and have adjustable vacuum advance. No distributor will be perfect out of the box without setting it up for your application. The flip side to that is, if you don't care about getting the most out of your boat and just want to turn the key and go then fallow the advice above.
  • 02-26-2015, 07:22 PM
    Fonz69
    I ran a msd hei similar to that one except it had the built in Rev limiter. Worked great.
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