BBC HEI Recommendation
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BBC HEI Recommendation

  1. #1
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    Default BBC HEI Recommendation

    My jet has a stock 454 (no engine cover)....Would this be a wise choice? Better choice(s)?

    Street Fire Chevrolet V8 GM HEI Distributor - 8362
    Last edited by 1320; 02-26-2015 at 09:32 AM.

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    Senior Member larryfknrocks's Avatar
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    MSD has a nice hei or a couple more dollars get a nice pertronix ignition system

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    Member Hibbitz's Avatar
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    The research I did said not to use an automotive dist (even if the engine is exposed) mainly because of the vac advance that is on automotive units. A marine engine is always under load and the advance curve is different but maybe others can chime in with recommendations.

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    Senior Member ICECREAMAN's Avatar
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    Pull the vacuum advance off the dist and lock out the mechanical advance. Set your timing where you want it, like 34* and run it. I think it's a great dist for most applications.

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    Senior Member Fonz69's Avatar
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    I ran a msd hei similar to that one except it had the built in Rev limiter. Worked great.

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    Member sneakyneon's Avatar
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    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.

  9. #7
    Senior Member ICECREAMAN's Avatar
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    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.

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    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.

  11. #9
    Senior Member H20MOFO's Avatar
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    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.
    Another Hot Boat refugee

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    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.

  13. #11
    Senior Member ICECREAMAN's Avatar
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    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.

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    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!

  15. #13
    Member sneakyneon's Avatar
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    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
    Click image for larger version. 

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    Last edited by sneakyneon; 02-28-2015 at 10:06 AM.

  16. #14
    Junior Member motorhead's Avatar
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    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.
    This vehicle makes frequent roosts!

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