How to make my '79 Commander sound like a '73??
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Category: General Correct Craft Discussion
Forum Name: Common Questions
Forum Discription: Visit here first for common questions regarding your Correct Craft
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=46870
Printed Date: November-24-2024 at 5:47am
Topic: How to make my '79 Commander sound like a '73??
Posted By: Off Trail
Subject: How to make my '79 Commander sound like a '73??
Date Posted: October-05-2018 at 3:24pm
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I have spent several hours searching around here and PN and can't get to the bottom of my dilemna. I just purchase a '79 SN with the 351 Commander. At least that is what the Manifolds say. The boat runs strong - same top speed as my '99 Response LX with the Monsoon! My first question is - Why doesn't my '79 sound anywhere near as cool as my friends '73 SN with the 351 Windsor? I believe his has had some motor work done before he purchased it, but neither of us have good info on what was done. I can't remember what manifolds are on it, so I'm still waiting for a picture from him. But it looks and sounds almost exactly like the youtube link below. Without exact motor info, can anyone tell me what I would need to do to my '79 to make it sound like this - https://www.youtube.com/watch?v=yqprxbDz_FM Right now mine has the round black manifolds that say Commander on them. On a separate note, I am looking at doing GT40p heads, maybe hitek manifolds to get a little more hp since we are running at high elevation... Haven't determined if it has electronic ignition on it yet. Seems to be plenty of info on these mods, just need to continue my research. I have owned and worked on a '98 SNOB and a '99 Malibu Response LX, but this is my first carb motor. We run at 8,200 ft of elevation, and I have a lot to learn about carb tuning, but the boat is running really strong right now so I'm a little hesitant to mess with it. A better exhaust note and a few more mph would be nice for barefooting though. Any info would be appreciated! I'm posting on PN as well. |
Replies:
Posted By: TRBenj
Date Posted: October-05-2018 at 3:31pm
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Mufflers. Don’t bother with PN. |
Posted By: Orlando76
Date Posted: October-05-2018 at 4:28pm
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1) Mufflers 2)Exhaust Manifolds play 20% factor Most if not all 73’s came without mufflers. Most if not all 79’s came with mufflers. Commanders have a log style manifold. They do lose some tone. Your friends 73 May have a riser style manifold which is deeper sounding. My dad and I have nearly identical 75’s, his has an original and starting to get tired 351 with risers. Mine has a potent 351 with very similar manifolds as your Commander. My dads sounds definitely meaner and deeper despite stock and high hours. ------------- Please support The Cystic Fibrosis Foundation 1976 Ski Nautique 351 Escort 1993 Ski Nautique purple and black 351 HO PCM |
Posted By: Off Trail
Date Posted: October-05-2018 at 5:00pm
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Thanks Orlando! If I have mufflers, would they be under the floor in the back of the boat, like my Malibu? If I were to remove mufflers and use exhaust hose instead, is there any concern about water intrusion back up into the manifolds? Probably a stupid question but don't want to miss something. |
Posted By: Off Trail
Date Posted: October-05-2018 at 5:02pm
| Also, anyone run the Hitek's without mufflers? Any idea how those sound? |
Posted By: Off Trail
Date Posted: October-05-2018 at 5:08pm
| Just saw the price on the hiteks.....maybe ignore my question, don't think I'm going down that road anytime soon. |
Posted By: TRBenj
Date Posted: October-05-2018 at 5:19pm
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(Lack of) mufflers, larger exhaust outlets, more metal in the exhaust path (as opposed to hose), compression ratio, cam, exhaust manifold material are all contributors to volume and tone. Aluminum and SS manifolds are louder than cast iron, in my experience. I have not noticed the same difference between logs and center riser... some of the loudest boats I’ve heard have logs. 73’s did not have mufflers (stringers/exh pockets are too narrow), but they were standard by around ‘75 or ‘76 in the SN- check the brochures. Yes, below the floor. HiTek’s + no mufflers are very loud for the aforementioned reasons. |
Posted By: Off Trail
Date Posted: October-05-2018 at 5:28pm
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Thanks for the info TRBenj! I'm planning to start with GT40p heads and straight exhaust (intent is HP and MPH, but definitely want to achieve the exhaust note of an early 70's in the process). If I feel the need to mess with it more after next summer progression would probably be: 1) Electronic Ignition 2) Risers 3) Cam Looking forward to taking things apart this winter. |
Posted By: 8122pbrainard
Date Posted: October-05-2018 at 5:57pm
Aaron, I agree!!  ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
TRBenj wrote:Posted By: TRBenj
Date Posted: October-05-2018 at 6:14pm
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Would recommend an intake when you do the heads. Do the cam at the same time or skip it altogether, but I wouldn’t disassemble the top end twice. Skip the EI conversion entirely, consider a new distributor with a healthy advance curve if you want a performance improvement. Risers are a maintenance item rather than performance. If all you want is the sound, the mufflers are the only difference between 73 and 79. Replace with copper or SS for maximum effect (73 likely had copper). Don’t expect a performance difference with the change, the mufflers aren’t restrictive. |
Posted By: JoeinNY
Date Posted: October-05-2018 at 6:20pm
I don't think so ... tone is certainly subjective so maybe deeper but certainly IMHO not meaner - I have found the aluminum logs to be some of the snappiest sounding manifolds and the pyramids to generally mute the tone - that's my experience on the same engine and just swapping manifolds... The old mustang video in my signature was a set of commander style logs ... that boat had some fresh gt40ps so a little bit higher than stock compression and good sealing valves which makes for a bit more clean bark but in my experience no cast iron pyramids sound like that. This video https://youtu.be/G7MVnKgTmPE" rel="nofollow - Chrysler Idle is a High compression Chrysler at idle with cast iron log manifolds and copper pipes (no mufflers) and it subjectively sounds just about right Mufflers got to go either way for a boat to sound mean... after that that less corrugated hose and tight bends in the hose the better- replacing straight runs with copper or stainless pipe has been considered by some to be sonically enhancing. Engines with more aggressive cam profiles and higher compression effect sound, but so does the amount of water running through the exhaust system If you take off your mufflers, insert stainless pipes in their place, add gt40p heads, a performer or performer rpm intake (wont change the exhaust note but still do it), maybe some 1:7 to 1 rockers it will pick up significant amounts of power and sound pretty good with those commanders. Don't sell or scrap the mufflers until you live with it a while though ... Personally I have found that opening up the exhaust ports on the log manifolds with a die grinder makes the boat a bit louder as well... I doubt it does anything positive to the performance that justifies the effort but it'll sound faster. I have seen no evidence that hi-tek manifolds contribute significantly to the performance of one of these boats in a significant way at hp levels under 350 or so - a little weight removal sure and maybe 50 to 100 rpm - but the intake and gt40p conversion is way better bang for the buck. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: Hollywood
Date Posted: October-05-2018 at 6:44pm
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lol where did 20% come from? Copper tubes + aluminum logs = rough & rowdy 
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Posted By: Orlando76
Date Posted: October-05-2018 at 11:13pm
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Found the 20% in the funk that builds up underneath the couch. ------------- Please support The Cystic Fibrosis Foundation 1976 Ski Nautique 351 Escort 1993 Ski Nautique purple and black 351 HO PCM |
Posted By: MrMcD
Date Posted: October-06-2018 at 12:39am
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I replaced the factory pipes in my 1978 Nautique when they rotted out. I had access to 3" Stainless steel pipes so I bought them and installed. They sounded fantastic. I also used a set of old Mustang GT HI PO heads from the late 60's that had small chambers. They were modified with porting and larger valves. It really woke that engine up. Today you can buy GT40P heads or aftermarket heads with smaller chambers and bump your compression up. At 8,200 feet you need all the help you can get. A small 13x12 Prop or maybe even a 12x12 will help also. I ran at sea level most times, sometimes at 1,500 ft. Once we ran on Lake Tahoe. That pumped up 351W was a whimp trying to turn my 13x14 prop at 6,000 feet. elevation really hurts horsepower. We could still pull skiers well but the power drop was really noticeable. ------------- |
Posted By: Off Trail
Date Posted: October-06-2018 at 1:22am
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Thanks TRBenj and JoeinNY. Based on your info I'm sold on doing the following this winter: 1) Replace muffler with 3" copper or stainless. Are either readily available used/cheap, or am I likely buying new tube cut to length? 2) GT40p heads. Can I buy these from any of the aftermarket retailers for Mustangs, or do I need to find something marinized? 3) Performer Intake 4) Cam - I've never had a head off before, so certainly haven't messed with a Cam, rockers etc. Can someone give me a specific list of things I need if I take this on? 5) No EI. Distributor with advanced timing. Is this something I can order off the shelf with the timing I want, or do I have to tune it? Right now, at 8,200 feet the boat runs solid 40.0mph at 4,500 RPM, so I think it is propped pretty well at the moment. When I finally got my Response LX with a 325hp Monsoon dialed in for 8,200 ft it could barely break 40mph at peak RPM (about 5,000). So, either this Commander has already been built up a bit, or I am very excited about the potential. Thanks all, any more insight is appreciated. |
Posted By: Duane in Indy
Date Posted: October-06-2018 at 11:52am
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There is a RR Mallory EI Dist. and coil on e-bay for $125 obo Says it fits a 351 ------------- Keep it as original as YOU want it 1978 Mustang (modified) |
Posted By: 8122pbrainard
Date Posted: October-06-2018 at 12:40pm
Aaron, There are plenty of on line stores to shop for metals but one thing to consider is stainless VS: copper. The typical copper (plumbing) you find may be sized by the I.D. so 3" will have an O.D. of 3.125" and that makes it harder to get the exhaust hose on. Stainless tube will be sized by the O.D. and then the wall thickness.. So, a 3" tube (.065" wall is plenty) will fit nicely on the exhaust hose. Some will say 400 series (muffler grade) is adequate for corrosion protection but I recommend using 304. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: JoeinNY
Date Posted: October-07-2018 at 12:36pm
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1) Replace muffler with 3" copper or stainless. Are either readily available used/cheap, or am I likely buying new tube cut to length? New and cut to length is the answer, but unlike pete I don't think you will ever have an issue with 400 series muffler pipe in fresh water – if it didn't last 100 years I would be surprised… 2) GT40p heads. Can I buy these from any of the aftermarket retailers for Mustangs, or do I need to find something marinized? These used to be relatively cheap from national rebuilders like tristate or Clearwater cylinder heads… there are a couple plugs that would be nice if they were brass/bronze instead of standard super cheap zinc/steel you could change them yourself or talk to the cylinder head rebuilder about upgrading them- gt40ps were intended to be used on 302s with smaller head bolts than your 351, they will either have to be drilled out by you or you can request it from the rebuilder. Covered here many times in many threads… 4) Cam - I've never had a head off before, so certainly haven't messed with a Cam, rockers etc. Can someone give me a specific list of things I need if I take this on? Again its covered quite a few times on here – cams are reverse rotation specific and there aren’t any real great performance options out there and they sometimes fail on install if not broken in quite perfectly. If there is no real wear on the lobes or lifter bottoms I wouldn't mess with the came and would instead invest in a decent set of increased ratio roller rockers. You will likely also need a shim kit for the rockers and maybe different length pushrods.. depending on stuff and things 5) No EI. Distributor with advanced timing. Is this something I can order off the shelf with the timing I want, or do I have to tune it? There is a lot of money to be spent here without huge improvements in speed or power – if what you have is in decent shape it is likely better to run with and invest the money in a fancy new prop… ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: MrMcD
Date Posted: October-07-2018 at 5:40pm
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Check Craigslist for heads, AFR heads were on many Mustang Engines and are out there on Craigslist at reasonable cost. New I think they are $1,500-$2,000. There are some other reputable companies making these aftermarket Aluminum heads, I only mention AFR because they have a great reputation. If you find a set of the P heads they do run really well and are usually much cheaper. ------------- |
Posted By: Off Trail
Date Posted: October-08-2018 at 12:24pm
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I got a bunch of pictures last night and thought I would throw them out here. Anyone see anything that looks different from the original/factory setup? Want to make sure my starting point is in fact stock. I bought the bought from the 2nd owner, who hadn't owned it long. He said the original owner said the hours probably weren't accurate and that a new motor may have been put in a while back. Trying to get more specifics but not sure I'll get them.    |
Posted By: Off Trail
Date Posted: October-08-2018 at 12:43pm
http://s31.photobucket.com/user/ecrogers/media/79%20Nautique/hours_zps4a3nflnz.jpg.html" rel="nofollow"> http://s31.photobucket.com/user/ecrogers/media/79%20Nautique/front%20seats_zpsfsblfq78.jpg.html" rel="nofollow">  http://s31.photobucket.com/user/ecrogers/media/79%20Nautique/exhaust%20elbow_zpsocx6kvcr.jpg.html" rel="nofollow">  http://s31.photobucket.com/user/ecrogers/media/79%20Nautique/id%20plate_zpswnrltjvi.jpg.html" rel="nofollow">  http://s31.photobucket.com/user/ecrogers/media/79%20Nautique/carb_zpsh7yku8by.jpg.html" rel="nofollow">  http://s31.photobucket.com/user/ecrogers/media/79%20Nautique/electronic%20regulator_zpsh2jygqrx.jpg.html" rel="nofollow">  http://s31.photobucket.com/user/ecrogers/media/79%20Nautique/manifold_zpsu4j1mwyc.jpg.html" rel="nofollow">  http://s31.photobucket.com/user/ecrogers/media/79%20Nautique/commander%20351%20label_zpsqectx3wh.jpg.html" rel="nofollow"> 
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Posted By: JoeinNY
Date Posted: October-08-2018 at 1:02pm
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Looks like a tasty little nugget to me - i would probably pull the mufflers, put an acme 542 on it and not touch anything else until it needs it... Yeah 542 thats what I meant.... ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: TRBenj
Date Posted: October-08-2018 at 1:41pm
| *542 |
Posted By: Off Trail
Date Posted: October-08-2018 at 11:52pm
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Even if I want a couple more mph for barefooting?? I've tried to read the existing prop, but the nut covers the numbers and there is nothing stamped on the spine. I think I am seeing OJ 13 x 11 behind the nut, but there is definitely some interpolation going on. As I mentioned, I'm currently getting 40 mph at 4,500 rpms with 2 guys in the boat and no extra gear. This probably means 38 mph if I'm footing. And at 4,500 rpm's on the stock motor, I think the prop is about as perfect as it could be. Am I wrong? You think I'll get more MPH and more RPM out of a 542?? Or.....are you just saying that this motor has too many hours on it to start dropping a bunch of $$ on it?? |
Posted By: JoeinNY
Date Posted: October-09-2018 at 12:05am
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I am not worried about the hours, it looks like a nice clean package that would be a shame to tear into. If it's an OJ prop that's not a cnc prop then there is likely a mile an hour or 2 to be had with an acme. With the increased elevation that acme is likely A542 You might pick up a couple of rpm but I'm thinking you could get to 42 miles per hour. Either way the first biggest bang per buck is usually a modern prop the second is the gt40p heads. If you did the heads you still would want the prop imho, so with an engine that clean i would make sure the prop alone wasnt enough before I took it out.... but its your boat and your money. I would suspect a gt40p swap well done and propped might get you to 46 at 5000 rpm at your elevation. Have you considered moving downhill? ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: KENO
Date Posted: October-09-2018 at 12:11am
Click on the link below for some reading about someone with the same high altitude dilemma as you  Lots of reading and you'll probably be able to decide for yourself what you should do or not do as far as props go. You could also pull the nut off so you can read what your current prop is http://correctcraftfan.com/forum/forum_posts.asp?TID=38359&KW=&title=prop-question-suggestion-problem" rel="nofollow - link |
Posted By: KENO
Date Posted: October-09-2018 at 12:30am
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I figure you already know that you're at about 75% of what the engine has for power at sea level. If you want some good noticeable extra speed, jack up the power like Joe mentioned with GT40P heads, and add to that a better intake along with a new cam and/or 1.7 rockers |
Posted By: Off Trail
Date Posted: October-10-2018 at 11:45pm
Moving downhill would definitely solve a long list of issues for me at this point in life.....but still not worth it. Thanks for the feedback. Based on my experience with other boats at this elevation, I really think this thing is doing great and probably about as dialed as it could get (prop-wise) at stock horsepower (minus elevation penalty). As I mentioned, my '99 Malibu Response LX (325hp monsoon) with 600 well-maintained hours, and the perfect acme prop got that boat to 42 mph after a bunch of prop swapping, re-cupping etc. And that diamond hull was a fast hull - 49-50mph at sea level. I'm impressed the '79 will hit 40 mph. I WILL pull the nut off and report back on what prop it has when I get the boat to my house. |
Posted By: Off Trail
Date Posted: October-10-2018 at 11:51pm
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I think I have 2 paths to choose, and it is going to be tough to decide: 1) Get it in the garage before the snow flies, and spend my spare time this winter getting the GT40p's and performer intake installed. Put it all back together before the lake thaws out, and cross my fingers that I did it right and have a boat for the summer that will pull me at 42 mph footing. 2) Get the mufflers out and put it to bed for the winter. Play with prop'ing in the spring but likely have to deal with 38mph barefoot speeds for the summer. Decide if this is really my barefoot boat and if it is really worth tearing the motor apart next winter.... A smart man probably chooses #2. But...a '79 that can do a better job pulling me footing than my 'modern' Malibu did....sure is tempting. Then again, I'm not throwing long-line toe-holds....or any toe-holds. So maybe just suck it up and enjoy my 38mph boat that looks and sounds better than anything else on the lake. Decisions.....decisions..... |
Posted By: TRBenj
Date Posted: October-11-2018 at 4:05am
| The top end upgrade is a 1-2 day project... no need to string it out over a full season (or 2) if you don’t want to. I would expect a 3-4mph gain with the heads and intake. |
Posted By: MrMcD
Date Posted: October-11-2018 at 4:27am
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I can say firsthand that the smaller chamber heads will raise compression and flow better to give you 30-40 horsepower more. At sea level it made my boat feel much more powerful . I installed my new heads at 1,000 hours and it still sounded and ran like new when I sold it some years later with more than 1,500 hours. My buddy liked to one foot at 45 mph, this boat at sea level did that without running wide open. He owned a new 2001 hull at the time that was BLACK. Only Black 2001 I ever saw. He could not one foot in his boat it did not have enough Speed. This was 1983. You will see a difference. If you think it will be weak start looking for a 454 to swap in. ------------- |
Posted By: Off Trail
Date Posted: October-11-2018 at 4:29pm
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That's the push I needed.... Wasn't implying it will take the whole season, but it will be my first time pulling heads off of a motor, so it will take me quite a bit of time to research, get all the stuff I need, and get it done and back together. Don't want to lose any of our 2.5 months of summer so I'm going to give myself the whole winter to do it. Can't wait to get it out on the water next spring! We have 6" of snow on the ground already..... |
Posted By: Off Trail
Date Posted: October-18-2018 at 11:59pm
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Hey JoeinNY - Finally got a look at the prop and it is in fact an Acme 542. Good call, that might explain why the boat seems to be performing so well! I'm going to mention this and have some questions on the other thread I started in General Discussion. |
Posted By: ultrarunner
Date Posted: November-02-2018 at 12:12pm
From my previous boat, here is a pic of a completely bone-stock Commander 351.
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Posted By: KENO
Date Posted: November-02-2018 at 2:45pm
I guess the missing belt and water hoses must have been options
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Posted By: ultrarunner
Date Posted: November-02-2018 at 3:00pm
| Good catch KENO. Yeah, I took that pic the day bought and hauled that boat back from a barn, where it had been sitting for a number of years. |
Posted By: Off Trail
Date Posted: January-20-2019 at 2:48pm
| Thanks for the stock photos ultra! - I hadn't been following this thread since I started the '79 build' thread. |