Engine swap
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=2700
Printed Date: November-23-2024 at 6:48am
Topic: Engine swap
Posted By: Jimbodawg
Subject: Engine swap
Date Posted: November-07-2005 at 7:08pm
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I have a 79 Ski Tique with a bone stock 302, 2 valve per cylinder, 2 barrel Holley carb...she's got about 250 hours on her and runs great. I'm thinking of buying my buddy's 302 with boss heads for $875 and putting it in the Tique (I'll have to hire someone to put it in...I'm not that mechanically inclined) I'm told that my buddies 302 is a ~ 1980 block with a mild cam and 1969 Boss heads. We're guessing his motor makes ~ 300 horsepower??? Does that sound accurate? I'm guessing my stock 302 makes somewhere between 180 & 220 horsepower??? His "boss" 302 was oringinally in a car. What all is involved in "marinizing" a "street" 302??? Can I simply place my marine alternator & starter on the "boss" 302 and bolt it in??? Are both of these motors standard/clockwise rotation?
Any input would be appreciated. Thanks, Jim |
Replies:
Posted By: GottaSki
Date Posted: November-08-2005 at 4:58am
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Your exhaust manifold won't work. Good luck finding cleveland 4V port marine manifolds.
Plus the rotation is wrong. The probability they are really boss heads is questionable. Not something to undertake if you are not mechanically and have to hire this out. ------------- "There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing." River Rat to Mole |
Posted By: David F
Date Posted: November-08-2005 at 8:57am
| I agree with GottaSki. Also, the Boss (i.e. Cleveland heads) enigne makes most of its power at the upper rpm range due to the high flow heads and thus are not known for strong low end torque (I think I remember this right). Marine engines need gobs of low end torque. My vote is forget about it (said with an Arnold accent). |
Posted By: jameski
Date Posted: November-08-2005 at 9:25am
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For a fraction of the cost, you could change intake and carb to 4BBL and probably get the biggest improvement for your money. ...but 220HP in a Tique is certainly not underpowered. What are you trying to accomplish? It might be that a new prop would be the best money you could spend on improving performance. ------------- current boat http://www.correctcraftfan.com/diaries/details.asp?ID=1977 - 94 Sport Nautique previous boat http://www.correctcraftfan.com/diaries/details.asp?ID=601 - 78 Martinique |
Posted By: mackwrench
Date Posted: November-08-2005 at 12:16pm
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Do a forum search here. The "boss" issue was covered here in a thread a few months ago, There was a lot more to a for real "Boss 302" than just putting 351 Clevlend heads on a 302 windsor block. The real Boss 302 was built in very limited numbers and none where marine use.
Your '79 302 has only 250 hours on it? Wow I'll give you the $875 for it when if you think your doing this swap! My advice, enjoy the boat as is, with ample power enough, maybe a prop change will improve performance... ------------- NO LONGER A MEMBER |
Posted By: Jimbodawg
Date Posted: November-08-2005 at 8:57pm
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Thanks for the info guys. I now have the "boss" 302 in my garage suspended on an engine dolly. It turns out it's NOT a true boss motor. However it does look to have some HI PO heads...not sure if they are Clevland or aftermarket??? I have been told that it also has a "mean" cam in it. I'm tempted to push forward and attempt to swap the stock 302 for the "HI PO 302" but this may be an uphill battle. I've learned that the initial obstacle is that my exhaust manifolds won't mount up to the "Hi Po 302" The bolt pattern is differnt. (Gotta Ski, you were right) This issue alone could be a show stoper. The stock 302 actually makes good power as is...I was just thinking about really "hot rodding" it up! I may look into a prop, some head work, a cam, hi flow intake, 4 BBl carb, etc...
Anybody out there able to list a few suggested engine mods??? Thanks! Jim |
Posted By: 64 Skier
Date Posted: November-09-2005 at 8:54am
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Compression test both motors so we know what your starting out with.
I agree with the earlier posts about designing around low end torque. Prop would be the first modification to improve pull and with the new technology you get top end gain also. If compression is equal, I would think the 2bbl will have more low end torque than the 4 bbl and assume the "Boss" has a lot of carb and intake. Depending on the rotation, if you do use the car engine, you'll have to reverse the rotation on the tranny. CC's old hull designs need a lot of low end torque to to get out of the water especially if you like deep water starts with a slalom skier who weighs in over 200 lbs. A high end motor with a "mean" cam may not have the torque to push the hulls design. ------------- 64 Skier 66" HO VTX and 67" HO Triumph http://www.correctcraftfan.com/diaries/details.asp?ID=1071&sort=&pagenum=3&yrstart=1971&yrend=1975 - 71CC |
Posted By: 65 'cuda
Date Posted: November-09-2005 at 3:57pm
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A "mean cam" may have too much overlap for a wet exhaust. ------------- Gary http://www.correctcraftfan.com/diaries/details.asp?ID=941" rel="nofollow - 1965 Barracuda SS |
Posted By: bwooton
Date Posted: November-09-2005 at 4:03pm
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Im building an engine for my 78 tique. Im wondering if anyone knows what an "ideal cam" would be? I want the low end torque. by the way im building a 350 not a 351. yes my boat came stock with the 305. that my PO cracked ------------- Thanks Bobby there's no replacement for displacement |
Posted By: stang72
Date Posted: November-10-2005 at 8:40pm
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I'm with Jameski all the way...put a high performance intake on...4 bb carb...acme 540 3 blade...maybe flow the heads....and you rollin.@ 250 hrs on the 302...keep it! ------------- stang Face plants are not that funny when it's you face! http://www.correctcraftfan.com/diaries/images/3720/photo1.jpg" rel="nofollow - The Super Air |
Posted By: nuttyskier2002
Date Posted: November-11-2005 at 6:46am
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This message is to bwooton in response to your cam question. Here's a link to Comp Cams website catalog:
http://www.compcams.com/Technical/CurrentCatalog/HTML/128-169.asp Listed under Extreme Marine are 3 part numbers: (12-232-3, 12-236-3 and 12-240-4) I would stay with either of the first two as the third is a bit aggressive if you are concentrating on building bottom end torque. Now Comp Cams are a little on the expensive side so if I were you I'd do my homework and compare cam specs and find a cam from a different grinder with similar specs. However, if your engine is "CCW" rotation, your selection is very limited. Comp Cams can grind cams for either rotation,… and do so on a routine basis. From there home page http://www.compcams.com/ click on Charts, Graphs, Specs then cam specs and enter the part number to get the specs of the above cams. I used to run a Comp Cams 268H (12-210-2) in a 327 Chevy engine powering a 1959 Chris Craft (19 ft. wooden boat) with very good results. I loved the responsiveness, torque and overall performance from the engine. I wouldn't particularly recommend this cam due to its lobe separation (110 degrees). I would select one with a minimum of 112. ------------- 95 Malibu Echelon w/Mercruiser 350 Magnum Skier Former boats: 88 Ski Centurion Tru Trac II 59 Chris Craft Capri (woody) |
Posted By: bwooton
Date Posted: November-11-2005 at 8:33am
Thanks nuttyskier2002. I knew i had to watch how aggressive of a cam i got with wet exhaust, and now i do. Im looking for that low end torque and something that will sound good as i idle around. cause lets face it vintage CC's are just hotrods that pull skiers well.  ------------- Thanks Bobby there's no replacement for displacement |
Posted By: 79nautique
Date Posted: November-11-2005 at 11:26am
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changing from a 2V to a 4V carb with out changing the cam is really a waste of time and money. You will only see, if any at all, a slight increase in perfomance and will see the gas gauge drop a lot faster. You really need to change the cam when you replace a two barrel carb with a four barrel carb.
There is a lot more gas/air mixture to flow through the new intake and carb but the cam will only allow so much of it to pass into the cylinder where it counts. So without a new cam that is designed for a 4V carb, you can not take advatage of the increase in air through the carb. so what really happens is that it is always rich because the carb is oversized for the cam. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=756&sort=&pagenum=1&yrstart=1979&yrend=1979 - 79 nautique |
Posted By: reidp
Date Posted: November-11-2005 at 5:04pm
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I've got to go with '79 on this one in regards to the 4V-without-the-cam upgrade, and especially with this engine, unless your 302-2V has a firing order of 18456273. Here's what the firing order has to do with it. This is the typical 351 firing order which was used on almost all but the very earliest 302 4Vs, which meant it shared the same came and 351 heads. If you have a firing order of 18736245 then you have a lower profile cam than the 351 model and the 4V isn't gonna help that much. If you have the 351 firing and if by chance the 351 heads as well, (look under the valve cover for "351") then the 4V may do you a lot of good. Depends on what you have.
As for the cam, an economical one is from Clevite marine cams, and check this site/page which someone recently posted the specs on: http://engineparts.com/motorhead/techstuff/2003marine/Camshafts_Lifters_TimingComponents.pdf Cam part number 229-1834 has been used several times by myself and Jim-in-Houston, and performs very well on the bottom and top. Something neat to be realized about upgraded cams in marine engines (from my experience) is that you basically have an inherent stall speed converter as a result of the unavoidable prop slip allowing the engine to rev immediately. I initially worried about loosing low end power but found that the bottom end-out of the hole power increased somewhat significantly, however this cam spec listed above isn't all that dramatic, but somewhat comparable or slightly better than a factory 5.0 HO Mustang auto cam, which we all know is no slouch. We've also got an older Crane cam engine (who's no longer providing Rev Rot cams I was told) which is a significant step upward with a split pattern and 494-512" +/- lift, and it has gobs of low end power as well. A good combination of parts on a 302 in a 16' CC, will accelerate like nobody's business. ------------- ReidP /diaries/details.asp?ID=231&yrstart=1971&yrend=1975 - 1973 Mustang |
Posted By: 64 Skier
Date Posted: November-11-2005 at 11:41pm
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79 & Keith...great posts.
I still think the original 302 Marine engine will outpull the questionable BOSS. Like you guy's stated, if the PO just placed HP heads on a rotating assembly designed around a 2V design it will have less power. I made this same mistake on an old Bronco. Upgraded the carb and intake to 4BBL and put on a great set of headers. Thing wouldn;t get out of it's own way much less push some larger tires. Went to a Dyno shop and he gave me the same advice you guy's just posted! He basically told me the engine was the choke point between my new carb and headers. Added a "stump puller" cam and about 50 lbs of compression and it will smoke 35" by 14 1/2" tires. Same goes for these old boats. ------------- 64 Skier 66" HO VTX and 67" HO Triumph http://www.correctcraftfan.com/diaries/details.asp?ID=1071&sort=&pagenum=3&yrstart=1971&yrend=1975 - 71CC |