351w cam upgrade?
Printed From: CorrectCraftFan.com
Category: General Correct Craft Discussion
Forum Name: General Discussion
Forum Discription: Anything Correct Craft
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=28221
Printed Date: June-28-2024 at 2:19am
Topic: 351w cam upgrade?
Posted By: Waternut
Subject: 351w cam upgrade?
Date Posted: October-29-2012 at 11:04pm
| Just curious if anyone has upgraded their camshaft on these reverse spinning engines? I've got a carbureted 351w PCM that I recently put GT40P heads on. I'm getting ready to pull the engine this winter to fix the floor and will be checking the engine over. Just looking at options for cams while everything is apart. |
Replies:
Posted By: kapla
Date Posted: October-30-2012 at 1:19am
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cam research is the shop many have chosen for grinding ford cams...they can fab RR cam as well ------------- <a href="">1992 ski nautique |
Posted By: phatsat67
Date Posted: October-30-2012 at 11:09am
| You will probably want to look at the cam spec that Tim B is running in his 90. He will chime in. It's a cam research Flat tappet grind. Not a lot of duration so idle quality and drivability stay top notch. |
Posted By: Hollywood
Date Posted: October-30-2012 at 12:09pm
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Which is not RR ------------- |
Posted By: Waternut
Date Posted: October-30-2012 at 12:34pm
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Sorry for the noob question but what is RR? Reverse rotating? ------------- |
Posted By: Hollywood
Date Posted: October-30-2012 at 12:36pm
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Yes. I was looking at some lunati "voodoos" but Tim was strongly talking me out of them. ------------- |
Posted By: fumanchu
Date Posted: October-30-2012 at 3:01pm
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I'm in the same boat, can we get some actual duration and lift numbers? Mine motor is standard rotation so I could technically get an off the shelf grind. I will stay away from the XE grinds Comp has, heard way to many bad things. ------------- '89 2001 |
Posted By: phatsat67
Date Posted: October-30-2012 at 3:03pm
| They should be able to duplicate the same cam in RR I would assume. I think lift was .490 and duration at .050 was in the 220 range. |
Posted By: fumanchu
Date Posted: October-30-2012 at 3:18pm
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duration and lift numbers posted above are actually more aggressive than I would have thought. What about LSA? 112-110? ------------- '89 2001 |
Posted By: Gary S
Date Posted: October-30-2012 at 3:52pm
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The person who has all the good info,Tim, has not been on all morning.I'm afraid he's out dancing with Sandy,hope everything is ok. I know he always says Cam Research is conserative on their recommendations. My Crane from 20 yrs ago is 260* on the intake 272 on exhaust.Lift is 456 on intake and 484 on exhaust. No lobe seperation is listed. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: phatsat67
Date Posted: October-30-2012 at 4:13pm
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I think Tims was in the 110 range... Don't remember. Gary your boat probably lopes a bit at idle? That cam is very similar to what I put in the 350 I built for the Skylark. I personally wouldn't want my main boat(the 86)to lope at all. I like smooth as silk on it but the Skylark is for fun so party on. |
Posted By: TX Wind
Date Posted: October-30-2012 at 4:46pm
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That is correct from other postings I've seen him put up. Separation was 110. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=5622" rel="nofollow - 1967 SN Interceptor 1985 |
Posted By: Gary S
Date Posted: October-30-2012 at 4:48pm
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No Zach it does not lope at all. I wonder if thats why Tim says you can go some more? ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: phatsat67
Date Posted: October-30-2012 at 5:08pm
| I figured it would be just on the threshold of a lope and no lope. The dual pattern cams are generally more behaved at idle than old school single pattern with more overlap. I'm considering going with something more modern in my car. Guess im getting old haha. My car sounds like it wants to kill other cars haha. |
Posted By: TX Wind
Date Posted: October-30-2012 at 5:12pm
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Tim was actually on the Mastercraft site talking about this somewhere. They had the factory cam grind numbers on the site. The earlier engines sported durations of 194 at .050 but the later engines were closer to 206 and the hp at 221. They say that after about 200 it starts to get a bit more lopey. I can say that is pretty accurate. I have one of each of those factory grinds. I would guess that Gary's cam at .050 is closer to the 206, 221 dual pattern grind that was the middle of those. It has a noticeable difference in idle compared to the 194 as it has a faint hint of a lope like an RV cam grind but is still very smooth. Is that pretty accurate Gary? ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=5622" rel="nofollow - 1967 SN Interceptor 1985 |
Posted By: TRBenj
Date Posted: October-30-2012 at 5:29pm
...And that is where you'd be wrong.  As far as Ive been able to tell, there is only one type of reverse rotation Windsor core out there. LSA is fixed at 112, and due to their size and heat treat, there are limitations on the blank as to how far you can go with lift (and subsequently, duration). Cam Research isnt comfortable grinding anything more aggressive than their common .460 grind (1.6 rockers), so not much more aggressive than stock (~.450). Lunati will grind you something a bit more aggressive (in the neighborhood of .500) but I suspect that theyre pulling from the same group of cores as everyone else, and are simply willing to push the envelope on reliability a bit. Not a gamble I like very much. The common .460 grind with 1.7 rockers will get you in the .489 ballpark. Not a bad place to be, and as Alan saw on his '81, can run pretty darn well. Not a bad match for the common ~325hp GT40p head upgrade, IMHO. If you want to make >1hp/ci, then Id be looking to spend the money to go roller. None of the cam sizes in question will give any hint of lope, at least not that Ive experienced. I know Hotboat was running something way wilder in his hot 351w (north of .550). Reid had something pretty stout in his 347 as well. We're north of .600 on our big block, and thats got some lope to it... but thats a whole different ballgame. ------------- |
phatsat67 wrote:
Posted By: TX Wind
Date Posted: October-30-2012 at 5:46pm
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Ahhh...there you are Tim. I was just looking up the postings on this from Team Talk. Here is what I gleaned from there STD 351w camshaft specs Duration 206 int./221 exh. @ .050 Valve Lift 0.445 int./0.453 exh 115° HO 351w Duration 210 int./221 exh. @ .050 Valve Lift 0.453 int./0.453 exh 115.5° Correct me if I'm wrong Tim but it's not so much the lift that causes lope but the duration. I do agree with you on the roller though. You can get a great deal more lift with less duration. It keeps the idle smoother. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=5622" rel="nofollow - 1967 SN Interceptor 1985 |
Posted By: TRBenj
Date Posted: October-30-2012 at 5:55pm
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Youre correct, duration causes the lope... but obviously its closely related to lift and the 2 will travel together- especially on flat tappets, which simply cant handle the aggressive ramp rates that rollers can. ------------- |
Posted By: Gary S
Date Posted: October-30-2012 at 6:05pm
Yes 204 and 216 @ .050 ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: TX Wind
Date Posted: October-30-2012 at 6:12pm
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My understanding is that the ramp rates on rollers are almost 25-30% better than flat tappets. Of course the lobe separation adjusts your power band as well. I'd say a 112 degree lobe separation isn't bad for the RR cams and Tim's suggestion on running a 1.7 rocker ratio is really good advice. For those of you interested....the Tim Benjamin cam specs.... RPM Range: 2500-5200 Duration @.050" (I/E): 218/222 Lift w/ 1.6 Rocker (I/E): .490/.490 LSA: 110 degrees I'm surprised this doesn't lope Tim, I've had cars with similar grinds and they loped a bit. But that's a subjective way to describe it really. All engines will lope. It's just a matter of what RPM they are going to do it at. And for the record Tim...I've seen the video of your BB and it lopes more than just a bit. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=5622" rel="nofollow - 1967 SN Interceptor 1985 |
Posted By: Waternut
Date Posted: October-30-2012 at 6:13pm
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I have done a lot of research on cams in the last week or two so I'm sure I know just enough to sound like an idiot. It wasn't until last night that I realized that RR cams were different from standard which put a damper on my plans. From the sounds of it, I'm guessing there are no "off the shelf" RR cams available. Is that correct? BTW when I was looking up standard cams on Summit Racing, I found that a lot of them have a couple videos that give, what I thought was, an excellent explanation of what all the numbers on a cam mean and do. ------------- |
Posted By: TX Wind
Date Posted: October-30-2012 at 6:16pm
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Here is a link to the cam specs on this site. http://www.correctcraftfan.com/forum/forum_posts.asp?TID=5627&title=351w-cam-specs" rel="nofollow - 351w cam specs ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=5622" rel="nofollow - 1967 SN Interceptor 1985 |
Posted By: TX Wind
Date Posted: October-30-2012 at 6:17pm
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More than you wanted to know about cams. http://www.camcoindex.com/Svcman/moonbook.pdf" rel="nofollow - Cam design ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=5622" rel="nofollow - 1967 SN Interceptor 1985 |
Posted By: Waternut
Date Posted: October-30-2012 at 7:10pm
Link is broken. ------------- |
Posted By: TX Wind
Date Posted: October-30-2012 at 7:19pm
Link has been repaired ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=5622" rel="nofollow - 1967 SN Interceptor 1985 |
Posted By: phatsat67
Date Posted: October-30-2012 at 7:20pm
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Ahhh Silly camshaft blanks! Yeah the overlap and duration cause lope and also determin where the engine will make peak power/torque. Lift needs to match up well with the flow numbers of said head. I can't see a stock GT-40p or GT-40 Port needing much more than the numbers Tim posted with the 1.7 ratio rockers(unported configuration). A lot of times too much lift will effect port velocity and make less power. The key is in the total power package. Well matched parts to one another. The advantage of roller camshafts is less friction and more aggressive ramp rates as Tim stated. The more agressive ramp allows the valve to achieve max lift much sooner than a flat tappet application and allows. It also allows the valve to stay closer to that max lift number longer.(although duration can be the same as a flat tappet application). Valves stay open the same ammount of time but roller achieves greater flow because of its ramp rates. With rollers you don't have to worry about wiping off a lobe at first start up or running ZDDP in your oil. I'm considering a roller swap in the car to keep the power but gain drivability. |
Posted By: phatsat67
Date Posted: October-30-2012 at 7:38pm
| There is a guy that has done research for years on 440 6 bbl motors for pure stock cars(stock eliminator). He has the cams so well fit to the engine that it idles like a 318. Stock lift has to remain but he can alter duration, lobe seperation, ramp rates, and centerline, The cams take the cars from low 13 second cars deep into the mid 12's depending on driver and vehicle. Very impressive. |
Posted By: fumanchu
Date Posted: October-30-2012 at 8:13pm
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Thanks for the info. Cant really see going more than .500 on lift w/ P heads, due to the fact that flow drops off .... Just wasnt sure how much duration I can get away with, especially since I dont want to suck water into a cylinder. I wouldnt mind a bit more lope at idle,.. I'm not passing emmissions or needing vacuum to power accessories like a car. Performance on a budget is what I'm after. ------------- '89 2001 |
Posted By: TX Wind
Date Posted: October-30-2012 at 8:27pm
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Quite honestly, if you take a look at Tim's cam specs and the factory ones there's not a lot of difference if you use 1.7 rockers. The big difference is in the lobe separation. The reason for this is that the tighter lobe separation gives more hole shot. So....a pretty close to stock grind with the 112 separation should give you a real nice match to Tim's cam if you use the 1.7 rockers. You will have a little less hole shot but a wider power band. If you're custom grinding one, you can probably ask for a tiny bit more duration but there's not much need for it. You're already gonna make about a 60 H.P. improvement by adding new rockers and heads. It should be pretty noticeable. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=5622" rel="nofollow - 1967 SN Interceptor 1985 |
Posted By: ultrarunner
Date Posted: October-31-2012 at 5:41pm
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Hey Jeff, just noticed your comment above..... I have the GT-40 in my '99 Sport and while it doesn't have a ton of hours on it, they are working hours, so I suspect an overhaul will be in order in the next few years.... With that said, with it all apart, would your recommendation, for course and wakeboard use, be to go with P-heads, cam and rockers during the rebuild. It would seem the most bank for the buck and certainly a significant power increase over stock.... Thanks, Mark |
Posted By: TRBenj
Date Posted: October-31-2012 at 5:47pm
The 60hp increase comment was in reference to the base (240-255hp) 351w, not the HO (285-310hp). I would expect a 15-20hp upgrade over the 310hp GT40 with a better cam and P heads. The p heads are a *little* better than the regular GT40's that came on the GT40, but not a lot- so you wont see the same bang for your buck by upgrading. That being said, it wont cost much more to go with new/refurb'd P's on the rebuild than it would be to have your GT40's rebuilt... and the P's dont seem to be as prone to external water jacket cracks as the regular GT40's are. So, while you wont see the big gain in hp by switching, you'll see something with the slightly better flow and smaller combustion chambers. Plus, if your GT40 heads are still in good shape, you can make some of your $$ back by reselling to a Mustang guy, as theyre more sought after for automotive applications. ------------- |
Posted By: TX Wind
Date Posted: October-31-2012 at 9:55pm
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I concur Tim. He may even get all of his money back as the 40's go for a bit more money than the P's. A little more lift in the cam will give a few more ponies. Maybe 15 and 20 if you're lucky. If you really want to get more than that you could have the heads ported. That will open the flow up a bit. But honestly, 330 hp in the older boats is a heck of a punch. Maybe you could under drive the tranny. The 1.52:1 Velvet drives are awesome and IMHO offer a significant advantage in hole shot over the PCM 1.23:1. We have boats with all 3 trannies and the 1.52:1 is amazing. IF....you were going to try to do that, research a bit. The typical prop size on the 1.52:1 is 14x18 and I don't know if that will fit your boat or not. It also requires a 1 1/8" shaft and strut. For slalom and wake board, I'd stay 310hp and look at the tranny. OK Tim....blast me apart now. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=5622" rel="nofollow - 1967 SN Interceptor 1985 |
Posted By: TX Wind
Date Posted: October-31-2012 at 10:05pm
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I might add to that, the 351w properly maintained is designed to withstand a TON of working hours. I would not be surprised to see many of the boats on here with a thousand plus and still pumping strong. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=5622" rel="nofollow - 1967 SN Interceptor 1985 |
Posted By: TRBenj
Date Posted: October-31-2012 at 11:36pm
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I disagree that the 1.52 is worth considering. There's a reason why mc has gravitated closer to the PCM reduction ratio (1.26) in their mainstream motor(s). I think it's been found to be pretty optimal for all around ski boat use. Besides, the bw can't reverse the direction of engine rotation, so you're talking a lh prop with that set up, and all the handling abnormalities that come with it. Would need to change prop, strut, shaft log, shaft, and most likely rear engine mounts- in addition to the tranny itself. It's also commonly accepted that the slot boats are slower up top, which is not the case with the 1.23's (as compared to the 1:1's). ------------- |
Posted By: TX Wind
Date Posted: November-01-2012 at 4:59am
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Mark, Tim is right about the handling issues. If you have a 1.23:1 tranny, you're stuck with it unless you reverse the rotation of your engine when you change trannies. In other words, it would become expensive and involved and adding h.p. is a much cheaper route. There's a reason Tim is a Grand Poobah here. He knows a ton about boats. However...for a slalom and wake board boat, especially a larger heavier one like yours, I will say this at the expense of having my head handed to me. There is a reason that a less than 15 yr old Mastercraft boat company snatched top sales honors from Correct Craft and it was called the Powerslot(the 1.52:1 tranny). With the advent of wake boarding and so many boats going to v-drives, the direct drive had to become more versatile. A very small percentage of boats are direct drive now. Because the new engines made so much power, it made more sense to go to the 1.23 ratios. Like Tim says, they are better all around. However, if you wanted a slalom/ wake board boat and could custom design the setup, the 1.52:1 is my choice 6 days a week and twice on Sunday. The difference in hole shot is overwhelming. That's just my personal experience without discounting anything Tim has said. If you have a 1.23:1 setup, that's an expensive transition in order to keep the prop rotation right. However Tim, in these newer, longer, heavier, and wider platforms I would think that is less of an issue than it is in the older smaller boats. I could be wrong. If you do have a 1.23:1 already, I would spend my money on H.P. For the difference in what the conversion costs, you could do some awesome power upgrades. The truth is, unless you do some aftermarket head work, I doubt you will get the 351 to do much better than 330 h.p. and still have normal functionality and that's about where the new rockers and 40P heads will take you. Porting the heads might get you a little more. Question Tim. Was the 351w with the 1.23 still a RR engine because a LR engine opens some new doors honestly. I could swear my brother's Nautique with the 1.23 is LR. If it's LR, go roller, then think about the 40P vs. 40 heads. The roller cam allows the lifter to stay at the max. lift for longer and also allows for much higher lifts than the flat tappet cams. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=5622" rel="nofollow - 1967 SN Interceptor 1985 |
Posted By: phatsat67
Date Posted: November-01-2012 at 11:18am
| Anything to my knowledge with a right hand prop and a direct drive 1.23 was a standard rotation engine TX. |
Posted By: TX Wind
Date Posted: November-01-2012 at 11:34am
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What tranny do you have Mark? If you have a LH engine, you have more choices than the RR guys do. ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=5622" rel="nofollow - 1967 SN Interceptor 1985 |
Posted By: ultrarunner
Date Posted: November-01-2012 at 11:38am
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Hi Jeff, thanks for the recap. I do have the PCM 1:23 with the GT-40. So it sounds like cam, rockers, and P-heads...maybe even flow 'em. Then prop accordingly..... MS |
Posted By: TX Wind
Date Posted: November-01-2012 at 11:49am
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Sorry Mark. I was so caught up in the RR talk that it didn't occur to me immediately you might have a LR engine. So cool...I'd go roller cam then personally. Maybe the GT-40P heads and some porting. I wouldn't be surprised to see you climbing above the 1hp per cube mark that way but you need to make your head decisions before anyone can advise you on best cam. What would you say Tim? ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=5622" rel="nofollow - 1967 SN Interceptor 1985 |
Posted By: gun-driver
Date Posted: November-01-2012 at 12:05pm
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The GT-40 with a 1.23:1 is a lefty with a right hand prop. When I rebuilt my GT-40 I went with the P's and a CR cam (dont have the cam #'s in front of me now)I stayed with the stock rockers because I didn't want to mess with different valve covers. It did up my top end a little, it will run around the 50 mark maybe a touch north of 50 but I never got a GPS speed on the stock 1442. I did play with a 1442 that I had Delta take some cup out of and as the hole shot may have increased some the top speed dropped to 47/48 mph as the RPM increased to the 5400/5500 mark. With the stock 1442 the hole shot is still more than you would ever need and gives a better top end. |
Posted By: 81nautique
Date Posted: November-01-2012 at 12:08pm
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A little late to the party but if you are going to go with a set of P heads and spend money to have them ported it would be prudent to look into some aftermarket heads that will perform better out of the box than just about anything you can do to a set of P heads. If you're porting the P's yourself then go for it but I wouldn't spend money on them to have someone else do it, there are better options out there. You can find aftermarkets starting around $1000/set fully assembled and they will blow the P's away. Check out RHS and of course AFR are very popular but do some homework on whats out there. P's are a great drop in for a stock 240 hp base motor but the gains per dollar might be greater with something else. Ancient history for me now but my 81 was up around 380 hp with a set of cast iron RHS heads ported and gasket matched to the intake and exhaust and that was running a fairly mild .460 cam. I also don't like the geometry of the 1.7 rockers so I would try to spec the cam properly from the start and stay with 1.6 ratio rockers. Assuming you go with aftermarket heads you will need stud rockers and my 1.7 rockers bound on the studs and needed some machining to get them working properly. I just think there's some more planning needed before you jump the gun and start buying parts. Any head swap costs a lot more than you think once you get into gaskets, etc so do it once and do it right. ------------- You can’t change the wind but you can adjust your sails |
Posted By: phatsat67
Date Posted: November-01-2012 at 12:14pm
| RHS kicks but at all 3 of the big 3 heads and they are cheap! |
Posted By: 81nautique
Date Posted: November-01-2012 at 12:25pm
Plus, you will never get the ports on the top set of heads from the heads in the bottom of the photo.  And don't forget about the larger valves aftermarkets will have  I just think it's time to stop and do some more homework before spending any money. ------------- You can’t change the wind but you can adjust your sails |
Posted By: phatsat67
Date Posted: November-01-2012 at 12:30pm
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.....and the smaller combustion chambers with better quench area! Those sure are pretty. Those heads solve the problem of small Ford exhaust ports ;) Whats the valve size 2.02? 1.88? I'm considering a ported set of those on my 360 this winter 
|
Posted By: TRBenj
Date Posted: November-01-2012 at 12:41pm
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Again, the 1.52 is not worth considering... LOTS of expense with all new running gear, and you'll end up with a LH prop unless you revert back to a reverse rotation engine (a whole different can of worms and $$$). For what might amount to a VERY slight holeshot advantage and a reduction in top speed. Ive held my own against 330+hp 'slot boats with my 1.23 out of the hole, and then walked away. The PCM trans is a great all around box with the reduction, and also allows a LH engine to turn a RH prop. Win/win/win, dont try and reinvent the wheel here. I agree with Alan... if wanting to freshen things up and get a little more hp (~325ish) then bolt on some P's and throw in a flat tappet Cam Research stick. Paul's '95 siggy runs real strong, as he said. If wanting to push it beyond that point, aftermarket cylinder heads and a roller cam are worth considering... in the end those 2 upgrades will probably set you back an additional $1000-1500 over the p-head combo, and allow you to push the 375-400hp mark, if done right. Whether the stock GT40 fuel and ignition system will allow you to take advantage of the better parts or not remains to be seen... if youre going to be upgrading injectors and remapping A/F curves, the project becomes a bit more involved (and expensive). It all depends how fast you want to go and how much you want to spend. Like Joe said, "Whats money, but paper waiting to be turned into horsepower?" ------------- |
Posted By: 81nautique
Date Posted: November-01-2012 at 12:49pm
2.02/1.60, Stock pistons (on a SBF)should have plenty of relief for them but clearance must be checked when changing cams. ------------- You can’t change the wind but you can adjust your sails |
Posted By: phatsat67
Date Posted: November-01-2012 at 12:50pm
| You can go as fast as your wallet. |
Posted By: gun-driver
Date Posted: November-01-2012 at 3:32pm
| As Tim said about the GT-40 I don't think you can do too much untill someone comes up with a tuner for the computer. |
Posted By: TRBenj
Date Posted: November-01-2012 at 3:40pm
Youre probably right, but its still TBD how far you can push it based on the stock GT40 ignition, fuel system and ECM. Theres at least one http://correctcraftfan.com/diaries/details.asp?ID=683" rel="nofollow - stroker GT40 in existence, no idea how extreme it is or what modifications (if any) were made to make it run reliably (or not). Personally, Im waiting on Joe to be the pioneer... he's got that '95 GT40 dissected and all the parts identified- just waiting for some love. I plan to follow suit with an EFI Ford stroker, right after he figures out all the hard stuff.  ------------- |
Posted By: ultrarunner
Date Posted: November-01-2012 at 4:24pm
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Well, plenty of Mustang tuners out there that may be able to provide some input, and there are tools out there to let us re-map the existing chip, but not sure how effective that would be on just the stock motor, being normally aspirated. I re-chiped my Audi a bunch of years ago, but in that case, I started with a twin-turbo V6 and could take advantage of what that motor turns out in other applications.... But with all that said, I'm thinking it would be fairly easy to remap our existing chip to account for another 50 hp's or so. That or I'll just get a Python and be done with it
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Posted By: TRBenj
Date Posted: November-01-2012 at 4:31pm
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I dont think its possible to reprogram the existing ECM- PCM has it locked down. It could, of course, be replaced with something tunable... but you'll be starting from scratch on the A/F curves. I would guess it to be a slightly more complicated than a "fairly easy" task, as surely there are significant differences between automotive and marine applications (otherwise PCM would be slapping a generic tune on their motors rather than putting the R&D into their own). But then again, Im no software guy! A healthy 351w (north of 1hp/ci), or better yet, a stroker 351 (393/408/etc) thats built properly should outperform the Python powered boats without much of a problem... and not have the 300 lb weight penalty associated with the big block. Those Python boats only ran 50-51mph. ------------- |
Posted By: ultrarunner
Date Posted: November-01-2012 at 4:40pm
| I'd agree, you could make a much better motor out of the 351 than a Python... |
Posted By: TX Wind
Date Posted: November-01-2012 at 10:25pm
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Just to clarify Tim. I thought we were initially talking about a RR engine with some limitations because of the cam sizing available. That is why the suggestion of the 1.52:1 for hole shot. However, with a LH engine, that's another story. Lots of better options to choose from. I was unaware AFM heads could be had that cheap. The ones I've seen have been twice that much. As far as the ECM's go, there are definitely tunable marine ECM's out there. They start around a thousand bucks or so. http://www.whiteracing.com/ecms.html%20" rel="nofollow - Programmable ECM's ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=5622" rel="nofollow - 1967 SN Interceptor 1985 |