5200 rpm from 302
Printed From: CorrectCraftFan.com
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=39589
Printed Date: November-24-2024 at 4:07pm
Topic: 5200 rpm from 302
Posted By: wolfman
Subject: 5200 rpm from 302
Date Posted: August-04-2016 at 10:16am
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The 78 tique is hitting 45 mph GPS at about 5200 rpm. Noticed this last night after a tuneup. I only do it for 30 seconds or so. Should I be not letting it get above 4400 rpm like the owners manual says? Just got a boom this week and am going to start footing. I am 6'6" 250 lbs so my barefoot speed is about 45. Wondering if I am overdoing it or maybe my tachometer is off. Thanks for input. Will test more this weekend but I think my speed at 4400 is about 41 or so. Jeff |
Replies:
Posted By: 8122pbrainard
Date Posted: August-04-2016 at 10:26am
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Jeff, Confirm the RPM with a shop tach. What prop is on the Tique? If the 5200 is correct, it's on the high side. Even though the manual says 4400, you can run them higher. My Tique at WOT runs about 4800. ------------- /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: halfnelly
Date Posted: August-04-2016 at 10:31am
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I would verify on a good shop tach, the in-dash gauges are famously inaccurate. My tach in my 94 is at least 200 RPM off what the PerfectPass says at WOT. 5200 won't hurt anything if it is actually revving that high, but you might pick up a bit more top end with a prop with more pitch since it'll put you back in the powerband a few hundred RPM lower. Any idea what prop is on there now? |
Posted By: TRBenj
Date Posted: August-04-2016 at 10:42am
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Pete, you've always reporte 4200 with your 12x14 Oj. If it's creeped up over the years you may want to break out the shop tach too! Propping for 4400-4600 at wot will net the best performance. Tell us which prop you have and we can likely tell you whether the tach is lying or if you're propped incorrectly. 5200 won't damage the motor but you'll be underperforming if it's legit. A footer will drag down the top speed of a 16'/302 boat about 3-4mph in my experience, FYI. |
Posted By: 8122pbrainard
Date Posted: August-04-2016 at 11:40am
Tim, Yes, I did report the 4200 when I first got the Tique. Then I did break out the shop tach! Jeff, As mentioned, the dash tachs can be off pretty much. Plus, they have a tendency to jump around making them hard to get a good reading. ------------- /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: August-04-2016 at 11:51am
I think you need a new shop tach... Either that or your prop is worn out. Or maybe your Tique is running ~51-52mph? 
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Posted By: Gary S
Date Posted: August-04-2016 at 11:58am
Should have a prop on there Tim that's not as old as his points or impeller,remember not that long ago his son rearranged the underwater gear  ------------- 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: 8122pbrainard
Date Posted: August-04-2016 at 12:27pm
I'm still running the OJ. ------------- /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: TRBenj
Date Posted: August-04-2016 at 1:02pm
| Then the shop tach is lying, or your prop is tired/improperly rebuilt... A 12x14 Oj should under turn by 300-400rpm on that hull. I assume you're running the more typical 46-47mph vs the atypical 50-52? The latter would indicate a pretty fast hull and/or 250-275hp from that 302. |
Posted By: Hollywood
Date Posted: August-04-2016 at 1:38pm
| If your tach needle is bouncing you've got issues. |
Posted By: 8122pbrainard
Date Posted: August-04-2016 at 2:03pm
Yes, it's called rough water and or hull porpoising.  ------------- /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: 8122pbrainard
Date Posted: August-04-2016 at 2:18pm
Tim, Well now I'm going to have to go and buy a new shop tach dwell meter. Then, I suppose I'll also need one of those new fancy phones with GPS on it since my old Trac Phone only makes phone calls!! BTW, since you have that memory like an iron trap and mine is fuzzy, aren't I running a 13x12 OJ? You mentioned a 12 x 14. ------------- /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: TRBenj
Date Posted: August-04-2016 at 2:25pm
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Should be a 12x14, Pete... 12x13 is ideal but you always claimed you wanted to lower the revs for all the wot runs your family likes to do when you're not around. 13" diameter is too big for that hull- hull clearance is too tight, especially on an oj or federal. Acmes aren't so bad with all their aft rake, a 12.5" diam has as much clearance as a 12" hand finished. I believe you tried a 540 acme (13x12) and took it right off because it buzzed. |
Posted By: wolfman
Date Posted: August-05-2016 at 12:24am
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It has the original Federal 12 x 14. We have a good shop tach so I will get a reading in the next day or two and will report back. My wife is even itching for a few extra mph so a new prop could maybe happen. The original has many nicks. Hopefully I get to try out the boom at the same time. Can't wait! Thanks again for all the help over the past year. Boat has gone from a backyard with a pine cone in the distributor hole I had to fish out(from a squirrel) to a fast fun reliable toy we use often. |
Posted By: MrMcD
Date Posted: August-05-2016 at 4:31am
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My 78 Ski Nautique would run over 50 MPH with a 13 x14 3 blade and tach up to 5,200 RPM regularly. The only thing not stock was the heads, I had a set of 289 HP heads, smaller chambers bumped the compression and they had extensive porting and larger valves. They did add quite a bit of pop to that 351W engine. Sold it with 1,500 hours on it so the RPM never hurt it any it still ran great. On a good day it seems that old boat would run 52+ MPH. Used to tick off the owner of West Coast Correct Craft. We skied together many times and we would launch at the same time and have to cross the lake to get to the river for the smooth water. It was about a 10 minute run across. He could not stay with me when I opened it up. His boat was equipped with a 454. He could pull stumps for sure but I had him on top speed. I don't think I ever shared the fact I was running the 13x14 prop.
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Posted By: fanofccfan
Date Posted: August-05-2016 at 10:08am
We are taking the 78 out today for the first time since early 90's.....just bought it back...will gps the speed and probably look for a 13x14. When does this pursuit of fast fun things end?!! |
Posted By: Waterdog
Date Posted: August-05-2016 at 10:55am
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With a Chevy 350 in my Tique it 's pretty fast and around 50 ish it will porpous and the speed will drop off. Feathering the throttle and driving through it could take a 1/4 mile. ------------- - waterdog - http://www.correctcraftfan.com/diaries/details.asp?ID=3896&sort=&pagenum=2&yrstart=1978&yrend=1978" rel="nofollow - 78 Ski Tique |
Posted By: TRBenj
Date Posted: August-05-2016 at 11:17am
Propping for speed isn't as simple as bolting on a steeper prop. I would skip the search for a 13x14. |
Posted By: MrMcD
Date Posted: August-05-2016 at 12:46pm
| There is a trade off in the bottom end power with a 13x14. Mine was still strong before and after adding the heads. I had to replace it twice in 10 years and performance remained the same so the prop was not a special tweak. If you ski a course regularly certainly pass on the 13x14. |
Posted By: TRBenj
Date Posted: August-05-2016 at 12:56pm
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4800rpm and 48-49 with an Acme 540 is as strong as I've seen a stock ford-powered 2gen run. Jackie's 350 with the 540 can bounce it's way to 50-51 under the right conditions. Some hulls run slow (nose planters) and only run 45. 5200rpm should have netted more than 52mph with a 13x14 on that hull so I suspect the tach and/or speedo was off... It should have been under turning by at least 200rpm. The little I know about 289 heads is that they have smaller chambers (so higher CR), I do not think they have a good reputation for flow. DO0E 351w heads from 69-70 are the only factory head I'm aware of that was worth a darn (prior to gt40's in '92 and gt40p's in '96). Still must have run pretty good if it was outrunning big blocks. |
Posted By: GlassSeeker
Date Posted: August-05-2016 at 1:00pm
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It takes alot of horsepower to turn a 13 14 at 5200rpms...like near 400...so maybe some #'s aren't quite remembered right. ------------- This is the life |
Posted By: GlassSeeker
Date Posted: August-05-2016 at 1:05pm
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My experience using 350HP on a 13x13 5100...50mph...same motor 13x14 4800 49 mph ------------- This is the life |
Posted By: fanofccfan
Date Posted: August-05-2016 at 3:27pm
| Ha! I wasn't really going to look for the 14". my first priority is a new cnc for the marauder. its running an old federal. |
Posted By: MrMcD
Date Posted: August-06-2016 at 5:59am
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I sold my 78 in 1989, but memory's is accurate. The hi po 289 head worked really well, keep in mind they are feeding the 351 at only 5200. Mine did have extensive port and polish work done. Prior to the 289 heads this 78 still ran well up to 900 hours when it burned a valve. It felt 10-15 % stronger with the new heads. We ran it another 600 hours before selling. This was all before GPS. Keaton boats introduced the updated Keaton Utility in the early 80s. Keaton advertised the top speed as approaching 55 mph and sold them as great barefoot boats. I never beat the Keaton's but ran nearly even with them. 2 of them ran with us back then. |
Posted By: fgroce
Date Posted: August-15-2016 at 9:41pm
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I know the 302 will turn up past 4400, But the farther you go past the limit the more likely you are to stretch a rod bolt. If the motor is from the mid 80's or later I would be very careful. May run a day, week, month or forever. Frank ------------- FGroce 88 Ski Nautique For 28 years Now 2002 Ski Nautique |