422 acme
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=48835
Printed Date: March-05-2025 at 10:30pm
Topic: 422 acme
Posted By: schultz227
Subject: 422 acme
Date Posted: June-10-2020 at 10:16pm
| 1992 SNOB 351 1 23 1 tranny, put a 422 on yesterday and my rpms dropped from around 4800 to 4100. Had an acme 1868 on with the higher rpms. Just wondering if the lower rpms is ok on the engine. Boat runs smoother and quieter with the 422. I am happy with it as I don’t care about top end really. just want to know if my rpms being that much lower is correct for that prop. |
Replies:
Posted By: schultz227
Date Posted: June-10-2020 at 10:22pm
| NOT High Output 351 , by the way |
Posted By: MrMcD
Date Posted: June-10-2020 at 10:36pm
I have a new 422 Acme on our 95 closed bow Ski Nautique, 310 hp version, spins a touch over 5,000. Maybe it’s time for a power upgrade!  ------------- |
Posted By: TRBenj
Date Posted: June-10-2020 at 11:12pm
| If you’re not pulling a 422 4400ish then you’re either at altitude or in a poor state of tune... or your tach is lying. Get some reliable speed numbers to help us pinpoint. |
Posted By: AAM196
Date Posted: June-15-2020 at 2:37am
| agreed... I run my 422 om my 99SN gt40 at 2,465 ft above sea level at 4,860 rpms 46 mph... |
Posted By: stepper459
Date Posted: June-15-2020 at 1:40pm
|
4,100 does seem a bit low. On my old boat I ran the 1868, 654, and 422 back to back just to see what the numbers would be. I saw a 200 RPM difference each time The boat wasn't a CC but it had a GT-40 and PCM 1.23:1 transmission. 1868 - 4700 RPM 654 - 4500 RPM 422 - 4300 RPM I'm curious to hear from NON-GT-40 people with a 422, what they're seeing for WOT RPM. |
Posted By: gun-driver
Date Posted: June-15-2020 at 1:52pm
| The OP has a ‘92 so non GT-40 not sure on which version HP motor he has. |
Posted By: Jonny Quest
Date Posted: June-15-2020 at 1:54pm
|
I'm at 4,400 to 6,000 feet of elevation with a GT-40 and I run the 654. My old boat had the H.O. carb engine and it also ran the 654. When I moved from Texas to Utah, I ran the 1868 at first, but the RPMs were too high at WOT. Great hole-shot, but I went down to the 654. I realize that your engine is NOT the High Output, so I would be leaning toward the 654. I agree that 4,100 RPMs seems too low. As Tim mentioned, you should verify that RPMs are correct and that engine is properly tuned before making too many decisions. JQ ------------- Current 2003 Ski Nautique 206 Limited Previous 2001 Ski Nautique Open Bow 1994 Ski Nautique Open Bow Aqua skiing, ergo sum |
Posted By: TRBenj
Date Posted: June-15-2020 at 1:58pm
|
schultz227 wrote: