WOT RPM for a 390 with 7.4

[riptide]

Does anyone have a 390 with 7.4/caburators that is running good,what is the top RPM and speed also what is your timing set at/ Thanks ...Rip

 

[390x]

With 4 blade dyna-quad's (19x17), timing set at factory specs (can't remember what that is, 8*btdc, I think), 4300rpms @ 28.5mph

 

[Searaybio270]

Not sure if this helps but I tested my boat a few weeks ago. At 3200RPM I was at 27MPH. I do have the 7.4L but not carbs. I have 3 blade props.

 

[rondds]

Spec is 4200-4400.

 

[Nehalennia]

Not sure if this helps but I tested my boat a few weeks ago. At 3200RPM I was at 27MPH. I do have the 7.4L but not carbs. I have 3 blade props.

Are you on a trailer?

 

[Searaybio270]

No. Not on trailer. The data came from my GPS after I reset to zero and then tested it going up the river and then back down.

 

[rondds]

are you on a trailer?

lol!!

 

[Gone Boating]

Not sure if this helps but I tested my boat a few weeks ago. At 3200RPM I was at 27MPH. I do have the 7.4L but not carbs. I have 3 blade props.

Wow. That's impressive.

 

[rondds]

Joe, that IS impressive, bordering on impossible. Are you sure? I have the same engines as you, and with 20 gallons of water, 1/4 tanks and three people on board, I can barely break 21mph at 3200rpm. Granted I have a lot more wind resistance than you, but you're heavier, wider and longer. Also have 3 bladers which are Prop-scanned and the boat is tuned up. I've had the boat for 7 years and never got that speed at that rpm - I WISH!!!

 

[sea salt]

No. Not on trailer. The data came from my GPS after I reset to zero and then tested it going up the river and then back down.

GPS is accurate but how accurate are your tachs? Also, what is your WOT RPM and speed?

 

[Searaybio270]

GPS is accurate but how accurate are your tachs? Also, what is your WOT RPM and speed?

Good question about the tachs. Now I am questioning what I saw. WOT per the survey is 4500 RPM. I will have to re-read the survey to get the speed. I have to go to NY this weekend but when I get back I will check the speed and the tachs again.

 

[Summer Fun II]

I have to go to NY this weekend

What part of NY are you coming to ??.

 

[xravenx]

Good question about the tachs. Now I am questioning what I saw. WOT per the survey is 4500 RPM. I will have to re-read the survey to get the speed. I have to go to Baltimore Inner Harbor this weekend, I will check the speed and the tachs again.

Fixed it for ya

John

 

[techmitch]

Joe, that IS impressive, bordering on impossible. Are you sure? I have the same engines as you, and with 20 gallons of water, 1/4 tanks and three people on board, I can barely break 21mph at 3200rpm. Granted I have a lot more wind resistance than you, but you're heavier, wider and longer. Also have 3 bladers which are Prop-scanned and the boat is tuned up. I've had the boat for 7 years and never got that speed at that rpm - I WISH!!!

Ron, remember he's got that super slick bottom paint on his boat. LOL

 

[rondds]

Ah, the teflon bottom!

 

[Searaybio270]

What part of NY are you coming to ??.

Delaware County, small town called Roxbury. South and West of Albany and Kingston.

 

[Searaybio270]

Ron, remember he's got that super slick bottom paint on his boat. LOL

Ok, I said I will check it again when I get back. I did say I was going "Down" the river. LOL