V-drive gear selection help PLZ......

[Jim W]

I want to get about 1,000 more RPM out of my set up so I can put a bad case of whoop ass on Dans1973blownnordic....
Starting up at the top.....396 BBC 60 hrs on rebuild.
Weiand tunnel ram with 2 Holley 600's
Cast iron unported heads Code3872702 these are oval port, closed chamber, with a 3 angle valve job, 1 hr run time
Forged TRW pistons with very small pop ups
Forged crank, rods but dont know rod bolt size??? Want to stay below 6,000
Cam is a Comp Cam PN# 11-236-4 Hydraulic cam
Gross intake lift 544---Duration @ .050 226
Gross ex lift 547---Duration @ .050 236
110 C/L and is installed straight up
2 blade prop, 15 1/2 X 11 from memory???????
Motor runs hard up to 4,900 and then boat wont carry the nose up
My top gear says 6.71 38T 1.12 LH
Bottom gear says 6.71 34T 1.12 LH
Am I correct that I have 1.18 gears and 12 degree box?
To gain something close to 1,000 RPM, with my set up, what gears should I be looking for?
Anyone have a used set?
Thanks for the help, and look out Dan, Im gunning for ya!!!!!!
Be good, Jim

[Carnivalride]

My top gear says 6.71 38T 1.12 LH
Bottom gear says 6.71 34T 1.12 LH
Am I correct that I have 1.18 gears and 12 degree box?
To gain something close to 1,000 RPM, with my set up, what gears should I be looking for?
Anyone have a used set?
Thanks for the help, and look out Dan, Im gunning for ya!!!!!!
Be good, Jim
Jim,
Your gears are 1.12% overdrive, the 38T & 34T is the number of teeth per gear, the 6.71 is the made on date June of 1971 in your case. Sorry on the degree you'll have to measure the angle on the 34T gear or find the number on the housing.
Personal thought here if you can't spin 12's 6000rpm I'd look a little closer at the engine. 4900rpm with 12's and an 11-1/2 x 15p prop sounds a little off to me, I'm not familiar with your boat though either.
JMO,
Loren

[steelcomp]

I'm in agreement with Loren. IMO you should have good power to at least 5500 with that combination. You might want to check some things like making sure your secondaries are fully opening, make sure you're at the best timing, etc., and one other thing...where the valve springs upgraded with the cam??

[Jim W]

Thanks for the info Loren,
if it has 12's I am not going to mess with the gears, 18's I would have.
No matter what I do with the engine, I cant get it past 4,900 RPM. Even went to a Edelbrock RPM air gap, single carb and MSD HEI dist. and still got 4,900. Pulled all that back off and returned to the original set up.
About the only thing I have not done is check fuel pressure at WOT. The engine runs good at WOT and the plugs look good so, I have a hard time believing it's fuel starved.
I am open to suggestions.....:idea:
Be good, Jim

[steelcomp]

Thanks for the info Loren,
if it has 12's I am not going to mess with the gears, 18's I would have.
No matter what I do with the engine, I cant get it past 4,900 RPM. Even went to a Edelbrock RPM air gap, single carb and MSD HEI dist. and still got 4,900. Pulled all that back off and returned to the original set up.
About the only thing I have not done is check fuel pressure at WOT. The engine runs good at WOT and the plugs look good so, I have a hard time believing it's fuel starved.
I am open to suggestions.....:idea:
Be good, JimTurn your prop down to 15

[DansBlown1973Nordic]

You need a hole thread to figure out how to beat me.......
Maybe you have a set of pliers stuck in your intake manifold???
Maybe your fan belt is Ass Backwards.....:idea:
Maybe you have it in reverse???????
Or just maybe im a little faster.....

[Jim W]

Valve springs are new and matched to the cam.
Secondaries open fully.
Timing is at 34* although TDC has never been set with a degree wheel. Factory balancer and timing indicator on the timing chain cover. Might be something to check and verify.....
Is turning down the prop something a prop shop back here in the east could do? I deal with 2 local shops for my customers usual Merc alu props but dont know if they can do this?
Kind of funny but, I had a guy looking to buy this boat and brought his own GPS. After 4-5 passes it always showed 59.8 MPH. Dans1973blownnordic and I went out a week later and between the two of us, one of us hit 75 MPH+/- (we passed the GPS back and forth) and our boats are pretty close on top end speed. Weird.....
Be good, Jim

[DansBlown1973Nordic]

Mine was faster........

[Carnivalride]

Valve springs are new and matched to the cam.
Secondaries open fully.
Timing is at 34* although TDC has never been set with a degree wheel. Factory balancer and timing indicator on the timing chain cover. Might be something to check and verify.....
Is turning down the prop something a prop shop back here in the east could do? I deal with 2 local shops for my customers usual Merc alu props but dont know if they can do this?
Kind of funny but, I had a guy looking to buy this boat and brought his own GPS. After 4-5 passes it always showed 59.8 MPH. Dans1973blownnordic and I went out a week later and between the two of us, one of us hit 75 MPH+/- (we passed the GPS back and forth) and our boats are pretty close on top end speed. Weird.....
Be good, Jim
Jim,
I understand that the springs and cam are new and supposed to be matched but have you ever checked the seat pressure or the over the nose pressure? I'm not sure with your hydraulic cam but I would think you'd want around 130lbs seat pressure. The timing 34 sounds a little low for a BBC with iron heads. Did you read the plugs, where on the ground strap was the coloration, the elbow, or more toward the electrode? I realize I have open chamber 990's and 46cc dome pistons but mine runs best around 37.5-38 degrees for total timing.
Loren

[Marty Gras]

Dan, blown houseboats go 75MPH on Havasu, and unblown pontoons go 70MPH, what are you bragging about? Your buddy just has not given enough information to us about his boat. When he does, you will be "looking at his transom", if all you have is 75MPH!