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!!!!!!:D
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!!!!!!:D
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.......:D
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!

[Jim W]

Found this on the Drag boat alley boards.....for what it's worth.
Happy New Year everyone. I bought my wife a '73 19' Hallett flatbottom for our 20th Anniversary (Don't believe it? That's ok, she couldn't either.) Anyway, I've had about 20 different tournament inboards over the years, but this is my first flatbottom, and I suspect it is massively mal-propped.
It has (according to the guy I bought it from on eBay) a mild (9.5:1) 468 bbc with a single 750 cfm Holley and wet Bassets w/hi-perf free-flow mufflers. It's supposed to be about 450 hp. Casale is supposed to 18 over, don't know what angle.
The prop is a steel two-blade of unknown pitch, no discernable cup, that measures 11.5" diameter. It looks like a lot of pitch to me, but it's a 2-blade and I know they look a little different than the 3's and 4's I'm used to looking at.
PS: The bottom looks clean and straight and the stringers are new, so I don't think it's deforming. It sets nicely and the trim stops are set where it porpoises slightly when I'm flat out with the pedal released.
I got a gps to see what the boat was running, (well, I had to get her something for Christmas!) and at wot it runs only 56 mph at 4600 rpm. (It has a 125 hp nitrous kit on it that pushes the r's up to 5100, but the tank was empty and I couldn't get it filled over the holidays to see what the top end was with the gps.)
I just want the boat to play with on the river, but 56 mph out of a boat like this is pathetic. I like the idea of a frugal, dependable motor for cruising that you can "juice" when you want a little thrill, but am open to any tuning/set-up suggestions.
Here are my prop questions:
1. Is the diameter just too large? Most of what I read suggests 11". I don't really want to start working over this prop if it's the wrong diameter to begin with.
2. Anybody got any suggestions on diameter and pitch? What max rpm should I be shooting for? I had heard that the bbc could take 5500 safely, so is that what I should pitch for on gas, and then just let it go to 6000 when I occassionally shoot it the juice?
3. Do you guys run straight blades or do you cup them?
I would appreciate any advice anyone has to offer.
Thanks.
Steve
-------------------------------------------------------------------------
Carnivale, springs were set at 120# on the seats.
Going to check my timing tab to verify TDC and start upping the timing until the WOT speed drops according to a GPS. Figure 2* at a time will work.
Also will check fuel pressure at WOT.
Some people have said the Hallett is a poor hull. Sounds like it but I am going to tune until I got all there is to get......
Be good, Jim

[motormonkey]

I think from the information given so far, the problem is your heads.

[steelcomp]

I think from the information given so far, the problem is your heads.If they're the standard large oval port heads, they can support a whole lot more power than he's making here. More timing may help. Have you tried moving the cam around? How did you go about choosing that specific cam grind? My guess is there's room for improvement there with a little more duration.
120 on the seat is plenty.

[CircleJerk]

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
Thanks for the help, and look out Dan, Im gunning for ya!!!!!!:D
Be good, Jim
Am I missing something here, what kind of boat? an old heavy weight? Kind of makes a difference I think. I have run two 402s in circle racing 700Lb hulls aand found you need open chamber heads for whatever compression you are running unless your motor sees 7500 frequently. I have never got closed chambered 325 ccs to work below 7000 even though you have a relatively small volume oval port. Your camshaft is way smaller than I run example: lift 610-640 with 280-300 degrees duration and a solid or roller lifter. Dual fours we have found are only for looks in a boat unless you see the high rpms to adequately use the cfms. However, in a flat bottom, your combination should see 65-75 mph. Incidently, I hate Comp cams, we cant keep them alive and my favorite one just snapped in half while my wife was driving about 60mph! I guess I am not much help....

[Jim W]

If they're the standard large oval port heads, they can support a whole lot more power than he's making here. More timing may help. Have you tried moving the cam around? How did you go about choosing that specific cam grind? My guess is there's room for improvement there with a little more duration.
120 on the seat is plenty.
Steel,
to answer your questions......
Agreed, more timing may help. I will check TDC, index the timing tab and see what advancing 2* at a time does.
Have not tried moving the cam timing around. If I remember right, the gears are set up so they can be moved around.
The original cam flattened 3 lobes and the new cam was picked by going by what was in there. Not an exact replacement, but close. I wouldnt have a problem buying a new solid lifter cam if one could be speced out.
Also have a good set of 130# springs, Edelbrock RPM air gap and MSD HEI if needed. I am just not convinced that the engine is holding things back (hull????) since I have made pretty big changes with no more RPM.
Your thoughts?
Be good, Jim

[Jim W]

Am I missing something here, what kind of boat? an old heavy weight? Kind of makes a difference I think. I have run two 402s in circle racing 700Lb hulls aand found you need open chamber heads for whatever compression you are running unless your motor sees 7500 frequently. I have never got closed chambered 325 ccs to work below 7000 even though you have a relatively small volume oval port. Your camshaft is way smaller than I run example: lift 610-640 with 280-300 degrees duration and a solid or roller lifter. Dual fours we have found are only for looks in a boat unless you see the high rpms to adequately use the cfms. However, in a flat bottom, your combination should see 65-75 mph. Incidently, I hate Comp cams, we cant keep them alive and my favorite one just snapped in half while my wife was driving about 60mph! I guess I am not much help....
Circle,
1971 Hallett flatty v-drive.
I do have 2 or 3 sets of bare heads in my shop. Will check and post up casting #'s today.
Agree with the dual 4 thinking. That's why I tried the RPM Air Gap, Demon 850 (too big I know) and MSD HEI. All that and a cam/lifter swap, fresh valve job and gained 100 RPM??????
Anyone here know of a sorted out 396 with some big HP#'s???? Would love to copy it.
Be good, Jim

[058]

Here is my take on this...The Hallet is a good hull, quality wise in the same league with Howard, Mandella, lavey etc. So I doubt the hull is what the problem is. heavy? yes but I doubt weight is the issue. 1st thing I would do is bump the total timing up to 37-38 deg. 2nd: I would zero lash the valves as I think the hydralic lifters are pumping up, killing power above your stated 4900 rpms. Do the simple and easy things first before you go chasing your tail swapping heads, manifolds, pistons etc. Your 396 should have no problem turning 5500-6K with 12% gear and a 11 x 15[?] prop. Many years ago when I bought my Howard wood deck [950-1000lbs bare hull] I threw a 429 BBF from a 70 T-Bird together that had 150+K miles on the clock when pulled, installed a fresh set of stock D0VE heads, lumpy hyd. cam and a Weiand tunnel ram w/2 600 Holleys but untouched stock short block. It turned the 11.5" x 15 prop 5800 rpms thru a 22% geared split case box.

[QuickJet]

Just bury the up pedal when it noses over........;)
Seriously though, I'd move that cam. Put it somewhere in the garage on a shelf and save it for when you buy an RV with a 454.
The Isky Z-89 is a great solid flat tappet camshaft.
I had a 396 in a 69 Chevelle with a single Victor, Isky Z-89, 049 heads (which never work) and a set of 4.10's that ran 11.90's. The car weighed 3,800 lbs with me in it. I was surprised that little motor ran so good.
Of course the 454 I put in later ran much better..........

[Jim W]

OK, just looked at the spare heads.
353049
Ported and polished by who knows who. Open chamber, oval port 122 CC chambers. These heads would put my C/R down around 8-1
336781
Untouched. Open chamber, oval port 118 CC chambers. these would put me down around 8.5-1 C/R
With the 3872702's I am using now, I should be around 10.5-1 C/r
I think after checking fuel pressure, ign timing and zeroing the valves a cam change might be the thing to do.
A couple of years ago I spoke to 76barron (John) about a strong runing 396 he had but dont think he is still active on Hot Boat?
Here in NY it's a whopping 58 degrees and misting rain so, it might be later this week I can get back on the water.
Be good, Jim

[502 JET]

Is it possible for the top and bottom gears of the v-drive to get switched around? Or will they only go in one way?
A hypothetical situation, if they were switched would this contribute to holding back the engine/rpm's?

[DansBlown1973Nordic]

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!
Ha Ha Ha!!!!!!!:D

[Jim W]

Ha Ha Ha!!!!!!!:D
Shut up Dan!!!!!
The experts are thinking........Don't disturb em.
Be good, Jim

[motormonkey]

Check and make sure that your heads have had the guides cut. Any lift over .490 will push against your guides and flatten a cam.Oval port heads with stock size intake valves wont make the rpm you think in a boat, cars will make it because the is less.

[steelcomp]

Jim W...sent you a PM.

[cstraub]

I'd get the 049's flowed, put a cam in the ole girl and run the hell out of it....

[Jim W]

I'd get the 049's flowed, put a cam in the ole girl and run the hell out of it....
The only problem with that is going from 98 CC chambers to 122 CC chambers. Compression goes from approx 10.5-1 to 8.7-1.
Of course I could run old stale gas which would be cheap enough to run but the HP might just suffer a bit......
Be good, Jim

[steelcomp]

Well, you can get another set of pistons. While you're at it, see if you can find a 454 crank, and maybe bore the block (you're buying new pistons anyway) then you'll have plenty of compression. :D
It's no problem for us here to spend your $$ for you. We just want to see you go faster!!! :eek: :)
Faster, faster, faster!!!!!!!!

[DUCKY]

Even good valve springs if installed at an incorrect height will cause valve float at very low RPM. You need to pop a few springs off and check your installed height, seat pressure and open pressure. If think you will find the problem there......

[DansBlown73Nordic]

This picture tells the story.....:D
http://www.***boat.com/image_center/data/500/100_1336.jpg

[DansBlown73Nordic]

Jim you better get use to this picture......Its all your going to SEE!!!!!:D :D :D
http://www.***boat.com/image_center/data/500/100_1287.jpg

[Carnivalride]

And just what story is that neither boat is planed out or under hard acceleration? :rolleyes: :D
This picture tells the story.....:D
http://www.***boat.com/image_center/data/500/100_1336.jpg

[MACHINEHEAD]

Verify TDC, Verify fuel preasure. Do the zero lash thing. 38-39 degrees is the number with closed chambers if I recall. A 226 at .050 cam. 4900 sounds about right. To answer your Question. Divide the rpm you WANT by your current rpm and that will be the percentage of more/less gear you need to buy.

[Moneypitt]

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?
Circle,
1971 Hallett flatty v-drive.
Jim
Sorry, doesn't compute......LH circle boat??
34/38 teeth= 1.117647....or 12% over, I would call those gears 12s...MP

[palhal]

Jim W-----Time your boat at the lake. Have someone drive it at 3000 RPMs and hold it there while you turn the Ign. back and forth until you find the sweet spot and lock it down. Stop the boat and see if it will start. If it bumps and has a hard time turning over retard the Ign.just a little until the starter is happy (retard goes with rotation). Don't worry you can't hurt the Engine. We time them on the dyno at full throttle! Once this is done the Engine will be happy and you can go on to find out the other problems you might have.-----PALHAL

[Jim W]

MP,
I just went through my posts and dont see where I said circle???
Did I miss it?
MP, just found what you are refering to. I was replying to circlejerk's comment.
Be good, Jim

[Moneypitt]

MP,
I just went through my posts and dont see where I said circle???
Did I miss it?
MP, just found what you are refering to. I was replying to circlejerk's comment.
Be good, Jim
Yeah, now I see how it was written......I always call Boyd CJ.....I think 120# on the seat is a little weak for a solid cam........Could be your "governer"......MP