Prop to Cavitation plate Distance??

[biesemeyer34]

The distance from the back center of prop to back center of cavitation plate was given on forum a while back. I think it was 28 inches or more??? Does anyone have that figure and does it make any difference whether you have a runner bottom or circle boat --- How about the strut angle 7, 8 , or 9 , will the distance be different??? This relationship must be critical because of the nickle in the coupler trick to change a few thousands. Jimmy D

[V-DRIVE VIDEO]

JD
Since your trying to replicate the performance of a top notch superstock or prostock boat, why not go to the guys who build them. These boards are bound to bring a plethora of different answers, why waste your time trying to make heads or tales of a bunch of different answers when the best set up is just a phone call away from the true experts. :confused:
JG

[biesemeyer34]

You are probably right but I like to get answers from the forum gang. How about that Vice Presidential debate. A real snoozer. Jerry I will follow your advice and make some calls . Jimmy D.

[Moneypitt]

b34, I think the dimension you're looking for is to the back of the strut barrel. The location of the strut is usually forever, the actual position of the prop could vary with different props, shorter prop shafts, and/or the addition of 25 cents or so worth of nickels. If you walk around the circle boat pits you will see all sorts of different set ups, as each boat, and each driver are different. 2 boats, from the same mold, made back to back, will be different in some minute ways. I would gladly give you the number from the PS 89 boat, but the boat lives in BHC and I'm in Newbury Park Ca..........I'll bet Billy can give you some ballpark #s, and if Finishline George sees your post, he could also take an educated guess as well as tell you WHY..............Ray

[CircleJerk]

Hi jimmy, did you get the pictures I sent? Did you like the butt shot? Kyle is a good photographer, maybe we can hire him..........Does anyone think an old ambulance tow rig is over the wall??? I have a 1963 Belair 409 one for sale......How about it JD? :notam:

[biesemeyer34]

I have a ski - sprint bottom hondo that has a 11 inch plate. Although the barrel of the strut is fixed I can cut the plate down up to an inch and a half and not get too close to the plate bosses. The plate sucks down terrible at over 80 and chatters like a nervous virgin on her first date. No matter how high you raise the center for propwash relief it still sucks and has a 150 foot roost tail indicating massive drag . In nickles in the prop shaft coupler I would run out of set screw area to get close to where I think the prop should be in relation to the "true back" of boat. Moneypit can you see what options I have now? Another history about the boat ---- It had a 10 degree strut from Hondo and I changed it to a 7degree 30 minute Wayne Mettler Strut to get the casale out to 96 inches.

[BILLY.B]

I have a ski - sprint bottom hondo that has a 11 inch plate. Although the barrel of the strut is fixed I can cut the plate down up to an inch and a half and not get too close to the plate bosses. The plate sucks down terrible at over 80 and chatters like a nervous virgin on her first date. No matter how high you raise the center for propwash relief it still sucks and has a 150 foot roost tail indicating massive drag . In nickles in the prop shaft coupler I would run out of set screw area to get close to where I think the prop should be in relation to the "true back" of boat. Moneypit can you see what options I have now? Another history about the boat ---- It had a 10 degree strut from Hondo and I changed it to a 7degree 30 minute Wayne Mettler Strut to get the casale out to 96 inches. B34, what kinda HP do you have?. My strut from the back of the barrel to the transom is 21". Now I can tell you this location is the same as when I ran the boat as a SS or a K. The problem I had when switching to more HP or less as was the case with the SS was the cavatation plate length. Shorter plate with lots of HP would suck the plate and cause the bow to search. The second I put the longer plates on the boat ( with more HP) that problem went away (along with some other little stuff I did :rollside: :rollside: ). Sounds like you need more spring pressure to hold the plate, and by moving the prop back as you say with nickles that will cause the bow to stick and why do you want to do that????. My plates are only 10" long from the transom to the end of the plate. I think you should be around 7" to 9", again this depends on HP!!!!. Just my .02.

[LeE ss13]

The distance from the back center of prop to back center of cavitation plate was given on forum a while back. I think it was 28 inches or more??? Does anyone have that figure and does it make any difference whether you have a runner bottom or circle boat --- How about the strut angle 7, 8 , or 9 , will the distance be different??? This relationship must be critical because of the nickle in the coupler trick to change a few thousands. Jimmy D
26" with 7 1/2 degree strut with the V-Drive at 96".

[Moneypitt]

B34, just last weekend @ Bakersfield I was trying to help the PS 360 boat figure out a plate setting problem, only to discover the bellcrank at the back of the plate rod was loose on the cross bar that operates the arms to the plate. This was also a problem on our PS 89 boat back in the early 90s. Could this be a factor in your attempts to stablize your boat? Have someone hold the plate, use the pedals, and check for actual travel/stability of the plate. MP
PS: come on Billy, you can tell him the other things you've done. "Little" as they may be, I won't look................Ray

[biesemeyer34]

Billy, thanks for your response. The horsepower is approximately 825. It is a bow tie 495 inch with dart 320's , roller , 14.5-1 comp. Single dominator. running on 116 octane. LeE ss13 thanks for your post also , is there a formula for that figure or just a hell of a lot of trial and error and experience.

[BILLY.B]

Billy, thanks for your response. The horsepower is approximately 825. It is a bow tie 495 inch with dart 320's , roller , 14.5-1 comp. Single dominator. running on 116 octane. LeE ss13 thanks for your post also , is there a formula for that figure or just a hell of a lot of trial and error and experience. You said the the v-drive is now in at 96". Where's the engine in at???. My strut to the back of the cav plate is 31". I stand corrected on the strut to the transom. Mines at 21", plus a 10" plate= the 31"#. I would ck the control arm to make sure it's not slipping on the transom bar (worn out keyway or sloppy control arm if it's aluminum), MORE SPRING PRESSURE!!!!, and proper plate setting. As far as your HP goes i'd still stay with the 7" to 9" plate . A buddy of mine has the twin turbo small block Biesemeyer that has been on these boards in picture form. He had terrible handling problems before we did a complete make-over. Moved the engine forward 12" and then I had him shorten the plates from 11" to 7" and walla a hole new animal was born. Boat ran around 105 out of control and went up to 121 on gps and stable after the re-due. Of course there was some bottom work done but i'd say the major deal was the engine placement and cav plates. Oh his HP is 875.

[Thunderbutt]

Hi jimmy, did you get the pictures I sent? Did you like the butt shot? Kyle is a good photographer, maybe we can hire him..........Does anyone think an old ambulance tow rig is over the wall??? I have a 1963 Belair 409 one for sale......How about it JD? :notam:
Do remember the Mortician? and it was black

[V-DRIVE VIDEO]

MORE SPRING PRESSURE!!!!, and proper plate setting.
Well Jimmy D, its not like you haven't heard this suggestion before! :notam:
Billy, JD uses rubberbands to hold his cavitation plates up. :devil:
JD, Are you trying to duplicate the B' boat set up on the Hondo????? :confused: I thought you were selling that boat???
Billy obviously has solid advise and Moneypitt crews on one of Billy's old boats so your in good hands there....FOR YOUR BIESEMEYER!!! :p
I can't believe I got out of Washington without a good woodshed beating. :messedup:
Jerry :D

[biesemeyer34]

v-drive Do you know the other way to use rubber bands, ---farmer/ranchers use them on young male bulls to control their sex drive completely. Go ahead and bitch about my spring pressure but still think there are other adjustments I should be addressing.. Billy, my engine is out 35 inches and I just measured and the barrel to back of cavitation plate is 28.5 inches. The plate is 10 inches instead to 11 and I have enough plate behind the bosses to cut off 2 inches easy. I know jerry's plate is only 9 inches but he has never really bragged on how his hondo sprint sets and proforms. Jjimmy D

[boatguy222]

[ Go ahead and bitch about my spring pressure but still think there are other adjustments I should be addressing.. Jjimmy D[/QUOTE]
JD
Yes there is..... It's called doing it the HARD WAY!!!! Listen to these guys they know their chit. Are you this hard headed when your tractor is broken and need fixing???? :rolleyes:

[GofastRacer]

Well for whatever it's worth, my strut tube is 22 1/4", motor is 34" and the plates are 7 1/2". When I had the 440(aprx 550hp) in it I was on the up pedal, 7500r's 106 and change!..

[biesemeyer34]

I'll put on some more spring pressure because I know that is definitely part of the problem before I back off the valve springs for the winter. Thank for everybody's contribution. Jimmy D To be continued!