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Motor placement for SBC

Tahoe540

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I am helping a friend build a new 427 cu in SBC to go racing. It has a alky digger tunnel ram with 2 1050 carbs and planning on running a 400hp shot of nitrous so it should be pretty stout. The boat is a TR3 and from what he tells me it used to be a blown gas boat and has been over 140 MPH. I would have to assume this boat is dialed in.

I was talking to another friend who has a blown gas flatty and he has had to lower his motor because of drivability issues. This was an unrigged boat so there were no existing motor plates or "starting point". This got me thinking about this boat that is going from a BBC to a SBC and with less power. I have no experience with v-drive drag boats so I have been reading a lot, but wanted to ask your opinions before we set the motor plates.

Should we keep the rear motor plate in the same spot to start?
Will the weight/HP reduction require the engine to be moved forward or backwards/up or down?
Does a large shot of nitrous affect the boat? Does it need to come in before the starting line?

Should anything else need to changed/modified going to a SBC?

Thanks
 

warpt71

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I have always heard that 36" and 96" are good starting points. These measurements are from the inside of the transom to the front motor plate (front of motor, back of boat) 36" and from the inside of the transom to the midplate of the v-drive 96". The reality is that there are several other measurements that will affect the overall combo. Strut location and degree are the big ones. More measurements and pictures please! TR3's had a lot of rocker in them and got a bad rep.

I honestly think I would put the SBC flywheel side in the same location as the BBC. I also believe that there will be trial and error here to get the most out of this combo. Im ready to learn
 

Tahoe540

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I am with you on starting with the motor placement at where the current rear motor plate is. Like I mentioned this has been a drag boat for a long time and from what I am told it has done pretty well so the setup has to be good. But that is for a blown BBC.

I come from nostalgia drag racing so this is totally new to me and have enjoyed learning what these boats and different hulls are about. I have also spoken to some local guys about this but there is a lot of knowledge on this site.

These are the only pics I have now. He is bringing it over on Sunday and we're going to start wiring it and place the motor. He bought a Racepak IQ3 Dash so I need to get my wiring skills together. I will post more pics next week after I finally see it in person.
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Clank123

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It’s all about balance.
The small block is lighter, so you will need as much weight forward as you can get.
Having done this more than a few times…if you brought it to me, I would use the front motor plate(flywheel end) and bolt a bare block to that(same bolt pattern) and then fabricate a rear plate to support the rear. You are going to have to make a new one anyway as the small block has a different bolt pattern.
By doing this you will be much closer to having the proper balance to lift the boat up to ride on the center pad where it should be at speed.
I always set drag boats up to have as little weight on the tail as possible to help with lift to make the boat air out sooner including moving the battery ahead of the engine.
Also, put the wing in the rafters, no need for one under 135 mph.
Unless you like the look. Your call but it is a disadvantage.
PM me if you want and we can talk on the phone.
 

Clank123

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Did the above in a Canyon I had.
Boat ran High 8’s at 120 or so.
Done a few since including a circle boat I just finished.
Should give you a great starting point to tune the boat from. 8C79F67A-7042-4A9F-A7BA-8999D360E1D9.jpeg
 

warpt71

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It’s all about balance.
The small block is lighter, so you will need as much weight forward as you can get.
Having done this more than a few times…if you brought it to me, I would use the front motor plate(flywheel end) and bolt a bare block to that(same bolt pattern) and then fabricate a rear plate to support the rear. You are going to have to make a new one anyway as the small block has a different bolt pattern.
By doing this you will be much closer to having the proper balance to lift the boat up to ride on the center pad where it should be at speed.
I always set drag boats up to have as little weight on the tail as possible to help with lift to make the boat air out sooner including moving the battery ahead of the engine.
Also, put the wing in the rafters, no need for one under 135 mph.
Unless you like the look. Your call but it is a disadvantage.
PM me if you want and we can talk on the phone.

Im glad you chimed in. I was going to tag you this morning on my way to work but forgot to, it was 2am when I was thinking about it lol
 

Tahoe540

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Thanks for the responses. My buddy is bringing over the boat and a bare block this morning so I will let you know how things go.

The boat does not have the wing anymore.
 

Mark Caton

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It’s all about balance.
The small block is lighter, so you will need as much weight forward as you can get.
Having done this more than a few times…if you brought it to me, I would use the front motor plate(flywheel end) and bolt a bare block to that(same bolt pattern) and then fabricate a rear plate to support the rear. You are going to have to make a new one anyway as the small block has a different bolt pattern.
By doing this you will be much closer to having the proper balance to lift the boat up to ride on the center pad where it should be at speed.
I always set drag boats up to have as little weight on the tail as possible to help with lift to make the boat air out sooner including moving the battery ahead of the engine.
Also, put the wing in the rafters, no need for one under 135 mph.
Unless you like the look. Your call but it is a disadvantage.
PM me if you want and we can talk on the phone.
Mr Clank 123: Looking for someone to re-rig my Spectra 20. Would love to talk to you. Tnx Mark 760 709 6427 Needles, Ca
 

Clank123

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Mr Clank 123: Looking for someone to re-rig my Spectra 20. Would love to talk to you. Tnx Mark 760 709 6427 Needles, Ca
Hey Mark!
I’ll give you a call first of the week.
Problem is I’m pretty well booked for probably 3-4 months.
I’ve got a 23 foot Silverwing that still needs plumbing and wiring.
Should have the Blown Fuel Hydro from the 70’s “Shockwave” from Billy B by Christmas that I am restoring for the Lions Dragstrip mueseum.
A 64 Hallett to rig at my river house.
Finally(as far as I know) a long deck Biesemeyer to totally rig on its way from the paint shop as well.
Hopefully we can figure something out.
Post up a few pics of what ya got!
Talk soon,
Dave
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Mark Caton

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Hey Mark!
I’ll give you a call first of the week.
Problem is I’m pretty well booked for probably 3-4 months.
I’ve got a 23 foot Silverwing that still needs plumbing and wiring.
Should have the Blown Fuel Hydro from the 70’s “Shockwave” from Billy B by Christmas that I am restoring for the Lions Dragstrip mueseum.
A 64 Hallett to rig at my river house.
Finally(as far as I know) a long deck Biesemeyer to totally rig on its way from the paint shop as well.
Hopefully we can figure something out.
Post up a few pics of what ya got!
Talk soon,
Dave
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Hello Dave: Thank you getting back to me. Your time frame is ok. Currently building a BBC 522 Blower motor with 400 trans. Will get pic off this weekend. TNX Mark
 

instagator

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TR- 2, BBC according to Jim Cole, 36 " from transom, A blower motor, maybe a little more forward than that ?
 
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