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oldstuckinthemud
Samba Member
Joined: February 08, 2018
Posts: 15
Location: been under a rock for years
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 Posted: Thu Feb 08, 2018 1:58 pm Post subject: VW airboat HELP Pictures added |
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Thanks for letting me in.
I don't have a VW never did BUT...
I'm building a mini airboat and I have a 1971 VW 1600cc motor powering it.
It is still a long way from hitting the water or Ice.
I an far enough along I have the prop on that I intend to use.
It was a used motor that was in storage a LONG time with a single carb.
It starts easy and has an even 90 pounds of compression all the way around.
I'm driving off the BACK of the motor where the trany should bolt on.
I'm using a old snowmobile belt drive to a chain then the prop.
It starts out at 3 to 1 reduction the as the rpm goes up it morphs to about 1 to 1.
It should get there at around 3000 rpm, but I'm not quite getting there.
I can get the rpms of the motor there but the prop is still under 1 to 1.
That means I don't have all the HP I need.
I an very close . What would be the easiest and cheapest way to get 5 or 10 more HP ?
It is still a unproven hull and drive set up and don't want to sink a bunch of $$$ to find out it is a NO GO.
Ideas?
Thanks
Last edited by oldstuckinthemud on Fri Feb 09, 2018 10:53 am; edited 1 time in total |
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my59
Samba Member
Joined: August 13, 2003
Posts: 3793
Location: connecting the dots
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| Posted: Thu Feb 08, 2018 5:22 pm Post subject: Re: VW airboat HELP |
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90 lbs is on the low side for compression reading, might be time to go thru the engine. Have you adjusted the valves and set the timing? I'd start there and then test compression again. You want to see more compression that what you have. I think new it was like 135 or more.
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my59: Well son, my grandfather died before I got to drive it, so does that answer your question?
our79: sunroof bus w/camper interior and 2.0 FI
Other:'12 Jetta, '77 Benz 300D, and a 74 MG Midget. |
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busdaddy
Samba Member
Joined: February 12, 2004
Posts: 51153
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Thu Feb 08, 2018 5:37 pm Post subject: Re: VW airboat HELP |
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^^What he said^^
What kind of exhaust are you running?, I see naked heat exchangers, what kind of muffler do they lead to?
Am I seeing things or is that prop on backwards? (assuming this is a pusher setup), any change in static RPM with it flipped?.
Speaking of static RPM is that what you calculate VS: what's stamped into the prop?, where are you getting this 3K RPM goal? You do know that once you get moving the RPM will increase with airspeed as well, right?
If a tuneup and better exhaust don't do it there's always the option of shortening the prop a little, but save that as a last resort.
That chain kinda jeebs me out, avoid standing in the path of flying parts in case it lets go.
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Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
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oldstuckinthemud
Samba Member
Joined: February 08, 2018
Posts: 15
Location: been under a rock for years
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| Posted: Thu Feb 08, 2018 6:15 pm Post subject: Re: VW airboat HELP |
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I went back and checked my notes from when I got the motor.
I was wrong the compression was around 120 all the way around.
Yes I did time it kinda...Very complicated way to time the old bug motors. I'll do a better job now that I can run the motor.
I did a tune up with plugs, points ,condenser ,cap , and wires.
Set the valves. No muffler yet just out of the manifolds. New carb still set at factory settings. I have a low pressure high volume electric fuel pump.
It was not till just the other day that I could start it up. no trany means no place to hang a starter. I do not have any cage or covers over the drive or prop, yes stand back. And yes in that pic the prop was backward I did change it around. I also have a bit smaller prop with 3 blades but more pitch.
Both run about the same. 3100 rpm is the max to spin either prop.
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vwracerdave
Samba Member
Joined: November 11, 2004
Posts: 15309
Location: Deep in the 405
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| Posted: Fri Feb 09, 2018 1:28 am Post subject: Re: VW airboat HELP |
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Welcome to The Samba.
Post a few pics of your engine so we can see what you got.
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2017 Street Comp Champion - Thunder Valley Raceway Park - Noble, OK
2010 Sportsman ET Champion - Mid-America Dragway - Arkansas City, KS
1997 Sportsman ET Champion - Thunder Valley Raceway Park - Noble ,OK |
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oldstuckinthemud
Samba Member
Joined: February 08, 2018
Posts: 15
Location: been under a rock for years
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| Posted: Fri Feb 09, 2018 5:39 am Post subject: Re: VW airboat HELP |
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| OK |
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williamM
Samba Member
Joined: August 07, 2008
Posts: 4333
Location: southwest Arizona
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| Posted: Fri Feb 09, 2018 6:50 am Post subject: Re: VW airboat HELP |
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 when I was living in Rogue River , Or, a friend of mine built one and it swamped on the first rapid- never to be seen again for years- when I found the motor n prop- He had reported the engine stalled after the first rapid due to the carb bouncing around-- so you might look into FI or a diaphragm type float bowl carb-
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some days I get up and just sit and think. Some days I just sit.
opinion untempered by fact is ignorance.
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oldstuckinthemud
Samba Member
Joined: February 08, 2018
Posts: 15
Location: been under a rock for years
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| Posted: Fri Feb 09, 2018 7:32 am Post subject: Re: VW airboat HELP |
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| I cant imagine it "Bouncing" any worse then in a dune buggy |
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oldstuckinthemud
Samba Member
Joined: February 08, 2018
Posts: 15
Location: been under a rock for years
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| Posted: Fri Feb 09, 2018 10:55 am Post subject: Re: VW airboat HELP Pictures added |
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oldstuckinthemud
Samba Member
Joined: February 08, 2018
Posts: 15
Location: been under a rock for years
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| Posted: Fri Feb 09, 2018 10:57 am Post subject: Re: VW airboat HELP Pictures added |
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oldstuckinthemud
Samba Member
Joined: February 08, 2018
Posts: 15
Location: been under a rock for years
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| Posted: Fri Feb 09, 2018 10:59 am Post subject: Re: VW airboat HELP Pictures added |
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KTPhil 
Samba Member
Joined: April 06, 2006
Posts: 34018
Location: Conejo Valley, CA
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| Posted: Fri Feb 09, 2018 11:02 am Post subject: Re: VW airboat HELP Pictures added |
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| Are your fan shroud heater outlets unplugged? |
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oldstuckinthemud
Samba Member
Joined: February 08, 2018
Posts: 15
Location: been under a rock for years
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| Posted: Fri Feb 09, 2018 11:04 am Post subject: Re: VW airboat HELP Pictures added |
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| YES |
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busdaddy
Samba Member
Joined: February 12, 2004
Posts: 51153
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Fri Feb 09, 2018 11:33 am Post subject: Re: VW airboat HELP Pictures added |
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Your distributor is plumbed backwards, the hose on the side facing away from the distributor goes on the nipple on the left side of the carb, leave the port facing the distributor open and cap that line coming off the back of the carb.
_________________
Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!
Слава Україні! |
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KTPhil
Samba Member
Joined: April 06, 2006
Posts: 34018
Location: Conejo Valley, CA
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| Posted: Fri Feb 09, 2018 11:39 am Post subject: Re: VW airboat HELP Pictures added |
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| oldstuckinthemud wrote: |
| YES |
This means you are losing your cooling air and overheating the motor. |
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oldstuckinthemud
Samba Member
Joined: February 08, 2018
Posts: 15
Location: been under a rock for years
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| Posted: Fri Feb 09, 2018 12:06 pm Post subject: Re: VW airboat HELP Pictures added |
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| KTPhil wrote: |
| oldstuckinthemud wrote: |
| YES |
This means you are losing your cooling air and overheating the motor. |
Not sure what your saying.
The ducts that would normally be heating the car are open to the air. There blowing out hot air.
The intake in the back I put a shroud around so the motor fan can pull in air and not have the prop steel the air.
The rest of the cooling tin I think is intact.
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oldstuckinthemud
Samba Member
Joined: February 08, 2018
Posts: 15
Location: been under a rock for years
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| Posted: Fri Feb 09, 2018 12:10 pm Post subject: Re: VW airboat HELP Pictures added |
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| busdaddy wrote: |
| Your distributor is plumbed backwards, the hose on the side facing away from the distributor goes on the nipple on the left side of the carb, leave the port facing the distributor open and cap that line coming off the back of the carb. |
Really.
I was using the hoses off the old carb and put them back on the new carb by size they where located in a little different place I thought but the hoses fit. That would be why my attempt to time it did not work well and I set it by ear.
Thanks I'll it open on the distributor and pinch it off at the carb I'll bet that will help.
Is there anything else you can see I have wrong ?
Never even looked at a VW motor before running blind here. |
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Busstom
Samba Member
Joined: November 23, 2014
Posts: 3853
Location: San Jose, CA
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| Posted: Fri Feb 09, 2018 12:44 pm Post subject: Re: VW airboat HELP Pictures added |
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| oldstuckinthemud wrote: |
| KTPhil wrote: |
| oldstuckinthemud wrote: |
| YES |
This means you are losing your cooling air and overheating the motor. |
Not sure what your saying.
The ducts that would normally be heating the car are open to the air. There blowing out hot air.
The intake in the back I put a shroud around so the motor fan can pull in air and not have the prop steel the air.
The rest of the cooling tin I think is intact.
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What he's saying is that you're losing cooling air 
Yes, you're new to these, so you don't quite understand why, yet. Those ducts are NOT blowing hot air...they're just blowing air. And that air would normally be going down to heat exchangers which would THEN make it hot. Those heat exchangers provide some back pressure, as part of a "balanced" cooling system. You open those ducts on the shroud, and let that air blow straight out into the atmosphere, then that's lost air pressure that would normally go to cool the cylinder heads and, to a lesser extent, the cylinders.
There's a different, ongoing unsettled dispute about whether simply plugging the outlets results in turbulence inside the shroud, further reducing cooling system efficiency. I don't buy it...but whatever. If nothing else, get some freeze plugs and plug them up the best way you see fit 
And stop yelling  |
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Busstom
Samba Member
Joined: November 23, 2014
Posts: 3853
Location: San Jose, CA
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| Posted: Fri Feb 09, 2018 12:51 pm Post subject: Re: VW airboat HELP Pictures added |
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| oldstuckinthemud wrote: |
| busdaddy wrote: |
| Your distributor is plumbed backwards, the hose on the side facing away from the distributor goes on the nipple on the left side of the carb, leave the port facing the distributor open and cap that line coming off the back of the carb. |
Really.
I was using the hoses off the old carb and put them back on the new carb by size they where located in a little different place I thought but the hoses fit. That would be why my attempt to time it did not work well and I set it by ear.
Thanks I'll it open on the distributor and pinch it off at the carb I'll bet that will help.
Is there anything else you can see I have wrong ?
Never even looked at a VW motor before running blind here. |
You're timing it wrong...read busdaddy's "sermon" on timing, here! https://www.thesamba.com/vw/forum/viewtopic.php?t=691429&highlight=sermon
Oh yeah...and STOP YELLING  |
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oldstuckinthemud
Samba Member
Joined: February 08, 2018
Posts: 15
Location: been under a rock for years
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| Posted: Fri Feb 09, 2018 2:45 pm Post subject: Re: VW airboat HELP Pictures added |
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Thanks again I'll do it asap.
"Oh yeah...and STOP YELLING"
Sorry I'm so hard of hearing I can't tell I talking loud |
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