Working out bugs on new build..

A general, non-powerplant specific, discussion on airboat technology, ie., hulls, rigging, polymer, etc..
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SthrnStyle3
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Working out bugs on new build..

Post by SthrnStyle3 » Sat Sep 05, 2015 11:33 pm

My build info is in my signature but I'm wondering if any of yall are running a similar setup and what pitch you're turning. I still have timing to fine tune but as of now, I have the prop set at C at 15 and I'm only getting about 4000 rpm's. On the hub, C 10 seems to be the lowest pitch setting. I feel like I should be getting more pitch! I am getting a bad vibration that seems like it may be coming from the motor. So tomorrow I'm going to check for a dead cylinder or what.. Also, the timing when my motor (before rebuild) was DD, was around 32-34 total timing and had no problems getting there. After the rebuild I can only get total timing to around 25. I'm hoping that after I get the vibration and timing fixed, I'll pick up more rpm's. Or maybe I need to put even lighter springs in the distributor??
12' aluminum hull, 350 sbc w/ flattop Pistons and camel hump heads, side by side seating w/ double in front, 2:1 gearbox and a 78" whirlwind whispertip 2.0

SWAMPHUNTER45
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Re: Working out bugs on new build..

Post by SWAMPHUNTER45 » Sun Sep 06, 2015 12:24 am

Did you degree the cam?

SthrnStyle3
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Re: Working out bugs on new build..

Post by SthrnStyle3 » Sun Sep 06, 2015 1:05 am

No. The cam spec sheet said it wasn't required.
12' aluminum hull, 350 sbc w/ flattop Pistons and camel hump heads, side by side seating w/ double in front, 2:1 gearbox and a 78" whirlwind whispertip 2.0

Olf Art
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Re: Working out bugs on new build..

Post by Olf Art » Sun Sep 06, 2015 11:49 am

Did you have the heads shaved when you rebuilt? Sometimes you'll get a slight seating mismatch of the intake when you do and be getting a vacuum leak around t. Just a thought. Hope you find it!
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keebo
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Re: Working out bugs on new build..

Post by keebo » Sun Sep 06, 2015 1:53 pm

Same distributor or different? After market or stock? Are you setting just total timing and how did you do it? If you set by total have you double checked initial static? Lots of questions to be answered over a computer to give a decent guess. As far as prop whirlwind has A,B, and C settings, sounds like too much pitch for a 2:1 box. When the engine is running right just set the prop to where it likes it for desired max prop rpm, I think you may be in the High B range. You went from DD LH rotation to a gear box did you get a RH rotation prop? Just asking because I have seen people get the wrong prop before and don't know what you do or don't know. Trying to guess over the computer is sketchy at best but maybe we can get you there.
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SthrnStyle3
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Re: Working out bugs on new build..

Post by SthrnStyle3 » Sun Sep 06, 2015 7:54 pm

Yea it's a brand new prop, RH rotation. I think I got some of it figured out... We took the prop off and the vibration went away. So I'm guessing it needs to be pitched better. While we had the prop off, I set total timing to 34* but when we let it idle back down, the timing stayed at 34*. When the motor cooled down, I took the distributor apart and found the weights to be sticking and the plastic bushings are shot. I bought a new curve kit and I'm going to try that tomorrow. When I set the pitch on the prop, I set one blade by lining up the letter C to number 15. I then clamped a paint stir stick to the transom so that it barely touches the trailing edge of the blade. I then rotated the prop to the other blade and made sure that it too touched the paint stick. I then varified that both blades read the same letter/number set up. Why would there then be vibration? Is there a better way to adjust the pitch? Im only use to pitching warp drives lol.

Note: Also, the distributor is the same one from when my boat was a DD. It's an Accel Hei. I have the vacuum blocked off.
12' aluminum hull, 350 sbc w/ flattop Pistons and camel hump heads, side by side seating w/ double in front, 2:1 gearbox and a 78" whirlwind whispertip 2.0

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Re: Working out bugs on new build..

Post by Afflicted » Sun Sep 06, 2015 9:02 pm

U can get the props real close with a digital level. Zero it out on the flywheel 1st
U can order 1 online from sears

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keebo
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Re: Working out bugs on new build..

Post by keebo » Sun Sep 06, 2015 9:14 pm

Go get a digital level from Home Depot is about the best way I've found to set the prop, play with it a bit and set it at max rpm desired, done deal. As far as distributor, fix it up and see what you have. I take it you have the correct timing tape on your balancer to set total timing, also you are setting total with rpm @ around 3k rpm? Also you didn't say what cam your using, a longer duration cam requires a quicker advance. Let us know what you end up with
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Olf Art
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Re: Working out bugs on new build..

Post by Olf Art » Mon Sep 07, 2015 12:06 pm

All good stuff above. You definitely want to use a digital level to set props. Take the plugs out of the engine when you're settin' pitch ..... it makes it a whole lot easier to rotate the prop to exactly where you want it for setting.

As far as the distributor is concerned ...... I've never been able to get a lot of service from anything from Accel. Their coils are especially bad. Consider getting something from MSD to replace it. I had an MSD marine distributor (sealed) on my last boat. That puppy could sit in a pouring rain overnight and fire right up when you hit the starter.
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SthrnStyle3
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Re: Working out bugs on new build..

Post by SthrnStyle3 » Mon Sep 07, 2015 2:08 pm

I'm still having problems with the timing. I installed the new curve kit with the new weights and lightest springs. Vacuum advance is plugged off and never used. I can set the total timing to what ever I want, but when I let it idle back down, the initial timing remains high and it's hard to start. For example, I had the total timing at around 30-32 and at idle it would be in the 20's.. Is there something else that can be worn out or bad on my distributor? By the way, I'm setting total timing at around 3k rpm's.
12' aluminum hull, 350 sbc w/ flattop Pistons and camel hump heads, side by side seating w/ double in front, 2:1 gearbox and a 78" whirlwind whispertip 2.0

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90chevy396
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Re: Working out bugs on new build..

Post by 90chevy396 » Mon Sep 07, 2015 9:38 pm

I just had similar problems only getting 6 degrees advance out of distributor. Double check the amount of movement you get out of the rotor button. Use a cheap protractor and measure the amount the rotor moves by hand. My distributor was from a computer controlled hei vehicle that was designed for only 6 degrees. Just start with only 1 change at a time and test dont perform multiple changes because you will never figure out what solved the problem

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Re: Working out bugs on new build..

Post by Sun Tuned » Thu Sep 10, 2015 9:32 am

Hi gents,
I am new here, but been reading all I can on here for last year and a half.
Just acquired a 15' Panther CM boat.

I rework ignition systems as a hobby for the last 25 years.
The people at Performance distributors know me very well.
So my skills are known. I didn't just watch an episode of ESPN, to figure it out.

Southernstyle your problem is very common. The combination of the curve kit you got which likely is an accel/mr gasket type and the very thin springs supplied are simply not allowing your advance weights to come back to their at rest or 0 position. Very very common issue.

The solution is actually a stiffer set of springs than what is currently installed. The advance must repeatably return to 0 every time. I'm not saying that the initial setting must return to zero, as that setting is manually set with a light by hand, but the centrifugal part(the spring and weight part) must advance and freely retract back to zero.

I almost bet when you returned to idle that the idle speed was higher than it was initially set. Also the rotor can bind the advance assy and cause them to hang up.

Have been reworking HEI distributors for many years. Soloution...
Disassemble clean it up well and lightly lube the shaft and advance assy. I'd also like the original weights and centercam back on. We sometimes use one of the mid weight springs from the kits but very seldom.

I have my own springs made here that work much better.

The main problem with the aftermarket stuff is that they are so light they allow excess advance to come in under the idle speed artificially bumping up the timing. You want that initial timing number rock steady and the advance numbers here dead nuts repeatable.

Hope that helps.

Olf Art
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Re: Working out bugs on new build..

Post by Olf Art » Thu Sep 10, 2015 10:12 pm

Sun Tuned, that was an excellent post. A man is never too old to learn, and I got some good stuff from it. Thank you, sir. :thumbleft:
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Sun Tuned
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Re: Working out bugs on new build..

Post by Sun Tuned » Thu Sep 10, 2015 11:44 pm

Well I appreciate that.

Not sure if you guys have a resident ignition specialist or not already, so if you do, I'm not trying to step on toes. If you don't, you guys are stuck with me.

Besides, I'm gonna have lots of questions here shortly myself.

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