ISO Sensenich Q to try out

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Deano
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Re: ISO Sensenich Q to try out

Post by Deano » Tue Jul 17, 2018 8:19 am

First of all, I will say that I'm in total 100% agreement with the assessment that you will not beat a properly built Quadrajet for a 500 DD when and if you have one one hand. Unfortunately, they are not as plentiful as they once were. They baffle people who don't know how to tune them, who have subsequently given them a bad rep.

With that having been said, I think you may be much closer to solving your problem than you realize:
radtech wrote:. . . The old 2 barrel that came off my original engine (a 220 GPU) doesn't seem to give the ol cad enough juice and that may be one of the problems. . .
If your old 2 barrel off your 220 is a 500 Holley and has not been re-tuned for your current engine, that is likely a much larger part of your problem than you realize. It is possible in many cases to put that carb on a 472 and get away with it, but unless it was running pig rich on your ground power, it is not supplying enough fuel for you to exercise an early 500 Caddy.

This could very well explain a good part the difference between your results and mine, where coming out of the hole is concerned. There should be no justifiable reason that a reasonably fresh 500 needs to turn over 3k to get on a plane. Quiet has always been part of my quest; I don't think I've ever heard anything turn over three grand that wasn't loud enough to be irritating.

Hypothetically, if it currently has 72or4 jets and a 30cc Accelerator Pump, you most likely would see measurable difference with 76or8 jets and a 50cc pump. IF that IS the case, I would be very surprised if a hundred bucks @ Summit did not provide you with such an improvement that you might not view it as having been band aid. As Slidin Gator eluded to, 500 CFM is plenty of carb in and of itself. I'm just guessing, but if a 4412 is what you have, every indication is that it is internally restricted and is hampering your ability to do what it should be able to do. If it is not a 4412, all the same thought process applies, it just may not be as easy or cost effective to remedy, if it's even possible.

I am not claiming to be any carb guru, but there are some here. If you can identify and share exactly what you have now (jets, acl pump, power valve, etc) you may find you are closer than you think to the performance you aren't attaining right now.

With everything else that's been thrown around in this thread, it would seem logical to me to at least definitively exhaust the possibility before you go to the expense of changing props or spending money elsewhere. I believe you have more performance there to be tapped.
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Re: ISO Sensenich Q to try out

Post by Deano » Tue Jul 17, 2018 8:23 am

radtech wrote:. . .Not a lot of difference price wise in a manual or electric choke, but I have an HEI distributor, so manual may no longer be an option. Any thoughts?
No reason you can't run a manual choke with your HEI ignition.
I prefer a manual as it is very seldom needed, although I realize I'm further south than you are.
Really is a personal choice, I prefer manual largley because it's one less thing to puke when you don't want it to.

PS Just answering that question, not meaning to endorse making that switch on a DD.
I'm partial to the 2 barrel Holley if that's what you have. But then again, I do admit to
being a CSOB when it comes to buying parts that I don't perceive are necessary.
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Re: ISO Sensenich Q to try out

Post by radtech » Tue Jul 17, 2018 8:37 am

Deano, I have been thinking that very thing (manual vs electric) Just wasn't sure if it would work with the HEI. I'll be honest and say that I have no idea what exact carb is on my boat, and not sure how to find out. The internals are an even bigger mystery. Nothing has ben changed on it. It was simply swapped over to the new engine. Not sure if it makes a difference, but my engine is extremely cold natured. It takes almost a full heat-up to get it to idle without shutting down.

Yes, I am certainly aware that this thread has gone in 12 different directions. I know there are several issues that I need to address and that makes it more difficult. But I would like to eventually see what other props can do. Like I said, I have only had this prop and the ol wood prop from my gpu. Thanks a lot for your input!

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Re: ISO Sensenich Q to try out

Post by Deano » Tue Jul 17, 2018 9:47 am

Nothing wrong with the thread going all over the place, you are acquiring information you can use up the road.
Nothing wrong with wanting to try different props and expand your knowledge base either. The thing to bear in mind when making prop comparisons is that you need to have a steady, defined, unchanging baseline on which the comparisons can be based. If, or when you make engine changes/improvements you have corrupted your baseline and the validity of future comparisons.

This is only one of many reasons that in my opinion, spending money elsewhere, is somewhat akin to putting the cart before the horse so to speak. You may have a bunch of changes needing made (maybe you don't), but you need the engine performance squared away first so you can assess the effectiveness of the subsequent changes after that. In spite of everything you think is causing a problem, the possibility realistically exists that getting the performance that engine is capable of would address half of your list! 8)

Based on my results compared with yours, you have me totally convinced that your engine is under performing (possibly a lot).
radtech wrote: Not sure if it makes a difference, but my engine is extremely cold natured. It takes almost a full heat-up to get it to idle without shutting down.

This confirms the assessment I made in the earlier post. IMO your engine is not cold natured, it is running to lean. The carb is not providing enough fuel. Right now when you choke it to get beyond that problem, you are literally allowing less air into the engine to compensate for the lack of fuel. This is why it's more willing to idle after it's warmed up.

I wish you were closer so I could show you how mine starts and idles. No choke ever, unless it's under 50 degrees. In fact, it doesn't have a cable on it. It has a set screw that holds it open. If I've used the boat in the last three days, just hit the key and it idles. If it has been sitting, tap the pedal once, hit the key and it idles. I have to believe that people who would opt for something different have never had one that ran like this one does. Maybe all Caddies don't like 500 Holleys, but all of mine damn sure have.

We need to figure out if that is what you have. If it is what I'm hoping, the way to identify it is to remove the air cleaner and you should find the list number stamped on the front of the air horn something like this:

Image

If that's the case, report back with that list number and we can identify exactly which one it is. If you don't find it there, take a couple pictures of it while you have the cleaner off and post them instead. How far north in GA are you?
Last edited by Deano on Tue Jul 17, 2018 10:05 am, edited 1 time in total.
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Re: ISO Sensenich Q to try out

Post by radtech » Tue Jul 17, 2018 9:58 am

I will do that, Deano. I have to work tonight, so I am at odds of doing it now, but will run out there real quick and check. I am essentially in Warner Robins, right in the middle of the State.

My current plan is to correct the carb issue, and get a few maintenance issues straight, get a bigger air cleaner, and then I would like to see what the difference is in props. For now, getting the carb and all set up and running is 1st priority. I can then test it between now and next month as I was drawn for a tag on Seminole this year. I certainly appreciate all your input. Maybe we can meet up one day and ride, Deano. I'm itching to get back on the water

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Re: ISO Sensenich Q to try out

Post by radtech » Tue Jul 17, 2018 10:10 am

OK, the numbers on it say 6R (3250) B Pic to follow

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Re: ISO Sensenich Q to try out

Post by One Eyed Gator » Tue Jul 17, 2018 10:13 am

I had High compression .020 over 472 and a cam. The 500 holley I ran had 74 High flow jets, 50cc pump and 6.5 pv. Ran very well. I tried Holley 650, 750 and 850. Also tried 750 edelbrock. All of them ran about the same when dialed with an A/F meter. None were really better then the rest when they were tuned.
I did change the main body in the 750 Holley to a proform main body with annular boosters. Annular booster gave it better throttle repsonse.

I did find the off idle response was better when I adjust the idle feed restrictor. Caddy have a strong carb signal and pull a good bit of fuel.

Some days I miss my old caddy love the sound, but I also love my gearboxed LS motor, making less HP (5.3, 285hp), turning more prop and it weigh about about 100lbs less.

Just my 2 cent
Have a great day

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Re: ISO Sensenich Q to try out

Post by radtech » Tue Jul 17, 2018 10:14 am

Here is a pic. Definitely has some age and a vacuum leak somewhere. Maybe someone will want it when I take it off. lol
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Re: ISO Sensenich Q to try out

Post by radtech » Tue Jul 17, 2018 10:18 am

One Eyed Gator wrote:I had High compression .020 over 472 and a cam. The 500 holley I ran had 74 High flow jets, 50cc pump and 6.5 pv. Ran very well. I tried Holley 650, 750 and 850. Also tried 750 edelbrock. All of them ran about the same when dialed with an A/F meter. None were really better then the rest when they were tuned.
I did change the main body in the 750 Holley to a proform main body with annular boosters. Annular booster gave it better throttle repsonse.

I did find the off idle response was better when I adjust the idle feed restrictor. Caddy have a strong carb signal and pull a good bit of fuel.

Some days I miss my old caddy love the sound, but I also love my gearboxed LS motor, making less HP (5.3, 285hp), turning more prop and it weigh about about 100lbs less.

Just my 2 cent
Have a great day
I hear ya there, one eyed gator! I love mine. The idea of going to something like an LS is tempting, but I'm a poor boy and my boat often gets wet. All that electronics would surely short-circuit costing me a lot of money in no time. lol

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Re: ISO Sensenich Q to try out

Post by One Eyed Gator » Tue Jul 17, 2018 10:56 am

I was worried about the EFI wiring but have help 2 buddies build EFI boats for the gulf. and my next one will be EFI.

Take a pic of Acc. pump looks like 30cc. I am with Deano 50cc pump and bigger jets. I ran the 74HP jets,so a 500 would definitely need a little more fuel. Also the correct pump cam. Find someone with a A/F meter they are an awesome tool for tuning.

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Re: ISO Sensenich Q to try out

Post by One Eyed Gator » Tue Jul 17, 2018 11:17 am

Too much coffee I guess Double posted

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Re: ISO Sensenich Q to try out

Post by radtech » Tue Jul 17, 2018 1:27 pm

Not following on the acc. pump, gator. I really don't know anything about carbs. I rebuilt my engine from the ground up, so I am familiar with it, but wiring and carb eludes me.

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Re: ISO Sensenich Q to try out

Post by One Eyed Gator » Tue Jul 17, 2018 2:50 pm

Go to holly's website and look at the Pump arm for the 50cc pump and see if that is what you have on your carb. The pump size is like that holding tank for fuel needed at acceleration.
https://www.holley.com/blog/post/carb_c ... _the_boot/ Explains the the 3 main parts of the pump and what they do.

My boat got on plane better when I get Acc. pump dial in. Change to bigger pump 30 to 50cc, larger squirter .28 to (.35 or .37) I beleive and changed the pump cam.

Sent you a PM

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Re: ISO Sensenich Q to try out

Post by radtech » Tue Jul 17, 2018 3:06 pm

Thanks, brother! I'll definitely look into it and see what I have

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Re: ISO Sensenich Q to try out

Post by Deano » Tue Jul 17, 2018 4:42 pm

If you have some carb cleaner or acetone on a rag, wiping the face there by the
air horn (marked yellow areas) should easily reveal the list number you want.

It is stamped there, so it's generally not necessary to remove all of that soot (although that wouldn't hurt anything either).

Image
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Re: ISO Sensenich Q to try out

Post by cowboy » Tue Jul 17, 2018 7:34 pm

Nice Posting Deano

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Re: ISO Sensenich Q to try out

Post by Striker543 » Tue Jul 17, 2018 8:24 pm

radtech wrote:I have been given the advice to try a edelbrock 650 cfm annular carb and have found one quite reasonable. I'm thinking of going that route rather than spending almost as much for a q-jet and having to rebuild it. Not a lot of difference price wise in a manual or electric choke, but I have an HEI distributor, so manual may no longer be an option. Any thoughts?
When I was running a Caddy I bought a brand new Edelbrock 650 Thunder Series and had it tuned by Buddy Branch for a little over $300. It was Buddy's recommendation and was money well spent.

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Re: ISO Sensenich Q to try out

Post by radtech » Wed Jul 18, 2018 9:46 am

Deano, I didn't see anything significant on the right side, but I will look again. It seems all I saw was maybe 1 number and a letter. I'll clean it up this weekend and see what I can find. Thanks again.

blackwater, what exactly is the problem with edelbrock? I have always heard it was a good carb. Holley and Edelbrock are certainly the 2 best from what I hear. Could it be a Ford/Chevy thing? Or is there a long history of failure I'm not aware of?

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Re: ISO Sensenich Q to try out

Post by Deano » Wed Jul 18, 2018 6:23 pm

If wiping it with a solvent doesn't expose the number(s), you may need to use an old toothbrush (or something similar).
Sometimes the stamping of the numbers is fainter than it should be. With the carb installed where you can't turn it, a
flashlight may in fact help ascertain what they are. Rest assured they are there. The 2 bbl ones I've seen have all been on the right side.
I've read that isn't always the case, but I think it may be on these.

There are two rows of numbers there. The top line is the list number. The four digits on the second row are the date code.
If you can get the date code as well, that's great. What is more important though is the list number on the top line.

I attempted to take a pic of one I had on the shelf, but my digital camera puked and the ol camera phone doesn't focus that well.
In any case, this is the best I could come up with so you maybe have a better idea what you are looking for. Be aware that will only
be the general neighborhood, they don't use a stencil to place them so they can be moved around quite a bit.

Image
radtech wrote:. . . Definitely has some age and a vacuum leak somewhere. Maybe someone will want it when I take it off. . .
Rest assured whenever you finally part with it, I will happily take it off your hands. I am partial to these for a Caddy and don't foresee jumping ship anytime soon. I do hope though, that's not 'till up the road when you upgrade to a gearbox because at that point it will be necessary in any case; well ... short of building an intake to hold two of them. :twisted:
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Re: ISO Sensenich Q to try out

Post by Slidin Gator » Wed Jul 18, 2018 11:18 pm

All last season my buggy was bogging down in deep water. Between deer and turkey season I pulled the carb and found the throttle bushings were worn and feeding water to the motor. I dug into the corner of the shop and pulled out my carb bucket. My son suggested I put the new(ish) edelbrock carb on, the one in the bag "all good to go".

I opted for digging through the bucket to find a good throttle body and slapping together another Quadrajet using the horn and jets from the original (the whole carb tune except idle), a throttle body from the bucket and new gaskets from my stash. Luckily around here, I get away with just pulling the choke plates etc. off everything I own, one last thing to fail.

Image

My point is that the Edelbrock in the picture is free, first come, first served. Come get it or pay shipping. I will spend the time up front to sort out a Q jet vs. spending the rest of my life monkeying around with that Edelbrock that showed up in my bucket.

My experience and thinking regarding Holley carbs is similar (oh, another blown power valve) :cherry:

In this case the requirement is borderline 2/4 BBL, all 500 CFM rated. It needs a decent accelerator pump to feed the motor for proper response.

#1, Deano is right, If the Holley on hand is a 500 CFM unit, that is the optimum and it needs to be tuned.
#2, See #1, get a 500 CFM 2 BBL
#3, Look at 4 BBL upgrades, don't expect much, but don't waste money on the wrong rabbit hole.

I like Q-Jets and Varijets. It usually take 2-3 times pulling them apart and swapping jets to get the best tune. But once set you can dive them in the local canal, pull them off, shake the water out of the bowl, put them back on and run, let alone swap the carb to another motor and go.

Folks that have learned to keep tools, power valves and adjusting screwdrivers like Holley carbs. :stirpot:

Broke down folks run Edelbrocks, you want mine? :violent1:


Now, in the interest of keeping this thread all over the place, have you checked your distributor to confirm that the vacuum and mechanical advance systems are working and the bushing are not worn out? Timing is the most critical when demanding maximum torque at low revs, the right amount of timing advance can really wake up a motor when planing. Worn distributor thrust bushings can really throw off a good tune. I have a parts bin of shim washers I use to keep HEI distributors tight.
Just sayin :dontknow:
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Re: ISO Sensenich Q to try out

Post by SWAMPHUNTER45 » Wed Jul 18, 2018 11:20 pm

From experience I can tell you the Edelbrock Thunder 650cfm AVS works excellent on a DD 500 Cadillac.

Mr Branch is a fantastic resource on setting up the proper jetting and metering rods for the application. Like was said if you get one of his carbs it will be done right. His DD engines leave with a Edelbrock 650 Thunder and they run flawlessly.

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Re: ISO Sensenich Q to try out

Post by Slidin Gator » Wed Jul 18, 2018 11:58 pm

SWAMPHUNTER45 wrote:From experience I can tell you the Edelbrock Thunder 650cfm AVS works excellent on a DD 500 Cadillac.

Mr Branch is a fantastic resource on setting up the proper jetting and metering rods for the application. Like was said if you get one of his carbs it will be done right. His DD engines leave with a Edelbrock 650 Thunder and they run flawlessly.
Fair enough Swamp, everyone has their favorite, this one is not mine. First PM with a ship to and the carb is yours free after sorting out postage. The damn thing is filling up spot in the shop that should hold good juck.

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Re: ISO Sensenich Q to try out

Post by radtech » Thu Jul 19, 2018 9:19 am

Sent you a pm, blackwater

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Re: ISO Sensenich Q to try out

Post by kwanjangnihm » Thu Jul 19, 2018 9:38 am

Tim,
I ran a 72" 3 blade Sig on my AV540, heavy cottonmouth hull n rigging. Lariat and i tested Q blades on it and found it would break dry ground at 300 rpms's less than the Sigs. I have found the Sigs need to wind up to a faster rpm to make thrust. The Q comes in quicker.
At 74", either blade should give good thrust & push, but given the chance test the Q and see for yourself.
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Re: ISO Sensenich Q to try out

Post by radtech » Thu Jul 19, 2018 9:42 am

kwanjangnihm wrote:Tim,
I ran a 72" 3 blade Sig on my AV540, heavy cottonmouth hull n rigging. Lariat and i tested Q blades on it and found it would break dry ground at 300 rpms's less than the Sigs. I have found the Sigs need to wind up to a faster rpm to make thrust. The Q comes in quicker.
At 74", either blade should give good thrust & push, but given the chance test the Q and see for yourself.
:rebel:
Thanks, brother! That's just the kind of info I needed....as far as the blades are concerned. I intend to try them out as soon as I can make it happen, but I gotta get the other stuff worked out first. I should have that taken care of in the next couple weeks, so I'm gonna try to make a trip down after I fill my gator tag and try them out.

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