Re: Carb Adjustments
 

I'm with PatriYacht on that one.

Re: Carb Adjustments
 

Another day at the office....(slip). Changed all 8 plugs again. (I should buy stock in NGK) I think things are getting better. The plugs were dark but clean on Cyl 1 & 2. 3&4 a little darker with some carbon, 5&6 Darker still with lots of carbon caked on and slightly damp, 7&8 carbon caked. It seems the front bank is leaner and the back... far richer.

I re-checked the timing and set it at 10 Deg base. At 3300 RPM that advances to 32 degrees or so, about the most that I should want I think. (89 octane pump gas and a heavy boat) I checked both engines and set the timing the same. I would like to advance a little more thinking it would lean things out, but I don't want too much total advance. (V8-HP module and Thunderbolt IV) I re-checked the idle setting with my vacuum gauge, and it seems to be running fine at the dock.

Bad fuel should not be a problem soon since I am now on fumes and any left over nasty fuel should be run out. I'm thinking about letting it run out completely and adding fuel at my dock to get any old crud out of there. Then change the fuel filters etc. This baby is burning a serious amount of fuel in the limited time I have run it, especially since 100% of the fuel burned (about 160 gallons) was with some kind of problem. 14 hours on the motors now and only about 2.0 or so on plane.

I'll get new gas tomorrow and take her for a spin to see if anything is better. It is wierd to me that the plugs are fouling so un-evenly though. Could that be a limitation with the intake that I have. It is a power plus "hurricane" high rise aluminum single plane. Totally square open throat with no square bore passages to direct the fuel, outside of the square bore spacer. Could fuel distribution also be a problem here?

Re: Carb Adjustments
 

I would buy a new carb and start there. You are running a real risk of ruining a near new engine. Switching carbs from engine to engine pointed directly to the carb as the problem, no?

BT

Re: Carb Adjustments
 

Always check plug 6 for fuel, Its the leanest cylinder

Re: Carb Adjustments
 

you should buy one of those plug sandblasters. Im no carb guru, but could it be possible that your fuel pump has too much psi, blowing the needle of the seat? Or a pin hole in the float causing it to sink?

You said it ran better when you swapped the carbs, but you also said you werent positive. So, Im assuming the crappy carb was originally on the port motor. You swapped it to the starboard and the problem followed to the starboard? Am I correct? I just want you to be 100% that its the carb.

I only say this because I had similiar problems. i started fooling with the carbs, took them apart, got rebuild kits, went thru them, put them back on, and still the same. Turned out to be ignition. My motor wouldnt rev past 3500, puked when I put it in gear, didnt pull under load, smelled super rich, but yet idled in nuetral and revved in nuetral to 5k with no problem.


I agree with blue thunder. You want to solve this problem asap especially being that you have a new engine that has spent its most crucial part of its life(break in) running bad, missing, idling, and probably has a lot of gas mixed in the oil.

Not that your intakes are an ideal setup, but I doubt fuel distribution is your problem, or clogged fuel lines, etc. Its clear that you are getting plenty of fuel, its just that you need to be able to burn it. Which either means a better a/f ratio, or better spark, assuming the compression is good.

Maybe you can sell those carbs on ebay, and buy some smaller carbs like 800's. Id look into it, cause when I had my 540 with the 1050 dominator it was good on the top end but on the low end it was lazy. Several carb guys told me to go to a 950 4150 stlye and I would get better low end response.

Re: Carb Adjustments
 

You have me thinking about the ignition now MT since my problem seems to immitate yours. I'm trying to think about the entire package here, and not just that the problem seemed to follow the carb, but that there could be another problem here with the engine as well.

When I pulled the wire off the coil yesterday to brighten up my timing marks I noticed a light orange colored oil where the ignition wire plugs in. The coil lead wire hole was full of it. I think the coil is housed in a light oil and this is making me wonder if the coil is bad as well. The port coil lead wire plug was dry.

This is an older MSD Blaster coil sparking the Thunderbolt IV. This part was not replaced and came with my boat when I purchased it with the old engines. The mechanic re-used this part and it could possibly be bad, which certainly would not be helping things and I'm thinking creating a weak spark.

Re: Carb Adjustments
 

could be a bad coil. I beieve the oil keeps the coil cool, and maybe its overheating. Also, change the cap and rotor for the hell of it. Throw some locktite on the rotor shaft before you put the new one on.

Re: Carb Adjustments
 

Changed the coil with another MSD Blaster2, put on a fuel pressure gauge, reading 9-9.5 psi. Ordered 2 Holley fuel pressure regulators to try tomorrow to correct that down to 6-7 psi. Need to change the oil, add fuel, change fuel filters, and see what happens. I'm thinking if the fuel pressure is too high, I can't correctly adjust the float levels, since I am adjusting against the pressure of incoming fuel. This could also add to my extremely poor economy I'm thinking, coupled with a bad spark, and possibly timing that was off some. After I get the regulators installed I'll re-adjust the carbs and see if I can get a better vacuum reading adjustment and lean them out some more, at that point I'll re-evaluate the correct power valve to use based on that vacuum, and see if I can get this baby running right finally. If it all comes down to excess fuel pressure I will have to laugh. I had asked the guy if I would need regulators with the fuel pumps that he installed and he said no, and not to worry about it. The Holley literature for this pump 12-454-130 (130 GPH) I just found out specifically states that a fuel pressure regulator is required with the use of that pump. It is also an automotive pump, and if excess pressure is the problem, I'll break down and buy a couple of 110 GPH marine pumps with the dual diaphrams, and the sight tube and put them in over the winter.

More tomorrow after a test run....too much wind howling out there today to take the chance of having a dead engine on return.

Re: Carb Adjustments
 

yeah, 9psi seems high, I think holleys can only handle about 7 psi before the needle blows off the seat. Im anxiuos to hear the outcome!!!

Re: Carb Adjustments
 

fuel pump for 500hp carb is 130gph to. buy a regulator

Re: Carb Adjustments
 

While it is true that the fuel pressure should be regulated to 7 lbs., if the needle were off the seat , the fuel level in the bowls would rise until it poured out of the vents. Maybe that's happening at higher rpms. Something to check but I don't think so.

Re: Carb Adjustments
 

If those are automotive fuel pumps like you say, Running them in a boat is a NO-NO!! Break down and buy the marine pumps, before you blow up!
They should have a closed vent system connecting to the carb with a small hose.
Also, in my opinion, Blaster 2 coils suck. I've had a few of them go bad on me (primary side open), for no apparent reason.

Re: Carb Adjustments
 

I know all about the differences in marine vs auto parts, but I'm trying to get it going with what I have. I have all winter to marineize. I just with the marine mechanic who put this thing together has used marine parts instead of trying to save himself money and throw auto parts on marine engines. Thats a whole other issue with this job.

Today I added fuel pressure regulators, changed the oil and replaced the carb power valve again, just to be sure after a few more pops while adjusting the other day. I ran the fuel down to nothing , added new fuel, replaced the fuel filters and went for a ride.......all in vain. No change in performance or lack thereof.

I'm going to try blowing the carb out again, cleaning the pickup tubes and anti-siphon valves, and perhaps advance the timing a few degrees to see if that will make a difference. I don't have the cam specs so I don't know exactly what advance this cam likes, and I can't get a response from my old mechanic about the details.

I have thrown lots of time and wrenches at this thing, I figure it's time to throw some money at it and invest in new carbs. Not an expense I wanted but I can't keep chasing my tail over this and wasting day after day trying to figure it out. I also have spent enough in fouled plugs to pay for 1/3 of a carb.

I'm thinking I don't need anything bigger than 750's perhaps an 800, for my low rpm application. Perhaps even vac secondaries in the interest of efficiency. Any opinions on this?

Thanks for all the advise on this frustrating problem. Hopefully it will come to an end soon.

Re: Carb Adjustments
 

My comments on carb size - having carbs, say, rated 100 - 150 cfm higher than you need would not cause the problems you are having. I just looked at a chart that shows an 850 is perfect for a 454 at about 6500 rpm. 750 seems good up to about 5500 rpm. But a little overcarbureted won't cause the problems you are having. What about accelerator pumps - are they leakinginto the carb? Can you borrow a known working carb from a buddy and try it out?

Have you checked compression? Next time you pull all the plugs, do so and report your numbers. And are you sure you are getting a hot spark at all plugs at the correct time, all the time?

Re: Carb Adjustments
 

Did you change the oil leaker coil? How bout those caps? Waybomb is right, youre a little overcarbed, but nothing that should cause your symptoms. I'd still look in the ignition system for a little while and give the fuel system a break. Dont get discouraged, its probably something really simple

Re: Carb Adjustments
 

If you do change carbs, stick to a square bore,double pumper type carb. I had 800's on a pair of 454/420's and they worked great.

Re: Carb Adjustments
 

850's are too large for optimal performance, but should not be causing this problem, especially if you've swaped carburetors, ant the problem followed the carburetor? Have you swapped them back yet?

The first thing to do would be to take the carburetor apart spray out all of the orifices in the main body, and metering blocks with some carburetor cleaner and compressed air and try it again. Now re-try it at the dock. Carburetors are extremely simple, if there is a problem there is either too much fuel, or not enough. Put the engine in gear (tied to the dock as you have before) and bring it up to the RPM it is having a problem. Now press on the accelerator pump arm. This will add fuel without changing the amount of air the engine has, and will either make the problem better or worse. It may not solve the problem, but it will let us know what to look at.

Re: Carb Adjustments
 

Took the ailing carb off today and swoped them again motor for motor.

I took the suspect carb to dad's shop where I had everything I needed. Hit it hard with carb cleaner, compressed air in every hole I could find about 12 times each and from every angle. Cleaned the transition slots, and blew out every hole on the carb body. Re-gasketed and put it back together. Put it on the boat and took it out after re-checking timing, and settings etc. I did not run the engine in the river until I got out. I warmed it for a few minutes and brought her up on plane. It was hesitant to accelerate, but reached a new weekly high of 2900 RPM's and no higher. Average was 2600 or so. It just did not have any guts to it at all. The other engine accelerated mostly normally. The problem followed the carb to the port engine!

I slowed her down after a few minutes of trying to nurse the power in, and checked the vacuum readings of the two engines. The port engine was showing a larger drop in vacuum under load, and would not accelerate but only chug along. The stbd engine had higher vacuum under load by a few inches at the same rpm (1500 or so) When I goosed them together I could get the port engine to accelerate only up to 2600 RPM and it really did not want to go. I brought it to idle and it would idle all day long. I shut it down for the ride back to the dock.

It was still running extremely rich evidenced by a fuel slick in the exhaust and real smokey running. The 4 corner screws are almost all the way in. Highest vacuum was with the screws all the way in and I would then richen by 1/4 to 1/2 turn. Any more turns out and the engine would want to die. I also advanced the timing a few degrees to try to lean it out a little but that had no effect. The book says 36 degrees total advance, but that seems too high to me so I kept it around 12 base which gave 32-34 total. That seems to be the best place for it.

I think it's time to pony up the dough for a few new carbs that are more appropriate for this setup. It seems these 850 Speed Demons are just too big for what I have. Not to mention I used nearly 20 gallons of gas (by the gauge) for a 5 -10 minute time on plane at 2600 and 3000 RPM respectively, and idle on one engine to and from the dock for a total of about 40 minutes. This seems extremely excessive for this kind of setup. I can get a nice price on a rebuilt set of 0-9022 marine Holleys (800's) locally and just may do that. I'm wondering if the 0-9015 750 carb would be a better choice though for my application. I really wish I knew the cam specs to help me decide. I'm thinking only 420 - 450 HP tops, at 5000 RPM and below. The mechanic said the cam was 0 overlap with a slightly higher lift for tourque, and I think he said they are Crane Cams. I know almost nothing about camshafts and how I should pick my carb, intake, and set timing based on the cam.

Thanks to all, I'll keep you all advised.

Re: Carb Adjustments
 

Go to www.holley.com. You can access their charts there. I think a 454 at 5000 r's is 700 or 750.
There must be something radically wrong with that carb you have. There has to be a blocked passage, and accelerator pump check busted, or a real crack in the casting.
I still believe the carb size is ok - the other engine runs fine, correct? If you've relegated yourself to buying anew carb, and I would probably do the same after what you've bennthrough, I'd buy a duplicate of what you ahve on the good running engine. Only buy one carb; why two.
But me being me, I'd be going through that bad carb with a magnifying glass. I'd wanna know what's up doc.

Re: Carb Adjustments
 

I just read you have a single plane intake manifold. With that, I would say the 850 is too big. 750 will work much better. I am sure there are people who are successfully using an 850 on a 454 but more likely than not, its on a dual plane.

Re: Carb Adjustments
 

I asked this before and didn't see where you tried this. Have you tried swapping metering blocks between the good and bad carb?

Re: Carb Adjustments
 

When you bought these engines, did the carbs come with them, and were they used carbs? If so you probably don't know the history behind them, and god knows what was done to them. I think the simplest (and cheapest) thing to do first is try to borrow a known good carb from someone (as Waybomb said), and see if that cures your problem. If so, then I would invest in new carbs, and maybe something a little smaller which will probably give you crisper throttle response.

Re: Carb Adjustments
 

The carbs did come with the engines. They were in a Sutphen 30 with Kamma drives and the guy I traded engines with had never run the boat, so god knows how these carbs even ran on that boat, much less a big heavy Stinger. They were also set up on a dual plane manifold, which would have definitely been better. I wanted new marine carbs along with this trade as well but he convinced me he could marineize the existing Demons and make them work with the package. The carbs were also never marinized with the j-tubes, making me want them gone even more.

Part of the trade included rebuilding these engines to Mercruiser 440 cyclone specs which is what they were from the start, I think they are close to that, but he shaved some of his costs by putting on cheap intakes, re-using his Demon carbs, using automotive pumps, and parts, and who knows what else. I just wish I even have the information on what is in these so I know whats going on with compression, pistons, cam etc. I know what is bolted on , but as for the guts I am not informed and I should be. I left it to him to do what was right and trusted him and his machine shop to build good motors, I now think I should have intervened more, but I'm no expert on what should be and what should not be. If I knew then what I know now. (the milk has been spilled, I'll stop crying now.....)

Just the induction system alone on the engines I traded to him are worth nearly the value of these base engines that still don't run right. I am starting to wish I ran the boat the way it was rather than get into all this troubble with the unknown, but I was afraid the engines I bought the boat with were a ticking time bomb, and I did not want the hastles and maintenance, and short life span on supercharged motors. (however reportedly this big heavy old Stinger 390 did over 100 MPH with the engine package I bought it with.) I am wondering now what I was thinking then. Who knows though, they could have blown up right away after sitting for 3 years or so. The things just scared me looking at them, my knowledge level and experience with blower motos is non-existant.

I'm sick of the crap that has become the relationship between me and this mechanic and the battles over the engines quality and service, now all I want is the mass of iron sitting in the back of my boat to do more than weigh it down. Nothing has lived up to my expectations or the arrangement we made, and I just want this thing running with no more battles. I have taken to doing everything myself and figure that is the best way for things to get done, and correctly, and the way I want even if I make mistakes along the way.

Thank you all for all the help you have given me with this project. This is my first performance boat and I am now on my own with it at this point, and learning something new every day both with experimentation and through this forum. Without this helpful online resource I think my learning curve would be much flatter than it has been. I figure if I keep throwing tools, time, and money at it ......it just might run! (unfortunately I am running short of all three)

Before and after pictures......

Re: Carb Adjustments
 

Okay, so the problems are definitly in the carb, so thats good. If I were you , at this point, I would do the following

Order two NEW holley 800 double pumpers.

Order two New marine fuel pumps

New distributor caps, rotors, and plug wires

New coils

New pickup sensors for the distributors

You will probably have to spend another 1500 bucks, but in the end, you should have a good running Stinger with all new components. It sounds like the mechanic kind of stuck you with some garbage parts. It sucks to have to straighten out someone elses shoddy work. I also know how it feels to throw money and time into something with zero results. Save some cash over the next few months, and get the correct parts you need. Do it first thing in the spring because you dont want to spend next season wrenching. You'll have your hands full gassing, cleaning, and enjoying the boat.

Re: Carb Adjustments
 

I know how you feel, trusting people to do the right thing, and being disappointed in the end. I have always been the kind of person who always did his own work, and I learned a lot along the way. Fortunately, most of my lessons were on cars and bikes (a lot cheaper). It seems like any time I thought something was beyond my skill level, and I sent it out, that's the item I usually had problems with. There are some great people out there who are honest, and do great work (a bunch are on this board). Just keep asking questions, you'll learn a lot from them. You'll get your problems ironed out, just try not to get frustrated. I would press the mechanic for the engine specs. I think once you really know what you have, you'll be in a better position to fix your problems, and the people on this board will be in a better position to help you. If your engines are mild, and you're not planning on revving them too high, you might be better off with dual plane manifolds. I'm sure there are plenty of guys on here that could give you better advice in that area than me.

Re: Carb Adjustments
 

Thunder,
I guess I was writing my previous post while you were posting yours.
I couldn't agree with you more. But, I think he should try to find out a little more about the engines. Given the way this mechanic treated him, who knows what's really in there. Pulling the intake and one cylinder head could really reveal a lot. A dial indicator, and a degree wheel could reveal even more. I don't know if he wants to go that far, but given the situation, I wouldn't be comfortable unless I did that. That's just my opinion though.

Paul

Re: Carb Adjustments
 

I'm wondering if 800's are even a bit too much. I can get a pretty good price on 800's, but I'm thinking 750's might be more appropriate. Will 50CFM between what I have now and 800's and / or between 750's and 800's make that much difference in performance, response, and fuel burn? Especially with a single plane intake that I have now?

I would like to replace the intake with a dual plane, however if the difference will not be really noticable than I would rather not blow the money on that right now. I think I need to see what smaller carbs will do, but how much smaller? I know the formula says a 750 should be plenty (and I'm sure these engines are not nearly 100% volumetric efficient) however Mercruiser orriginally put a 9022 800 CFM on the 420's and 440's, which makes me think that was the best match, or they just wanted the factory motors to run a little rich.....

I'm not really frustrated anymore since I think we have narrowed down the problem. I bought this boat because I wanted to wrench on the engines and learn something about them, which is exactly what I am doing, and could not be happier, although after all the work I have done I would like 1 or 2 nice rides this year. I am far more positive and far less frustrated than my wife for sure. At this point she would be elated if it blew up or sank (with or without me on it.... :D )

Re: Carb Adjustments
 

After read your post about the history, I am with Mild Thunder. As for carb size. I always like a little fatter carb.
And if you have time, I'd also do as Liberator says, if not for anything else but peace of mind.

Re: Carb Adjustments
 

I would go with the 800 holleys especially if you can get a good deal. They worked great on the 420's, and mine have the dual plane intakes. You should be able to get something back on ebay for the 850 bg carbs

Re: Carb Adjustments
 

This won't have anything to do with the problem but have you changed props since you've changed engines? This be part of your acceleration problem.

I'd yank the timing change cover, and get the part number off of the camshaft. Yes, it will be more time, but you'll save money in the end. With engines this size you'll be happier with dual plane intakes, and good 750's. You should be able to sell the open plenum intakes, and carbs for enough to pay for the intakes, and half the cost of the carburetors.

Regardless of if you don't care or not, keep in mind that the automotive parts on your engines will void your insurance.

Re: Carb Adjustments
 

Yes, I changed to 22P Bravo 1 props when I switched engines. They should turn fine once I get to spin up the engines.

I have also had several recommendations concerning the secondary opening on the new carbs I am looking at. It seems mechanical secondaries are simpler but less efficient, but more widely used than vacuum secondaries. The vacuum are also significantly cheaper than mechanical. I'm sure there are tons of opinions about the merits of each. Does anyone use the Holley 750 vacuum's and are happy with them? Any opinions on efficiency?

I'm looking to cruise this boat, not race, or even concern myself with very much wide open running. I'm leaning towards 750's or 800's with mechanical secondaries for simplicity.

Re: Carb Adjustments
 

I have to agree with RumRunner on the intakes. I think you'll be happy with the mid range performance, and good bottom end the dual planes will give you. The dual plane/750 combo should give you some snappy throttle response.

Re: Carb Adjustments
 

Mechanical Secondary Carburetors are going to be easier to dial in. You may also want to make sure you get carburetors with electric chokes to aid in starting.

Re: Carb Adjustments
 

Ive run vacuums for years and they took years to set up right, but, this summer I tried mech secondarys I dont like the way they behave compared to the properly setup vacuums. They dont have the "punch" the vacuums did. Thats not surprising. Top end is the same. Fuel mileage pretty much the same too which surprised me, I thought the mech would be worse for some reason. Ill be on a dyno this winter so I will check their behavior side by side. My primary concern is the transition between primary and secondary opening, a typically lean point.

Re: Carb Adjustments
 

Today I tried a different power valve (5.0) since I started seeing 10 - 10.5 vac numbers at idle. I figured it could not hurt to try. I also dropped jets in the primary's 2 sizes as well. Idles great, but no power under load.....black transom on the left side only. When I accelerate slowly, the engine comes up to 2500 - 2600 and when I put the power to the right engine, the right one will pull the left one up to 2700 - 2800 or so once on plane and trimmed out. If I try to add power beyond that I can hear a slight "dieseling" and immediately pull it back to the previous setting to get rid of that. It seems the carb is so rich when I try to add more power it can't pull any higher, and floods the plugs which I'm thinking is what I am hearing. Timing is the same on both engines and that dieseling sound followed the carb from one engine to the other as well when I switched carbs. Pull it back to idle and it works great. There is some slight hesitation on both engines accelerating through 1400 rpm or so but it clears out above that. I think that could be another symptom of being over carbed and over intaked. The right engine will accelerate to about 4200 rpm and I figure that is because the left engine is no longer helping to push the boat after 2600 or so.

I called Barry Grant tech this morning and tried a few things they reccommended, like changing the butterfly idle setting, lowering the float level to the lowest setting, re-jetting, changing power valves, but they also suggested advancing my timing to 16 degrees base which would top me at about 36 - 38 degrees total advance. Way too high in my opinion so I did not try that.

I think it is time to try different carbs. I am going to try a used 800 0-9022 tomorrow that the local performance boat shop is letting me try before I buy new ones from them. I hate to give up and buy others, but I think I have reasonably tried almost everything except swoping the metering blocks. I have one good carb on my steering engine and really don't want to screw myself into a tow if I can't steer my way in. At least they are letting me take a test drive on the 800 to be sure before I spend the money. I still want to figure out what is wrong with the BG carb since I would like to sell them and don't want to pawn off my problem on someone else. (even though I'll sell them for auto use.) What are all the things that could cause the carb to be extremely rich?

over jetting (77 front / 83 rear now)
blown power valve or oversized power valve (new again today)
cold operating temperatures (water temp 140 - 150 degrees)
high float level (I'm between the lowest and middle setting)
high fuel pressure (I'm at 7 lbs)
4 corner screws rich, (only 1/4 to 1/2 out on all)
retarded timing (I'm at 11-12 degrees base and 32-34 degrees total)

what am I missing? Maybe I will have to take that chance and switch primary and then secondary metering blocks and see what happens. I just really hate to screw with a good running carb, but I guess that is the last thing to rule out. Maybe I'll try that tomorrow when I have that nice 800 sitting there that I can strap on if I need to after that test.

This mystery has been baffling the local best as well. I'm thinking it might remain a mystery as I am about to give up on these old carbs.

Sorry for the continued lengthy posts, but I want to be as clear as I can be about the things I am experiencing with this problem. Thank you all again for your continued interest and advice in this mystery.

Todd

Re: Carb Adjustments
 

With all the work you've done by now I'm sure you have inspected the internal seals and gaskets of the carb for any internal leak that could bypass fuel into the motor?


Sorry, Just re-read your post where you regasketed.

Re: Carb Adjustments
 

The only gasket I did not change was the one between the base plate and the throttle body. I did not have a gasket for that, and did not take it appart. I did'nt think there was much there to check anyway. Should that have come appart as well?

Re: Carb Adjustments
 

Don't know. Was just thinking out loud. :eek: I've only worked on Holleys and quadrajets.

Re: Carb Adjustments
 

I think I'm also going to try the full rebuild kit. I have been replacing parts in kind of a scattered way, but everything has looked good. I guess I should just replace every single gasket, o-ring, seal etc just to make sure. Who knows, this carb may not work great on this big heavy boat, but could work perfectly on a car engine (thinking towards selling them)

I was thinking about just buying another Speed Demon 850 for now and only spending another $400 instead of $800. Will 50 CFM make that much difference between the Holley 800's I'm looking at and another Demon 850? Does anyone know where I can get J-tubes to marineize the auto carbs I have installed? I have not been able to find them. I suppose I could make them to fit the vent tubes if I can't find them. ( I was specing the differences in the Speed Demon 850's and the Speed Marine Demon 850's and they are nearly identical except for the J tubes and nearly 200 bucks each.) I feel like after having them appart so many times now I know the Barry Grant product pretty well (in an amature kind of way), and feel comfortable with servicing it.

Re: Carb Adjustments
 

I too would like to find some j tubes. But anyway, I suppose if you could get an 850 to run okay on that engine, might be ok for a season. Just watch the rich condition because it could do lots of damage to the plugs, cylinder walls, and if the fuel contaminates the oil, bearings, etc can be damaged. Let us know how the holley works. You'' ll probaly see about 4600-4800 on the good engine once the other one picks up rpm. Then you might have to tweak the props to get you around 5000-5200.