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some test results for the gas guzzling 454

Hey guys...I just found something a little weird, I pulled the port carb (q-jet) and expected to see a square bore manifold under it,instead I found a sreadbore manifold and the wedge spacer. I thought this was a little unusual as on all the Q-jets I've pulled I've always found the square bore. I checked to make sure it wasn't an adapter and it is the manifold. I don't know if this would make any difference but thought I'd mention it.....Lee
 
Lee, earlier you had said "I don't want this to remain a mystery, it will drive me crazy".....I hate to tell you but, It will make a bunch here crazy too....You may have stumbled on something ....AL
 
Bulletine.....thanks for the tip....I can't believe I forgot about that site, I'm on there a lot,just a senior moment ,I guess. But your right , that's the manifold, it just took me by surprise I wasn't expecting to see that....Lee Al....Sometimes I feel like I'm stumbling over myself !!! I'll know more tomorrow afternoon, I plan to work on it all morning. After all this posting if I don't find something, somebody may put a hit out on me. :)
 
leokow said:
Hey guys...I just found something a little weird, I pulled the port carb (q-jet) and expected to see a square bore manifold under it,instead I found a sreadbore manifold and the wedge spacer. I thought this was a little unusual as on all the Q-jets I've pulled I've always found the square bore. I checked to make sure it wasn't an adapter and it is the manifold. I don't know if this would make any difference but thought I'd mention it.....Lee
Click to expand...

Nope. marine Q jets use the spreadbore intake.
 
Lee, Dave is correct....., the Q-jet is a spread bore, and the manifold should also be spread bore.
If there is a wedge plate being used, it too should be spread bore.

Now, the cruiser SBC should also be using a dual plane intake manifold..... either the OEM, or something that would be similar to Edelbrock's Aluminum Performer.

.
 
Typical parts catalog and lack of complete info. It is very difficult for these companies to maintain a accurate parts catalog with all the part changes by the OEM's.

My example is my 7.4.s have Prestolite Distributors, every where I look I see the Mallory dists for my '89s. Soon I plan on replacing the caps and rotors, hope I can find them locally.
 
I've got a parts catalog for the mid '80s Gen IV that shows both EST and the Prestolites. I can send a copy to those interested. PM me.
 
Thanks, I have everything I need. I try to grab all information that can be found, especially OEM manuals. The problem is finding parts locally, so I have to resort to ordering online in many cases.
 
Yes, ALL the q-jets are spreadbores, not squarebores. also, the wedge plate is standard for installations using inline gears.

Hopefully, you've got marine gaskets to replace what was there. They are typically "more substantial" than their auto cousins and do a much better job of sealing. If they leak, you'll have the opposite problem, likely with a minor overheating issue on top of it.
 
Mark....I learned that gasket lesson the hard way yesterday, I tried to re-use the wedge plate gaskets over again and couldn't get the engine to run at less than 1800 and it popped like crazy. So I ordered the new wedge plates and the gaskets to go with them, should have known better than to try and get away with that.....Lee
 
As much as I do not like the adapters and wedges I have with the Edelbrocks, THANK GOODNESS they have a square edged rubber o-ring gasket that is recessed fit into the fitting. I had taken those carbs on and off MORE than several times a few seasons ago.

Lee, are you out now? We may try for the first weekend in Dec. I would like to try and run into you (figure of speech)
 
Al....I'm still in the water, I decided to go with the 1409 edelbrocks to see if I can improve this gas situation, it's far from a plug and play operation, But things are under control, I got the new wedges and gaskets last night so I'll put everything together again today(thurs.) and see how she runs, I really wasn't happy with the first 3 times I tried,too many vacuum leaks,tried to cheat using the same wedge gaskets,just wouldn't work. I'll be around this weekend If you would like to meet up at Tommys'...I'll treat to breakfast, on Sunday, just name the time. Then we can go down and look at the boat if you want too, if not , that's ok too......Lee
 
Lee:

be more than happy to give your old q-jets a new home. You can send a PM if you want to exercise the option.

mark
 
May I interject some reality here? Big block 454s are gas guzzlers. Period! One can reduce their thirst with careful tuning, perfect propping, and the use of a fuel flow metering system to determine best gas mileage throttle settings, but them doggies gotta drink!

Jeff
 
OK Jeff'....here's my reality ! I know they have to drink , I expected that when I bought her....but what I have is ridiculous ! Here's a boat that has everything you mention in your post, that used to get 20knts. at 3000 and use 23.4 gals/hr. that's .89nmpg. I would be very happy to achieve those numbers now. That is my normal cruise speed. What I have in reality is 14knts. at 3000 and use 48 gals/hr, that's .5nmpg. my range has gone from 260 nautical miles down to 170. Now, I'm not trying to get it all back, after all the boat is 21 yrs. old, I would be happy with 75% and that is what I've been trying to do for these past few weeks. I know it's been a frustrating problem for everyone on here, there doesn't seem to be an answer but believe me there is one, it's just a real hair pulling pain in the a$$ when every test you do comes out ok and you don't know where to look next, from your post I assume you don't agree with the carb change, that's ok, but if I achieve just a fraction of what I am after then they will pay for themselves in the 1st 2 weeks of the season. Then I can look at the prop situation and see if I can pick up some more, how much pitch do you think I should try to start out with, they are 18x18's now ? thank you....Lee
 
Lee,
I just read though all the posts on your issue again. I would still wonder about the weight and props. I assume you have the new carbs up and running and have tried them out by now. As for the weight, when they haul you out can you possibly get her weighed then? How hard would it be to cut a hole and then put an acces hatch in the deck to check the foam? Hang tight, you will find the cure eventualy. (miss that pacemaker yet?) Have a good wekend and thanksgiving.
Paul
 
Hi Paul...I just finished the carbs today ,I have one more thing to do on each engine and then I'll take her out for some test runs and see what happens,I'm still working on trying to get it weighed, so far no luck, the marina I use doesn't have a scale tied in to its lift. I still have to try my friend that works at viking he may be able to do something,a nice set of truck weighing scales would do the trick but not so easy to come by. I just thought of something, my next door neighbor is a iron worker rigger and works with cranes everyday,maybe if he has one working in the area I could ask him to lift it,I know all the cranes have weighing systems tied into them,I'll put a call in to him and see what he says. Boy, would that answer some questions fast. I'll see if I can get lucky.:) Not like the carbs they were far from a plug and play replacement for these engines , I had to replace the wedge inserts along with using the spreadbore to squarebore adapter plate and replace all the bolts they give you to do the install, they're all too short also had to re-drill the bracket for the linkage as the holes don't line up anymore and run a switched 12 volt line for the choke,plus new fuel lines, but that I knew from the beginning . As far as the pacemaker, I didn't have a choice in letting her go, I had my knees replaced a couple of years ago and I just couldn't climb that damn bridge anymore,but to be honest, I have had second thoughts. I could have chopped the bridge and made her into a cruiser !Just a thought, LOL. Thanks for the interest, Paul,you have a good holiday too....Lee
 
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Before I bought Miss Nancy, I looked at a boat that was a 28' fly bridge with only the one helm station. Loved the boat but where I boat alone most of the time I could just see me tumbling down the ladder trying to get tied up and decided to go with this one instead. Don't regret it in the least.
 
Well Well and HI DI HO !! It's not completely fixed but it's a helluva lot better than it was. I just came back from a test run after changing the carbs and at 2900 rpm I picked up 7 gals.per hour on each engine ! If I go over 3000 I start to lose it pretty fast, it drops to about 3 gph difference, but I'll take whatever I can get at this point. I think I'll put a physical stop on the throttles at that point !LOL Now if I can get some info from Jeff , I'll look into some props and maybe be able to pick up a little more speed at the mid range throttle settings. Thank you to everyone that tried to help, it was definitely appreciated....Lee
 
That is great Lee, I meant to ask, do you have trim tabs on that old gal? I know that I can get onto a semblance of a plane with them but without them she has a tendency to drag her butt like a dog with worms. Most of the weight is aft which of course does not help. At 2900 how fast is she moving?
 
Hi Paul...yes it does have trim tabs, but I think they need a little work and she moving at just 14 knots at 2900. I'm hoping that Jeff will come back on and give me some help with the prop sizing so I can start hunting for them. I just missed a set on ebay last week , they were 18x23's and they went for $425 . So now I'm looking again, but I don't have any idea of what size to go for.
 
I am not an expert, but with twin 454's I would be expecting more then 14 knots at 2900. We have an outfit here called H&H propeller who can give you a good idea as to what you need when you give them all the spec's, I would imagine you have some one simaler down there.

As for the trim tabs, if they are Bennet's, they are very helpful when you have problems. Mine were on the boat when I bought her and they were leaking by so they would not stay where I set them. I emailed them for a trouble shooting guide and they sent that and the parts free of charge. Great folk's.
 
leokow said:
Hi Paul...yes it does have trim tabs, but I think they need a little work and she moving at just 14 knots at 2900. I'm hoping that Jeff will come back on and give me some help with the prop sizing so I can start hunting for them. I just missed a set on ebay last week , they were 18x23's and they went for $425 . So now I'm looking again, but I don't have any idea of what size to go for.
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you are at 20" P and thinking of 23" P, currently having trouble reaching even 4k rpm at WOT. I think that would be trouble in your situation. The engines are struggling now to reach rpm, today's cruise rpm gives you slow speed numbers, likely due to higher than design loads on them. I know you are pursuing getting the rig weighed, I think that is still the best plan right now. Also, contact others with your same engine/hull combo. Get some advice from other owners. If they get the 20" props to work, you will also. Right now, it seems your boat is towing an anchor when underway. :confused: Trim tabs, Get them extended down!
 
diver_dave said:
you are at 20" P and thinking of 23" P, currently having trouble reaching even 4k rpm at WOT. I think that would be trouble in your situation.

The engines are struggling now to reach rpm, today's cruise rpm gives you slow speed numbers, likely due to higher than design loads on them.

I know you are pursuing getting the rig weighed, I think that is still the best plan right now. Also, contact others with your same engine/hull combo. Get some advice from other owners. If they get the 20" props to work, you will also. Right now, it seems your boat is towing an anchor when underway. :confused: Trim tabs, Get them extended down!
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Dave, I could not agree more with you.
Add to this that 14kts @ 2,900 rpm is an ineffecient speed, and certainly an RPM to avoid for any length of time.
Either hull speed.... or get her on top of the water... plus some!
For a planing type hull, the "Plus Some" is what usually gets us where we want to be!

.
 
Thank for the input you guys, this is one end of the business I know very little about,that's why I've been asking Jeff and anyone else for suggestions in this area.I feel like the boat is dragging too, Paul's description of the dog fits it well, the trim tabs are Bennets and they are recessed into the hull, they worked last year at launch but I think they failed somewhere during the year. I'll get them working again when I pull her out.
Rick...you couldn't have said it better with the draggin anchor comment,but as soon as I go from 2900 to 3100 the fuel increases to 23 gph from 14 for each engine. I know I need to get it to run right at 31 or 3200 where she is the most comfortable to drive but right now that 200 rpm jump is costing me 18 gals/hr. in fuel. On the original test boat the break is at the same rpm, she goes from 14 to 23 but for both engines so in reality I'm still at double the fuel of the original test,and it was worse than that before the carb change. I guess there's no sense in messing with anything until I can get this puppy weighed. As far as finding another boat similar to mine, that's going to be tough. 1st finding a Boston whaler with an inboard is rare and finding one with inboard gas engines is even rarer still, I have never found another even on the whaler forum although I'm sure there are some out there somewhere. It would probably easier to locate a 31 Tiara or another boat like that to compare to.
 
I do not know what my boat weighs, Tiara list it at 11.5k lbs, but I have a very heavy tuna tower. Firends estimate the tower to be 3500 lbs.

I forgot the size of my props, I would have to find the receipt. In the spring I had my props tunes and I could shoot up on plane without the trim tabs. I was very surprised the the increased performance:

Here's the performance data from my 3300 with 454 carb'd crusaders via gps full fuel, water, and lots of gear aboard--basically cruising condition.

mph knots gph rpms nmpg mpg
11.5 10.0 16 2200 0.63 0.72
16.7 14.5 18 2500 0.81 0.93
17.9 15.6 20 2800 0.78 0.90
19.6 17.0 21 2900 0.81 0.93
21.9 19.0 24 3000 0.79 0.91
23.2 20.2 28 3100 0.72 0.83
24.8 21.6 30 3200 0.72 0.83
26.8 23.3 36 3400 0.65 0.74
28.8 25.0 38 3600 0.66 0.76

I didn't run it to WOT for this test as I was looking for optimum cruise. It goes scary fast. I've been well over 30 knots at 4200 rpm.

Hope this helps, I am enclosing a prop spec doc, forgot where I found this but it is interesting to look at. I will have to see how to attach this doc.
 
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