SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: LBsuperjet on February 02, 2008, 03:28:59 PM
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my 460? its the thermostate block off plate in the pic below, next to the dist. i checked team C, ebay, offyparts.com, and others without any luck...it would go on my new offy TR that i just bought, since everything circled was stolen in the theft. does anyone have any ideas before i go find someone to make it for me? :-\ thanx,
Reid
(https://www.socaljetboats.com/proxy.php?request=http%3A%2F%2Fwww.hotboat.com%2Fimage_center%2Fdata%2F500%2FPicture_022k.JPG&hash=ccfc113a6242c9e5363592cdbbaa70e142c90945)
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If its just a plate , i would make one . But i have seen them before but i forget where ???
So im no help..........
2sav
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also, can anyone tell in the pic wether my holleys on there were double pumpers or not? they dont look like it although what do i know? lol...all i know is that they were 650cfm.
Reid
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If its just a plate , i would make one . But i have seen them before but i forget where ???
So im no help..........
2sav
yeah 10-4...that was my fear...how the hell would i make one? its like 1/8th alluminum or something, im not sure.
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yeah 10-4...that was my fear...how the hell would i make one? its like 1/8th alluminum or something, im not sure.
Trace out a thermo housing. That would be the way i would do it ;D
2sav
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yeah 10-4...that was my fear...how the hell would i make one? its like 1/8th alluminum or something, im not sure.
I've got some 1/4" aluminum plate here that I'm cutting up. I can trace out a cover for you from a new gasket I've got and then you could trim it to fit the way you want it to. I've got a 460.
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really? thats kick ass!...you mean you'd send me some metal w/ the trace on it? shit how much do you want?....i cant find one anywhere.
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really? thats kick ass!...you mean you'd send me some metal w/ the trace on it? shit how much do you want?....i cant find one anywhere.
How soon do you need it? Traced??? Hell no, cut out and the holes drilled. Whatever the postage is is all I'd ask.
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also, can anyone tell in the pic wether my holleys on there were double pumpers or not? they dont look like it although what do i know? lol...all i know is that they were 650cfm.
Reid
No vaccum secondary canister - BUT I dont see a secondary acc pump. The main pump is a 50cc unit, leading me to believe they are 660 center squirters (mech secondary).
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How soon do you need it? Traced??? Hell no, cut out and the holes drilled. Whatever the postage is is all I'd ask.
not super soon, im just going to mount the bottom part of the TR as soon as i get it back next week...but i wont need one for about 2 more weeks...take yer time, and thank you, ill totally hook you up w/ whatever you want, its really appreciated!
Reid
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No vaccum secondary canister - BUT I dont see a secondary acc pump. The main pump is a 50cc unit, leading me to believe they are 660 center squirters (mech secondary).
okay, that sounds good, so they're not DP's? i think i have another pic of the other side w/ all the action on it...ill post it up soon...thanx for your help bud.
Reid
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okay, that sounds good, so they're not DP's? i think i have another pic of the other side w/ all the action on it...ill post it up soon...thanx for your help bud.
Reid
Technically no, but they are based on the DP carbs and have 1:1 ratio (pri and sec open together), and the acc pump shoots from the center rather than the side. These are race carbs typically, and designed for a 2x4 application. They are good carbs. Most people would still consider them double pumpers...
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also, can anyone tell in the pic wether my holleys on there were double pumpers or not? they dont look like it although what do i know? lol...all i know is that they were 650cfm.
Reid
The side hung float bowls are most common on vacuum secondary single feed carbs, but speedymopars might be right about them being 660's.
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I've got a question, if you block off the thermostat outlet, how do you keep the top end of your motor cooled off? I'll have that plate laid out and ready to cut tomorrow, if the wind and rain let up. :)
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I've got a question, if you block off the thermostat outlet, how do you keep the top end of your motor cooled off?
Two hoses go into the intake right under where the thermostat is for water to flow around. At least thats how my intake is setup.
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Yes the heater hose outlets are under the thermostat housing. I just tapped and plugged one, and the other came tapped. My old manifold I clamped a rubber end over the untapped outlet and it eventually broke, blew off and almost sunk me, twice... :-\
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Those carbs could also be 450cfm 9776's with 50cc pumps. But its hard to tell from the pic. the 9776's are a stripped down inexpencive version of a 4160 style carb with mechanical secondaries but only one accelorator pump (not center squirters). Designed for 2 x 4 applications only, decent for the price but the 660's definetly are the hot ticket.
BTW Glenwood makes that block off plate, but it looks like Gregs got ya taken care of. -Later
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Those carbs could also be 450cfm 9776's with 50cc pumps. But its hard to tell from the pic. the 9776's are a stripped down inexpencive version of a 4160 style carb with mechanical secondaries but only one accelorator pump (not center squirters). Designed for 2 x 4 applications only, decent for the price but the 660's definetly are the hot ticket.
BTW Glenwood makes that block off plate, but it looks like Gregs got ya taken care of. -Later
glenwood eh? is there a web site? id sure like to let greg off the hook, but hell, if i cant find it at a shop like team C or any others online, shit how am i supposed to find it? thanx for the info, ill look them up!
Reid
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Most marine dealers in our industry sell Glenwood, they don't sell retail. But they do have a website www.glenwoodmarine.com, mostly a PDF version of their catalog, but i'll save ya the trouble its an item number 686.
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Those carbs could also be 450cfm 9776's with 50cc pumps. But its hard to tell from the pic. the 9776's are a stripped down inexpencive version of a 4160 style carb with mechanical secondaries but only one accelorator pump (not center squirters). Designed for 2 x 4 applications only, decent for the price but the 660's definetly are the hot ticket.
I agree (I originally thought that too - I have a pair of those 450's on my tunnel ram), but that 50 cc pump made me think otherwise. The 450's (and the 390's for that matter) have such a small verturi bore that the secondary pump is unnessasary. If the pump was bumped to 50cc, it would probably only run right on a really small ci engine (that really over carbed) - as you would have major bogging out of the hole. That was my thought anyway.
A pic of the other side would really help (the secondary linkage is a tail tell sign) - one without the scoop would be the nail in the coffin. They are probably one of these carbs:
390 mech secondary
450 mech secondary
660 center squirter
The 850 center squirter comes with cathedral bowls so we can eliminate that.
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Hey guys, i have a couple pics of the linkage side of the carbs and TR...remember, everything from the intake up, was stolen so im starting from scratch...i already have the same exact offy TR, which is out at embee right now being ceramic coated...so anyway, heres the pics of what i had:::
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1:1 Linkage on pri/sec - no acc pump linkage on secondaries - 50 cc pump - non cathedral bowls - definately a 660 center squirter carb in my opinion.
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Will the fuel pressure be the same in the second carb with that set up or should there be a pressure regulator with 2 outlets?
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Will the fuel pressure be the same in the second carb with that set up or should there be a pressure regulator with 2 outlets?
I bought the Holley Marine fuel pump kit and it comes with a regulator that is set up for either one or two carbs. So I would think that it would take care of getting the proper fuel pressure to each carb. It also had a plug so if you were only running one carb you could block off that outlet. It is bottom fed.
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Will the fuel pressure be the same in the second carb with that set up or should there be a pressure regulator with 2 outlets?
I don't think we could use enough fuel at the rpm we turn to be a problem.
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I agree. It should be the same pressure at both carbs.
There isn't enough line there to cause a pressure drop from primary to secondary, and unless you max out the pump volume wise, there isn't going to be an issue.
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I agree. It should be the same pressure at both carbs.
There isn't enough line there to cause a pressure drop from primary to secondary, and unless you max out the pump volume wise, there isn't going to be an issue.
But, shouldn't you regulate the amount of fuel from the fuel pump to the carbs so as to not pump more fuel through the carbs than needed and therefore have unused fuel dumped out through the exhaust? I have read that most people seem to think big CFM numbers means more power and in reality it just means waisted gas. Most people over size the carb, be it car or boat.
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The main reason for a regulator is to bring the fuel pressure down to and acceptable rate so you don't push fuel past the needle and seat and flood the bowls.
I agree that a lot of people think that bigger is better in carburetion, but some engines like CFM (air flow) and with proper jetting (fuel flow) can get good results with a large carburetor.
My Hondo has a relatively mild BBC with two 600 Holley vacuum secondary carbs and my plug readings look good. But with the vacuum secondaries working properly, I probably rarely get full throttle.
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The main reason for a regulator is to bring the fuel pressure down to and acceptable rate so you don't push fuel past the needle and seat and flood the bowls.
I agree that a lot of people think that bigger is better in carburetion, but some engines like CFM (air flow) and with proper jetting (fuel flow) can get good results with a large carburetor.
My Hondo has a relatively mild BBC with two 600 Holley vacuum secondary carbs and my plug readings look good. But with the vacuum secondaries working properly, I probably rarely get full throttle.
Hi Crew, Most people don't mess with jetting and CFM. I'm guilty, I don't mess with any adjustments if I don't have to. I like a plug-n-play approach to things I replaced my 750 with a 750 on my rebuilt 460 but only because that's what was on it and it was mildly over built from what it was. I could have done very well suing a 650 or even a 600, since I'm not racing or out for competition in any form. I figure that if I do stomp on it I'll have some gas going out the exhaust that isn't completely burned.
Greg
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CFM is not adjustable without modifications to the carb, but jetting is fairly easy to adjust for tuning. I'd bet that many jet boats could stand to be jetted down a little without the chance of running lean, and doing damage.
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CFM is not adjustable without modifications to the carb, but jetting is fairly easy to adjust for tuning. I'd bet that many jet boats could stand to be jetted down a little without the chance of running lean, and doing damage.
I agree and I'll say MOST jet boats are over carbed.
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there was a thermostat housing on e-bay last night
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there was a thermostat housing on e-bay last night
btw....i left that one on your manifold.
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But, shouldn't you regulate the amount of fuel from the fuel pump to the carbs so as to not pump more fuel through the carbs than needed and therefore have unused fuel dumped out through the exhaust? I have read that most people seem to think big CFM numbers means more power and in reality it just means waisted gas. Most people over size the carb, be it car or boat.
There is a needle and seat on the carbs - think about the toilet in your house. Same thing. You have 60-100 PSI going to the inlet of the toilet. As long as you dont overpressurize the house to 200 psi, water will not flow unless the bowl gets low (like when you flush).
A carb is the same thing. The fuel is pressurized to the float bowl, which acts as a mini gas tank. There is a needle and seat which shuts off the inlet flow of gas when the float bowls are full. As long as the fuel pressure doesn't push the needle open, it will work as planned. Above 9-10 PSI this can get pushed open. A mechanical pump and some of the lower flow electric pumps are preset to pump a maximum of 7 psi.
For the most part, changing PSI will not alter your jetting (there are some exceptions I'm not going to get into now). Jetting is where you are either being rich (dumping fuel out the exhaust), correct, or lean (melting a hole in your piston from the lack of fuel and the heat it creates).
There is more to carb CFM and requirements than just RPM. Intake manifold, head cfm, valve diameter, cam duration, all play a part. I have a 454 that needs 450 cfm max - while one of my 440's needs around 900 and the other 440 needs 1700. Factory 440's with a 5500 rpm shift point came from the factory with 1300 CFM. The same engine also came with a single 625 CFM 4bbl.
If you run a single plane you should run a smaller carb than if you have a true dual plane. This is because the engine only sees half of the carb. If you run a tunnel ram, the manifold makes the head flow better, so you need a larger carb.
If you are running a dual plane and want to experiment, try different open carb spacers (1/2, 1 and 2 inch). This will allow the engine to "see" a bigger carb, and make your intake look bigger. If you gain RPM, then you know you needed more CFM (or a different runner length).
I'm leaving some stuff out so this post isn't too long....but you guys get my drift..
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I know nothing about this, but when I play with my desktop dyno, I always get bigger HP/torque numbers with bigger carbs...