Motor out of tune after hard run...
07-09-2002 | 02:02 PM
#11
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From: Virginia Beach
I'm also running a q-jet so the two really don't compare as far as the carbs go. I can't remember right off hand but I have it setup a little more on the rich side of things to keep it safe. There may be some power hidden in there. I'm thinking of ordering up a new Holley, though I don't think that the CFO is going to like that one too much. I'm goign to work with the qjet for a little while longer.
Off to lunch!
Off to lunch!
07-09-2002 | 02:23 PM
#13
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Posts: n/a
This probably more accurate than DeskTop Dyno.
http://www.compcams.com/information/...74H-10_001.asp
http://www.compcams.com/information/...74H-10_001.asp
07-09-2002 | 09:38 PM
#15
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Here you go Tom.
2000 Torque 347 HP 132
2500 363 173
3000 365 209
3500 384 256
4000 397 302
4500 401 344
5000 389 371
5500 366 384
Like you mentioned. You thought you may have to spin it. You don't get your max HP until 5500. Which is at or close to the max for your intake too.
2000 Torque 347 HP 132
2500 363 173
3000 365 209
3500 384 256
4000 397 302
4500 401 344
5000 389 371
5500 366 384
Like you mentioned. You thought you may have to spin it. You don't get your max HP until 5500. Which is at or close to the max for your intake too.
07-10-2002 | 12:14 AM
#16
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Posts: 4,295
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From: Virginia Beach
Yeah, that just looks too peaky for a boat combo, ya think??
What cam are you running in the 409s again? I wrote a long-winded question to Comp regarding the specs and how to proceed. There's another post here talking about peak torque vs horsepower and it brought up a good point in regards to efficiency and larger props. I'd like to cut down the RPM needed to reach peak HP and at the same time create a broad, flat-as-a-board torque curve. I have not had any luck spinning my 21P prop though I have not had it on the boat since cleaning out the fuel system (and getting rid of my detonation problem that existed with the old gas.. not to worry though because I was very gentle then). I figure that the boat weighs around 5k pounds with me, full fuel (I always go out full), the wife, and our stuff, maybe a couple hundred pounds less or so but I doubt it. I think that with the 21P prop the engine was not getting into its really heavy torque before the prop was able to overcome the hull (if that makes sense). In other workd, I think that the cam is pretty much wrong for the application (I know that I said I loved it before, but I have now put roughly 15 hours or so on it and can tell that it doesn;t quite work, at least not yet).
Oh well, I'll let you know what Comp has to say. I think they like the duration figures and such but would go with a wider LSA (maybe 112*).
Later!
What cam are you running in the 409s again? I wrote a long-winded question to Comp regarding the specs and how to proceed. There's another post here talking about peak torque vs horsepower and it brought up a good point in regards to efficiency and larger props. I'd like to cut down the RPM needed to reach peak HP and at the same time create a broad, flat-as-a-board torque curve. I have not had any luck spinning my 21P prop though I have not had it on the boat since cleaning out the fuel system (and getting rid of my detonation problem that existed with the old gas.. not to worry though because I was very gentle then). I figure that the boat weighs around 5k pounds with me, full fuel (I always go out full), the wife, and our stuff, maybe a couple hundred pounds less or so but I doubt it. I think that with the 21P prop the engine was not getting into its really heavy torque before the prop was able to overcome the hull (if that makes sense). In other workd, I think that the cam is pretty much wrong for the application (I know that I said I loved it before, but I have now put roughly 15 hours or so on it and can tell that it doesn;t quite work, at least not yet).
Oh well, I'll let you know what Comp has to say. I think they like the duration figures and such but would go with a wider LSA (maybe 112*).
Later!
07-10-2002 | 12:57 AM
#17
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From: Abita Springs, La.
Tom
Quadrajets are notorious for having sunk floats. This will cause the engine to run VERY rich- fouling plugs, etc. When an established motor/plug/jet combination goes wacky, almost all plug problems are really carb problems.
Did the engine ever backfire or burp??? this can rupture the power valve. Not sure on the quadrajet, but on Holleys there is a power valve that can leak and also dump fuel big time.
If most or all plugs are black and wet, its carb rebuild time.
If the hissing soud drops or goes away when you accelerate, you have a vacuum leak.
Good Luck
Ronnie
Quadrajets are notorious for having sunk floats. This will cause the engine to run VERY rich- fouling plugs, etc. When an established motor/plug/jet combination goes wacky, almost all plug problems are really carb problems.
Did the engine ever backfire or burp??? this can rupture the power valve. Not sure on the quadrajet, but on Holleys there is a power valve that can leak and also dump fuel big time.
If most or all plugs are black and wet, its carb rebuild time.
If the hissing soud drops or goes away when you accelerate, you have a vacuum leak.
Good Luck
Ronnie
07-10-2002 | 10:08 AM
#18
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Posts: 4,295
Likes: 1,458
From: Virginia Beach
Yay me!
Loose plug wire. Seems that all that rough water on the way back (read partially airborne) took its toll on the plug wires. One was "just dangling on the number two plug. That would eplain the "hissing" noise that I was hearing that would not go away. The boot was still attached to the plug, but when I touched it, the wire just fell away. I have not started it yet to check it out but I would have to assume that was the problem.
On a not so good note... Jeannette and I are on the way to the hospital this morning with complications due to our having a miscarriage. As if things couldn't get any worse for us in the baby department, it seems as if there are more serious things happening. Can we ever catch a break here with this baby stuff?? Sorry, had to vent a little.
Loose plug wire. Seems that all that rough water on the way back (read partially airborne) took its toll on the plug wires. One was "just dangling on the number two plug. That would eplain the "hissing" noise that I was hearing that would not go away. The boot was still attached to the plug, but when I touched it, the wire just fell away. I have not started it yet to check it out but I would have to assume that was the problem.
On a not so good note... Jeannette and I are on the way to the hospital this morning with complications due to our having a miscarriage. As if things couldn't get any worse for us in the baby department, it seems as if there are more serious things happening. Can we ever catch a break here with this baby stuff?? Sorry, had to vent a little.
