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Re: Engine falling off just past 4k - carb limit?
[Re: RapidRobert]
#1177553
02/21/12 01:06 AM
02/21/12 01:06 AM
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Joined: Jul 2011
Posts: 817
Eugene, Oregon
Secret Chimp
OP
super stock
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OP
super stock
Joined: Jul 2011
Posts: 817
Eugene, Oregon
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Couple of things:
I tried running it up until it seemed to nose off, backed off, then floored it again. Every time I did this it got up to around 4400-4500 rpm and started making an angry ping pong ball noise that sounded like detonation and power fell off with a "stop flooring it" type of feeling. I don't know if I ought to not be running 87 now or if it's getting so lean up top that it's pinging (maybe holding a higher RPM at lean-ish mixture heats the cylinders to the point of detonation will happen at higher RPMs but not when running it up in one go? I dunno, maybe something was rattling), but that's what happened.
I also tested my fuel pressure and I'm getting a good 6.5-7 psi at idle. I couldn't get my dang metal tees to seal well enough at driving RPMs in my garage to be comfortable actually driving with the gauge hanging out from my hood, but the pump seems strong.
My guess at this point is that the carb is just too low-capacity and too lean for the amount of air I'm trying to pull through it at this point. I'm all set to put my 650 Carter AVS on save for an air cleaner and a pressure regulator (didn't expect to have such a He-Man old pump but I sure need one now) so I'm just going to go ahead and do the swap and see what happens when it can get more fuel down.
1967 Dodge Coronet Deluxe station wagon
1.03" T-bars, QA1 arms/rods, Cordoba/GM Metric/Volare brake & knuckle, XHDs, Hellwig rear sway, 318 Magnum w/ air gap, 727, 3.23s
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Re: Engine falling off just past 4k - carb limit?
[Re: Secret Chimp]
#1177554
02/21/12 02:51 AM
02/21/12 02:51 AM
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Joined: Jul 2011
Posts: 817
Eugene, Oregon
Secret Chimp
OP
super stock
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OP
super stock
Joined: Jul 2011
Posts: 817
Eugene, Oregon
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Before I go throwing on the parts I have on hand and getting disappointed, should I run a fuel pressure regulator with the carb I'm using? I can't find any definitive specs for AVSes, only AFBs.
1967 Dodge Coronet Deluxe station wagon
1.03" T-bars, QA1 arms/rods, Cordoba/GM Metric/Volare brake & knuckle, XHDs, Hellwig rear sway, 318 Magnum w/ air gap, 727, 3.23s
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Re: Engine falling off just past 4k - carb limit?
[Re: Secret Chimp]
#1177555
02/21/12 12:14 PM
02/21/12 12:14 PM
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Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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OE avs/afb's have the same type float leverage system so the psi limits would be the same. Can I persuade you to check psi at the carb inlet at the rpm/pedal depression (load)AT SPEED that it acts up at. Need ~several psi. I still think you have a fuel delivery prob  . I'd set a can of gas in the eng compartment plumbed to the mech pump inlet & retry it & that takes the hard lines to the rear of the pump and the 2 neoprene connector hoses and the sender hard line pinholes and partly plugged sock all of it out of the equation. The mech pump may be weak & cannot handle the full throttle fuel demands of 4K+ but will handle 5K no load. less likely would be if there's a partly plugged screen filter in the carb inlet. Check float drop spec also. To ans your Q My "airtex" parts house pump puts out over 7 psi & I'm getting a reg (mileage is poor). eddy 1406
live every 24 hour block of time like it's your last day on earth
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Re: Engine falling off just past 4k - carb limit?
[Re: Secret Chimp]
#1177556
02/21/12 12:26 PM
02/21/12 12:26 PM
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Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Quote:
Couple of things:
I tried running it up until it seemed to nose off, backed off, then floored it again. Every time I did this it got up to around 4400-4500 rpm and started making an angry ping pong ball noise that sounded like detonation and power fell off with a "stop flooring it" type of feeling. I don't know if I ought to not be running 87 now or if it's getting so lean up top that it's pinging (maybe holding a higher RPM at lean-ish mixture heats the cylinders to the point of detonation will happen at higher RPMs but not when running it up in one go? I dunno, maybe something was rattling), but that's what happened.
I also tested my fuel pressure and I'm getting a good 6.5-7 psi at idle. I couldn't get my dang metal tees to seal well enough at driving RPMs in my garage to be comfortable actually driving with the gauge hanging out from my hood, but the pump seems strong.
My guess at this point is that the carb is just too low-capacity and too lean for the amount of air I'm trying to pull through it at this point. I'm all set to put my 650 Carter AVS on save for an air cleaner and a pressure regulator (didn't expect to have such a He-Man old pump but I sure need one now) so I'm just going to go ahead and do the swap and see what happens when it can get more fuel down.
did you swap the cam out when you changed the t-chain? are you sure you didn't bend a few push rods when the old chain was stretched out? Have you tried higher octane gas? I ran a bone stock 318 2bbl 69 coronet to 15.69 1/4's shifting at 5200 w/ the stock 2bbl on 93. Have you checked the plugs? Maybe go run it hard and get it back to the garage and take a look at a few of them.
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Re: Engine falling off just past 4k - carb limit?
[Re: Mr.Yuck]
#1177557
03/01/12 05:16 PM
03/01/12 05:16 PM
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Joined: Jul 2011
Posts: 817
Eugene, Oregon
Secret Chimp
OP
super stock
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OP
super stock
Joined: Jul 2011
Posts: 817
Eugene, Oregon
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It was the carb. I just took my car out for its first run with the AVS on - HOLY F^*# this thing GOES now! Runs like the stink with the secondaries open and has more poke in normal driving too. But holy crap this car is fast now. I'm still grinning.
1967 Dodge Coronet Deluxe station wagon
1.03" T-bars, QA1 arms/rods, Cordoba/GM Metric/Volare brake & knuckle, XHDs, Hellwig rear sway, 318 Magnum w/ air gap, 727, 3.23s
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Re: Engine falling off just past 4k - carb limit?
[Re: Secret Chimp]
#1177558
03/01/12 05:24 PM
03/01/12 05:24 PM
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Joined: Jan 2003
Posts: 75,015
U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,015
U.S.S.A.
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Quote:
It was the carb. I just took my car out for its first run with the AVS on - HOLY F^*# this thing GOES now! Runs like the stink with the secondaries open and has more poke in normal driving too. But holy crap this car is fast now. I'm still grinning.
What carb did you originally have on it that was causing this problem ?
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Re: Engine falling off just past 4k - carb limit?
[Re: JohnRR]
#1177559
03/01/12 05:46 PM
03/01/12 05:46 PM
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Joined: Jul 2011
Posts: 817
Eugene, Oregon
Secret Chimp
OP
super stock
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OP
super stock
Joined: Jul 2011
Posts: 817
Eugene, Oregon
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The original Carter BBD 2 barrel.
1967 Dodge Coronet Deluxe station wagon
1.03" T-bars, QA1 arms/rods, Cordoba/GM Metric/Volare brake & knuckle, XHDs, Hellwig rear sway, 318 Magnum w/ air gap, 727, 3.23s
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Re: Engine falling off just past 4k - carb limit?
[Re: RapidRobert]
#1177561
03/01/12 05:58 PM
03/01/12 05:58 PM
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Joined: Jul 2011
Posts: 817
Eugene, Oregon
Secret Chimp
OP
super stock
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OP
super stock
Joined: Jul 2011
Posts: 817
Eugene, Oregon
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LOL yes. Now I just need to get rid of these 2.93 gears for some 3.55s and I'll really be grinning...
1967 Dodge Coronet Deluxe station wagon
1.03" T-bars, QA1 arms/rods, Cordoba/GM Metric/Volare brake & knuckle, XHDs, Hellwig rear sway, 318 Magnum w/ air gap, 727, 3.23s
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Re: Engine falling off just past 4k - carb limit?
[Re: Secret Chimp]
#1177562
03/01/12 06:03 PM
03/01/12 06:03 PM
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Joined: Jan 2003
Posts: 24,562
Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Quote:
The original Carter BBD 2 barrel.
ohh I thought you had a small 4bbl on it.. go get some gears son
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Re: Engine falling off just past 4k - carb limit?
[Re: Mr.Yuck]
#1177563
03/01/12 06:11 PM
03/01/12 06:11 PM
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Joined: Jul 2011
Posts: 817
Eugene, Oregon
Secret Chimp
OP
super stock
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OP
super stock
Joined: Jul 2011
Posts: 817
Eugene, Oregon
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This is my first run in it (empty road by the local ce-ment plant, no animals harmed during filming) http://www.youtube.com/watch?v=xJMXl09IAEs&feature=youtu.beI'm sure that looks glacial to you guys but my fastest car previously was my 1.8 liter 140 horsepower Miata :P
1967 Dodge Coronet Deluxe station wagon
1.03" T-bars, QA1 arms/rods, Cordoba/GM Metric/Volare brake & knuckle, XHDs, Hellwig rear sway, 318 Magnum w/ air gap, 727, 3.23s
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. Didn't you get like that once before!