Carburetor problem
#975809
04/18/11 02:46 PM
04/18/11 02:46 PM
|
Joined: Jan 2003
Posts: 5,788
Hamilton, Ontario Canada
Magnum
OP
master
|
OP
master
Joined: Jan 2003
Posts: 5,788
Hamilton, Ontario Canada
|
I had a 670 Holley Street Avenger on my 87 Ram truck. It's a regular truck for hauling an open trailer, trips to Home Depot, regular pick up. Swapped in a 5.9 Magnum, converted to carb and swapped in a 5 spd manual. Previously it ran a 14.9-15.0@91. Got over 600km per tank. Ran good except for the first 5 minutes, when cold. Without a choke, I expected that. Heard dual plane intakes should be overcarbed. On that theory I switched to a 770. Even seemed to pick up power under 1200rpm. I could now take off in 2nd and climb grades in 5th at 1000rpm. Power was up too. It's not a race truck but I did take it to the track to jet it. Bigger jet slowed it from stock. Each step smaller was faster until I reached 70 which was the smallest in my kit. That was worth a 14.70 @ 93. Another odd thing was it requires 3/4 of a turn on one mixture screw and 1/2 on the other. Usually I've seen 1 1/2 turns and even if not, at least same side to side. All is great in the world with my Ram but my mileage is history. I can NOT reach 400km/ tank. Another thing is it runs great cold and without a choke, we both know that's not right.
69 Super Bee, 93 Mustang LX, 04 Allure Super
|
|
|
Re: Carburetor problem
[Re: roe]
#975812
04/18/11 08:09 PM
04/18/11 08:09 PM
|
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
|
Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
|
On a Holley (assuming the holley clones are the same) rock it slightly from side to side & gas should just dribble out the sight plug(s). Eddy 1406 want the fuel level to b right at the slot in the float bowl slosh baffle(s). Level ground of course. I think the 1406 dry float setting is 7/16"
live every 24 hour block of time like it's your last day on earth
|
|
|
Re: Carburetor problem
[Re: RapidRobert]
#975813
04/19/11 10:29 AM
04/19/11 10:29 AM
|
Joined: Jan 2003
Posts: 5,788
Hamilton, Ontario Canada
Magnum
OP
master
|
OP
master
Joined: Jan 2003
Posts: 5,788
Hamilton, Ontario Canada
|
I've taken the carb apart and cleaned it a few times. Tried the proper float level, just a slight bit dripping out and tried running it a bit low and a bit high.
I'm starting to think I need to try another metering block or throttle body.
69 Super Bee, 93 Mustang LX, 04 Allure Super
|
|
|
Re: Carburetor problem
[Re: Magnum]
#975815
04/19/11 12:57 PM
04/19/11 12:57 PM
|
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
joedust451
super gas
|
super gas
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
|
Quote:
I had a 670 Holley Street Avenger on my 87 Ram truck. It's a regular truck for hauling an open trailer, trips to Home Depot, regular pick up. Swapped in a 5.9 Magnum, converted to carb and swapped in a 5 spd manual.
Previously it ran a [Email]14.9-15.0@91.[/Email] Got over 600km per tank. Ran good except for the first 5 minutes, when cold. Without a choke, I expected that.
Heard dual plane intakes should be overcarbed. On that theory I switched to a 770. Even seemed to pick up power under 1200rpm. I could now take off in 2nd and climb grades in 5th at 1000rpm.
Power was up too. It's not a race truck but I did take it to the track to jet it. Bigger jet slowed it from stock. Each step smaller was faster until I reached 70 which was the smallest in my kit.
That was worth a 14.70 @ 93.
Another odd thing was it requires 3/4 of a turn on one mixture screw and 1/2 on the other. Usually I've seen 1 1/2 turns and even if not, at least same side to side.
All is great in the world with my Ram but my mileage is history. I can NOT reach 400km/ tank. Another thing is it runs great cold and without a choke, we both know that's not right.
Its a common "myth" that your car shouldn't run good when cold without a choke, sure, it shouldn't fire up in 10* weather & purr like a kitten from the start, but it shouldn't be real finicky either, to the point where it needs to run 3-4 minutes before it'll idle decent, I wouldn't mess with the jetting, your problem is in the idle curcuit, its a bit too rich (thats where some of your mileage is going), jetting doesn't really affect the idle curcuit at all, only the main metering, seeing your idle screws are only out 1/2 turn, you need to at least see if the engines will stall out when you bring 1 in fully, if not, then it's still getting fuel. Have you read your manifold vacuum to determine what PV to run? It is somehow getting too much fuel through the idle curcuit, either from an incurrect PV, PV gasket not seated propperly, IFRs too large, or IABs too small or blocked, floats too high (you have ruled that out).
It is also common to have a larger primary bore carb feel better at part too moderate throttle (especially on a dual plane intake) & at higher Alt., your letting in more air, the engine will respond to this, but under WOT from a dead stop is a different story, it'll either respond better or not depending on the circumstances.
|
|
|
Re: Carburetor problem
[Re: Magnum]
#975817
04/20/11 10:04 AM
04/20/11 10:04 AM
|
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
joedust451
super gas
|
super gas
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
|
Quote:
Yes, either idle mixture screw will stall the engine if it's screwed in.
It's a stock 5.9 Magnum with the original fuel injected camshaft. Vacuum is unbelieveably high.
Well into the teens, even at speed.
The throttle response is excellent. In fact it runs great and the power is up. Besides the fact my mileage is history and I"m suspicious something is defective in the carb making me run such a small jet and so little mixture screw. I'm a happy customer.
In this vid you can see the throttle response. Off idle to WOT with the clutch fully engaged.
If your happy with it, i'd say just suck up the mileage loss & have fun, another thing you should remember is in "most" cases a larger cfm carb will use more fuel.
|
|
|
Re: Carburetor problem
[Re: joedust451]
#975818
04/21/11 12:11 AM
04/21/11 12:11 AM
|
Joined: Jan 2003
Posts: 5,788
Hamilton, Ontario Canada
Magnum
OP
master
|
OP
master
Joined: Jan 2003
Posts: 5,788
Hamilton, Ontario Canada
|
Thanks for your replies and keeping my post active but I think this carb has a problem.
I've lost 200km per tank. That's a bunch of distance and it's not from a gain of 100cfm.
I suspect raw fuel is being introduced into my engine but from where?
69 Super Bee, 93 Mustang LX, 04 Allure Super
|
|
|
|
|
