Dual quad 409 problems...

models916

models916

Well Known Member
Supporting Member 7
here is my suggestion

I would remove the thermostat, re-curve the distributor for quick all in advance, run a richer primary jetting. It is possible the throtle shafts are worn and sucking in air. Could have a vaccum leak somewhere. Generally run on is a lean condition. You could just shut it off in gear or dump the clutch to stop the run on. Lots of variables here to explore. Keep us all posted.
 
dq409

dq409

Well Known Member
Supporting Member 3
Check your timing !!!!! then the thermostat ,,, but my guess is you need to check all the basics of the engine first,,, i.e.,,,, timing , jetting, plug temp,wires,, radiator condition, etc,,,

I`ll tell ya what ,,, ,,,,,,,I`ll trade you strait across,,,,, a 383 for you 409 !!!!!:deal ,,,dq
 
jester

jester

Well Known Member
Supporting Member 5
trade?

Smooooth move DQ, real smoooooth !
I think there is more then just one problem . As Model said, vacuum leak and lean fuel mixture will do that.
I have a 454 and a statue of a budda I'll trade for your 09.:roll :roll :roll
Good luck.
 
dq409

dq409

Well Known Member
Supporting Member 3
jester said:
I think there is more then just one problem . As Model said, vacuum leak and lean fuel mixture will do that.
.
Click to expand...

OK,,,, now that the beer ain`t flowing though my brain,,,,, Model is closer to the solution to the problem.

Also ,,Check the carbs and see if the butterflies are set proper as in they should be almost closed at idle then adjust your idle jets at the low idle,,, around 600 . then set the idle up with the idle screw at the linkage,,,
This can be a little tricky with two carbs ,,, but you`ll see a difference right away if the carbs are out of adj,,
Good luck,, let us know what you found,,dq
 
S

ssx61

Member
Well I haven't had much time to mess with the car the last week or so (sitter was sick so Daddy had to watch the boys: 2years and 2months-Whew that is hard work!)Anyway I did drive the car to work the other day and it ran flawlessly both to work and back home the next day (about 40 miles each way) It was mentioned to me that fuel percolation may be a problem. I think this idea may be valid also was told that a removed thermostatic valve on the rear carb during rebuilding is a common problem that will become evident only in areas where the temps get into the 80-s -90's. Reasons being I leave early morning for work when the outside temps are in the 60's and return home when the temps are in the 70's early-mid morning. The only time I have had problems is when I drive it to "town" in mid day when temps are in the 80's-90's. Checked the timing again etc all is good. I'll keep messing with stuff mentioned and let you all know what happens. Thanks for the input!
 
Impalaguru

Impalaguru

Well Known Member
Supporting Member 1
If your car wasn't an original 348, with the 3/8" fuel line, you may be having problems with your small block (5/16") fuel line. The 3/8" line ( 348s and 409s and all 327s) was routed arround the upper a-arm in order to keep it away from the pass. side exhaust manifold. The 283/6 cylinder line simply ran on top of the frame rail. I put a 409 where a 283 had once resided and in town the fuel would start to boil and the car would run terribly, if at all.

What I did was cut the fuel like at about where it starts to bend upward, or roughly even with the firewall. Then I bought some more tubing and formed a new line based on the shape of the original 3/8" line. I joined the two with some hose. The 3/8" line was actaully joined in this way. It cured the problem instantly!!! Good luck!!!

Ross
 
S

ssx61

Member
I'm at work and can't check right now. I do believe that my car was an original 348 car? Not real sure the emblems are the Bigblock ones and as far as I know original, I know the engine in my car is from a 63' but it's possible at least that my car was a original 409 car??? Not likely as only 140 or so had the 409 in 61' if I am correct. Anyway thanks for the idea, I will check the fuel lines when I get home from work tomorrow.
 
You must log in or register to reply here.
Top