Motor Tuning ?s

[nmdart]

I need some help. I have a 71 318 fresh rebuild. I am running 10.2-1 compression with speed pro pistons and ported 302 casting heads with 1.88 and 1.60 valves, an edelbrock airgap intake and a 600 cfm eddie carb. The cam is a Mopar purple shaft 284/484. Ignition is mopar electronic.I am running Champion rn12yc plugs and hedman headers with accel 8mm wires. It either starts good and runs bad or starts bad and runs decent. I have payed with the timing and got it running a lot better, but when I drive it down the street and mash on the gas it pops and blows all of the vacuum plugs off of the carb. Is this likely a carb or timing or ignition problem. This is my first project and I am learning as I go. Any help would be appreciated.

[rumblefish360]

At this point, it could be a weeeeee, bit of both.
Popping through the carb is lean. However, since your playing with timing...
Start over, from the top.
Get to top dead zero on piston #1. then realign the rotor on the distributor.. Time the engine so there no advance or retard with the timing light.
When you advance the distrib, the engine will run faster. Reduce the speed of the engine with the adjustment screw on the carb. Carb idle speed screw. Reverse on the retarding of the distrbutor and carb.
As a basic setting, the distributor should be in fully (Done advancing) by 3000 rpm. When you reach this, lock the distrib. down and return the carb to normal position (Idle) and tune carb in that spot.
With that cam, it should idle ruff. Chopping like an axe.
Also, the Orange box should be removed in favor of the Chrome box as a min. upgrade with a HP coil.
When you get there, theres more to be done. More later. Just get it in this way. Which is ruffly in there.

[powerdodge]

jup, bet you gonna givit more fuel on the accelratorpump(adjust at the 3 holes in the upper arm. shorter arm(in)= more fuel and longer(out) less shot! does it stumble when in park and you rev it/mash the pedal?

if rev fine, but stuble on road,

I guess it's too lean secondaries,or maybe the spring on the metringrod. this spring being controlled by the vacuum engine have... you runnin a nice cam
check this by loosen one of the blank metalplates on top(one on each side-right,left) bolted with one small bolt. loosen a bit, and push slow around, then you see the metring rod. if you start the engine, the rod will be pulled down by the vacuum, but if you try to open the butterflies,fast and alot, you will see the rod is popping up(carefully,that it does not pop out of the hole and in the engine!) IF the metringrod does not being pulled down when you start the engine,you have too strong spring compared to your vacuum.. the spring tension deside when to set the carb in rich/powermode. -as the powervalve on the holleys.

I'm sure someone else can explain way better than me, i'm not good explaining on english..


when Mine 625 was backfiring when WOT from idle, I tried everything, but when I bored up the secondaries jets, all good!

when a lean condition appear, the fuel burn so slow that it burn when the intakevalve open again, and then the air/fuel in the intake and carb get fired up, and this crate this pop/backfire (correct me if i'm wrong..)

[nmdart]

Ok i started over with the timing. I also changed the plugs becuase they were fouled out like they have been flooded. It runs a lot better but now it wants to race when I adjust the idle. Its acting like a vacuum leak but i cannot find one. It still has light popping at low rpm(below 2500) only when in drive. When idling in park It will rev with no stumble or pop. Would going to a different plug help.
Thanks for all your help.

[rumblefish360]

Probably not. A 1-3 step cooler or hotter plug helps in other areas. You need to continue to tune the carb and check for leaks. Spray allmost anuthing to find the leak. WD-40, carb cleaner...
Of course, if the idle picks up, you found your leak.

[nmdart]

I have sprayed carb cleaner all around the intake and carb with no results. As far as tuning the carb goes, the left adjustment A/F needle doesnt make any difference when adjusted in or out. I even pulled it completely out with no change. Must be blocked internally, has anyone else experienced problems with brand new Eddies. Thanks Again

[rumblefish360]

Once with my Carter AFB. Problem was dirt in the passage. Cleaned, cleared and back up to par.

[nmdart]

Ok cleaned the carb, helped a little, changed the ecu to the chrome box helped even more. Drained the fuel tank put in some super premiun unleaded, higher octane than before. Looks like the only problem I have now is gonna be keeping tires on this mother. Thanks for all your help.

[rumblefish360]

powerdodge "i'm not good explaining on english.." But it's no bad ethier. Keep at it.

nmdart: Keep at it. Check the air fuel ratio if you can. If not, look at the plugs. They should not be to discolored in any one shade. Keep on the carb it'll it sings (Works) great. Your getting there.