hey guys, i'm jason... i'm new to the boards, and forums in general, since most times i just google what i need, but i'm kind of in a pickle here... if this is in the wrong section or anything i apologize..

background- 84 dodge d150, 5.2... i got the truck for 500 bucks, went ahead and put another set of 318 heads on there that i ported real nice, slapped headers, an intake and a holley 600 on it...

-- on fire up initially i was really pleased, throttle response was awesome, from the bay, driving was a different story, but i'm gettin to that.. but heres my issues, BEFORE i put all this stuff on it started doin something pretty wierd.. i'd be drivin along and punch the gas and the whole thing would fall on its face, no engine noise.. let off and itd grab.. after all this stuff, same deal.. except now it idles reallllly rough, putters down the road, no power, if i barely even touch the gas more than just to go around 25, it wants to die... and it backfires like a machine gun, little pops in the exhaust...

new fuel filter, fuel pump, coil, plugs, cap, wires, rotor.. carb is new, and may not be hooked up right, i have no idea, i'm not good with carburetors...

any advice guys?? i got no ride til this thing is running..

 

Sounds like the timing chain jumped

 

I was thinkin the same thing but I replaced the whole set when I did the front main seal. Less that 100 miles ago... I could pull it to #1 tdc and see where the rotor is pointing but given that its all new timing gear set, you think it could have still jumped?

 

If the chain is new, it most likely didn't jump. Once they start to stretch, that is when they can jump.

Have you adjusted the timing and setup the carb to how the manual states? Nice thing about Holley, is that they usually include an install CD that helps you through the installation.

 

I actually didn't get an install DVD. And I didn't Jack with timing at all. After the install things were fine, minus the whole falling on its face under a loaded acceleration, but that was there before... now I'm trying to diagnose both.. this backfiring literally came out of nowhere. Drove my car to a buddy's house. Worked on his car. Drove home and Viola.. massive lack of power and tons of backfiring. I'm at a loss.

 

Start with what I said before and go from there. Also look into any and all vacuum leaks. From what some people on here say, once a Holley backfires, you may start to have issues with a power valve (?). I'm not that up-to-date with my holley carbs but I'm sure that others who are will chime in.

There is another member here who just installed a new Holley carb on his 340 in a Dakota with the same issue. Barfly is his user name.

 

It's sounding like a vacuum leak. Break out the propane.

 

alright, caps new, and i checked for cracks and its good... here's what i did so far and seeeeemingly got the timing decent...

brought #1 to tdc and pulled the cap. it was pointing like 3 towers from one, so since the 318 distributor only sets normal or 180 out, i just shifted the wires so #1 was at the tower, then ear timed it... got rid of the backfire.. runs decent again... stalls if i punch the gas... still lacking power that i think it should have... sounds really mean though, minus a stupid header leak...

i do know there is something wrong either in the tranny or the rear end... its a nice thick grinding noise that happens loud as hell and goes away randomly, usually neighborhood speeds.. i do know it needs ujoints... a trusted mechanic told me there was nothin in the tranny that could make that noise and is sure i need a rear end... my question is, could a crappy rear end drag that much power, or lock up when i punch the gas enough to stall it and then when i let off it frees and i go on...?

thanks for the help so far guys

 

It sort of sounds like the accelerator pump circuit is not working on the carb. When you floor it the accelerator pump should squirt extra gas so it doesn't stumble or die. Check it when it is not running by looking down the carburetor throat and push the fuel linkage wide open. You should see a stream of gas shooting into the primary carb throats.

 

My buddy said the action on the accelerator pump was engaging late or something... its brand spankin new though. Except off eBay so who knows. Is there a kit to fix that?

 

Should be in the instructions. The accel pump should start moving as soon as the throttle cable starts to move. Its set at the factory, but who knows now. Can you adjust it to do what it needs? You want it barely resting on the accel pump cam when at idle.

 

Alright. Thanks guys for all ur help. I kind of feel like an idiot now. The hose clamp screw was binding up with the accelerator pump screw and not letting it move.... wow! Easy fix but would've never even checked the accelerator pump without the insight. I'm guessing before the swap, my 1984 1 bbl Carb had a bad one too since it was doin the same...

Anyway. I'm runnin pretty rich and the overall performance is lacking based on my setup.. I'll have someone tune it that knows what they're doin probably and I'm puttin the rear end in Saturday. We'll see how that goes

Thanks guys

 

We are here to help. There are no cliques here