Timing issue??????????????? or not?????

[ford1386]

i adjusted the accelerator pump and it still has a hesitation, but i was mistaken holley said if it hesitates for a second or less to increase discharge nozzle size, but then i told them its shooting flames out of the headers and he said its getting plenty of fuel so i dont know now what to do maybe advance timing a little more its at 14 degrees now

 

[baddad457]

Flames out of the headers ? You trying to tune it with open headers ? You gonna run it that way on the street ? If you're not, then you're going about it all wrong. Tune it with the exhaust installed. You cannot accurately tune a carb with open headers, then expect it to be also tuned with the exhaust bolted up.

 

[kimcrwbr1]

The venturi is the bore size where the air flow is restricted the most and the venturi booster is the round things in the middle of the venturi that the fuel vapor flows from. Have you tried pony carbs those guys really get into the high performance jetting but it still sounds more like a vacuum issue to me once you get the vacuum up around 20 at an idle and you are sure your power valve is working correct and the accelerator pump is dumping enough fuel. Do you have the advance from manifold vacuum or ported from the carb it kinna sounds to me like you are not advanced far enough. I was reading and to my understanding advance it until it pings under a load then retard it to where the pinging just goes away. How old the damper is will effect the timing mark so take it until it almost pings and see how that works. Once you find the best setting then mark your damper for future reference.

 

[kimcrwbr1]

Once you get the exhaust all put together then you can adjust your jet size you want the rich side of lean so you don`t burn valves or pistons if you know someone with a CO reader is the best to determine that other wise run a little rich so your not pulling it out in the near future. A 670 is a little big for your engine so you will probably be on the rich side anyway.

 

[baddad457]

You're correct about the Venturis, but wrong about it being rich due to a slightly bigger carb. If anything it'll be slightly lean due to the slower airflow thru the Venturis.

 

[ford1386]

ok well i called about getting stainless bent up yesterday, they said about $550 installed if i supply mufflers and tips, i was just trying to get it tuned close so i could drive it there but i think i'm gonna just trailer it anyway cuz its way loud..........................

 

[originalnitro]

does your truck still fall on its face and back fire through the carb?
if so adjust pump shot volume yours is to lean [ adjust/swap pump shot cam and discharge nozzle ]

 

[ford1386]

truck is getting exhaust in it now so we'll see how it runs when i get it back

 

[jimmy3970]

Mine Too Was Running Bad & It was a Crack in one of My Spark Plug's so I replace all of them & had my Timming check too. I was running on 7 cinadlers cause of the bad spark plug & now the engine is running bad out of hell. I also won 2 free dyno pulls & before I had my first pull we found the crack spark plug so we replace all 8 of them & the 302 engine proved awesome for me at Eng Torque T WC ( ft-lb ) was at 203 Avg was 195.
Eng Power T WC (HP) i was at 144 & the Avg was 118 & the AFR ( Ratio ) was 15.3 & the Avg is 14.0 that was on my 2nd pull. I was very happy with what the 302 engine did at 4000rpm's. Check on seeing if you have a crack spark plug first before you screw up your 302 engine.

Jimmy3970

 

[ford1386]

I got it back from the exhaust shop yesterday and started it up and it doesnt have a hesitation when you crack the throttle from an idle anymore but, when i drove it down the road it has a hesitation when you first get on throttle when pulling out in first, then when getting back on throttle after shifting into every gear. It sputters through till prolly 3000 rpm then it takes off like a raped ape. And when your back at the tailpipes it even smells rich and everyone is telling me i need to rejet, or change discharge nozzle size?????

 

[ford1386]

just got off the phone with holley and they said it is prolly a lean condition so i ordered a .035 discharge nozzle and a .028 the one that is in it now is a .031 so i'll try the bigger one tomorrow since more people are telling me its a lean condition but if it gets worse i'll put in the smaller one and see what that does, tomorrow....

 

[ford1386]

I changed the discharge nozzle out from the .031 to a .035 and it runs alot better no more hesitation on throttle, but its still running rich can smell the fuel from 20 feet away......

 

[doorgunner]

I wasn't paying attention....what's the fuel pressure reading at the carb inlet??????

Stupi(e)d question...but did you re-adjust the 2 idle air screws again??????

 

[Psychopete]

I didn't read all through the thread

but if you have a hesitation off idle, or it's not smooth going into the next circuit, sounds like the accelerator pump needs tweaked.

I just went through this process, tried lots of different cams and squirters. It's just something that needs hit and miss. Typically a hesitation off idle and/or back fire indicates that it's lean and black smoke and/or crappy transition can mean it's getting too much.

The squirters and the cam need to work together. I was changing cams with out changing squirters, and wasn't getting anywhere. I was changing squirters without changing cams, and wasn't getting anywhere. The smaller the squirter size, the longer the duration of fuel. The amount of fuel will be the same that comes out. There's no set way to determine what cam and what squirter you need, every engine has different needs.

My brother had a stash of Holley parts that I was able to rummage through, but I would have eventually bought a Holley trick kit. I never would have got mine running decent without the additional parts to experiment with.

The goal is to provide enough fuel for long enough to supplement the fact that when you romp on the gas, the vacuum is going to drop - which vacuum is needed to get fuel into the engine through the venturis.

But I agree, check your fuel pressure, float level, idle adjustment (highest vacuum in drive, screws are equal), be sure to have .015" clearance between the accelerator pump arms when the throttle is at WOT to make sure it doesn't kill the diaphram when making adjustments. Not going to get it right the first try, I've been working on tuning mine out for a while now, but the first experience I have working on a carb. And it gives you a different outlook on EFI problems as some of the same principals apply I've noticed.

If it's still running rich, you might just have gas leaking somewhere right into the motor that's un-metered if everything checks out. Also make sure that engine engine dies with either of the idle mixture screws are turned all the way in also. Might also try disconnection the vac sec, if you have them, to verify that the spring is not too light, and that they're opening way too soon.

 

[baddad457]

I didn't read all through the thread

but if you have a hesitation off idle, or it's not smooth going into the next circuit, sounds like the accelerator pump needs tweaked.

I just went through this process, tried lots of different cams and squirters. It's just something that needs hit and miss. Typically a hesitation off idle and/or back fire indicates that it's lean and black smoke and/or crappy transition can mean it's getting too much.

The squirters and the cam need to work together. I was changing cams with out changing squirters, and wasn't getting anywhere. I was changing squirters without changing cams, and wasn't getting anywhere. The smaller the squirter size, the longer the duration of fuel. The amount of fuel will be the same that comes out. There's no set way to determine what cam and what squirter you need, every engine has different needs.

My brother had a stash of Holley parts that I was able to rummage through, but I would have eventually bought a Holley trick kit. I never would have got mine running decent without the additional parts to experiment with.

The goal is to provide enough fuel for long enough to supplement the fact that when you romp on the gas, the vacuum is going to drop - which vacuum is needed to get fuel into the engine through the venturis.

But I agree, check your fuel pressure, float level, idle adjustment (highest vacuum in drive, screws are equal), be sure to have .015" clearance between the accelerator pump arms when the throttle is at WOT to make sure it doesn't kill the diaphram when making adjustments. Not going to get it right the first try, I've been working on tuning mine out for a while now, but the first experience I have working on a carb. And it gives you a different outlook on EFI problems as some of the same principals apply I've noticed.

If it's still running rich, you might just have gas leaking somewhere right into the motor that's un-metered if everything checks out. Also make sure that engine engine dies with either of the idle mixture screws are turned all the way in also. Might also try disconnection the vac sec, if you have them, to verify that the spring is not too light, and that they're opening way too soon.

You left off the part about changing the cam timing by moving it on the throttle lever. Just one more monkey wrench to throw into the mix of playing with the accellerator pump.