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2K views 19 replies 6 participants last post by  nightstalker00 
#1 ·
ok so i have been working on a small project truck that turned into a big headache...so i got deployed ya know boy meets truck boy leaves truck stuff...so anyway when i got back i found a guy that had this great motor that had 40,000 on it bored out shorty headers n edelbrock intake and carb with msd distributor...so after i gave the guy the money, the carb and distributor turned into a myth....so after going and purchasing my own i got the motor set in my rig...modify the header so it doesnt hit on the steering hook it all up and it runs, but it has a pop up threw the carb...me and a bud hook up a timing light and set it at 8deg advance...it only does it on acceleration between 1000 to 3500 after that nothing and coming back down its fine...it has an edelbrock 600 on it...he says its the carb...get a second carb not it...try a new distributor not it...then i change the heads cause it has some bad valves...it still does it and i dont have a clue...so heres my question for all of you on here...what is wrong with it...any insight or sugestions are appreciated...

:usa:
 
#3 ·
the block is a 89...the original heads that were on it when i got it were 69 heads...now the heads are off of a 93...with the old heads it had a real problem with over fueling like bad...couldnt stay in the garage for more than a minute without your eyes wanting to fall out...i have changed everything not to say they are new but different plugs and wires and distributor i even switched to the new cap...it originally had the female style cap...so i changed that out also...
with the old heads and wires: i took off each wire off the spark plugs while idleing to see if it made a difference num. 3 cylinder and i think 7 didnt make a difference all the rest killed the motor...but it didnt matter what plug wire was off it still poped up through the carb...can the duraspark box do this???
 
#5 · (Edited)
ya i have checked the firing order multiple times just hoping that i might have done something wrong...then also i have tried the 302 firing order cause i have been told they did use two different orders...with no luck...i really dont have a clue i have been hoping its something simple...i have tried moving the distributor one tooth one way and the other and nothing...it wont even fire...thats the only thing i dont get when it sits for a few days...it acts like the distributor is off cause it just dont wana start or fire...after getting frustrated with it after a lil while of messing around with it i get ignition...then takes another 5 minutes to get it to run...i know everyone is thinking timing...i would think the same but i have tried and i have had two others have tried too...i put the cylinder up and check the timing mark...usualy around 3deg btdc is what i go for...that is about the point where the rotor points right at the number one on the cap...i was told once that the over fueling can cause fowled plugs that can lead to pre ignition...but i put new plugs in and wires and same issue...the coil is maybe two years old but actual run time is maybe 20 hrs...but if anyone can sugest trying something else let me know...

:usa:
 
#8 ·
no i dont know anyone with a msd box...what i dont get is i had a 72 351w all stock in there and i could run that one...i took it out behind my house to play a little bit but ever sence day one with this motor it has acted this way...
as for it being 180 off i dont think so i have tried that...spark controller like the durakspark box right...i know with a gm motor if the control module goes out it has multiple purposes so i was wondering if the duraspark box does too...also i was wondering why there are different color coded duraspark boxes...the plug that goes into them i have seen different colored ones, why is that???

:usa:
 
#9 ·
I would start over from scratch. Pull your plugs, make sure you are absolutely positive that you are on the compression stroke on #1. And go from there. With it sneezing back thru the carb and running super rich, something is just not firing when its supposed to. I'm pretty sure if your box was bad, you would have no spark at all
 
#10 ·
ok sounds good to me but can we make it barney simple and explain a little more in detail...cause what i have been doing i dont think is working...
number one up with both valves closed, using the timing marks on the balancer going to about 3deg btdc, droping the distributor in with the rotor pointing at the 1 on the cap, and from there playing with it till she runs...i really dont know what else i will check the firing order again when i get home and tell you what im using on there...

:usa:
 
#12 ·
with the previous heads on the motor that had some bad valves there was alot of raw gas coming out the exhaust i am open to any suggestions but this is my first carbed motor that i have messed with...so tips on how to set up the carb would be helpful...i did rebuild the carb, i followed the edelbrock instructions that came with the kit...i put everything the way they said to...after rebuilding the carb i drove it about a half mile and it ran fine no backfires nothing...but when i went to stop and turn around some of the plug wires caught on the steering and came apart and it started missing as it should and then after putting new plug wires on it returned to running like crap...the carb is an edelbrock 600 manual choke...someone that knows more about these carbs lend me some advice...can the carb be causing this???cause there was a brief short life where it ran right...

:usa:
 
#13 · (Edited)
I think your ign. box is good. When they fail, they fail bad.

Since it ran fine before damaging the wires. Double check the wires. Did they come assembled or did you have to install the clips and boots. Check them with an ohm meter.

Double check the firing order since you installed new wires....13726548.

Your initial (static) timing is too low. Without knowing your cam specs, start at 10-12. If your cam has more than 270 duration, bump it up to 12-14.

Make sure your vacuum advance is connected to the proper vacuum port. And speaking of vacuum, hook up a vacuum meter and set your primaries (two screws on the front of the carb). You should adjust them until you have reached max vacuum. When you have one side set, set the other, then start over one more time. Your vacuum should be around 20 in. +/- 2.

Check for vacuum leaks. Can also detect leaks with a vacuum guage if significant enough. It will indicate low vacuum.

After you get everything checked and adjusted, read your timing curve. Hopefully you have a tach. Have someone call out rpm's while they slowly increase throttle and you call out where your timing is at. Have someone write it down while your doing it. Hopefully you have a couple bored buddies. You want to be able to review how much timing you have through the entire curve and where total advance is at.

Post up what you find. I'm curious. I also agree with Bigbert on the lean condition. But if it was good before I cant think of why it would have changed.
 
#15 ·
i did have one more question if the problem is the carb, i did try a second carb on there...i put on a stock holley carb...the ones they made for motorcraft...it did leak fuel out the bottom of the bowls...or maybe just one but still shouldnt it had performed better???

:usa:
 
#16 ·
Damm you are far away. I have a new points and also a new duraspark dist I would liet you try, at least to take that out of the equation. The points one would also take the box out of the equation.

I think checking the carb for proper operation would be good. Are the valves seating? If they are leaking fuel, start there.
 
#17 ·
ford rockers arent adjustable correct???if that were the case and the valves just arent closing i have heard this theory before...but the guy i bought the motor from has been less than helpfull so aside from tearing it down i dont know what cam it has...but if it can be just the carb not being tuned correctly than i will try...i tried with the vacum gauge before and setting the idle mixture but it didnt seem like the vacum went up any...but i will work from there...when removing the motor i had a slight incident with a child a screw driver and a radiator so im in the process of putting in a new one...got that in last night...and this weekend intend on filling it back up and trying it out...i really didnt think that it could be something like just the carb not being tuned...

:usa:
 
#18 ·
ok so heres the down and dirty for the weekend...got the radiator all set...tried to tune the carb like suggested and all i can manage is 17/18 for vacum preasure...there is alot of gas coming out the exhaust though...you cant stay in the garage for more than a couple minutes...what do i do

:usa:
 
#19 · (Edited)
i had a few more things i wanted to add to the last post...with the gas coming out the exhaust i have duals and it is only coming out on the right side of the motor...also the motor idles up and down, rpm goes from 700 to 1000 and the vacum goes from 14/15 up to 18...sounds like a vacum leak right???could this cause the firing up the carb???i have sprayed carb clean all around the intake and with it idleing like it does it makes it hard to notice something...cause on its own it will idle up...

:usa:
 
#20 ·
holly crap it runs!!!!!!:nana: i took it to the local mechanic and the firing order was all it was...i have messed around for months with this and it was just the firing order...and the crazy thing is i tried two different ones...but its not a 302 or a 351 is this right is there yet a third or no???cause all he did was pull off the plug wires on the cap and he had four off and it didnt change the idle at all...so he switched em around and as he put em on it idled higher...so after TWO MINUTES it was all beter...WTF!!!thats all i got but she deffinantly turns the 35x15 boggers nice...so now this chapter is coming to a close so gang heres on from me :beerbang: and have a nice night!!!

:usa:
 
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