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Old 08-14-2011, 10:44 PM   #1
83highsierra
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help ASAP

ok so im still trying to get the 305 swap complete in the c10 so i figured out the stock carb wasnt going to work because the motor was newer and had plug ins all over so i got on craigslist and found a holley(which i believe is a 600) and an edelbrock performer intake for $75 not bad. the carb and intake have been sitting for about 3 months. keep in mind i still have never heard the 305 run.... i put intake on and carb and its not starting it seems like it wants to but when it sounds like its about to it quits cranking as hard as it was.... also it seems the carb is full of fuel when trying to start it shoots flames straight out of the carb. i obvuisly am getting spark i put timing light on and it seems like im right on the money as far as timing. i just need help i wanna hear her live again...

thanks in advance
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Old 08-14-2011, 11:05 PM   #2
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Re: help ASAP

Backfire through the carb is normally an indication of the distributor being 180* out. Find #1 TDC and pull the cap to make sure the distributor is in correctly.
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Old 08-15-2011, 09:47 AM   #3
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Re: help ASAP

its not really backfiring when i had the old stock intake on it was backfiring and it made a pop and bang now its getting too much fuel and catching fire
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Old 08-15-2011, 10:11 AM   #4
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Re: help ASAP

Fire is a timing issue, not a fuel quantity issue. The intake valves are is open at the wrong time so the fire is showing up in the wrong places. Not saying you don't have a fuel quantity issue, it just not causing the carb fire. Excess fuel on a properly time engine will foul plugs carbon the piston and valves and run terrible.
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Old 08-15-2011, 10:36 AM   #5
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Re: help ASAP

When I swapped my 350, I had the same problem. I also had the Edlebrock intake with a Holley 600. Thought I was going to be good to go, fired up, backfired, and flames out the carb. Kids thought it was cool...LOL

Anyhow, I just adjusted the timing until it at least fired, then I could get it set to where it needed to be.
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Old 08-15-2011, 10:56 AM   #6
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Re: help ASAP

I do agree with the timing issue. Check tdc and throw that timing light on it a 2nd time. Start with recommended needle settings on that holley carb and give it a whirl. I usually start off with 2 turns out on any carb I don't know previous usage and owner and work it from there.
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Old 08-15-2011, 12:58 PM   #7
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Re: help ASAP

This is all great advice regarding trying to pin down the backfiring issue you're experiencing. It is likely a timing issue. As an aside, when setting the idle jets, one of the best investments I made was buying a vacuum gauge, no more guessing and a nice smooth idle, as well as diagnosing any vacuum leaks.

Good luck!
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Old 08-15-2011, 09:51 PM   #8
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Re: help ASAP

Ok so I tried the timing theory and its right on the money I even pulled distributor and turned it o180 got worse and lots of popping and I closed off all the vacuum ports you can tell its really wanting to start but its like right when it wants to the cracking kinda hesitates and yea I'm hopefully gonna try an edelbrock carb tomorrow cause everything seems to be good I kno I have bcompression cause I'm getting a below from. The headers
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Old 08-15-2011, 11:07 PM   #9
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Re: help ASAP

The rotor was pointing to #1 correctly and you pulled the distributor to rotate 180*? Interesting...Have you verified you have the plug wires routed correctly? 18436572
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Old 08-16-2011, 06:17 AM   #10
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Re: help ASAP

Yep when cylinder 1 is at tdc its pointing at number one I'm totally stumped I hope this carb sheds some light on it today
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Old 08-16-2011, 01:38 PM   #11
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Re: help ASAP

Firing order on distributor correct series? I couldnt care if it is pointing at #1 cylinder or the firewall as long as it is firing #1 plug.... Sounds too retarded to me.
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Old 08-16-2011, 11:18 PM   #12
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Re: help ASAP

I agree, it doesn't matter where #1 is at, just that you have the firing order correct and it's not 180 out. Changing the carb won't mystically fix it. I'm still curious why one would pull a distributor and restab 180* if it was correct to begin with. If it's not out, then timing is way retarded.
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Old 08-20-2011, 07:43 AM   #13
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Re: help ASAP

yea i just pulled distributer to check the 180 out theory and im thinking it may have to do with my cam timing cause everything is hooked up correct as far as wires and what not i did a compression test last night and all hit from 120-150 so im thinking its the cam timing may have jumped a tooth or two. im thinking the valves just are "synced" when openening and closing. so how do i check my cam timing when i pull water pump, balancer, and timing cover
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Old 08-22-2011, 10:49 AM   #14
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Re: help ASAP

there will be two recessed dimples... one on the cam gear and one on the crank gear. When installed they need to be pointing / aligned with each other. Only time this will be different is when tuners or builders try to advance cam timing out of normal spec. Highly doubt you are going to run into any of that.
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Old 08-22-2011, 10:21 PM   #15
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Re: help ASAP

ok so i pullud off timing cover hoping it was off a tooth or two and that was the reason it wasnt starting only to find the timing marks right on the frickin money... that said the timing chain has about 3/4" of play and it was slapping the cover could that much play in the chain cause the timing to be so far off it wont even start i guesstimate its about 10 degrees give or so im ready to roll it down a hill im stumped
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Old 08-23-2011, 08:33 AM   #16
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Re: help ASAP

Change the timing chain and try again. IMO, yes the timing chain can throw it that far off.
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Old 08-30-2011, 05:19 PM   #17
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Re: help ASAP

ok so the new timing chain all is right on the money i set the distributor with the 1st cylinder at tdc so thats right i have sealed off all vaccum ports on the carb and intake. im getting fuel and spark. all rocker arms are moving when trying to start i have compression on all 8 cylinders the battery is charged all spark plug wires are in correct order and im still not starting. when cranking on it we are moving the distributor and at times it seems like its right their then gone

what am i missing im going crazy
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Old 08-30-2011, 05:53 PM   #18
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Re: help ASAP

are you sure it's getting enough spark? my big block was firing like it wanted to start but wouldn't quite just get there. it was popin and getting spark,but apparently not enough. I changed the rotor and plug wires (that weren't that old) and it fired up.
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Old 08-30-2011, 06:17 PM   #19
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Re: help ASAP

i will have to try just curious we soaked the plugs in gas for a couple days could that have fouled them out?
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Old 08-31-2011, 07:15 AM   #20
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Re: help ASAP

just a thought
not sure what years they were used but did the chain have a nylon top gear?
seen them crack and rip a couple of teeth loose
the strip of teeth looked ok but with no chain/tension it could be lifted up
and i was having the same problem timing issues,fixed it for me i thought it was just the chain

never heard of soaking the plugs,were they bad/dirty?
but if you got fire happening they should be workin......
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Old 08-31-2011, 07:50 AM   #21
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Re: help ASAP

I'd get a fresh set of plugs, verify timing, check oil to see if it's now full of raw gas.
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Old 09-01-2011, 09:41 AM   #22
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Re: help ASAP

tonight im gonna try and put new on plugs, wires, and cap and hope it starts (or pray it starts). and a quick question on timing chain i put it in and had the crank at 12 and the cam gear at 6 lined up to the T. when i turn the crank and set cylinder 1 at tdc the gears are both at 12 is that right? also if their is gas in the oil what does that mean?
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Old 09-01-2011, 09:41 AM   #23
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Re: help ASAP

also could it be a something bad in distributor?
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Old 09-04-2011, 07:49 PM   #24
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Re: help ASAP

SHE LIVES!!!!!!!!!!!!!!!!
ok so i pulled the distributor because i bought a new wires, cap, button, and plugs
as i pulled the distributor rotor off i noticed one of the plugs was cracked beyond repair. while looking at it one of the wires on the exteroior plug just fell out of the terminal. so i sprung into action on my handy dandy phone got on craigslist and low and behold at the top labeled "SBC distributor brand new" so i called met that night and next thing you know vroom
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Old 09-04-2011, 07:53 PM   #25
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Re: help ASAP

thanks for all the help and advice
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