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Old 07-05-2005, 09:16 PM
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Until death does it backfire!!
 
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HELP!!!! Backfire...chevy 350

Long story short. I get good response and smooth acceleration out of the old beast in Neutral or Park, but put a load on it and WAMO I gat a backfire out the carb and (most assuredly beacuse of the backfire) loss of all engine function, then it's back to acceleration. This occurs somewhere around 3000 to 3500 RPM at over half throttle. Here's what I know about the engine as I have just recently bought the car and am learning by doing a whole lot of "well that didn't work......"

78 formula orig. 350 chevy 101 block .40 bore,2.02-1.60 327 camel hump 64cc heads,crane roller rockers,edelbrock performer carb,edelbrock torker 2 intake,b&m 3000 stahl converter,th400 trans w/b&m perf. kit and trans pack.10 bolt rear end w/ 3.73 gears,new bearings,seals,and gears.hooker super comp headers w/edelbrock mufflers.holley electric fuel pump,crane energizer cam and lifters 278 adv.dur.,467 gross lift.crane .500lift springs and manley valves. (I just put an edelbrock 750CFM, model # is 1407, carb)

guy told me that I'm supposed to be 18 retarded on the timing, but I don't really believe that. Checked the initial and I'm at 18 advanced...hmmm.... mechanical tops out at 30 advanced, vacuum hose is hooked up to the full advance (haven't tested timed advance yet) and gives me only 4 extra deg. advanced.

Anywhoo....that backfire is absolutely killing me and it's scaring the living bejesus out of me because I'm not sure I'm not doing damage somewhere. Oh and don't ask me if I'm getting ping or knock cause I can't even here myself going deaf. (There's no pipes on the car, just exhaust, and they end right under the seats.)

Oh and I'm new here so Hello ME

PS: how much would you estimate this guy put into this car?

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Last edited by interro1; 07-05-2005 at 09:32 PM.
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Old 07-06-2005, 05:07 PM
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WELCOME TO THE BOARD

let me be the first on to welcome you here !!!

what do you know about the timing chain??

if nothing then use a breaker bar on the crank shaft ( you might have to pull the plugs out) and also pop the dist cap off and rock the crank if the crank moves and the dist dont then its very likely the chain is stretched and done for.

try timing it by ear or vacuum.

could also try re adjusting the lifters but wait to see what kind of replies you get, there is a ton of more knowledgeable than me on this thread this place is freaking awesome

again welcome

rob
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Old 07-06-2005, 08:11 PM
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Until death does it backfire!!
 
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Here comes the BUMP!!!!

buddy of mine said he thinks it's the points floating. I don't think the timing chain is toast, though it is possible, because the derned thing is brand new.

thanks for the advice though...gonna go wiggle that buddy and see what happens.

Any other ideas?
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Old 07-06-2005, 08:26 PM
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Quote:
Originally Posted by interro1
Long story short. I get good response and smooth acceleration out of the old beast in Neutral or Park, but put a load on it and WAMO I gat a backfire out the carb and (most assuredly beacuse of the backfire) loss of all engine function, then it's back to acceleration. This occurs somewhere around 3000 to 3500 RPM at over half throttle. Here's what I know about the engine as I have just recently bought the car and am learning by doing a whole lot of "well that didn't work......"

78 formula orig. 350 chevy 101 block .40 bore,2.02-1.60 327 camel hump 64cc heads,crane roller rockers,edelbrock performer carb,edelbrock torker 2 intake,b&m 3000 stahl converter,th400 trans w/b&m perf. kit and trans pack.10 bolt rear end w/ 3.73 gears,new bearings,seals,and gears.hooker super comp headers w/edelbrock mufflers.holley electric fuel pump,crane energizer cam and lifters 278 adv.dur.,467 gross lift.crane .500lift springs and manley valves. (I just put an edelbrock 750CFM, model # is 1407, carb)

guy told me that I'm supposed to be 18 retarded on the timing, but I don't really believe that. Checked the initial and I'm at 18 advanced...hmmm.... mechanical tops out at 30 advanced, vacuum hose is hooked up to the full advance (haven't tested timed advance yet) and gives me only 4 extra deg. advanced.

Anywhoo....that backfire is absolutely killing me and it's scaring the living bejesus out of me because I'm not sure I'm not doing damage somewhere. Oh and don't ask me if I'm getting ping or knock cause I can't even here myself going deaf. (There's no pipes on the car, just exhaust, and they end right under the seats.)

Oh and I'm new here so Hello ME

PS: how much would you estimate this guy put into this car?
did ur car do this when u first purchased it
why did u replace carb
well if u checked and verified timing
next is distrib,and all component's concerning that.
if still popping
swap out carb.
whenever i had popping like that distr was 180 degrees out
but car ran very poor.
park , drive or otherwise
some timing event is wrong making it pop out carb
make sure you take vacuum readings
that will tell part of story

Last edited by BigDawgsEatFirst; 07-06-2005 at 08:50 PM.
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Old 07-06-2005, 08:31 PM
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Until death does it backfire!!
 
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BINGO!!!!!!!!!!!!!!!!

You're the first person that has answered that question with the same relative answer as another....

That says to me that, that is where I will start.

Thinking of swapping for HEI and going with electronic ignition. From what I've hear this makes life all the more simpler. And I like simple.

Got points right now, any suggestions on a goor route to go with the distro and ignition?
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Old 07-06-2005, 08:54 PM
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take them points
and make 2 points
when u
throw them in the trash
get a HEI and see what happens
points are bad
go HEI
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Old 07-06-2005, 09:21 PM
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Don't waste your time with all that other junk above.

First, you need to make sure the timing is right. An advance analyzing light makes this a lot easier. You want the total timing to be at 34o to 36o. You need to verify that is what you are getting. I like to run 16o to 18o initial advance. Running more initial will wake your engine combo up considerably. If you need any help doing this just ask. Most people on this site know how to do it.

Then, if you still have a bog you need to work out the carb. Check your fuel filter and make sure it isn't clogged first. Again, most people on this site can help get the carb worked out.

You need to start with a solid baseline otherwise you will end up doing goofy stuff like prying on the crankshaft to see the distributor play, or timing your engine by ear or by vacuum (never time your engine this way unless you want it to go boom).

An electronic distributor would help. I wouldn't go HEI they aren't easy to curve, and the curve is where all the performance is. I personally prefer the Mallory Unilite because when installed correctly, it is extremely reliable, and it is easy to curve.

The Edelbrock Torker II is a piss-poor intake. It makes less power all around than the RPM. You will see better results with an RPM. The Air Gap is the best dual plane intake. Or, if you decide to run better heads and a bigger cam later, the Victor Jr. would work well with your stall. Don't go the Victor Jr. route with what you have so far.
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Old 07-15-2005, 03:00 PM
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Until death does it backfire!!
 
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Still Going!!!

already had HEI I just didn't know it (I'm new to this engine deal),changed cap and rotor, still getting the derned backfire... old cap looked burnt and I had residue in the cap and on the weights (in another thread)

Car runs better though, which is good.

the carb has already been swapped out from the old one, and car is still doing it.

thinking maybe it could be the mech advance or something to do with it? or the vac advance?

what's the best way to take vacuum readings? and what exactly am I loking for?

thanks for the help so far. I'm sure I'll get this issue resolved before I take it to the rock quarry with some dynamite for a wrench.
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