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ZZZZZZ,,,,NOT likely! Popping/backfiring on deceleration is actually pretty common and can be caused by lots of thing. Most common problem is air leaking into the exhaust system. Unburned fuel in the exhaust (float level to high would be one cause for instance, jets to big, etc.). If I had the symptoms you describe the LAST thing I would be looking for is a bent push rod!
Ernie |
Cool
Thanks, I can sleep now.
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KobraKarl, 2x4 is that the same as an "8" thats what I have always used!!!:LOL:
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Oh my, You guys are brutes%/
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Trans am jim has it right. Put new plugs in, warm it up, floor it thru second and third, shut it off at the top of third, pull over and read plugs. Any other way of reading plugs is inaccurate. The ring seal can be determined by a leak down test. Now, to get it to run properly at part throttle, a good carb guy can help, but it is a bit tricky. The WOT part is easy. I would also run at least 36 total timing all in by 2500 rpm. Good luck, scott.
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everything coyled said, except: at least 36 degrees total timing.
Some motors only want 30 degrees, some like 36, many lke it somewhere in between, this is dependant on a number of factors. But do get at all in by 2600rpm |
This is exactly the reason I'm happy to send a check to Brent Mills each year to support this site!
I put in new plugs last Wed and drove it to work on Thurs. Drove it nice and hard, too. :D The car acted great. It was happy again. I haven't had a chance to do anything else yet, including checking the plugs because... 1. It's been raining ever since. 2. My newborn son has days and night mixed up which means... 3. I'm sleeping whenever I'm not working or eating Will post more when I catch up on sleep and have a chance to check the plugs again. Keith :o zzzzzz..... |
Kieth,
Feed him less but more often during the day and he won't get as much sleep when the suns up. Give the heavier feeding at night so he'll sleep longer in between.. Been there done that. And when reading the plugs don't run it to 3K and shut it off there if you have a carb. It's fine with injection since it won't continue squirting fuel. with a carb it will still be sucking gas from the carb into the cylinders and not burning it so they could appear wetter than they should. If carbed just run it hard and get it down to an idle quickly and then shut off. Scott |
Keith,
I love that quote from Patton. Is that from his memoirs? Those little runts can make one hell of a lot of noise can't they? Sleep, who needs sleep? My oldest boy is just starting into puberty. Now I get to loose sleep for other reasons.%/ Steven |
Run it through the first through 3 or 4 gear, hard. Push in clutch and kill motor, coast to your plug removal site and look at them. This will NOT continue to draw fuel and wet the plugs. The dragstrip is the ideal place for this, but you might not have one in your backyard.
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Mr fix it, you are correct in that some motors like only 30 total like mine. But, I am running yates heads and 12 to 1 compression, so the combination is very efficient. I doubt that a lower compression big block with any heads and 2 carbs is as efficient and in my experience they need closer to 38 to 40 degrees of timing to run there best. Not to rehash the plug reading thing but the very best way to get the best read is, new plugs, warm motor, second and third gear flat out, at top of third with foot floored, shut off motor, coast to side of road, pull plugs and read them. If you guys saw my plugs after a day of around town driving or after some use, the read looks like a way too rich oil burning mess. Now, new plugs, flat out on the race track, shut her down, they are text book in color. The only other way is with the use of a wide band o2 on a rear wheel dyno. good luck, scott.
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For total advance the plug position, piston shape, combustion chamber shape, cam and more will determine what the total advance should be. My builder told me that my flat tops should be at 34, but if I went with a dome style it should be 36 even though the CR would be higher. Something to do with the flame front. Mr. Fixit could probably splain much better since I is only repeatin' what I heard.
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Advance
Ther is no real baseline for advance versus compression. The theory that higher compression needs less advance is true in the big block but every motor will be different. This is for many reasons that have been previously explained to me that I could not begin to repeat.
One of the ways that I have found the easiest is to get right is make changes in 2 degree increment but, most importantly, read ALL the plugs for detonation. Due to the exhaust configuration, the back plugs will read different than the middle and front. You should try to get to the limit of no detonation and a trace. Then check again on colder days. Colder air is like an automatic timing bump. |
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