The Stovebolt Site Forums The Shop Area Engine Shop 235 loud bang

Newbie here...Good to be aroung folks that appriciate the good ole 235! All my buddies make fun of my engine! I recently set up my 235 with pertronix set up and the carb is making a popping noise when I give it gas? It was making this noise before the point conversion. I though it was the points but it's not. I also put a brand new carb 350 cfm 2 barrell and it still making the same noise. Can anyone lead me in the right direction into correcting this?

tattooboz,

Welcome to the Bolt Boz! Did you time your engine with a timing light after you did your Pertronix swap? Your vacuum advance must be hooked up and working, and no vacuum leaks allowed.

If this problem was there before the new carburetor and after the new carburetor, it probably isn't the carburetor! More info and hints are most likely on the way. Good luck.

Stuart

Welcome aboard, tattoboz! Stuart's on the right track. Sounds like you've got the timing retarded.
And trust me, once you get that 235 working right, your buddies won't be making fun of it. I get alot of people ask me if mine's a 350 when they hear it, then are shocked when the see it's a 235 6 cylinder.

I'll third the welcome tattoo, but suggest you check compression with an ear to insuring you don't have a burnt valve, or pop the cover and check the valve lash to make sure there's no intake valve too tight or sticking

Bill

Great suggestions! Thanks to all for that warm welcome!

Welcome.

I second the retarded timing suggestion. A burnt valve should cause a puffing of the exhaust at idle and would not only be evident when you try to accellerate.

Welocome also, I had this problem with an inline though it could happen to V types. The problem was a bent push or the push rod came off from under the rocker arm. Gas was getting in but not getting out. It would POP through the carb when reved up. Its been a long time since this happened. If you timed it and it still does it then take off the valve or push rod cover (side cover) a check for a push rod either major bent or somehow came off the lifter. If it does it constantly and not just occassionaly then its probably the trouble. Just replace the rod. They are great engines and last for years. Tough as nails. H.

Hi and ditto on the welcome. My guess too would be in looking at the valves. Pull the valve cover and see if the exhaust valves are opening. An exhaust valve not opening would cause the burnt gases to exit through the intake and carb. It would be accentuated at higher rpms because you're sending more gas into the cylinder. Could be caused by a bad lifter, bent or broken pushrod or burned valve. Let us all know what you find.

On a 350 I had,it had a slight miss,would quickly open accellerator pop,pop,pop.Problem lobe on cam shaft ground to round. What a bit@h.

My 54 was popping thru carb it was the valves. I hadn't properly tightened the rocker assembly after replacing bent push rod. pulled valve cover and imediately saw my error

Welcomr to the Bolt.I'll go to the valves also.An intake valve or related push rod.As mentioned before,a intake cam lobe

Now that i've had time to poder it, my 235 did do the same thing, and it did have a pushrod that had the end come off it. But it also did it after the pushrod was replaced and the lash was reset to spec. Turned out that the timing was also an issue, needing to be advanced approx 15 degrees.

I DON'T SUPPOSE IT MIGHT BE SOMETHING SIMPLE,
LIKE HAVING THE #3 THE #4 SPARKPLUG WIRES
REVERSED WOULD IT?

I'm not quite the mechanical genious that most are on this site, but has anyone considered a backfire through the carb due to too much fuel going through a 2bbl and potentially oversized jets?

I had a 72 SS Chevelle that the previous owner had put a hugh Holley on and did that kind of stuff all the time until I had the jets replaced.

On the flip side, my low pressure 235 in my 39 is currently doing the same thing and I am pretty sure it is a valve issue. I pulled the side plate to discover one displaced rod and two bent ones. Got the rods replaced, but I think the vavles on the number 2 and number 5 cylinder may be frozen shut, which is how the rods bent in the first place.

I was told if there is a dead cylinder to pull the condenser wire and push the starter to find the non-firing cylinders.

Finally got to work on my car! Well, Henry G nailed it! I pulled off the side cover and there she was! The rod was off the the lifter! Thanks for all that replied. You guys ROCK!

Hey tatooboz, I'm glad to help out. I had this problem on a slant six. Fixed it then ran like a song. Enjoy! Henry.

If you have a miss all the time look at fire order on plug wires,,check comp see if 1 cyl is down maybe intake valve leaking by or cam bad..If just poping when throttle is first opened,,check timing,,check acc pump flow,,fuel level in carb,,vacum leak at intake or carb,,dist advance...doc

doc41,

You might want to read through the previous posts..I think the smelly cheese in Denmark has been discovered.

Stuart