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#69110 11/24/2006 10:54 PM | Joined: Apr 2002 Posts: 17 Junior Member | | Junior Member Joined: Apr 2002 Posts: 17 | My 235 suddenly, started backfiring at high revs. I've checked or replaced most ignition parts, timing is at the ball, and I've tried moving it and no luck. Two years ago I rebuilt the engine and it has been running great. Last check valves were adjusted. The backfire is a rapid firing and it only occurs accelerating at higher rpms. Any ideas??? | | |
#69111 11/24/2006 11:13 PM | Joined: Jun 2004 Posts: 8,597 Riding in the Passing Lane | | Riding in the Passing Lane Joined: Jun 2004 Posts: 8,597 | Sounds like ign. breaking down. Check the plugs for cracks. Check the plug wires & dist cap.Make shure the points haven,t slip & not opening enough.
They say money can't buy happiness. It can buy old Chevy trucks though. Same thing. 1972 Chevy c10 Cheyenne SuperIn the Gallery Forum | | |
#69112 11/25/2006 12:01 AM | Joined: Jul 2004 Posts: 5,708 'Bolter | | 'Bolter Joined: Jul 2004 Posts: 5,708 | sadams, Pretty interesting handle!!  It almost sounds like a intake valve is hanging, or in slow motion with a weak/broken valve spring. I would take another look under the valve cover. Stuart | | |
#69113 11/25/2006 3:04 AM | Joined: Mar 2004 Posts: 3,068 'Bolter | | 'Bolter Joined: Mar 2004 Posts: 3,068 | Originally posted by atomarc: sadams,
Pretty interesting handle!!
Stuart I assume you were thinking what I thought at first! I think his name is S. Adams, I hope, Scott | | |
#69114 11/25/2006 3:26 AM | Joined: Feb 2006 Posts: 112 Member | | Member Joined: Feb 2006 Posts: 112 | my vote is for a valve problem...... | | |
#69115 11/25/2006 11:11 AM | Joined: Apr 2002 Posts: 17 Junior Member | | Junior Member Joined: Apr 2002 Posts: 17 | It comes from an old American name "Adams". I'll pull the valve cover today, since I've done most of the iginition stuff.
The truck was runnin great, then I installed a BW T-5 tranny (which I love) and then the engine acts up. Try and explain this to my wife.
Stephen | | |
#69116 11/25/2006 1:19 PM | Joined: Mar 2005 Posts: 1,636 'Bolter | | 'Bolter Joined: Mar 2005 Posts: 1,636 | My 58 235 did that one time. Was running fine, driving down the road. Engine had appx 60,000 miles on it. All of a sudden it would back fire when you put it under load, and had a slight miss at idle. I did everything else but look under the valve cover first. Finally found that a pushrod had broken on and exhaust valve. New pushrod, adjusted valves and her she went again. | | |
#69117 11/27/2006 3:29 PM | Joined: Sep 2006 Posts: 206 Wrench Fetcher | | Wrench Fetcher Joined: Sep 2006 Posts: 206 | I had one that did that, after checing timing,points, plugs,wires, i pulled the valve cover to find one valveguide bad.I could hold the valve with my finger while idling and the motor would smooth right out. | | |
#69118 11/27/2006 4:53 PM | Joined: Apr 2005 Posts: 2,832 'Bolter | | 'Bolter Joined: Apr 2005 Posts: 2,832 | Rapid backfiring through the carb is usually caused by an EXHAUST valve being closed, usually due to a pushrod problem. Possible rocker arm adjuster backed off but not likely. For the non-believers, back an exhaust rocker all the way off and rev the engine; it'll sound like a Tommy gun.
Evan
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#69119 11/27/2006 7:23 PM | Joined: Apr 2005 Posts: 1,971 'Bolter | | 'Bolter Joined: Apr 2005 Posts: 1,971 | I'll agree with Atomarc.
High revs? bent intake valve, leaking intake valve, floating intake valve, broken intake spring. | | |
#69120 11/28/2006 1:48 PM | Joined: Mar 2006 Posts: 483 Shop Shark | | Shop Shark Joined: Mar 2006 Posts: 483 | My 350 shaby had a slight miss when I would gas it under no load it would rapidly backfire thru carb.Pulled valve cover and noticed a lifter not operating properly.Long story short. Lobe on cam ground to round. | | |
#69121 11/30/2006 6:02 AM | Joined: Apr 2002 Posts: 17 Junior Member | | Junior Member Joined: Apr 2002 Posts: 17 | Sorry, no update yet, We've had a bit of a snow storm here in the NW (it doesn't take much to paralyze us)I've been clearing trees instead. Today, I found metal (aluminum shavings) in my 1957 Piper Pacer engine. At least my new 1990 Subaru is still running. | | |
#69122 11/30/2006 12:20 PM | Joined: May 2006 Posts: 119 Wrench Fetcher | | Wrench Fetcher Joined: May 2006 Posts: 119 | Check your distributor and make sure there isn't too much play in the shaft. | | |
#69123 11/30/2006 1:30 PM | Joined: Mar 2006 Posts: 483 Shop Shark | | Shop Shark Joined: Mar 2006 Posts: 483 | Don't like shavings of any kind in an engine, specaly, aircraft.Sound like teardown time. | | |
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