Is My Engine wanting To Play Dead?

[Canadian694x4]

Well I have recently started to experience a little engine trouble. I need help to figure out what is wrong so that maybe I can fix it or I can take it to the experts I suppose. Here's what I can discribe...

My 283 just the other day seemed to be slow on acceleratation (no Power when I punched it). That was fine, cause I figured it was just my timing (my dizzy doesn't want to stay put). Well before the day was out and I could reset my timing my truck started to backfire on deceleration under braking!! What causes this?

Well when I got it home I tried playing with my timing then took it for a spin. All seemed well as I did get some of that Power I was missing back and she even sounded healthier. But alas, after about a 20 minute run she started to backfire under braking once more

Is it that I need to play with my Carb? Running too rich or sumthin maybe? Any clues or help would be great.

Can anybody help me to understand whats up?

I'm not a master engine guru...so any help would be greatly appreciated.

Thanks

Brian

[cdowns]

with a high-milage engine i'd be lookin at the timing chain for excessive play

[walker]

I would run some diagnostic test to see. Also, give some more info, Points, hei, power brakes, what carb, what timing is set at, how you set it(light/by ear), etc.
I'd run a compression test, check the plugs/wires, check the engine with a vacuum guage(often overlooked diagnostic tool, look at an old truck manual to see what the readings mean), hit it with a timing light(remembering that those balancers are notorious for slipping and messing up the timing mark), check the point gap/dwell( for a points dizzy). May pull the timing cover and look at the chain for slop. Timing chain is a cheap investment, if I were pulling the cover I'd have a new chain to put in. While you got the cover off and the two little dots (#1TDC) lined up I'd be sure to check the balancer timing mark. Also check the dizzy cap for cracks, and rotor too.
Good luck.

[thisolechevy]

Cap and rotar, sound like what it needs.

[68C15]

why is your dist. turning? the low power & backfire are a result of retarded timing. might try a new hold down or make sure yours is actually on top of dist. flange. to check for worn timing chain use a timing light pointed at balancer & watch marks. good chain will be steady at same spot. worn chain marks will jump around. if by chance your chain is badly worn I recommend installing a double row roller NOT a stock replacement. they are not much more $5 or 10 more.
Todd

[Canadian694x4]

Originally Posted by 68C15

why is your dist. turning? the low power & backfire are a result of retarded timing. might try a new hold down or make sure yours is actually on top of dist. flange. to check for worn timing chain use a timing light pointed at balancer & watch marks. good chain will be steady at same spot. worn chain marks will jump around. if by chance your chain is badly worn I recommend installing a double row roller NOT a stock replacement. they are not much more $5 or 10 more.
Todd

I can't actually figure out why my Distributor turns...it looks to be held by the hold down. As for the retarded timing, well my truck has always run a little on the retarded side when checked by a timing light. It was the closest to middle ground I could get it to run well (enough). It seemed to run too advanced when I tried advancing it.

I don't know much about motors etc. but I want to learn, even if to have an idea what to tell mechanics what my prob may be. Around here the local mechanics give you the attitude that if your bringing in an older vehicle your bringing them a "Project", and that they don't have time for it. I've convienced my local mechanic to look at it (Retarded Timing) but never once has he done anthing or suggested a new cap and rotor or timing chain might be slack.

I want to thank all of you for your responses!

The help is appreciated!

Brian

[69 Short Fleet]

How many miles are on your engine or rebuild? It sounds to me like I'd be pulling your timing chain cover and if need be installing a double roller like 68C15 mentioned. A little OT but I have a 1968 283 (205 hp model) from what I can find apparently they made 4 different 283's (I ran the block # and checked it on a engine website). Best of luck, Doug

[Pont]

All of the above are good suggestions. I would definitely look into a worn timing chain as a possibility. If it has excessive wear, you want to replace that thing before it lets go. If not, you will be doing work on the valvetrain as well. I would also look into why your dizzy isn't staying put with the hold-down bracket.