Ignition or Fuel system problem ??

[Robert8096]

I have a 69 Stepside with a 283 3 speed with a 1450 Holley carb, the original point type ignition and 3.73 rear gears.

It idles fine, I can pop the clutch and smoke the tires or take of normally with no hesitation and go through the gears (either regular or hammering) and the engine responds well up to about 60mph or around 3000 RPMs, after that it will start sputtering and backfiring through the carb and in some cases die. I can pop the clutch and will start running again and will be fine until I reach the above speed again and then it starts all over. I can cruise with no problems until I pass 60 on the speedo.

I have owned this truck for about three months and when I got it the speedometer was broken and I guess I was driving it like a little old man because I did not notice this problem before I did the following:

I replaced the speedometer. ( don’t think this is the problem)

I added a tach. ( disconnected and it did not make a difference)

I upgraded the Holley from a manual choke to an electric. ( the positive lead for the choke is not connected to the coil) I blocked open the choke plate for testing purposes to make sure that the choke was not closing.

I pressured washed the engine ( covered the carb and distrubtor) done weeks ago.

I added a clear fuel filter ( temporary) to see if there was trash or rust coming from the tank and I don’t see any in the filter. It has fresh gas in the tank. Have not tested fuel pressure.

I did the carb spray looking for vacuum leaks and checked all the vacuum hoses for cracks. Nothing found.

I replaced the coil and did a visual inspection of the points and saw no issues ( I have since ordered the parts to switch to HEI)

I tested the voltage to the coil and it has around 5 volts with the key on and 9 volts with the engine running. I did notice that I do not have the wire running from the starter to the coil to supply 12 volts during cranking but it will crank on the second revolution when cold and one when it is warm.

According to the voltage gauge in the dash I see no extra or loss of voltage when this happens, it is always 11 volts or better.

With the above information what is your opinion, suggestions ?

Thanks
Robert

[Sinister]

I had this problem with my points dizzy after pressure washing my motor. I swapped to HEI, and the problems went away.

[68gmsee]

You've checked just about everything you can think of and still acts up around 60 mph or above?? That's a good one.

One thing that comes to mind is a flat cam or weak valve springs. Valves may start to float at the higher rpm's or if they're not opening up completely can cause similar problems. How many miles on the truck? I guess if the speedo was disconnected you won't know for sure but the cams were a weak spot on a lot of these old engines. 80K-100k or more and you'd start having problems.

Another thing, is the points. Make sure you have some good quality points and condenser and the vacuum advance is hooked up and working correctly. Try advancing the timing to see if it changes any thing.

[cdowns]

while you were looking at the points a few minutes extra to set the proper gap would have been time well spent// have you ever removed a sparkplug and checked the condition and gap? how about the timing ever put a timing light on it ?

[Robert8096]

I just checked Fedex tracking and my parts to convert to HEI should be on my door step, so hopefully I will be able to convert it this weekend.

I really don't know how many miles are on the engine but it does not smoke and runs well up to that point. If the HEI swap don't fix it then I will check out the cam and springs. If it needs that I have a running 454/400 combo sitting in a Surburban that may replace the 283. I really don't want to go that way because I want somting to cruise with decent mileage.

Thanks for all the help.

[68gmsee]

It would be nice if the HEI fixed it. Those 283's were great little engines. I'd be tempted to check the compression, and if it looked good, slap a cam and maybe a timing chain and gears and keep running it. But whatever you do, don't get rid of it.

Back in my younger years, I had a 56 Chevy with a 283 that ran like a scalded assed ape. Loved that car.

Let us know what you find.

[Robert8096]

I plan on keeping the 283 and really don't want the 454/400 combo in this truck.I want to put the 454/400 combo in my 82 short fleetside.

I just opened my Fedex box which contained my new HEI distributor and wouldn't you know it was damaged in shipment so I guess I won't be doing the HEI conversion this weekend.