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Cheepin 02-19-2002, 06:45 PM I have an 77 Chevy Crew cab with a 73-74 454 in it.It starts and runs fine but at part throttle it has a sputter.Once you get past this into the 4 barrels it revs fine.This happens both when you drive or if you just rev the motor a little.Any suggestions?I changed carbs thinking that was it.Maybe in the dis. cap/rotor?Thanks Blazin:D Shaker 02-20-2002, 06:10 AM check fuel pump/filter.....sounds like the "accelerator pump" needs to be rebuilt. What kind of carb. are you running.....Holley? Did you reuse the gasket when swapping carbs? It might be leaking .....Need more info.... Cheepin 02-20-2002, 06:02 PM It is a quadrajet.I used a new base gasket i had.Could this be the advance in the distributor not working?It has been rainning today so I didn't put a light on it to see if it is advancing.Did the same thing with both carbs not has bad with the current carb.And the current carb didn't have a problem on my blazer.I just rebuilt the carb for the blazer and put this one on the truck to see if it helped.Thanks Blazin:rasta: Lloyd 02-21-2002, 06:49 AM Pump going out? Plugged filter? Plugged screen on the pickup pipe in the tank? Hole in a hose on the suction side of the pump? Yank the fuel line off the carb and run it to a can, start it and see what the volume is; I'd bet not much. IF you've got good fuel volume, then it may have jumped a tooth on the timing chain. Those cam gears are plastic-coated to run quiet, and when they start to shed chunks everything can go to hell pretty fast. Muddin 02-21-2002, 02:24 PM I had a similar problem a while ago and it was the accelerator pump. Luckily, the carb was new so I just exchanged it while under warrentee. Things you might also check is fuel filter, vacuum leaks, and also make sure the carb is on there tight. Sometimes the bolts loosen. The gasket that sits inbetween the carb and the intake will cause all sorts of problems if it needs to be replaced. Cheepin 02-21-2002, 07:22 PM Ok there is plenty of fuel.Filled a 160z pop bottle in no time.Didn't find any vacuum leaks.And the accelerator pump is spraying lots of fuel.What do I look for if it is the timing chain.Could this be a flat lobe on the camshaft.Thinking if I need to do the timing chain should do the cam and lifters also.I had a light on it the other day and timed it 12 degrees BTD.Had no problem timing it.Blazin:rasta: Paul Gagnon 02-21-2002, 07:43 PM What's your oil pressure? Have you been having any oiling problems? Does it happen when the engine is warm or when it's cold? I had a similar problem and I thought it was fuel. Checked everything and no problems so I checked the ignition, still no problems. What it turned out to be was that I had knocked a lobe of the camshaft. It could be that you have done the same thing or you have a dead lifter. Cheepin 02-21-2002, 08:16 PM I just bought this truck 2 weekends ago and got it running last weekend.The oil pressure gauge reads 60 psi.Stock gauge.No rattles in the motor and I just changed the oil and filter.I guess I should pull the valve covers off and run it and see what the valves are doing.It starts and runs fine but has this sputter.I need this truck to tow with so I need it fixed right.Any other suggestions?Thanks Blazin:D Cheepin 02-21-2002, 08:19 PM Oh yeah it seems to happen warm or cold.But I have only driven it around town.And this is a really small town!!At the most down the hill and back like 10 miles round trip.Blazin:D Cheepin 02-23-2002, 06:31 PM Ok I still need to pull the covers and see what the vavles are doing.But if this is the problem.I would like to upgrade the cam since I will be changing it.What do you guys recomend.Remember this is a tow rig and needs power all around.It is a 4bbl and has dual exhaust.Will have headers soon also.I was thinking of a 266-272 grind.Also this has a 4 speed so it has granny low and is a dually with really low axle gears.Will hopefully swap in a NV2500 soon for the overdrive.Any suggestions?Thanks Blazin | |