i've got a 350 chevy engine that seems to have two dead cylinders..it's the two rear ones on the passenger side. checked and they ARE getting spark. when you put a digital temp gauge to the headers on the corresponding cylinders, the temp reading is much less than the others.. the others read somewhere around 270-300,,the two bad ones are @ around 190 or so...knowing it wouldn't make much, if any difference, i changed out the plugs anyway,,and,,,alas,,no real difference. so,,,,,since i am not a mechanic, i am posting here in the hopes someone can tell me whats possibly going on...do i need rings? since the two cyls are side by side, could it possibly be a head gasket problem (it doesn't blow white smoke out the tailpipes though),,AND if it does turn out to be either one of those two possibilities, would i be better off (and spend less money) buying a short block? i've spoken to a few friends regarding this, but thought i'd post something here, since there are so many engine experts here... ANY suggestions or advice will be appreciated much.. thanks guys
Seeing you know what side,take off valve cover and see if those rocker arms move like the others look very closely. I could be bad wire cap,worst bad cam.
Need to do some more testing otherwise we are shooting in the dark. Compression test, leakdown test, check rocker arms, try to bump each cylinder to the top and get a visual of the piston top. Make sure that you did not have the push rods fall out or that the cam is not dead on some lobs.
did not do a compression test yet, but figured that was the next logical step in ruling out rings.....a friend also suggested it might be a bad cam,,,,we inspected the rockers, and they seemed fine,,one of em was a tiny bit loose, but not enoght to make much difference he said.. i'm hoping maybe it turns out to be something super simple, like maybe just bad plug wires,,,,then i could just replace 'em and hit my head and go "doh" like homer simpson,,,,,,
Me being a cheap prick would, swap a plug wire that you know is working and try on dead cyl. or take the dead cyl wire and try on a working one, just to rule out or in the wires.
You said they were getting spark, so that pretty much rules out that it's a bad pair of spark plug wires. Do a compression check, you ( and everyone else) are guessing at best otherwise
Well the two that normally get crossed are 5 and 7 on the drivers side so crossed wires are most likely out. You might check the firing order to make sure though but I think you would get a bit of a backfire with 6 and 8 crossed. I'd be running a compression test first and go from there. Pull all of the plugs, either disconnect the power wire from the Hei or pull the coil wire and prop the throttle wide open and then check the compression in all 8 cylinders. If the compression is even you have external engine problems if the two cylinders are a lot lower than the others you have internal problems. Internal problems could be burned valves, bad guides letting the valves not seat right, bad cam lobes, head gasket blown between the cylinders or one of a few other things. External problems could be wires bad, wires crossed, vacuum leak to those two cylinders (not likely on both of them) bad plugs. "New' as in new plug wires doesn't always mean that they are good. I've seen plenty that had the ends crimped on them and the end wasn't making contact with the core of the wire. This sometimes happens when guys get the trim to fit wires and forget to strip some insulation off the wire and bend the core over under the terminal before crimping the terminal/end. Just do the standard tests and checks and process of elimination as you go.
That's not cheap - that's smart troubleshooting. Just because it has spark, doesn't indicate it's adequate for the job at hand.
A question I have not seen yet is, was it running well before? If it was, then you should be able to trace back what was done that changed to running quality. If it has run this way since you got it, then it will take logical troubleshooting to find the issue. Most of the potentials have been covered, so you just need to eliminate them one by one. Do you have the results from the compression test yet?
ended up being a cracked head,,,,,,,all fixed and back drivin' her....thanks for all the help guys.....much appreciated.
Hey, How's your custom car coming along? I was following your posts faithfully and then it just stopped once you moved to Texas. Peace, Chaz
digital temp gauge---is that just a fancy way of saying you spit on your finger and touched the header to check the sizzle ?
Actually a loose or not loose rocker is not an indication of a flattened cam. The rockers are adjusted on the heal of the cam and a cam normally flattens on the nose of the came. Roll the engine around and see if the valves are opening and closeing maybe compaire them to the other valves.
hoping to be back at it very soon,,,,,i THINK i have a solution for my lack of garage space dilemma....fingers crossed...
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