been a minute since I have had a chance to log on.....ok my 403 blew a head gasket i replaced them both and now she is running but,I have a missfire that I can't figure out.....new plugs,wires,distrubator and an older coil....had an extra thinking thats the problem.........timing is right just can't figure out what is going on......when im driving and jump on it it tries to clear up but doesnt......it's got to be something simple.....any advice??????? thanks ken
Double check firing order. Or did a valve get damaged when the head gasket went south? Try filling the cylinders with compressed air, listen for air leaking out either at the carb or exhaust in each cylinder. I do this test with a compression gauge adapter with the Schrader valve removed. Or it could be as simple as a bad wire, or carbon or other junk on the freshly installed plugs. Let us know what you find it's always good to hear the problem and the fix! Joe
sounds like wires #5-#7 are crossed .. at low loads not noticable but out on the road it feels like its loading up . also check for a plug wire that might be laying on metal and shorting out ( W Hei you have to use good wires cheap sets do not cut it . , just because its new doesn't mean its working right , fixed a O/T that just had new wires put on by someone lazy ( they make wire hangers and route them for a reason and not zip tie them together ) and the #1 plug wire was laying on the manifold and burned thru and was misfiring ocasionally when the wire layed near the manifold and always when it rained and also was getting crossfire where they were zip tied together ( cheap , cheap autozone wires )
Missing at idle, under power or both? Try running the engine at night, the darker the better, and have a look if you can see any blue glow around anything in the high tension side of your ignition.
Thanks for all the input......had to walk away for a few days gonna get back on it tomorrow......got to get her ready for the rust revival
ok....when i pulled the heads i never took the lifters loose could this be the problem.....wires are correct....no flashes when running in the dark....everything under the cap is new.....i am stumped
I'm not understanding that you didn't take the lifters loose? Are you saying you didn't remove the rocker bolts? I'm still thinking there is either a burnt or damaged valve from the blown head gasket. Joe
i lifted the heads straight up when i slid them back in place my wife slid the push rods back in and i bolted it down.....the valves looked good but ya never know
been looking around and found some posts about mixed up push rods....think that happened they are for the proper side just not in the orginal place......kinda got mixed up......
There really is no valve adjustment on that engine. You just torque the Rocker Arm Pivot Bolts to 25 FT.LBS. I believe is the spec. You might want to check my memory on that. Does the car spit through the carburetor at all? Joe
i'm thinking something with a valve. if you had 5 & 7 crossed (which some olds sm blocks have the firing order wrong on the intake) then you would have had to move the dizzy to make run. go with the compressed air trick as it will tell you if you have a valve problem. one thing i like about olds is you can remove the head with out removing the intake, just unbolt the side your working on.
yes there is but i would have to look in a book to get it right head to block but the rockers should be in sets of two and just run them even. if this is a motor that was gotten from somewhere else, someone may have shortened the shank that goes through the rocker to stop a lifter from tapping and it may now be in the wrong spot causing the valve to hang open.
Well did the dollar bill trick on the exhaust and it passed.........oulled plugs while running and all cylinders reacted......so its got to be a gremlin
That's great news. Maybe try checking the wires very close to see if you have a bad one. What type distributor are you running? Joe
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