Hello everyone. I have a 1940 Olds Series 90 8 cylinder straight eight. Here is my issue. Compression from the from to back here are my findings. 89 90 70 80 75 85 70 60. car has been sitting for 3 years. Currently missing and popping at the carb. Reset the gaps on the plugs. Wires are good. Dist cap is new. Just can't figure out why its running so ****ty. gas is good...... HERE ARE MY QUESTIONS: What is the plug wire sequence on the cap. I know the firing order. Maybe plug wire wrong wrong place Point gap Any other ideas. I am all ears!!
So you know the firing order, do you know which way the rotor spins? Find TDC for #1. The rotor should be pointing very close to a particular terminal on the cap. Put # 1 plug wire there. If say (because I don’t know) # 8 is next in the firing order, put #8 wire on the next cap terminal in the direction of the rotor rotation, follow it all the way around in the same sequence.
I had a similar issue on my 48 olds straight 8. I got it running and driving wonderfully but after a few spins around the block it would run like ****. Back fire out the carb all that. Ended up being the bolt that the condenser/ points was getting loose and grounding out in the distributor case. I put a new set of points sbc condenser from Napa in and tightened it and put a little thin card board like match box card board between the bolt and the distributor body. Runs great never had a problem
Oh and to find top dead center take the spark plug out of #1 cylinder. Rip a small sliver of a plastic bag like a grocery plastic bag next to the plug hole crank it over it will **** it on the down ward stroke and spit it out on the compression stroke. Back it up by hand to where it was there’s tdc
Although it sounds like it is ignition related, with the compression readings it could be a stuck valve on #8. A partially stuck open intake valve will cause the popping back into the intake manifold when the plug fires. A vacuum gauge will tell.
Just an update. I put some magical mystery oil down all the cylinders. Today I am doing another compression check. After that check the gap on the points. Check all wires under the distributor. then I will check to see if the wires are in the correct place. Try starting!!!!
Just noticed a ‘41 Olds manual in the antique cl***ifieds, I think the member is in Pa. Price seemed good at like 15 bucks? Might help out if 40/41 are the same.
HELLO!!! Well here we go! Thanks to all and especially my wife. she found the information I needed. Marvel Mystery oil in the cylinders for 2 days brought the compression from 60 to 85 the other cylinders were 90-95. Checked the plug wires and the points. they were all good. Replaced the plugs. Started up smoked (just like Up in smoke!!!). now is idled real nice doesn't smoke RUNS GREAT!!! THANKS EVERYONE for the info!!
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