broker-len Posted December 30, 2023 Share Posted December 30, 2023 four cylinder Motor Professionally rebuilt board out block new pistons new valves and guides head trued up new head gasket plug one and two producing good power but when I ground out number 3 not much differance 4 a little better vacuum is about 18 took the wires out of the loom and moved around different plugs if I clean and dry all four plugs and run for 5 minutes the plugs seem to be damp is that blow by not removed because the car is stationary ????? can't find problem bobnroman@yahoo.com Link to comment Share on other sites More sharing options...
TTR Posted December 30, 2023 Share Posted December 30, 2023 What are the compression and leak-down tests showing for each cylinder ? Link to comment Share on other sites More sharing options...
Oldtech Posted December 31, 2023 Share Posted December 31, 2023 Valve adjustment?? not enough clearance. Link to comment Share on other sites More sharing options...
broker-len Posted January 1 Author Share Posted January 1 thank you both all the compression are the same 36 LBs I think not sure how to do a leak down test I thought about the valves they are such a pain to get to and because the compression was good ruled them out ????? what do you think ? Link to comment Share on other sites More sharing options...
TTR Posted January 1 Share Posted January 1 If compression is even and within expected(?) range, there's usually no need for leak-down test. How much has the engine been used/driven since the rebuild ? If not much, I'd try to drive it 20-30 miles (hard) and see if anything changes Link to comment Share on other sites More sharing options...
broker-len Posted January 2 Author Share Posted January 2 Have driven it a little enough to seat every thing in low in power when idleing you can smell unburned gas out exhaust,,, just do not want to run hard with a condition that that I think in spring going to check the valve clearances ,,,real pain !!!! maybe put in another set of plugs Link to comment Share on other sites More sharing options...
DFeeney Posted January 2 Share Posted January 2 Are you saying the compression is 36 PSI. I think you typed in a error. Link to comment Share on other sites More sharing options...
broker-len Posted January 2 Author Share Posted January 2 I have one of those gauges with rubber end take out all plugs stick the gauge in each hole and hit the starter think think all holes are 35 PSI Link to comment Share on other sites More sharing options...
TTR Posted January 2 Share Posted January 2 31 minutes ago, broker-len said: I have one of those gauges with rubber end take out all plugs stick the gauge in each hole and hit the starter think think all holes are 35 PSI Seems low. Care to describe your compression test procedure in more detail ? For example: Hot or cold engine ? Fully charged, good battery (attached to a charger) ? Throttle closed or open ? How many cranking revolutions per each cylinder ? Etc… 1 Link to comment Share on other sites More sharing options...
Oldtech Posted January 3 Share Posted January 3 Yes, compression sounds low, even for a PA. should be more like 60 ish. How fresh is the gas? Link to comment Share on other sites More sharing options...
broker-len Posted January 3 Author Share Posted January 3 My mistake compression is 60 or 65 same on each hole all plugs out good battery as I said rebuilt motor Link to comment Share on other sites More sharing options...
broker-len Posted January 3 Author Share Posted January 3 not able to drive the car so gas is not fresh but problem is only with mainly third hole no matter what I do Link to comment Share on other sites More sharing options...
viv w Posted January 3 Share Posted January 3 If spark is weak at number 3 and 4 it is unlikely to be a compression issue, and more likely to be an electrical problem. Run the motor at night, in the dark, and see if there is any tracking of voltage to earth. Your distributor cap may have a hair crack or carbon build up and is tracking. Check your points gap and condenser. Wet plugs indicates either too rich a mixture or weak spark/wrong plugs. What spark plugs are you using? Link to comment Share on other sites More sharing options...
broker-len Posted January 3 Author Share Posted January 3 thanks cap is new but could be bad will check it and points I took the number 3 wire out of the loom insulated from ground will try the dark garage trick will also check plugs Link to comment Share on other sites More sharing options...
Oldtech Posted January 4 Share Posted January 4 Is the distributor cam worn? Pull the wire off no 3, preferably with insulated pliers, while it is running and see what there is for spark there when held near a head bolt. Link to comment Share on other sites More sharing options...
broker-len Posted January 5 Author Share Posted January 5 thanks Link to comment Share on other sites More sharing options...
broker-len Posted January 18 Author Share Posted January 18 bump Link to comment Share on other sites More sharing options...
Paul S Posted January 23 Share Posted January 23 Be careful on setting timing, the vac. chamber retards the timing unlike most cars where it advances it. So, at idle with full vac. the timing will be late. Also be sure you are running metal core plug wires. Link to comment Share on other sites More sharing options...
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