I just preformed a compression test on the 1960 235 cui in my panel, and I was wondering how much the compression is supposed to be. The comp. read: 154 on nr 1, 145 on nr. 2, 142 on nr. 3, 150 on nr. 4, 152 on nr. 5 and finally 152 on nr. 6. When I look in the books it state that it is supposed to be 130 or better, so this is good right? Or is the difference to big between the cylinders? maybe I should mention that the engine covers the whole area in smoke when started. It does gets a little less when driven, but it doesn't go away. The motor runs like a champ besides the smoking. Klaus
I have posted the same question on the HAMB and someone suggested that it was carbon build up that pushed the compression reading up. Do I need to remove the head to clean it or are there other options? If I need to clean it off at all!
This topic whas up for discussion not so long ago ! Depends on how many miles your engine has been running before the black smoke problem started ? It could be anything ( carburator , ignition , spark plugs , vacume pump) ? Make a check on these and notice the colour of the spark plugs . Are they grey/reddish , brown , wet and oily black ? I `ll recommend that you send a pm to vwnate1. He knows an alternativ way to dissolve the builded up carbon in the seats/valves , this before you start to take a part the cylinder head and have a lot of extra work! Martinius.
Hi Martinius I'll pm Nate and see what he have to say. I can say that the carb probably could need a rebuild kit, but the plan was to put on a dual intake, with new carbs, so I didn't wanna rebuild the carb unless I'd absolutely needed to. the ignition parts are new and timed in the best we could, you know timing dwell and so forth. Spark plugs are AC delco R45S and you say vacuum pump? Doesn't the vacuum come from the intake? I mean at least on an engine this old? The spark plugs are all black, (not oily) nr 2 it's slightly light brown like it's supposed to look.
235 engine spesifications This facts sheat tells you your engine spes. They are different as it counts for the 235 CI. To the right of the sheat it says about the factory new engines compression. Now you can compare and see if your engine has pressure anough ? So far so good. The vacume controller sits nearby your ignition device . But as your engine is timed and runs well you dont have to think about that. As your spark plugs are reddish/brown it burns the gasolin in a correct way. How many miles has the engine on the ODO meter ? If your thinking of a dual setup in the future i can recommend you to look at the web - sites of Tom Langdon Stovebolt in Michigan. What kinda carb do you run ? Martinius. http://enginefacts.com/chevrolet235.php
Well Martinius in all honesty it's just the spark plug in cylinder2 that's the brownish color, the other 5 are on the black side, but they're not black! I have no idea how much mileage is on the engine, but there's probably quite a bit! My carb is a carter YF. I have a dual intake with like new carter YF on ready to go. I alas have a set of Fenton headers, that I just brought home from the states. I do have a 1956 235 ci that I'm gonnna run in the panel, but I was just hoping that I could get the smoking to disappear at least long enough to get the truck inspected, then I can always rebuild the 1960 engine that's in the truck now. Thanks for all your help!
Smoking & Carbon Buildup Hi Klaus ; What color smoke ? . blue I assume as that's oil smoke . Before you do anything else , one last time , re check and adjust the valves with the engine stone cold , then re check the points gap / dwell to .016" / 33° , if you use a dwell meter , leave the spark plugs out and set the dwell as the engine is cranking , as it is much more accurate that way . Then , re gap the spark plugs to .035" using a wire gauge and re install them , set the timing dead bang Ball On Pointer with NO vacuum signal at the dist. , 600 RPM's or less . you can set the timing static by leaving the spark plugs out and turning the engine by hand & using a test light ,I had to do this to my current 250 CID to get it running right . I know , I know , you did it before but you ask and this is how I manage to drive the sorriest junkers you ever saw , all across America , no problems . All nice & idling sweetly but smoky ? . O.K. , get a hand sprayer bottle & fill it with clean water , run the engine a bit until it's fully warmed up (a 30 minute drive is best) , remove the air cleaner and hold the throttle open for as fast an idle as you can stand and begin spraying a water mist into the open carby ~ the engine will begin to skip and miss , don't let the throttle close nor allow the engine to stall out , stop spraying in water if you think it's going to stall , give it more throttle whatever it takes to keep it running , as soon as it clears out and begins to race again , spray more water in ~ the mist will flash to steam as soon as it enters the hot combustion chamber , this steam blows the carbon right off and it comes out the exhaust so so panic from the choking clouds of smoke you'll see . Keep at it a while . DO NOT allow any well meaning boobs to talk you into pouring water into the carby from a cup or bottle ! a spray mist is important to prevent internal engine damage . I assume this smoking is under throttle , not when you let off ? . The black sparkplugs tell you the float tang needs adjusting a *tiny* bit to lower the float . Don't worry about the compression , the head may have been planed or skimmed & this raises the compression a lot . Give this all a try , in the correct order , then drive it a bit , might take a few miles to get all the carbon out . If it smokes upon initial startup and trailing throttle , it's the valve guides . if it smokes when you're accelerating , it's the rings & pistons , easy to fix either way . as you say it runs well otherwise meaning the engine isn't damaged . I hope this helps .
