Well did the compression test last night on the 1951 chevy 216. Going from front to back they read 100,110,90,100,100,95. What should I do next? Could this be the cause of my knocking problem?
Could this be the cause of my knocking problem? No, thats not bad for an old six. Probably a wrist pin or rod bearing...
what kind of knock? is the knock at an idle? If so start the engine and pull a plug wire 1 at a time till the knock changes, if it does that is the cylinder with the issue. If it does not it is most likely main bearing.
not to point out the obvious, but how about a timing issue? I had the same problem when I had my staright 8 in the poncho and it turned out to be timing. It not only happend at hard acceleration but also at mid idle, just a thought Buzz Bomb
There is a ball in the face of the flywheel ,window in bellhousing with a pointer just above the starter . with vacuum advance disconnected ball lined up with pointer at idle. If it knocks at idle it ain't timing. Time to drop the pan and adjust the rod bearings if you have not totally pounded out the bearings. Get a "Motor's" manual for the 50s for the correct way to check/adjust your rod bearings.
I do not know what exact trans you have but...I seen a Flex plate crack arounnd the mounting holes to the crankshaft and have the same sound as a engine knock. Does it change when put in gear? [automatic] If not you gotta pull the engine
I've never heard of "adjustable rod bearing". Perhaps you meant to say check the bearing clearances? I'd drop the oil pan and examine the bearings(both the crank and the rods) Here's what they should be: http://www.adchevy.com/info/1951_216_specs/ You can measure the clearances with Plastigage, available from most automotive shops/machine shops. http://www.ehow.com/how_2142943_use-plastigage-measure-clearances.html
If it is an original engine it has babbit rods and the have to be adjusted with shims on the rod cap. lots of fun adjusting good luck
Motors with poured babbit bearings use shims between the main and rod caps. As the babbit bearing material wears away you can use thinner shims to tighten up the bearing clearance and adjust it to within specification. Once you run out of shim and tin-lead babbit material (or its pounded or spun out) then its time to have the rods and/or block bearings 'repoured'. -Bigchief.
If you're not familiar with how poured babbit bearings are done, here's a link with some interesting basic info and a bunch of good pics of the process. http://www.nwo-modelt.org/blocks.html
just a throught, i have run into carbon causing knocks, a piece breaks off lands on top the piston and it will knock like hell.have used gm top engine cleaner, liquid not the spray, get motor hot pull the plugs ,pour it in cylinders, let soak for a few hours, crank it over blow excess out, plugs in , run it i alittle hard, still there , repeat. carbon is hard, it can knock loud. worth a shot.
Back in the day [Im telling my age now] I had a 52 chevy and then a 53 chevy that the wrist pin worked out and cut a grove in the cyl wall. both of these engines had babbit rods. the 53 chevy with powerglide trans had inserts but the standard shift had babbit rods. In 54 they all went to inserts.
I've only had two problems with 216s- timing gears stripping and rods knocking. Get them too hot or run them too hard (who, me?) and you'll stretch the rod bolts. If it's not hurt too badly you can shim the rods, if you can find the shims (maybe Egge?). If you do this, don't forget to align the dipper "squirters". You do this by running water thru the oil pan oil input, scribing an "X" on the opposite side of the pan in the embossed "square", and bending the nozzle with a punch that fits inside the nozzle. I'd swap for a full pressure 235/261! Have fun!
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