Hi, So I'm working on a 1951 panel with a 1957 235, 4spd, 2wd. New to the car world so please bare with me if my descriptions or process is off. Just brought it home and going through it. I have changed the points to Petronix and I'm planning on a dual carb set up, fentons and duals but first seeing what needs to be done to get it running and driving. So the engine is making some sounds that i would say sounded pretty serious. Knocking and running rough. I thought maybe running on only 5 cylinders. I read that starting it up and pulling 1 plugwire at a time may give more clues. Sure enough, pulling the 3rd wire back did nothing to the way it ran while pulling the others mad the engine run worse. I checked continuity in that wire and it was fine. the cap appears new, the plugs are clean and gaped, even the offending cylinder. So what can i check next, what could it be? I'm hoping it i'snt major but I'd much rather know now before I start throwing $$$ at it. I want to run the 235 for sure but, I don't need to run this 235. Thanks
Pull the spark plug on the bad cylinder and see what it looks like. Replace the plug, it could be the problem.
If the knock isn't coming from the belly you may have carboned up or hung a valve. May want to look under valve cover at the valve train and watch the action. Good luck , post how you made out. I have in the past softened the carbon by running Marvel mystery oil right down the carburetor...you got to be at the throttle and it'll smoke like a barn on fire! Sent from my VS988 using The H.A.M.B. mobile app
I would pull the valve cover and make certain all the valves are working properly and the rockers oiling. set the valve lash. If its dirty 7 sludgy all a oil change is gonna do is break that crud loose and the oil pump will circulate it thru the engine. Or worse clog the pickup screen and burn the bearings. If it was mine I would pull the valve cover, side cover and oil pan and clean and regasket the engine. When I had the oil pan off I would take a look at the bearings. If the babbit rods are a bit loose you can remove shims and reduce clearance. Use plastiguage to measure & adjust the bearings. Your plan to add carbs and modify is Ok. But should only be done on a engine in good cond if you want it to live very long. I would also add a PCV and if it doesn't already have one add a oil filter. And add a FRANZ toilet paper oil cleaner. Pictured is the oil pan from a gas engine. The rockers where clean. but take a look at the oil pump screen and the goo in the oil pan. I just did the pulling of the pan a few days ago. Now I will not have any worry when I put the engine back in service.
Hey guys, thanks for all the info. Just got back from the parts store with a new set of plug wires and a cap. they look good but I'm gonna change them anyway. I also bought a compression tester. My fingers crossed i won't need it but I'm not optomistic!
So I did a compression test and all are between 140 and 150. so what do I look at next? the noise seems like a "belly" noise. It also gets a bit better when it warms up. could it be timing?
Those older engines sometimes carboned up. they would get a deposit on the piston and it would glow and cause a spark knock. the vacuum advance on the dist should move the entire unit. Ok do you have a dead cyl? Only two things if you have good compression . possibly a exhaust pushrod bent or off. Or a lack of spark at the correct time.
Ok so i rotated the distrubitor a bit counter clockwise and it seems to run better. To be honest, i took it for a ride and i was pretty impressed with it even with the rodchester one barrel it was pretty peppy. But there is that noise. I took a steathascope and listened. It is coming from or, is the most audiable behind the inspection cover on the plug side. the noise is present at idle, almost goes away when you accelarate, and returns just as the idle comes down. As for carbon, there was black soot on the floor of the garage under the tail pipe but no smoke/smell. Thanks for the replies. I really want to do this without calling my mechanic and I can't think it would be feasiable without this forum.
Hydraulic lifter could have collapsed common on the 235’s they can be disassembled and cleaned Bent push rod Something up with the tickets and valve train Your compression is good so, that’s great ! Your entire distributor turns when it’s advancing When setting the timing you go off of the ball or B.B.on the flywheel Octain adjust on dust set to 0 and adjust Keep us posted. A good running 235 even in stock form is a fun engine
This is damn near impossible to go over on the Internet. You're going to get a hundred people with a hundred different theories. I don't want to be left out so I can throw mine in. It could be a wrist pin slap.
One way to remove carbon from an engine is to run till it’s hot, then pour about a pop bottle of water down the carb, you will have to give the engine a lot of throttle, pour it slowly. It WILL clean the carbon off the top of the piston and the combustion chamber. But be sure this is what you want to do, as the carbon can become lodged under a valve. I always did this before I overhauled an engine, made cleaning easier. Bones
A 51 engine doesn't have hyd lifters. the hyd lifters came out in 53 on powerglide equipped cars. And the hyd lifters on the stovebolts weren't very good. I always threw them away and replaced them with solid lifters. And I know you aint supposed to run solid lifters on a hyd cam. But it worked for me several times. One time my dad told me pull the pan on a H farmall and see which rod is loose. So I took it off and told him it wasn't a rod bearing. it was a piston skirt. He asked what cyl. I replied all four. It was a Super H with domed over bore M&H pistons. and I had reworked the governor to give it another 600 RPM. That may be why the skirts broke off? A broken skirt sometimes lets the piston cock enough it will make contact with the cyl head. That makes a sound like a rod knock. Also the top ring will strike the ring ridge often breaking the piston ring and or the ring lands.
Ok, so the engine is a 57, cast # 3837004, date cast is g 20 6. I took the valve cover and inspection cover off and nothing seems out of place but, I'm not really sure what to look for. every thing seems in place and nothing broken. Rods are straight but there is some lateral movement in the rockers which could be what I'm hearing. Is it ok to run the enging with the valve cover and inspection plate off?
Yes, just can get a little messy with oil spatter/leaks.....otherwise no harm. Being a later engine, you may or do have hydraulic lifters. What to watch for would be a loose push rod while running if a lifter is collapsing in operation. The little cup in the top of the liffter is movable and is kept in contact with the pushrod by oil pressure under normal operation. If the lifter is defective for some reason, that little cup may not remain in contact and the 'slack' results in a noise. Ray
well, i started it up and didn't see anything out of the norm. i guess its coming from below the pistons. i think i'm gonna toss in the towel and let a pro diagnose the problem and take it from there. updates to follow. thanks again for all the help.
You say you adjusted the timing but didn't say if you set it correctly. Do that first as stated above with the BB. Also, when you find that BB put some white pain on it - it helps a LOT. Then try removing the plug wires one at a time again. If the knock disappears when you pull one, you most likely have a lower rod knock at on that piston. Doubt you have this issue but I'll throw it out there. I was spent a year looking for a knock on my freshly rebuilt '53 235. Turn out the harmonic dampener was lose and would move fore and aft during idle. This would thump the crank sending the sound throughout the lower end of the motor. Made me crazy. ~ Carl
What Carl said They were also bad IF it has the fibre timing gears for the gears to crack and chip and cause issues I’ve seen all steel ( crank and cam) Also seen steel crank and fibre cam And both fibre Have a better listen
Just as well pull the oil pan. If you engine is a 57 it will have insert bearings and full pressure crank lubrication. Just take the rod caps off one at a time and inspect the bearings. and also look at the main bearings. try and pry the crank back & forth to determine how much play there is in the thrust bearing.
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