Agreed. The valves can be bent pretty bad and still even seal, under spring pressure.
What could cause this? 360 problems ####update####
- Thread starter ike61
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Looking at pics in post #27, cam has been installed too far retarded. It's on overlap, intake lobe isn't anywhere close to where it should be.
Yup. There's your problem. Both lifters should be down all the way.
That is a BUNCH out of time. Being off using the 4* advance/retard keyway and the 0 mark to line up cam will put you about 60* out of time IIRC.
That's my guess, wrong mark on crank gear used to line up camshaft. Always ALWAYS ALWAYS on a proper SB mopar timing set, if the crank keyway isn't lined up roughly with the #1 cylinder when installing the set, it's OFF.
I think you got it backwards.
at least 40-50 degs
DionR
Well-Known Member
Hate to admit it, but I've done this.
Multi-key timing set, and used the "dot" (it was actually a zero) above the key way to line up the marks on my timing set. Missed that there was a "dot" (also a zero) near the teeth that was what was intended to be use to line up the timing set. Crank keyway should be about 45 degrees past straight up, and I had it at straight up.
I could find the thread where I outted myself after railing against the timing set manufacturer and then found it was my own dumb fault. But it still stings some so I'm not going to do it.
Multi-key timing set, and used the "dot" (it was actually a zero) above the key way to line up the marks on my timing set. Missed that there was a "dot" (also a zero) near the teeth that was what was intended to be use to line up the timing set. Crank keyway should be about 45 degrees past straight up, and I had it at straight up.
I could find the thread where I outted myself after railing against the timing set manufacturer and then found it was my own dumb fault. But it still stings some so I'm not going to do it.
furrystump
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Not piling on and not sure if this was just a cam swap or total build. I always check piston to valve clearance with play dough. Actually, anything that can be measured or checked, I do. I have trust issues. Paint you a picture, build it, run it and something is “off” anything you didn’t actually check is now “totally unknown” and it will probably suck to measure/check it now. The setup to degree a cam is “time consuming” part. Not really, but once set up, I will do it twice, just to be sure my numbers are repeatable.
Well, I DID beat a couple of slant 6 pushrods out straight with a hammer on a vise years ago. Put um back in, adjusted the valves and it ran great until I did the V8 swap.Nope, I didnt reef on it, but was firm. Surprised how "ez" they were to bend lol.
Corrected crank gear, straightened rods and moved on. 10 years and 10k miles ago.
**edit**, I DIDN'T straighten the bent push rods, I out used straight ones in lol. Figured I'd better clarify that
BillGrissom
Well-Known Member
Another confusion, when I installed a new timing set in my 273, I was surprised that the dots on the sprockets lined up (closest together) when #6 cyl was at TDC. I thought someone was wrong, but before creatively "fixing it", as I sometimes did as a dumb kid, I checked the Shop Manual and found that is correct. My timing set had the 3 sets of marks. I set for 4 deg advanced, to give slightly better low-end torque and mileage, plus that accounts for future timing chain wear.
BillGrissom
Well-Known Member
Should be easy with the spark plugs out. With spark plugs in, you have to fight each cylinder, which is a poor-man's test of "compression". If you have to wait 5 sec for each cyl to hiss down (over 2 crank revs), you know the engine is good. A quick test on a used car where you can't run a compression test with a gage. BTW, don't totally trust a gage test since several ways to get invalid readings. On a stand, you can use a socket wrench on the crank bolt. That isn't often easy in the car, especially with a many-groove crank pulley installed, radiator shroud, and trans cooler tubes. I got spoiled on my 1985 M-B diesel engine which has a hex head on the power steering pulley up top I use, so started using the alternator pulley on my 1965 Dart, using a pipe-wrench on the front nose disk. I also have to tighten the belt and push down on the belt to not slip, but much easier than fussing with socket extensions and working a wrench down on the crank which keeps falling off the bolt. Chews up the end of the alternator pulley, but I have spares on the shelf and could file off the nicks and paint if ever presenting the car at a show (not paying a fee so judges can diss my work anyway).
Re what compression values you should measure, with factory camshaft and unmilled block and OE heads, you can use the Shop Manual specs, which I recall is 145 psig for my 1965 273 2bbl (not HiPo). But, few have the OE camshaft today, so most sources just state "less than +/-10 psig variation between cylinders". I would think if any cylinders measure <100 psig, there are sealing problems, which you can go onto a "leak-down test" to determine. Apply ~10 psig with piston at TDC compression stroke. Might need to lock the crankshaft so it doesn't fly down if not perfectly TDC, or at least don't leave a wrench on. If bad, you will hear hissing, so try to find the source. If you hear at end of exhaust pipe (or flutters tissue paper), bad exhaust valve seal is likely. If coming past throttle, bad intake valve. If flowing out of oil fill stick, new getting past rings. If you pour a bit of oil down the spark plug hole and it minimizes the flow, that verifies flowing past the rings. Easier to distribute the oil over the rings in a Chevy/Ford six with vertical pistons. With V-8 on a stand, rotate so cylinder under test is vertical. Slight leak past the ring gaps is normal. With some racing camshafts, you may measure >200 psig compression, and can depend on how fast the engine is turning, due to air-pressure dynamics. Prop throttle open when testing so no pressure drop there. If you ever need to change the little Schrader valve in the tip of the compression gage, don't use a normal bicycle/car one. Needs to have a very weak spring, a special type usually with a white plastic collar.
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I meant with the valves hitting the pistons
If a hydraulic, you have that squish in the lifter plunger. May never touch as .050 plunger squish is theoretically .075 at valve. Plenty of clearance.
Ironracer
Gearhead
I've bent some in my 383. My Mopar racer bud Tommy told me to just roll them across a straight/ flat piece of concrete, tap em with a hammer where you need to, and then double check them on the mirror he said the glass should be nice and flat...
7e5hangten360
semi-pro
i could be wrong here, but look at reply #1 and the piston is so close to the deck. seems to be farther on reply #27 when the piston should be on tdc. could it be we have all been goofed by an incorrect crank damper ? something to think about.
PRH
Well-Known Member
Looks like the cam is retarded a few teeth.
That is minimal degrees of crank rotation from the top, if it isn't at TDC.
Found the problem. Timing chain was installed straight up matching both 0s as per directions. Installed properly i had to match the 0 on the top gear to the rectangle on the crank gear. Must be a factory defect.
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