I got my engine running for the first time since buying the car (1966 273 formula S) and there was a loud tapping noise coming from what sounds like the right side toward the rear. I added a few ounces of marvel mystery oil and ran it for a bit and I pulled the plugs one by one to see if I could narrow down the cause. I then pulled off the valve covers to check for obvious visual damage and to check the valve clearances. They were all too tight except for #5 intake which was too loose. I also noticed a huge amount of sideplay and observed that there were no shims or spacers which is odd to me coming from a background working on metric bikes and Harleys which all call for pretty tight clearences. What kind of side play should I be looking at? Thanks in advance for your help!
Chasing down a tapping noise
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kiss
Well-Known Member
Does it tap under load? or all the time? Tapping can often be an exhaust leak.
I'll find out tomorrow. I haven't driven it yet. I just finished bleeding the brakes (which still have more travel than I'd like but I dont know what a normal amount is) I also just installed the street demon and havent had a chance to tune it yet. The battery is also only reading about 12.18V so I dont want drive it until I've put in the new alternator
BlueDream
Aspiring Mopar enthusiast
With a lot of side play on the rockers I'd check for pushrods hitting the head.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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I put a set of those on a 318 and another on a 340, and they were baggy too, kindof like yours. They kindof have to be so the valve stems don't wear ruts in 'em.
Check the compression on that side and compare them. When an old engine sits for a long time the valves tend to stick in the guides. Then when you start it up the piston might whack it, and that makes an unforgetable sound. Of course that immediately bends the valve and the compression is gone.
Check the compression on that side and compare them. When an old engine sits for a long time the valves tend to stick in the guides. Then when you start it up the piston might whack it, and that makes an unforgetable sound. Of course that immediately bends the valve and the compression is gone.
Dartswinger70
Well-Known Member
is that a solid lifter engine? if so then you have to check the rocker arm lash with feeler gauges while hot to a specified clearance.
kiss
Well-Known Member
check for exhaust leaks
many ways to do this, search youtube
my choice way to even find small leaks is shove a hair dryer or shop vac (in reverse so it blows) into your exhaust pipe when engine is cold
feel around to see if there's any air coming out where manifold meets head or elsewhere. sometimes you can hear it hiss
while doing this you can also spray soapy water and check for bubbles
many ways to do this, search youtube
my choice way to even find small leaks is shove a hair dryer or shop vac (in reverse so it blows) into your exhaust pipe when engine is cold
feel around to see if there's any air coming out where manifold meets head or elsewhere. sometimes you can hear it hiss
while doing this you can also spray soapy water and check for bubbles
Yeah that was one of the first things I did. All the clearances were too small except for #5 intake which was way loose which makes me wonder if I may have a wrecked lifter and or cam face. Going to check compression as suggested and if thats normal I'll do the exhaust leak check and then pull the intake and inspect the cam lifters
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AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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I think I hear just rocker arms , but it kindof sounds normal for a 273 with adjustables.
Ok! I checked for exhaust leaks and I found one underneath the drivers seat where the header bolts to the rest of the pipe and another leak at #4 (not where I thought tge noise was coming from).
I also inspected the push rods more closely and found #3 intake practically touching the head. I spun the rod and found it about 1.5mm out of round. A few others were a little bent too. So since it looks like a few rods need replacing I'm going to have a look at the cam and lifters.
diymirage
HP@idle > hondaHP@redline
i would take that one pushrod, and move it to the other bank
if the racket moves along, youve found the problem
OK. So I removed the intake for some piece of mind. I only have 2-3 bent push rods. There is some cam wear and some lost material on the cam's surface on a couple of lobes but the lifters look like they're new so it's possible they've been replaced. Pushrod length seems like it might be a little on the long side. I put a marker on the valve stem's surface and rotated the engine and it seems it's slightly on the lower half which indicates I could possibly use a smaller rod. The rods installed are 7.5" perhaps 7.342 would be better?
What do you think gentlemen? I'm leaning towards replacing the bent rods and then running it until it breaks since new cams, lifters, and pushrods could cost as much as a 318 or 360 swap.
What do you think gentlemen? I'm leaning towards replacing the bent rods and then running it until it breaks since new cams, lifters, and pushrods could cost as much as a 318 or 360 swap.
nm9stheham
Well-Known Member
From what I can see of the pix, the cam wear looks normal, but the pix aren't really close up. Examine the peaks of the lobes and look for any indication of a flat spots or flat spots across the lobe surface; if you see any of those (like Fred Flintstone shaped it with his stone hammer LOL), then the lobe is going.
Put in the pushrods and then start it and look to see if all the pushrods are rotating; that is a good sign.
Changing pushrods is not going to change the contact point of the rocker on the valve tip one iota. Only moving relative positions of the the valve tips and the rocker shafts' centerlines will change that.
Put in the pushrods and then start it and look to see if all the pushrods are rotating; that is a good sign.
Changing pushrods is not going to change the contact point of the rocker on the valve tip one iota. Only moving relative positions of the the valve tips and the rocker shafts' centerlines will change that.
I'd replace those bent push rods and drive the hell out of it!
It will probably last a lot long than you'd think.....
Mopars make a little noise...I'd blame most of it on that nasty exhaust. ...
Jeff
nm9stheham
Well-Known Member
The bottom one looks normal; can't tell on the upper one. If it is smooth curved surface, OK, but the lighting is making it hard to tell if there are any breaks in the surface smoothness.
the upper tip of each lobe has a little chunk broken off but again, doesn't seem to have caused any wear marks on the lifters
nm9stheham
Well-Known Member
Yeah, that is normally negligible. It is the smooth curvature over the top of the lobe that indicates normal wear. It almost looks like there is a 'break' in that smooth curvature on the righthand edge of the top lobe where there is a bright line in the pix; but again, I'd have to run my finger over it or rotate it a bit to be sure. If that is a 'break' in the curvature, then that is the beginning of the end of that lobe.
MOPAROFFICIAL
Oogliboogli
Change the cam, now, not later.
When I was working for harley and bmw if a customer's bike had cams like that we'd tell them to replace it but on my own bike it was a different story. I'd ride it till it breaks because you know it's dependable and is gonna last a few thousand more than you think.
It's almost not worth it. If I replace the cam then I'm also looking at new lifters, possibly, new rods.... that's $350-450 right there. I can get a used 318 or 360 for a little more money.
MOPAROFFICIAL
Oogliboogli
That will be in the same condition as this one? My point made. Cam and kifter kit is under 300 bucks and you don't need new push rods. Do what you like, It's just advice.
racerhog
RacerHog likes his Mopars
My 2 cents..If the Compression is good.. Fix the exhaust leaks with new gaskets.... Put some push rods in it.... A can of STP and some good Castrol 30W engine oil and run it while you put the part together for an engine swap.
Just my 2 cents.
Just my 2 cents.
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