Camshaft out 180 degrees ?? - Page 2 - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep CJ Forum > Camshaft out 180 degrees ??

Smittybilt Hard Tops @ Oconee Off-Road! 706-534-9955XHD Heavy-Duty Hood Latches for JK and TJ available at OcoFS: Jeep Fog Light LED Bulbs! Several Brightness Options!

Reply
Unread 11-30-2011, 04:55 PM   #16
gosupes
Registered User
1986 CJ7 
 
Join Date: Jun 2004
Location: Monroe, WA
Posts: 1,530
Quote:
Originally Posted by Foundrydude View Post
Actually I think the OP has the wrong expectation of a 4 liter's off-idle torque production
It's not even that. It's a 232 (~3.8L) with 33" tires and 273 gears. Changing the gear ratio will do wonders. Probably over-carb'd too. Agree with you point about timing. 30*??? Wow. You can almost hear the ping from here.

__________________
1986 CJ7, 4.2 w/4.0 head, TFI-HEI hybrid ignition, Clifford manifold w/Holley 390 w/cold air intake, OBA, 4.5" lift, Woody CV shaft and Tattons in front, 4.10 gears - lunchbox in front, Truetrac in the back, twin-sticked, blower upgrade for running topless, trying to keep it simple.

It's just a Jeep, and if you don't wheel it once in a while, it's not even that.
gosupes is offline   Reply With Quote
Unread 11-30-2011, 05:54 PM   #17
bruteboy
Registered User
 
Join Date: May 2010
Location: british columbia ca
Posts: 476
Quote:
Originally Posted by gosupes View Post
Doesn't matter. Rotate the crank 360* and the cam will rotate 180*. The only way that things can go south is if there is multiple key slots on the crank gear and/or multiple pin index's on the cam gear and you don't pay attention to the drawings in the manual when installing the gears. If there is only one slot on the crank gear and one pin index on the cam gear, and you set the dots per the manual (lets say 12 for the crank and 6 for the cam) and count the links, you're basically set. Rotate the crank 360* and now the dots are at 12 and 12, or the cam would seem 180* out. I think the issue is people are getting confused with the cam gear or crank gear being indexed incorrectly. If the cam gear was installed 180* out on the cam, when the marks were lined up it would look to be 180* out. .
again I agree,I added the distinction between CAMSHAFT degrees and CRANKSHAFT degrees because in another thread on the same topic,some people were confused between the two.
if somone were to install the gears with the cam gear dot at 6 or 12 o'clock AND the crankshaft dot at 6 o'clock,the cam would be 180 crankshaft deg out which would equal 90 camshaft degrees.
bruteboy is offline   Reply With Quote
Unread 11-30-2011, 07:00 PM   #18
chooster5000
Registered User
1981 CJ7 
 
Join Date: Jan 2011
Location: scotland, ct
Posts: 372
Ok i appreciate all the info from everybody. Here are my specs on the jeep to clear up any thng at all. The jeep has a 75 amc 232 with a 4 barrel holly carb, a pacesetter hedder, it has the t176 tranny, stock 2.73 gears and right now has 235 75 15 tires on it. Ok so while we were doing the timing chain we did notice that the cam was timed to the exhaust stroke which makes it 180 out ? I think. Now my dads best friend was a amc mechanic back in the 70's and he himself knows so much more then i do, now im probably not being very clear on the info that i have posted or saying something and meaning a diiferent thing, sorry for any confusion. My dads friend says he has seen a 350 chevy run 180 out and yes it did run not great but ran, same as my jeep it ran wasnt great but i did get from a to b. Now for the timing yes i dont think i can hear it ping and me being inexpirenced might not notice it, but dads friend remembers running all the amc engines way advance until just beford they ping because thats where they liked to run. Now that its advaced way up i should run mid grade gas to prevent it from pinging, now also i just did the team rush upgrade and need to check the timing because every now and then it will cough or pop when trying to lug it. Now i will not say that anyone is wrong or affend people, but my dad has been around this guy for 35 years and he knows what he is talking about. Thanks again to everyone
__________________
1981 jeep cj-7 258 with t-176 4 speed and 31x10.5x15 tires,
1979 jeep cj-5 gone but not forgotten
chooster5000 is offline   Reply With Quote
Unread 11-30-2011, 09:10 PM   #19
gosupes
Registered User
1986 CJ7 
 
Join Date: Jun 2004
Location: Monroe, WA
Posts: 1,530
If you are running 30* in the timing, you are pinging and you are going to eat a piston. If you are 30* and not pinging, I'm thinking you harmonic balancer has shifted and not indicating correctly. Mine pings around 11 or 12, I normally run around 8* on the timing. You are probably over carb'd with the Holley if that is really a 232. The 81 Jeeps should have a 258 stock. Your sig says 33" tires but you actually have 235/75's which are closer to 29" which helps in your case. Honestly, your biggest problem is the gearing. I don't know if I have anyone ever say they like the way their Jeep performs with 2.73's. Do the normal stuff, get a better carb, check for vac leaks and make sure you don't have malfunctioning emission components. Make sure you don't have any blockage in the exhaust stream, like a broken up and melted cat from running too rich. And don't let it ping, bad things will happen.
__________________
1986 CJ7, 4.2 w/4.0 head, TFI-HEI hybrid ignition, Clifford manifold w/Holley 390 w/cold air intake, OBA, 4.5" lift, Woody CV shaft and Tattons in front, 4.10 gears - lunchbox in front, Truetrac in the back, twin-sticked, blower upgrade for running topless, trying to keep it simple.

It's just a Jeep, and if you don't wheel it once in a while, it's not even that.
gosupes is offline   Reply With Quote
Unread 11-30-2011, 09:24 PM   #20
Foundrydude
Registered User
1995 ZJ 
 
Join Date: Jan 2011
Location: Flatsville, IA
Posts: 2,692
If your dad's friend claims he's seen a chevy run with the distributor 180 out he's flat out wrong. I've installed distributors 180 out a dozen times (doh!) and straightened out 12 more for buddies........and all they do is belch and sputter and act like they're about to run. Having one run good enough to drive, never gonna happen.

Good luck sorting out your tuning issues, and good luck with the jeep. Happy trails!
Foundrydude is offline   Reply With Quote
Unread 11-30-2011, 09:35 PM   #21
Pacfanweb
Go Wolfpack
 
Pacfanweb's Avatar
1981 CJ7 
 
Join Date: Jan 2005
Location: Wake Forest, NC
Posts: 2,551
No such thing as a cam that's 180 degrees off. Both marks facing each other and both marks up, it is the same thing.

Put it in with both marks facing each other and rotate the crank 1 time and then both marks will be up.
:
is the same as
.
.

Sent from my DROID3 using JeepForum
__________________
I asked a ref if he could give me a technical foul for thinking bad things about him. He said, of course not. I said, well, I think you stink. And he gave me a technical. You can't trust em. -
Jimmy V
Pacfanweb is offline   Reply With Quote
Unread 12-01-2011, 06:46 AM   #22
JeepHammer
Running On Empty...
1973 CJ5 
 
Join Date: Aug 2007
Location: South West Indiana
Posts: 10,154
Quote:
Originally Posted by Pacfanweb View Post
No such thing as a cam that's 180 degrees off. Both marks facing each other and both marks up, it is the same thing.

Put it in with both marks facing each other and rotate the crank 1 time and then both marks will be up.
:
is the same as
.
.

Sent from my DROID3 using JeepForum
Probably not, when the piston is at TDC, and the cam sprocket mark is up, I think you will find once the chain is on, you are one tooth off one direction or the other when you rotate the crank and come back to TDC...

I can't swear EVERY engine is like that since I don't have every engine broken down in front of me, but it's certainly true with AMC V-8 engines.
Quirk in the tooth count and chain count... The ONLY time you come directly back to TDC and center line of the camshaft is when the marks face each other in the beginning.
JeepHammer is offline   Reply With Quote
Unread 12-01-2011, 07:14 AM   #23
Pacfanweb
Go Wolfpack
 
Pacfanweb's Avatar
1981 CJ7 
 
Join Date: Jan 2005
Location: Wake Forest, NC
Posts: 2,551
Quote:
Originally Posted by JeepHammer

Probably not, when the piston is at TDC, and the cam sprocket mark is up, I think you will find once the chain is on, you are one tooth off one direction or the other when you rotate the crank and come back to TDC...

I can't swear EVERY engine is like that since I don't have every engine broken down in front of me, but it's certainly true with AMC V-8 engines.
Quirk in the tooth count and chain count... The ONLY time you come directly back to TDC and center line of the camshaft is when the marks face each other in the beginning.
I remember the manual on one engine years ago that actually specified the install to be with both marks up. Might have been Pontiac.

Sent from my DROID3 using JeepForum
__________________
I asked a ref if he could give me a technical foul for thinking bad things about him. He said, of course not. I said, well, I think you stink. And he gave me a technical. You can't trust em. -
Jimmy V
Pacfanweb is offline   Reply With Quote
Unread 12-01-2011, 08:51 AM   #24
Foundrydude
Registered User
1995 ZJ 
 
Join Date: Jan 2011
Location: Flatsville, IA
Posts: 2,692
If marks align at the bottom then they also align at the top. It's a mathematic thing.

If they don't align at both points it means you're not 2:1 ratio. It would signify more like a 1.95:1 or 2.05:1 ratio which would make the cam out of phase with the crank after several revolutions.

The geometry of the engine may create an optical illusion where what appears to be the "top" is actually a few degrees to one side. But if you lay a straight edge on the crank and cam it will always allow the timing marks to align in the top and bottom position.

With some engines, the brand of the timing set determines if top/top or top/bottom is true TDC
Foundrydude is offline   Reply With Quote
Unread 12-01-2011, 09:10 AM   #25
halpeters
Registered User
1978 CJ7 
 
Join Date: Apr 2008
Location: Central Florida
Posts: 255
On all piston "4 stroke" engines, the cam turns at "half speed" of the crank. For every 2 rotations of the crank, the cam makes 1 rotation.

The tooth count of the gears, or chain, or belt makes no difference, it is the relative circumference of the drive gear on the crank and the cam gear. The ratio of circumference is 2 to 1.

If the cam wasn't 180 degrees different at one rotation of the crank, then the cam wouldn't be 360 degrees (one full rotation) at two rotations of the crank....

One note on tooth count, one sprocket will have an even number of teeth, and the other will have an odd number of teeth. This makes the chain or gear "walk" through all the teeth on the cam.

The number of teeth on the crank will be an odd number, and the number on the cam will be double that.

Quote:
Originally Posted by JeepHammer View Post
Probably not, when the piston is at TDC, and the cam sprocket mark is up, I think you will find once the chain is on, you are one tooth off one direction or the other when you rotate the crank and come back to TDC...

I can't swear EVERY engine is like that since I don't have every engine broken down in front of me, but it's certainly true with AMC V-8 engines.
Quirk in the tooth count and chain count... The ONLY time you come directly back to TDC and center line of the camshaft is when the marks face each other in the beginning.
__________________
1978 CJ-7
halpeters is offline   Reply With Quote
Unread 12-01-2011, 01:19 PM   #26
JeepHammer
Running On Empty...
1973 CJ5 
 
Join Date: Aug 2007
Location: South West Indiana
Posts: 10,154
Like 13 teeth on a distributor gear?
When you get the distributor gear on backwards, you are half a tooth off...

I don't know how to explain it without math, and every time I post math, people flee the thread.
JeepHammer is offline   Reply With Quote
Unread 12-01-2011, 02:03 PM   #27
Foundrydude
Registered User
1995 ZJ 
 
Join Date: Jan 2011
Location: Flatsville, IA
Posts: 2,692
Quote:
Originally Posted by JeepHammer View Post
Like 13 teeth on a distributor gear?
When you get the distributor gear on backwards, you are half a tooth off...

I don't know how to explain it without math, and every time I post math, people flee the thread.
if there's 13 on the distributor gear then there's 13 on the camshaft drive gear too. Because 13:13 is still a 1:1 relationship. Camshaft and distributor are 1:1 drive.

The only way a distributor is a tooth off is when the vacuum advance can begins to interfere with the firewall, valve cover, etc as you try to time it. As long as you can time it, it's on the right tooth. So saying an upside down gear makes it a half tooth off is a misleading statement.

Actually you can install a distributor at any position and then compensate by moving the plug wires around til they reflect the TDC position of the distributor. Have seen it many times. It's a hack way to do it but the engine runs perfectly.

The math here is not complicated. It's 1:1 for cam:distributor and 2:1 for crank:cam. The drive ratio specifies the points of alignment. 2:1 means they align with top/bottom and top/top. What you believe with "top/bottom" and "top/mostly top" is impossible.

This thread remains on topic yet totally derailed.

This is so basic yet so misunderstood I'm suprised nobody has recommended 4.56 distributor gears for better low end performance.
Foundrydude is offline   Reply With Quote
Unread 12-01-2011, 02:34 PM   #28
rblank3362
Registered User
1981 CJ5 
 
Join Date: Apr 2010
Location: sacramento
Posts: 3
you have to degree the cam with a degree wheel more then likely the crank shaft, timing gear set and the cam are made from different manufacturers. That's why on most timing set has 3 positions. The only way to know if the cam is set right is with a degree wheel.
rblank3362 is offline   Reply With Quote
Unread 12-01-2011, 03:13 PM   #29
CSP
Registered User
 
Join Date: Aug 2002
Location: Colorado
Posts: 12,296
Quote:
Originally Posted by Foundrydude View Post
This is so basic yet so misunderstood I'm suprised nobody has recommended 4.56 distributor gears for better low end performance.
No kidding. It may have been mentioned, but I haven't seen it, but it's the cam that determines which stroke the crankshaft is on. The crank doesn't know if #1 TDC is on the compression stroke or the exhaust stroke until you install the camshaft. That's why it's impossible for the cam to be 180 out.
CSP is offline   Reply With Quote
Unread 12-01-2011, 03:51 PM   #30
rblank3362
Registered User
1981 CJ5 
 
Join Date: Apr 2010
Location: sacramento
Posts: 3
I had a cam 4 degree out when you line up the marks, most timing gear sets are 2 degree adjustable, had to get a 4 degree adjustable timing set from summit racing. A cam cant be 180 degree out, rotate the crank 2 turns and the marks will line up from tdc. when you buy a new cam you get a cam card so you can set up the timing set properly. The only time you can be 180 out is with dual cams.
rblank3362 is offline   Reply With Quote
Reply
Thread Tools


Suggested Threads





Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.