273 cam & crank timing marks, confussed

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challenger57

cuda57
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I'm confussed about the timing mark alignment dots when installing a new cam. Should they be crank dot at 12 and cam dot at 6 or both at 12. Iam currently at 12 and 12 with # 1at TDC. The car runs but has no botttm power. If it should be 12 and 6 shouldn't I just be able to rotate the crank 360 and reinstall dist. at #1? Thanks for any help Mark
 
Sorry for the bad news - but the crank is supposed to be 12 and the cam at 6. Someone smarter than me, will have to answer your second question. My feeling is that changing the dist position won't fix the problem. You need to re-time the cam, unless I am wrong..
 
With the cam at 6 and the crank at 12 the engine will be at #6 firing not #1. There is nothing to change. The way you have it now (12 & 12) is the same as (6 & 12) the only difference is there is one crank (360 degrees)revolution difference.

If you rotate the crank 360 degrees and re-install the distributor the motor will not start because the distributor will be 180 degrees off. You can't force a firing order just by changing the distributor location. The firing order is a product of the camshaft arrangement.


The 273 is not known for very much bottom end power, especially if it has a large cam. Advancing the cam 2 or 4 degrees may give you some more bottom end power. You should check the cam with a degree wheel to see were it is now.


Chuck
 
Sorry to say if it were me I'd tear it all apart and put it together with the cam and crank in their respective positions with the cam at 6 and the crank at 12 and put the distributor in its stock state so you just might pick up some bottom end.
 
The timing marks should be at 12 and 12 to have #1 cylinder at tdc. You do not need to tear it down? You have it right. Now if you were building a chevy motor it's 12 and 6 for #1 at tdc. I think that's where all the confusion comes from.
 
Crank sprocket is EXACTLY half the size of the cam sprocket in ALL 4 cycle engines. Every other revolution of the crank the cam "dot" will be at 6 o'clock position with the crank "dot" at 12 o'clock. The pistons don't know if they are at TDC on the compression or exhaust stroke. The distributor position is relative to the cam shaft only.

Ever wonder why you can set your timing off #6 cylinder the same as #1?
 
if it runs but with no power you may be one tooth off on the cam install thats why it is best to degree the cam when it is installed the guys are right 12 and 12 or 12 and 6 will put
#1 and #6 both atTDC on both mopar and gm motors
 
Go with the 12 and 12 method and make sure when you install the oil pump driveshaft and distributor gear is pointing toward the #1 cylinder. So when you install the distributor you will be good to go. The gear will spin some when it finally seats so you have to compensate for that.

Good luck on the 273 but I have tried everything to get some low end out of it and I have did nothing but wasted time and money. Mine is bored .060 also. It takes nothing to over cam the motor also...been there done that. A .441 lift or .420 is about as far as you can go with the 273.....anything larger than that you can say good bye to low end torque.
 
Finally some straight non confussing answers with the 12 and 12 method which is what I thought was correct. Thanks guys. Now for the 273, I think it is history by way of a 360 I have if i could only identify the cam #940162. I remember it put out alot of fumes when it was in my former challenger, so I suspect it has a good bit of duration to it. Thanks for any info
 
63dartman said:
The timing marks should be at 12 and 12 to have #1 cylinder at tdc. You do not need to tear it down? You have it right. Now if you were building a chevy motor it's 12 and 6 for #1 at tdc. I think that's where all the confusion comes from.
Click to expand...

huh? a chevy has the exact same firing order bigblock and smallblock that a smallblock mopar has. even the same distributor rotation.

just put it at 12 o'clock on the cam and 6 o'clock at the crank and you will be set. use a straight edge to make sure you're not 1 tooth off.
 
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