Where to degree your cam??

[273]

I was reading an article and they where saying instead of just degreeing your cam to the remended. Instead find where it makes the most cranking PSI does anyone see fault in this logic.

 

[Mo-Par]

On a low compression engine it makes some sense.
Changing the event timing will also change the rpm range.

 

[skrews]

Its all in the combination (engine and chassis). Small displacement, low comp, over cammed, ect.... more advance will help.

 

[txstang84]

The only time that would be faulty logic is if the higher cranking pressure leads to detonation through increased dynamic compression...but that is only one part of the equation.

EDIT: beat me to it...

 

[OldmanRick]

Makes sense to me...to a point. No doubt would help with low rpm cylinder pressure/efficiency. I do have a question as to where the tipping point would be vs overall performance? Don't forget piston to valve clearance could come into play also.


P.S. My overall thoughts on this are, if you have a cam that's ground dead on, and you have to stray more then 4* either way from the recommended installed centerline to get what you need.........you need to "re cam" at some point. Although I realize there can be exceptions.

 

[william]

It works , I went from 166 to 178 cranking compression and it ran alot stronger. You may have to advance or retard the cam timming and alway check for valve clearance before making any changes.

 

[273]

I guess by what the article said is this is the best way for those with out setting it up on a dyno

 

[RustyRatRod]

I have always used a compression gauge in conjunction with the degree wheel. IF you make a good cam choice with the combination, you can advance the cam timing until the cranking pressure drops off and then back up to where it was highest.

However, if the camshaft choice is "too big" or has too late an intake valve closing event, it will usually not fall off within a reasonable amount of advance. I don't like to go anymore than 6*. Most cams are ground with 4* advance so that would be 10* total. It's all a personal preference. If you're going to race, it's probably best to install it where the cam card says. Advancing it further will cause the top end to drop off. But for a street car, that extra advance might be beneficial Just my 2 cents.

 

[273]

I like what you said there rustyratrod cause you could tell if your running the wrong cam also

 

[AJ/FormS]

I have a 10.7CR 366 with a 230* cam.! tried it straight up, 4*retarded, 4* adv. On the street I couldnt tell much difference. Seemed like a lot of work for very little gain.I left it in straight up........ Im also interested in turboing a 273, so will be following your project. Im more interested in the fuel economy end of it. Iv tuned those stock 273s for very good economy. But having tasted 400+hp, I know how unhappy I would be with the output of that motor, stock. Best of luck with your project.

 

[fishmens67]

Its all in the combination (engine and chassis). Small displacement, low comp, over cammed, ect.... more advance will help.

it's allways in the combo. there is no need to guess on cam choices or timing events for certain engine combo. too many guys are trying to overthink and undermind an engine build. too damm easy to get it right now days.