40/80 cams on stock motor?

carl

carl

True Classic
I know this has been beaten to death but I want to ask one more time for my driving situation. My 1500 motor is totally stock inside. I have dual 40 IDFs and headers with a turbo muffler, those are the only modifications. My X is for local pleasure driving in a suburban environment and some really nice country roads near me. No competition or track days (those days are far behind me). I really like the way the motor runs with surprising low torque but still revs to redline. Being one to never leave well enough alone, I have two different 40/80 cams sitting on a shelf and wonder what advantages, if any installing one of these cams would provide for me.

I did have one if these cams that came in the white X I had and could not get it to idle unless ignition timing was set at about 30+ degrees at idle....never did figure that one out but was totally happy when I retrofitted a stock cam in that motor.

Looking for responses from people who have done this, not theoretical or anecdotal stories.
 
You have to degree in those cams, otherwise they will not work. Unless they are regrinds then I have no experience with those.

Guy Croft has a great write up on degreeing aftermarket cams. I did it a couple times and it is very satisfying.
 
Carl I seem to remember something about having to remove material, so the lobes don't make contact with the base, or something??
 
It is pretty common that long duration came require more advance at idle. That is why I needed to dramatically reduce the amount of centrifugal advance in my distributor. I'm running 20 degrees at idle.

As far as cam timing that is a separate issue. I'm running the default cam timing with the stock pulley. Seems to come very close to where the cam card says it should be.
 
I know you said no theoretical responses, but this is more personal preference than theory; for a street driven car, low end torque is much more important than top end HP. The cam you mention is pretty radical (again, opinion) and will destroy the already "surprising low torque" even worse. Especially with a low compression (stock engine) and big carbs. I would not want that. In addition, the poor idle (you will end up with a fairly high idle RPM that will be rough) and advanced ignition timing (high octane fuel only) issues it presents will also make driving it more difficult on the street. I like the race car 'look', but not the race car 'driving' for the road. A good analogy might be having a race car ride with incredibly stiff suspension/hard springs...sucks on the street. But then again, I drop my street cars ridiculously low just for the 'look', which also isn't practical. So it's a personal choice. But didn't you say you already made that choice on the white car?

All that being said, if you do install it then the compression should be raised, cam timing should be dialed in (as mentioned), the carbs' jetting should be adjusted, and the ignition timing should be advanced (as mentioned) in order to make it all work together.
 
Running lots of advance with non regrind 40/80 cams is masking the fact that the cams are not dialed in properly.
 
I started this post with the assumption I would NOT put a hot cam in but wanted reinforcement on this. Keep it coming. Maybe the answer is to build another motor with some HC pistons and hot cam, although the reasonable answer is probably a Euro spec motor.

As stated, I really like the characteristics of my motor, just looking for enhancements without changing the character. Entirely possible the perfect engine or me is already in the car. Thinking of getting it on the dyno just for curiosity and baseline to anything else I do to it.
 
I have 40/80 regrind of a euro camshaft. Raised compression by shaving the head. I played with it a tooth either way and it is noticeable where the power band is and where I need it for street driving. A tooth retarded allows better idle and bottom end. A tooth advanced the bottom suffers but the high end between 3200 rpm and 7,000 rpm pulls crisply and first gear becomes very short as the engine rev's up quickly. More compression is needed for this to work correctly along with a way to move the flowing gas out the tail pipe. If you have the time experiment with it, you can always change the cam back again if it becomes to much of hassle to drive the car.

TonyK.

Grimsby Ontario Canada.
 
carl said:
just looking for enhancements without changing the character
Click to expand...
That was the principle drive for me to try a mild turbo on the SOHC. I did not want to build a high performance naturally aspirated SOHC for the very reasons being discussed here. And I did not want to do an engine swap at that time (although my opinion on that may be changing if I ever do another one). Basically I wanted to improve torque, general drivability, help overcome the drag of the AC compressor, and make it a bit more fun without dramatically changing the character. In other words more engine, but still very usable. With low boost on a basically stock SOHC it should have all of this....we'll see (if I ever get it finished).

As I alluded to a second ago, if I really want a "high performance" X1/9, then it will be with another (non Fiat) engine/trans.
 
If you don't want to change the character of the engine, look elsewhere.
Cam choice is THE biggest factor in engine character.
Raising CR and leaving the cam alone is what would make everything better and not change the charcter.

Raised CR AND a euro or 35/75 cam would be my recommendation.
For making the most of what you have, running the 40/80 in combination with a .060" head shave is what I would recommend.
 
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