alfetta stock cam timing. slight boost? - Alfa Romeo Bulletin Board & Forums
 
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post #1 of 6 (permalink) Old 12-03-2010, 09:43 AM Thread Starter
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alfetta stock cam timing. slight boost?

I have a 1978 Alfetta GT. California street car, 2.0 liter, SPICA, stock.

The Bible book hints that one of many simple ways of mildly (mildly) increasing power is stock cam timing adjustment. The book indicates a change of +5 and -5 degrees (1.5 degree per notch), respectively, for intake and exhaust. I've also seen a Joe Benson recommedndation of +5 and -1.

Opinions welcome on what adjustment is best .... if any at all(?). (I don't want to waste my time but if I can get a handful of horsepower here, a few there, thru various adjustments, addition of inexpensive mod's, etc, would be great.)

Also, if stock cam adjustment gain is utterly nominal, at best, will 1750 cam's do much more for me (and making smog passage doable)? I've read in other posts that 1750 cams and euro cams both still allow for smog passage ... if the rest of the system is set up properly. Thanks

Chris in Arcata, CA
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post #2 of 6 (permalink) Old 01-12-2011, 04:39 PM
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I just retimed my cams, and set them to 102/102. You need to figure out what is stock for your year, then adjust to get close to 102/102, a good compromise for all around drivability.

Lots of opinions on cam timing, search around a bit and I'm sure you'll find a lot of different opinions.
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post #3 of 6 (permalink) Old 01-12-2011, 04:58 PM
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77-79 cars had lobe centers of 102/102. I agree with archeologist that they are about optimum.

Ed Prytherch
79 Spider
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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post #4 of 6 (permalink) Old 02-05-2011, 03:26 PM Thread Starter
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Originally Posted by archeologist View Post
I just retimed my cams, and set them to 102/102. You need to figure out what is stock for your year, then adjust to get close to 102/102, a good compromise for all around drivability.

Lots of opinions on cam timing, search around a bit and I'm sure you'll find a lot of different opinions.
OK. What was your cam timing before you retimed? The reason I ask is because the Bible suggested simply retiming vs installing euro cams. Not sure if anything makes a difference for a CA car (smog) but I'm trying.

Too, I've only had 2 response to this question and I have looked around.
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post #5 of 6 (permalink) Old 02-05-2011, 05:14 PM
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Go to smaller numbers for lobe centers if you want more top end at the expense of low-mid range torque. I spent a good amount of time experimenting with lobe centers on the racing cams in my Spider. I was surprised what a difference a couple of degrees makes. I started at 102/104, then 100/102 and finally 104/104. Each combo had a noticeable effect on performance. We should be thankfull that our Alfa engines make it easy to experiment. I think that it is a lot ot of fun to make small adjustments and observe the effect on performance. I did a similar exercise with ignition advance curves and timing. It would be more scientific but less fun if I had a dyno.

Ed Prytherch
79 Spider
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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post #6 of 6 (permalink) Old 02-06-2011, 11:52 PM
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Chris, mine were way off, probably 98/98. It ran, but had major flat spots.

I know the PO and he told me how he timed it. He did it properly, but didn't realize that someone had swapped the cam caps, so the reference points were way off.

I would buy a whole bunch of lock tabs and do some experimenting. Moving one hole is relatively easy, and you'll get a swap down to an hour easy with practice.

You have to decide if you want low end torque, or high end power. But stock cams will only do so much for high end before you need something hotter.
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