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Small block chevy cam?

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Old 11 Jan 2013, 02:41 am
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Default Small block chevy cam?

350 stock internals rebuilt with ported 305 vortec heads and about 10:1 compression. I am thinking about running a cheap solid flat tappet circle track cam (cam and lifters are $120), i only have about $500 spent on this motor and this is last part i need. Unfortunately these cams are all pretty radical long duration,i feel the torque will suffer too much, i would like an opinion though. The cam i am looking at is 105lsa 256@.50 290 advertized.
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Old 11 Jan 2013, 03:03 am
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If you can stand the idle at 1500 rpms and you are not pulling fallen logs through the woods, it should not be a big deal.
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Old 11 Jan 2013, 03:25 am
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I would say an Edelbrock Performer cam. Your proposed cam would be good for a hot rod but you have a stock engine so stay with a mild cam. My opinion.
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Old 11 Jan 2013, 03:42 am
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Here are several issues: First, that cam is much too big and the LSA is too tight. Especially in the world of 2BBL carbs with headers.(if you are using a 4412 Holley 2 bbl, more than likely, the engien will NOT like a 50CC accelerator pump) It is also shy at .050 in light of the 290 advertised. It's a lazy ramp cam. It will be VERY explosive with your power band which will make it horrible when the track goes dry slick and it will be a PIG off the corners on a tacky track... Unless you can keep it wound up in excess of 4500. A car/cam relationship gets really good if you can cam/gear the car to come off the corners at peak torque RPM or slightly above.

You need to scale that cam back with duration a LOT. Especially if it has stock exhaust manifolds and/or a 2 BBL carb. Also, consider a 108 LSA when you scalle the duration back. You will have MUCH more useable torque and a MUCH better runner on the bottom and on the top end.

Get away from $120 shelf grind cams because they are either 40+ year old designs, or they are a copy of a cam that was likely another copy. Cams do not copy. When you copy, they blow up the advertised durationa and the durations shrink at .050 and even worse at .200.

Tell me a little about your vehicle set up, weight, carb choice, and wether Automatic or manual trans. I'll set you up on cam. We have MANY world records in Oval Track and many of our customers run with cars a class above them. For example: We have had many who have been competitive in a 400 cubic inch field with more than a 50 cubic inch handicap, and legal weight. (Many also winners who are cubic inch and car legal, but 500 lbs heavier than anyone in their class.)

The stock heads are not going to like anything greater than about 520 NET lift at the valve because they flow less at 550 lift than they do at 520. Vortec heads can keep going. Be conservative on lift when in doubt. It's not all about lift. Do NOT run 1.6 ratio rockers... esp on the exhaust side.

Your head choice is bad. It will net you some static compression but it will kill your dynamic compression becaues the head flows less air with the small chamber design (designed for a small bore 305, not a 4 inch bore 350) and the small valves. If you have to run stock heads, and if they will not allow you to run a true 350 Vortec head, then run a set of 441 castings.

You need to get your piston to head squish clearance set around .025... This includes head gasket thickness. At the very least, run a Fel Pro 1094 head gasket until you can deck your block.

I can also show you about 25HP simply from a fuel change, meaning what fuel ou use. (And it is NOT at all about octane, either.)

Email me.
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Old 11 Jan 2013, 03:50 am
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try around 800 rpms,,,thats about what it should idle at ,,,,
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