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Old 10-09-2012, 09:24 PM
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Need help choosing a cam. SBC 350

Hello all. I am looking to make some upgrades to cam/lifters/springs in my 350 sbc. The engine is currently in my 66 impala 2 door hardtop. It has a 700r4 trans and 3.08 rear axle ratio (I have a 3.73 ring+pinion that i am planning on installing ). The engine is mainly stock, RPM airgap intake, long tube headers, and 600 edelbrock performer. The car is only street driven, and my daily driver in the summer months as its not suitable for the cold months here in Canada. What Im looking to do is get some more horsepower without spending a ton of money on bottom end or new heads. I would like to change the cam to get some more lift and duration and of course put in the appropriate lifters/ springs. Any opinions are appreciated. thanks.

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Old 10-09-2012, 10:02 PM
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Depending on tire size those 373's are going to make first gear almost useless with your 700r4. Big car means big wheel well, fill them with a 275 to tame the gear a bit. As you already have your intake, vortec heads won't really be cost effective, so find some 416 castings, then read everything F-bird88 has to say about them, you will hear tons of negative on the subject, ignore it, do what he says for a very effective, very budget conscious power increase, the lunati barebones 10120101lk is cheap at 135$ with lifters. Make sure you run long tubes and a decent exhaust. A small converter and a good shift kit will make it all just that much more fun. It will make your buddies think you have lots more motor then you actually do, it will still be an excellent and reliable cruiser, get decent mileage for a tiny motor in a huge car, and have enough snot to make you feel like a hero when you want to.....and yes, it will absolutely tear the tires off when you want it too.......
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Old 10-09-2012, 10:08 PM
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And I would flip the edelbrock and find a 650vs Holley, a really good qjet, or if your mre concerned about going fast even a 750 Holley.
P.s, 66 Impala is one of the sexiest cars ever built......
P.s.s, I know u said "no heads" but at under 500$ out the door with your own sweat equity its a hugely gratifying experience.....ask me how I know....
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Old 10-09-2012, 10:31 PM
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Need help choosing a camshaft for a 350 SBC

This Summit Racing Camshaft and lifters is a good kit for your SBC 350. Summit Racing SUM-K1103 - Summit Racing® Cam and Lifter Kits - Overview - SummitRacing.com Add these suggested springs to complete the assembly. Summit Racing SUM-174001 - Summit Racing® Valve Spring and Retainer Kits - Overview - SummitRacing.com Do a search here on Hotrodders website for this camshaft. People say it is a great camshaft for the money.
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Old 10-09-2012, 11:17 PM
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Quote:
Originally Posted by grandslam1991 View Post
Hello all. I am looking to make some upgrades to cam/lifters/springs in my 350 sbc. The engine is currently in my 66 impala 2 door hardtop. It has a 700r4 trans and 3.08 rear axle ratio (I have a 3.73 ring+pinion that i am planning on installing ). The engine is mainly stock, RPM airgap intake, long tube headers, and 600 edelbrock performer. The car is only street driven, and my daily driver in the summer months as its not suitable for the cold months here in Canada. What Im looking to do is get some more horsepower without spending a ton of money on bottom end or new heads. I would like to change the cam to get some more lift and duration and of course put in the appropriate lifters/ springs. Any opinions are appreciated. thanks.
You cannot intelligently choose a camshaft for a motor until you know the static compression ratio. You might just as well write the candidates on little pieces of paper, tape them to the wall, stand back and throw a dart.
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Old 10-09-2012, 11:37 PM
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A small cam is not rocket science.I like cams with lower intake centrelines for stock compression engines.keep the duration short,220 or less and lift moderate.Yes ported heads work better.The heads you have would work better ported.dont expect huge gains in power just changing 1 item,,,
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Old 10-09-2012, 11:44 PM
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Quote:
Originally Posted by vinniekq2 View Post
A small cam is not rocket science.I like cams with lower intake centrelines for stock compression engines.keep the duration short,220 or less and lift moderate.Yes ported heads work better.The heads you have would work better ported.dont expect huge gains in power just changing 1 item,,,
You cannot intelligently choose a camshaft for a motor until you know the static compression ratio. You might just as well write the candidates on little pieces of paper, tape them to the wall, stand back and throw a dart.

From Crane Cams....
"Why is it necessary to know the Compression Ratio of an engine in order to choose the correct cam?
The compression ratio of the engine is one of three key factors in determining the engine's cylinder pressure. The other two are the duration of the camshaft (at .050" lifter rise) and the position of the cam in the engine (advanced or retarded). The result of how these three factors interact with one another is the amount of cylinder pressure the engine will generate. (This is usually expressed as the "cranking pressure" that can be measured with a gauge installed in the spark plug hole.)
It is important to be sure that the engine's compression ratio matches the recommended ratio for the cam you are selecting. Too little compression ratio (or too much duration) will cause the cylinder pressure to drop. This will lower the power output of the engine.
With too much compression ratio (or too little duration) the cylinder pressure will be too high, causing pre-ignition and detonation. This condition could severely damage engine components."
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Old 10-10-2012, 12:00 AM
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tech,I dont know why you posted that.If the cam is slightly more than he had and cr from 8.5 to 10 :1 a slightly bigger cam will improve the engines breathing.If his engine is 8:1 or 11:1 the cam will make a bigger difference and choice is more important.(The engine is mainly stock) was posted in OP,please tell me a slightly bigger grind that would make this engine perform worse?and
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Old 10-10-2012, 04:18 AM
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I reccomended the bare bones based on my head choice, he did say " stock bottom end" and its a 70's 350 so were fairly safe assuming small dish, 4 valve relief pistons. With a felpro 1094 gasket and a 60cc chamber (after de-shrouding) it gives you close to. 040 quench and a static of around 10.4 I believe.....or close to it.....
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Old 10-10-2012, 08:10 AM
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I did a compression test the other day, all cyclinders were in the range of 160-170 PSI, although not sure of the compression ratio. hope that helps ill try get compression ratio numbers.
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Old 10-10-2012, 09:54 AM
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You will need to do a search for a compression ratio calculator on google. FYI chevy 350 is 4.0 bore and 3.48 stroke stock.

Big car with gear and good intake/exhuast for low compression I would go with the edelbrock performer or the performer rpm if you find out you have high enough compression to run it.

Edelbrock could help you get the setup with the right stuff. Just give them a call.

You have got a massive amount of choices for cams. Edelbrock has shorten this down to a few good choices. Makes the selection easier.
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Old 10-10-2012, 10:03 AM
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Originally Posted by hcompton View Post
You will need to do a search for a compression ratio calculator on google. FYI chevy 350 is 4.0 bore and 3.48 stroke stock.

Big car with gear and good intake/exhuast for low compression I would go with the edelbrock performer or the performer rpm if you find out you have high enough compression to run it.

Edelbrock could help you get the setup with the right stuff. Just give them a call.

You have got a massive amount of choices for cams. Edelbrock has shorten this down to a few good choices. Makes the selection easier.

Or listen to people who have done it, built it, cruised it, raced it....as opposed to calling someone with a product to peddle.....that's the drawback to calling edelbrock, sure, you can buy a top end package, which is exactly what their going to reccomend, or you can mix and match, spend time and effort, not money, on something you did yourself with a little help from "real" people who understand budget and reality.....
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Old 10-10-2012, 10:36 AM
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Or listen to people who have done it, built it, cruised it, raced it....as opposed to calling someone with a product to peddle.....that's the drawback to calling edelbrock, sure, you can buy a top end package, which is exactly what their going to reccomend, or you can mix and match, spend time and effort, not money, on something you did yourself with a little help from "real" people who understand budget and reality.....

Sounds great for the soap box but its not to difficult to find a cam for a mostly stock 350 in a heavy car.

Really... cruised it, built it, raced it. You think you might have went a little far on that one....

When you get done researching all the stuff that guy said you will have a cam very close to the performer cam from edelbrock.

Top end kit is not really needed in this case its for street use only.

FYI: I called edelbrock a few years back for a cam i liked. they told me it would not work well. The guy i spoke with told me to call Lunati or comp. Glad they told me not to buy from them. Lobe center was way off and wasnt listed in the catalog.

grandslam1991:

Be sure to read up on cam break in proceedures these days they have changed and its very important to follow them 100%. If they say to do it then do it. You will be much happier no matter what cam you choose.
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Old 10-10-2012, 12:09 PM
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Quote:
Originally Posted by grandslam1991 View Post
I did a compression test the other day, all cyclinders were in the range of 160-170 PSI, although not sure of the compression ratio. hope that helps ill try get compression ratio numbers.
Crane Cams |
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Old 10-10-2012, 12:47 PM
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Quote:
Originally Posted by vinniekq2 View Post
tech,I dont know why you posted that.If the cam is slightly more than he had and cr from 8.5 to 10 :1 a slightly bigger cam will improve the engines breathing.If his engine is 8:1 or 11:1 the cam will make a bigger difference and choice is more important.(The engine is mainly stock) was posted in OP,please tell me a slightly bigger grind that would make this engine perform worse?and
OK Vinnie, let's work through this. Please see the link I posted in post #14 of this thread, in response to the OP's post #10. If his motor is maxed out now for cylinder pressure, then it is at the highest level of efficiency that it's going to be for pump gas. If going with more cam (which will extend the intake valve closing point), the piston will be further up the bore when the intake valve closes, thus pushing some of the mixture back up the intake tract (trapping less mixture than it does now) and making less cylinder pressure. That's the whole big deal with knowing the static compression ratio, the fact that you can figure the dynamic compression ratio from it and maximize the cylinder pressure for the fuel you're using. Otherwise, it's just a guess. In the case of this young man, I would advise him that his combination is maxed and that the only way to go faster now is with more cubic inches, because more cam will lower cylinder pressure and the car will likely slow down. I am aware that there are fellows who have run over 200 psi cylinder pressure on pump gas, but they had to ditch PCV and EGR and de-burr and polish everything in the chamber and on the piston to prevent detonation.

I will agree with you that this thing of building motors is not rocket science, but there are laws of physics that have to be observed if you intend to hit a home run with your build. I certainly don't know all the answers and I'm no mechanical engineer, but I have been doing this stuff since 1958, when I was 16, and I have made many mistakes. When I finally got fed up with guessing, I began reading what the engineers and professional engine builders were writing and learned enough to get a lot closer on my choice of components to reach the goals I had set for the motor I was building.

Choosing components for a build just is not that difficult if you pay attention to what the experts/professionals are telling you. Again, I'm no expert, but I do listen to the experts and read what they have to say. If I say something on these boards, it is the result of either having done it myself or quoting an expert who has done it. No hocus pocus, no guesswork, just physics and reality.

One final thought. If you did not buy this motor in a vehicle brand new and you were the first owner, then you have no idea what components are in the motor or what machining has been done to it. Don't assume.
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