390 Cam recommendation

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Feb 26, 2005 | 02:13 PM

sloop

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From: Raleigh, NC

390 Cam recommendation

I am getting ready to assemble my first engine.

I am starting with a 1973 360 block. I had it magnafluxed, bored 0.030 over, line honed, and the deck surfaced (where it meets the heads).

I've also already bought a machined 390 crank with bearings, 390 connecting rods and pistons

I plan to use my stock heads. I'd like to keep the same pushrods and hydraulic lifters to keep things simple. I want to run 87 octane gas at sea level, so my compression should be fine.. What cam should I get though? I'd like as much fuel economy and low-end power as possible.

thanks

Mark

Feb 26, 2005 | 03:19 PM

rusty70f100

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From: Iowa

First a couple questions:
1. What do you plan to use the motor for? Racing, towing, grocery getting, what?
2. What is your expected compression ratio?

Feb 26, 2005 | 03:20 PM

sloop

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From: Raleigh, NC

Motor will be used for towing and grocery getting. I'm not sure how to calculate the compression ratio.

Feb 26, 2005 | 06:34 PM

FORD352V8

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From: North Carolina

Go for the Crane Powermax truck cams, either the 901 or the 941, both are great cams.

Feb 26, 2005 | 06:57 PM

rusty70f100

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From: Iowa

Well the thing is, certain size cams work best with certain compression ratios. This is because of the intake valve closing angle. The later it is closed, the more compression is bled off at low rpms. So if you use a big cam with low compression, your motor will be a dog.

So the question becomes, what is your compression ratio? If you tell us what pistons you got we can calculate your approximate compression ratio and recommend a cam that will work well with it. If you got 390 truck pistons like I think you did, your compression is around 7.9. If they're dished it's even lower than that. The recommended compression ratio for the Crane 343901 cam is 8.0 - 9.5. The recommended compression ratio for the Crane 343941 is 8.75 - 10.75. The solution is to take those pistons back and get a set of 360 pistons, which it so happens are the same thing as some car 390 pistons. This will give you a compression ratio around 9.5. Then I'd use the Crane 343901 cam and tow away.

With the 390 truck pistons and the low compression, the Crane 343971 cam would work good.

Feb 27, 2005 | 04:04 PM

factoryhighboy73

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well this is what my dad did to my 390 and it runs like a raped ape and doesnt get to bad of fuel mileage he threw in a Super CJ Cam, 11.5:1 Pistons, edelbrock manifold, and a Carter AFB Carb trust me it works!!!