Cam question
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Cam question
Got a '70 Sport Custom that Im going through right now, and I want to put a nice cam in it but wasen't sure what the max lift on stock 360 heads was? Also any reccomendations on a nice lopey cam in the 1500-5000 rpm range? Not looking to put it in the 9's just something to pep it up alittle and sound good idling around the local rice burners!
Post Fiend
Joined: Jan 2003
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From: Iowa
For an otherwise stock 360? It is a low compression engine, around 8.5 (optimistic). Pretty much any cam that you put into it with a lope will turn your motor into a dog due to insufficient compression.
I would recommend the Crane 343971 as a step above the stock cam.
I would recommend the Crane 343971 as a step above the stock cam.
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Well I've got a Edelbrock Performer 4bbl( 500cfm) with mechanical secondaries, Dynomax headers with 2 1/2" Flowmaster 40 series, Accel coil, 8.5 mm Accel wires, Accel high rpm kit for the dizzy, B&M transpak, B&M Pro Ratchet shifter, 1" Carb spacer and 14x5" breather, 17'' permacool flexfan, ladder bars, and flame throwers, but yup its still an 8.5 compression motor. But the good news is the heads are in excellent shape, no burnt valves, still sealed good ( did the gas in the combustion chamber check and no leaks) and the pistons are all good with absolutly no movement inside the cylinder. I also plan on upgrading to a higher volume fuel pump to keep up with the new intake, and probably new timing chain and water pump while I've got it all out. Do you think that Crane cam you reccomended would be good for this application? Appreciate the input, looking forward to hearing more.
Post Fiend
Joined: Jan 2003
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From: Iowa
Well, the Crane 343901 has a recommended compression ratio of 8.0 to 9.5:1. I like to keep the compression ratio in the upper part of whatever they recommend. The Crane 343971 has a recommended compression ratio of 7.75 to 8.75, which for a 360 is about perfect IMO. It closes the intake valve sooner on the compression stroke, allowing it to build more compression.
For comparison, the stock cam that you have now is milder than even the 343971.
If you're going to have the motor out anyway, may I make a suggestion? Get a set of pistons for a 361FT. Take 'em to a machine shop, and have .022" shaved off the top of 'em. This will give you 0 deck clearance. Then, use .020" thick copper shim head gaskets. This will result in about 9.7:1 compression, allowing the use of that lopey cam you want. For this setup I recommend the Crane 343941.
For comparison, the stock cam that you have now is milder than even the 343971.
If you're going to have the motor out anyway, may I make a suggestion? Get a set of pistons for a 361FT. Take 'em to a machine shop, and have .022" shaved off the top of 'em. This will give you 0 deck clearance. Then, use .020" thick copper shim head gaskets. This will result in about 9.7:1 compression, allowing the use of that lopey cam you want. For this setup I recommend the Crane 343941.
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Joined: Feb 2004
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From: Fort Rucker, AL
Can I pose a question here? I've heard that the only stupid question was one not asked. I disagree but here goes. I've never changed cams except when I rebuilt a motor. Is there enough room in there to change cams without pulling the motor?
Post Fiend
Joined: Jan 2003
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From: Iowa
I haven't either, but I've heard it can be done by removing the radiator, grille, and condensor (if equipped). Honestly I'd rather have the motor out, disassembled and flipped over so I could hold it on the inside to keep it from nicking one of the cam bearings. But pulling the motor is a PITA. If you need to change one in the vehicle do it.
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Elder User
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From: Fort Rucker, AL
That's what I'm thinking. I believe that if you take your time and ever so gently install that cam, you won't nick any bearings.
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well where I'm sitting at now, just a few tranny bolts, couple of lines, and a hose or two and the motor would be out. Which has really crossed my mind, but all I've got to do is pull the radiator, condensor, water pump, and timing gear to do a swap in the truck, could go either way on this one. But right now just looking for a little freshing up, not a total rebuild.
Tuned
Joined: Mar 2004
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I did like rusty said with my f100/390. And used the crane 941. It is a little lopey but still idles nice. I did have the 901 and wasn't happy with that. The only thing you may want to think about is the lift on the 941. I believe it is borderline for the stock rockers and shaft.
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Cool, that's what I was looking for. Did it help your bottom end on your truck? Like I said I'm not looking to put it in the 9's, I just like to be thrown back in the seat once in awhile. Did you have any trouble with the vaccum on that particular cam? Just trying to get the most I can out of it without going through the bottom end on it right now, cause it doesn't need it. Thanks for the post.
Tuned
Joined: Mar 2004
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I would say the bottom end was helped a little. The biggest difference was in the mid to upper range. The power range of the 941 cam I beleive is 1500 to 5500rpm. The problem I had with the 901 was that it would cough out around 4500. Now it breaths great on top too. I did lose around an inch of vac with the 941 because of the overlap.
Its hard to get a heavy truck moving so, keep this in mind. Your 360 is a good motor. If you get the 941 cam you may want to think about getting the Edelbrock RPM manifold. If you have the stock or Edelbrock performer the RPM is a big improvment. I just did what you are talking about and went with a new top end. Cam, timing gears, manifold and new cj valved heads.
Its hard to get a heavy truck moving so, keep this in mind. Your 360 is a good motor. If you get the 941 cam you may want to think about getting the Edelbrock RPM manifold. If you have the stock or Edelbrock performer the RPM is a big improvment. I just did what you are talking about and went with a new top end. Cam, timing gears, manifold and new cj valved heads.
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Well believe it or not, it ran like it did before with a two bbl intake, and a 12 dollar bolt on four bbl adaptor plate from auto zone! So right now this stock 4 bbl intake ought to be a vast improvement!! I have never checked the compression on this motor, but to my surprise when I pulled the heads, only number 7 has any type of movement in the piston ( blows a little oil by the valves when I drive her exceptionally hard) and the cylinders look great. Did the loss of vaccum hurt you braking ability? There is not much there now, but I really don't want to lose anymore, that's gonna be my next project is a disc swap on the front, but for now I'm still drumming away. I really appreciate the input on this, sure makes it alot easier to pick when you've got some real input on them. Thanks!
Tuned
Joined: Mar 2004
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Curtis, how much vac do you have? You can tell a great deal with a vac. gauge on your engine. A good tight engine will usually have around 16 or 17" of vac. I am around 13 with the new cam but, I do not have power brakes. I would think however that would be plenty if I did.