need help with cam

[kennyhammond]

ok i am amking a motor for my daily driven c10 its a 98 chevy 350 block that i am putting in my 81 c10 now it has 2.72 gears i am going to just freshen the heads and use the factory vortec heads....i am lost on the cam (yes i am ging to replace springs) i have three gm performance cams that some recomended but dont understand duration and the lift thing can someone help please

[chopped68]

what are the specs on these cams.the lower the duration @ .050 is,the lower the cams' power range will be.

ken

[kennyhammond]

Duration 275/280. And lift is 474/510... there are others but that one looked like it would be a nice street can to me....
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[hotrod 80]

I used the XM 270 HR in a truck with vortecs and it worked really well . Kinda need a few more details , but with 2.72's you need torque .

[kennyhammond]

what kind of details and thank you for the help i am a rookie at the motor combinations stuff.... its a 98 350 block roller can and lifters i am just going to tear everything down rering the motor and freshen up ... then just go back with a little bit better cam and some flat tops (no head work cant afford it right now) then a intake and carb the truck is somethen for the street to drive to work and for me and son to cruise he loves the rough idel (he is 8) calls it a race truck i had a 82 stepside with a 383 stroker

[bustedknuckles]

You can't go over .450" lift on vortec heads without some machine work. the valve keepers will hit the seals.

[kennyhammond]

What kind of machine work are we talking a lot of money sorry somethen simple.... I have a guy that is right down the road that can do it
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[gGMC DOG]

Originally Posted by bustedknuckles

You can't go over .450" lift on vortec heads without some machine work. the valve keepers will hit the seals.

what if you change out the valve springs for ZZ4 units, that are good to .525 lift. ??
good link
http://www.nastyz28.com/forum/showthread.php?t=56505

[bustedknuckles]

GMC, the problem I am referring to is not the springs, it is a clearance issue with the cylinder head itself.

You need to have the bosses for the valve seals cut down for additional clearance and either buy stock diameter springs or have the spring seats machined out. I don't remember what it cost me to have mine done, but that part wasn't too expensive. I am running the K-motion K11 springs (stock diameter) and have them setup for .550" lift with .100" clearance.

[kennyhammond]

ok so i can most likely get by using the 288/308 duration with 431/451 lift with upgraded srpings then?? and thank you for the info in this totaly dint know anything about that

[bustedknuckles]

If nothing else you should have a machine shop check your clearance to be safe.
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[kennyhammond]

But that can I posted should make a good bottom end can nd nice little rumble. Right?
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[kennyhammond]

But that ca I posted should make a good bottom end can nd nice little rumble. Right?
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[bustedknuckles]

Have a link to it for the rest of the specs?

[gGMC DOG]

By measuring your individual spring pocket, from top of valve guide to underside of an installed valve spring retainer, on the valve that will be used in that position, is the only sure method of knowing exactly how much cam lift you can use on your assy. (you can get by with a 6 " dial caliper) You can not go by someone elses results ( because of machining tolerance accumulation). My personal experiance with my set of vortec heads on a 400 small block, using the stock retainers/locks, I was able to go up to .490 lift at the valve, without interference with the valve guide. (switched to Comp cams springs too), but as I said, you must measure "your" assy. to be sure.. I used the Comp Cam XE 268 and was very pleased with the torque. This cam is some what mild in the 400. Just my 2 cents...

[kennyhammond]

Brand GM Performance
Manufacturer's Part Number 14097395
Part Type Camshafts
Product Line GM Performance Hydraulic Roller Camshafts
Summit Racing Part Number NAL-14097395

Cam Style Hydraulic roller tappet
Intake Duration at 050 inch Lift 196
Exhaust Duration at 050 inch Lift 206
Duration at 050 inch Lift 196 int./206 exh.
Advertised Intake Duration 288
Advertised Exhaust Duration 308
Advertised Duration 288 int./308 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.431 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.451 in.
Valve Lift with Factory Rocker Arm Ratio 0.431 int./0.451 exh.
Lobe Separation (degrees) 109
Camshaft Gear Attachment 3-bolt
Computer-Controlled Compatible No
Valve Springs Required Yes
Quantity Sold individually.


all the info i have thank you everyone for the help

[bustedknuckles]

Looks like a great low end torque cam upgrade, but not going to give you that "lumpy" idle I think you're looking for.

here's what I found:

http://sdparts.com/details/gm-perfor...parts/14097395

[kennyhammond]

darn i was hopen for a little rumble but i can handle it being smooth for the torque it should give thanks and i am told i will still have to have machine work done to the heads to use the cam and springs.... sounds expensive (startig to think the vortecs arent worth the trouble

[bustedknuckles]

The springs I am running didn't require any machine work, just the extra lift. It wasn't too much, but you can have your heads checked for very cheap and then know without a doubt what you need to do. Vortec heads are worth every penny in my opinion.

[Marv D]

Wow at first glance at that cam I was about to scream NO WAY,, The 288/308 advertised is WAY HUGE,, but that's GM for you. The 0.050 numbers are more in line with a mild cam for a computer controled TBI ,, I guess that is first question. Your transplanting a 98 vortec motor into a 81,, you getting the Vortec / carb intake, or moving the entire EFI system?

If staying EFI, that cam would be a GREAT choice IMO, if your dumping the electronics and changing to a carb, a couple of things you need to dig deeper in to. The 98 with vortec heads used a dished piston to get compression down to 8.5:1 as I recall. That compression won't tolerate a lot of duration or you will make a real slug of a motor.

With the 2.73 gears,, don't get crazy with duration. Something like you listed that is going to make buttloads of low rpm torque will make you very happy in a heavy truck with high gears. Too much cam will make it an inefficient, under powered machine that is not that much fun to drive.

[hotrod 80]

Here are the cam specs on the XM270Hr . The only reason i suggest this one is i have experience with it . I used the factory roller cam not the retro fit . 1500-5500 rpm . This is actually a cam for boats powered by Mercruisers that are Vortec motors .
http://www.compcams.com/Company/CC/c...?csid=169&sb=2
The GM cams seem to to be good grinds also .

[kennyhammond]

OK yeah. I am going with a former intake and a Carb.... OK guys I am starting to buy parts for the motor as of Monday. So please guide me in the right direction on. What I need to to to make this a nice street motor for a 60 mile comute to work sometimes ..... that's round trip
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