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Whats the biggest cam I can put in my stock 350 (carb)

This is a discussion on Whats the biggest cam I can put in my stock 350 (carb) within the Performance forums, part of the General Discussion category; Hey guys , what's the biggest cam I can put in my 350 4 bolt main without damaging the engine. ...

  1. #1
    FSC's french Canadian shane_k1500's Avatar
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    Whats the biggest cam I can put in my stock 350 (carb)


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    Hey guys , what's the biggest cam I can put in my 350 4 bolt main without damaging the engine. The engine is stock and it is going in my 1984 4x4 chev 3/4 ton with 6 inch lift and 33's. The motor is stock and I don't do any mudding with it , it's strictly a town truck , I just want a nice lobby sound out of it. I already have true duals with cherry bombs.

    thanks

    shayne


    -1993 chevrolet k1500 ext.cab (5" lift with 33 BFG A/T's)
    -1984 chevrolet scottsdale 3/4 ton HD (7" lift with 38's)

    truck fixing time in the maritimes!

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    Registered User custm2500's Avatar
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    Re: Whats the biggest cam I can put in my stock 350 (carb)

    Well it can't be any longer then the block! That is the biggest.

    You need to stay with a mild cam. The big heavy truck and tires need the low end power. I don't know 350 cams but you can't put a big nasty cam that will loap. I had this dilemma when I put a cam and intake on my old ford. I wanted big, choppy, high hp but you can't because the truck won't leave a stop light. Look for cams that have a rpm range of 1000-1200 and most of them will spin to 5500 or 6000. Then do like I did and plan someday to make a high hp motor for a car or light weight truck down the road. My plan is to someday build a 1000 hp motor. It will happen also.(see what happens when you are forced to use small rpm performance parts.)

    "01 GMC 2500 HD, Bagged, BB Tuned, Dumped exaust, and Race built trans with 2800 Stall

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    FSC's french Canadian shane_k1500's Avatar
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    Re: Whats the biggest cam I can put in my stock 350 (carb)

    thanks , but that still doesn't really help me. I'd like to know the biggest size if you can be more specific. If you guys could give me a few example with brands and stuff.


    -1993 chevrolet k1500 ext.cab (5" lift with 33 BFG A/T's)
    -1984 chevrolet scottsdale 3/4 ton HD (7" lift with 38's)

    truck fixing time in the maritimes!

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    Large Marge sent me SUBURBIAN's Avatar
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    Re: Whats the biggest cam I can put in my stock 350 (carb)

    A few things need to be established prior to choosing a camshaft for your engine. Mainly, the static compression ratio of that piston/head combo in your "stock" smallblock.

    What is the casting number on your heads? Have you seen the pistons to be able to tell at least what profile they are...flat tops, flat tops with 2 or 4 valve reliefs, dished pistons, dished pistons with reliefs, etc. The piston profile combined with the volume of the combustion chamber volume of the heads you'll be running will dictate how much cam you can comfortably run. What year is the block? Does it have roller cam provisions? Are you going to be running a flat tappet cam? Are you aware of the inherent risks and certain and particular break-in and post break-in procedures?

    It isn't the smartest thing in the world to build an engine for sound. I'd rather have a smooth idling engine that gets some, than a slug of a pig that can't get out of its own way until it is revving 3000. You want something that will work off-idle with your converter

    Speaking in absolutes is tough...like "what is the biggest...".

    I'd love to help you choose a cam for your rig...but kind of need some more info to be able to do it the right way.
    Last edited by SUBURBIAN; 08-17-2010 at 08:46 AM.

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    FSC's french Canadian shane_k1500's Avatar
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    Re: Whats the biggest cam I can put in my stock 350 (carb)

    i dont know much about cams and for the pistons i'm not sure. I'll have to take the heads off to check. Some one told a 170 something would be a good cam to run. Some one else told me 291 lift and duration would be the biggest to run safely on a stock chev i'll post a VIDEO to show what i mean


    -1993 chevrolet k1500 ext.cab (5" lift with 33 BFG A/T's)
    -1984 chevrolet scottsdale 3/4 ton HD (7" lift with 38's)

    truck fixing time in the maritimes!

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    FSC's french Canadian shane_k1500's Avatar
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    Re: Whats the biggest cam I can put in my stock 350 (carb)

    here's what i mean check the video and description

    http://www.youtube.com/watch?v=8HVmjuuSFDw

    or this one

    http://www.youtube.com/watch?v=jgE_l...eature=related

    As for the install i'm getting it professionally installed.

    Thanks for the help guys
    Last edited by shane_k1500; 08-17-2010 at 09:53 AM.


    -1993 chevrolet k1500 ext.cab (5" lift with 33 BFG A/T's)
    -1984 chevrolet scottsdale 3/4 ton HD (7" lift with 38's)

    truck fixing time in the maritimes!

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    Large Marge sent me SUBURBIAN's Avatar
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    Re: Whats the biggest cam I can put in my stock 350 (carb)

    The cam in that truck is very lopey. Lope identifies an engine that is running crappy, honestly. A bigger cam generally makes less vacuum at idle. If you have vacuum accessories, they may not work so well with a lopey cam. I'm talking about vacuum-assisted power brakes and the possibility that your trans will require a hookup for vacuum needs. The firing and valve event are so poorly "timed" (and I use that word loosely), that the engine is popping just rhythmically enough to stay running. We're ultimately talking idle quality here. As the rpms come up, so does the smoothness of the engine's valve events. The more lopey a cam, the more duration, the higher the rpms are before the engine smooths out. The description says it is a 292 cam. That is an old "hot rod" cam meant for an engine/car that will be used mostly at higher rpm. The 292 number is an advertised duration value. Usually advertised duration describes the amount of degrees of a circle (the cam's front profile) that the valve is open, from just barely open to dang near shut...or "seat to seat duration". You have to be careful because none of the cam companies really advertise where they get their "advertised" numbers from. Some use lift at .004" others use lift at .006", etc. Also cam manufcturer marketing schemes have kind of confused things more. I am not going to touch that one right now.

    The more duration a cam has, the higher the usable powerband of the engine is, the more compression ratio it needs, and the more converter you need to be able to get it going. Cams are usually rated with a powerband. Idle to 4500, or 1500 to 5500, 2000 to 5800, 3,000 to 6500, etc. The more duration, the higher the powerband is.

    A 292 cam probably requires generally speaking, close to 10:1 compression. Your stock engine would be a big iron turd with that cam in it. That cam probably needs a converter with at least a 3000 rpm stall. There would be more to using that cam and having it work than just stabbing it in.

    Your truck would be bad to the bone with a big cam and a converter in it. A bud of mine has an OOBS with a 350, comp cams 276 (smaller than a 292), and a converter with a stall rating of 3000 rpm. He can roast them at will...and all the guys he wheels with drool and gargle over his truck.

    It would be a bad idea to just stick that cam in your engine. Are you willing to get the head casting number at least? What about pulling a head and looking at the pistons?

    Do you have $ to buy a bigger than stock converter to go with your cam?
    Last edited by SUBURBIAN; 08-17-2010 at 01:40 PM.
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    FSC's french Canadian shane_k1500's Avatar
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    Re: Whats the biggest cam I can put in my stock 350 (carb)

    Thanks a lot for the input!!!!!! Yes I have the cash for a bigger converter!
    I'll try to get the info as soon as I can! I really appreciate it! So are you suggesting a 276 with a larger torque converter is the heads and compression permit?


    -1993 chevrolet k1500 ext.cab (5" lift with 33 BFG A/T's)
    -1984 chevrolet scottsdale 3/4 ton HD (7" lift with 38's)

    truck fixing time in the maritimes!

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    Large Marge sent me SUBURBIAN's Avatar
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    Re: Whats the biggest cam I can put in my stock 350 (carb)

    Oh, you're welcome dude. I'll suggest a cam once you post the info we need to proceed.

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    Re: Whats the biggest cam I can put in my stock 350 (carb)

    Just to throw this out there, I'm running the Comp Extreme 4X4 270, and love it. But it is on a 10.1, 2400 stall setup, with professionally ported heads. Truck idles nice, pulls trailors awesome, and pulls hard to 6000, on 33" tires.

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    Large Marge sent me SUBURBIAN's Avatar
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    Re: Whats the biggest cam I can put in my stock 350 (carb)

    We might find out that he can't run a cam that big without a head swap.

    Here is my bud's truck...the day we fired it up...



    This thing rattles the windows in my house when he rides by.
    Last edited by SUBURBIAN; 08-17-2010 at 01:47 PM.

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    You won't like my tastes Swims350's Avatar
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    Re: Whats the biggest cam I can put in my stock 350 (carb)

    well I have a comp 268h and it's got some lope to it and works with all power accessories, and it works better for me with a stock tc and not a stall. I had a stall in it which was a tci sat. night special 2k stall and it sucked. I could break it loose a little in the monte carlo but now with a stock tc and same trans but 305 it'll smoke the tires. I put that motor in dad's truck with a th350 and that same stall tc and it was terrible, he had 2.73 rear end though but it barely did anything. Now it has another th350 with a stock tc and does alright it'll break em loose but not much with 2.73's. it really turned me againist stall converters. But they next cam up the magnum is the largest cam for stock TC and works with all power accessories. it must have more of a lope to it since it's bigger, but my comp specs out to 218 duration at 50 thousandths lift 454 lift and that's on intake and exhaust. I run a set of gm replacement 2.02 iron heads, and weiand action plus intake edelbrock 600cfm vac. sec. man. choke carb regular hei dist. and mallory wires. I think at the very least you should look into matching valve springs for the comp268 or anything bigger, and really might want to look into some port polish work or a set of better flowing heads to go with it. Not to mention and intake, headers, 4bbl etc. Also rear end ratio.

    BTW suburbian your buddies truck sounds great.

    But here's a video of the comp 268h.

    Last edited by Swims350; 08-17-2010 at 01:51 PM.

    Chris

    88 K1500 RCSB work in progress.

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    Large Marge sent me SUBURBIAN's Avatar
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    Re: Whats the biggest cam I can put in my stock 350 (carb)

    A torque converter is a fluid coupling, that replaces the clutch in a mechanical gear shifting setup. It activates or engages the engine's force to the transmission. The engine speed at which the transmission and engine are engaged is the stall speed. When driving a stick-shift, the clutch and throttle need to be manipulated together to launch the way the driver is intending to, nice and smooth, at the bottom of the powerband (if running a bigger-than-stock cam), or a dump at WOT. This can be tricky for some people to get right every time. A person with an automatic transmission has the opportunity to launch perfectly every time. I'd say the goal is to at least let the engine start into its sweet spot before making it push a 2 ton vehicle. See, en engine idles at what...800 rpm? A stock converter is set to start using power right off idle. Bigger than stock converters for bigger than stock cams and powerbands, when matched correctly, are set to start making and using power at the same time, too, but further up the rpm range. Every torque converter has a "stall" rating...and also has a flash rating.

    I'll bet a 268 cam would work real well with a stock converter. I have a bud that runs a 280 magnum cam in with a stock converter and that nova flat MOVES. A 292 may not work as well because it isn't making a lot of torque that low on the tach.

    A junky converter or mismatched converter shouldn't turn you off from them forever.

    Nutshell...A higher stall rating would allow the engine to rev up a little before putting it under load.

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    You won't like my tastes Swims350's Avatar
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    Re: Whats the biggest cam I can put in my stock 350 (carb)

    I would agree man I don't know all I need to about stalls and such but yea the 268 works very well with a stock converter. The truck needs better gears which is why we have 3.90's waitiing to go in lol. I know the magnum 270 says it's the largest for stock converter, never seen a 280 on one but sounds pretty good to me. I know that'd have to be a nasty idle cam being a 280 compared to the 268, even though 280 and 268 is just advertised and means basically nothing.

    Chris

    88 K1500 RCSB work in progress.

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    FSC's french Canadian shane_k1500's Avatar
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    Re: Whats the biggest cam I can put in my stock 350 (carb)

    here is my casting number 462624 , does this make sense?


    -1993 chevrolet k1500 ext.cab (5" lift with 33 BFG A/T's)
    -1984 chevrolet scottsdale 3/4 ton HD (7" lift with 38's)

    truck fixing time in the maritimes!

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    FSC's french Canadian shane_k1500's Avatar
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    Re: Whats the biggest cam I can put in my stock 350 (carb)

    your buddy's scottsdale with the 276 cam sounds real good


    -1993 chevrolet k1500 ext.cab (5" lift with 33 BFG A/T's)
    -1984 chevrolet scottsdale 3/4 ton HD (7" lift with 38's)

    truck fixing time in the maritimes!

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    2500 6.0 vortec
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    Re: Whats the biggest cam I can put in my stock 350 (carb)

    Yea lope mean its running crappy lol.

    2500 6.0 vortec 6in skyjacker lift with keys on 16in eagle wrapped in good year kevlar 285, LPP LT's, gmpp cam, efi live tuning software, true dual flowmaster 40 series Circle D 2500-2800.

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    Real 4x4s' Rust ryan_thompson87's Avatar
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    Re: Whats the biggest cam I can put in my stock 350 (carb)

    Uhh no it doesn't. It's caused by valve overlap.

    87 K30-355 Vortec TBI/TH350/208/Dana 60/14FF/4.56s/Detroit/37"Bogger/Ult.TBI Mods/XtremeFI FPR vac. reference/EP241 Pump/LS1 Fans

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    2500 6.0 vortec
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    Re: Whats the biggest cam I can put in my stock 350 (carb)

    um I was joking.

    2500 6.0 vortec 6in skyjacker lift with keys on 16in eagle wrapped in good year kevlar 285, LPP LT's, gmpp cam, efi live tuning software, true dual flowmaster 40 series Circle D 2500-2800.

  20. #20
    2500 6.0 vortec
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    Re: Whats the biggest cam I can put in my stock 350 (carb)

    Quote Originally Posted by SUBURBIAN View Post
    The cam in that truck is very lopey. Lope identifies an engine that is running crappy, honestly.
    Yea not really.
    Last edited by 6.0vortecchevy; 08-17-2010 at 03:24 PM.

    2500 6.0 vortec 6in skyjacker lift with keys on 16in eagle wrapped in good year kevlar 285, LPP LT's, gmpp cam, efi live tuning software, true dual flowmaster 40 series Circle D 2500-2800.

 

 
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