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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; Originally Posted by bobfig im new to this but would vortec heads be a better option instead of a cam ...

  1. #41
    Large Marge sent me SUBURBIAN's Avatar
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    Re: Whats the biggest cam I can put in my stock 350 (carb)


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    Quote Originally Posted by bobfig View Post
    im new to this but would vortec heads be a better option instead of a cam at this time for him? wouldn't that raise his compression ratio?

    Real GM vortec heads, or EQ or RHS, any of them might be a good match here. We need to know what pistons are inside that engine.

    Quote Originally Posted by Swims350 View Post
    man alot of good info and reading. I'm glad you take the time to school ppl instead of bash them for not knowing something or asking questions about it, or just saying something wrong. Good job and good info suburbian. I think after reading this we got a lower compression ratio in ours, from what I know they are gm replacement heads, and have 2.02 valves and 76 cc or 72 and it has dished pistons in it. Now it was a nasty beast in the other truck that was manual brakes 3 speed stick shift, posi out back with probably 3.73 or 4.10 and a bigger cam, it was nasty, and by big I mean like one of the two videos posted it had a very nasty idle to it. it ran great and would smoke em from the start, but that same motor, pistons, heads are in dad's 84 now with the comp 268h cam.

    You know what kinda CR that'd be? I'd bet very stinky low with them 72 or 76cc and dished pistons, that makes me sad lol. I can't much figure it out either it ran ALOT better with the bigger cam, but that could have been helped by the stick shift and the low gears out back i guess.
    Thanks...

    Lots (not all), maybe I should say "some" engines that have been generically "taken over .030" or similarly...and rebuilt with stock replacement parts got what are called rebuilder pistons, which are .020" shorter than stock pistons. This robs nearly a half point of compression for anyone that doesn't take it into consideration, and have the block decked to zero or at least milled back down to .025" piston to deck. If someone is trying to build an 8.5:1 engine, with dished pistons and 76cc heads, they may just wind up somewhere near 7.9:1 instead.

    There is also this stigma that cams need to be huge, and sound tough. Some people, generally want to overcam an engine. Not me, I had an overcammed 350, and it was a slug.

    Gears make a numerical advantage. That is a completely different ball of wax. Swapping gears can feel, on the butt-o-meter, like you swapped engines.
    Last edited by SUBURBIAN; 08-17-2010 at 07:58 PM.
    1996 GMC K1500 SUBURBAN SLE
    355" L31 : DELPHI MPFI : 2.25" THRUSH DUALS : RCX SUSPENSION LIFT : RCX STEERING STABILIZER : RCX 2.2 SHOCKS : MOOG EVERYTHING : SMITTYBILT NERF BARS : OPEN GT4'S : DICK CEPEK DC2'S : 295/65/18 DURATRACS

  2. #42
    I can't be trusted kunas's Avatar
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    Re: Whats the biggest cam I can put in my stock 350 (carb)

    man, where were you 2 years ago when I was rebuilding my 89 350 5.7l? I went with the 268 also. nice low end power, tbi, 33s, 3.73 gears, mild lope

    great info here guys. pay attention.
    99 jeep wrangler <- a real 4x4
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    Registered User hammer137's Avatar
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    Re: Whats the biggest cam I can put in my stock 350 (carb)

    Quote Originally Posted by SUBURBIAN View Post
    Your heads and the low CR are holding your engine back. That is no turd...and pardon me for saying so, man, but you're leaving some on the table.

    Did you measure an 8.5:1 ratio?
    It was calculated to be in that area, I can't remember exactly what head gaskets we used. The engine was just a budget build for a neighbors K2500. It made more than we expected.

    81' Silverado 377 SBC, built 700R4, 4:11 Eaton
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    Many thanks to Bill Little ofBelmont Automotive
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    Re: Whats the biggest cam I can put in my stock 350 (carb)

    suburbian , what kind of heads does your friend have? I have a few spare 350's I might be able to take apart for the heads! Just read your last post about gears , I have 4.10 gears in my truck.

    thanks!

    your a great guy!
    Last edited by shane_k1500; 08-18-2010 at 07:01 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)

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

    My friend is running aluminum heads. The are PBM's, which are the same or similar to the Pro Comp castings, purchased bare, and assembled at home. 64cc Chambers, 190cc intake runners, 2.05/1.60 valves. The only work done to them was a quick once over to remove casting flash. He had the block cleaned and zero decked.

    Post up the casting numbers from the other heads you have.
    1996 GMC K1500 SUBURBAN SLE
    355" L31 : DELPHI MPFI : 2.25" THRUSH DUALS : RCX SUSPENSION LIFT : RCX STEERING STABILIZER : RCX 2.2 SHOCKS : MOOG EVERYTHING : SMITTYBILT NERF BARS : OPEN GT4'S : DICK CEPEK DC2'S : 295/65/18 DURATRACS

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

    Quote Originally Posted by SUBURBIAN View Post
    My friend is running aluminum heads. The are PBM's, which are the same or similar to the Pro Comp castings, purchased bare, and assembled at home. 64cc Chambers, 190cc intake runners, 2.05/1.60 valves. The only work done to them was a quick once over to remove casting flash. He had the block cleaned and zero decked.

    Post up the casting numbers from the other heads you have.
    I'll start taking them apart and posting!

    thanks!!!

    What where the casting numbers on his head? WHat would be an ideal head to run?


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

    Keep in mind you do not have to rip the heads off of the blocks. Simply take the valve covers off and the casting #'s will be on top of the head. Under the rocker arms. I would say a vortec head is your best bang as far as factory heads. I do not have much knowledge with the old camel humps though. They were around before I was.


    Edit - But like Suburbian said, it depends on what kind of piston he has in there. He could have a flat top that would raise his CR higher than what he is wanting and causing PTV clearance with certain cams. More than likely not true in this case. But still.
    Last edited by XLR8N; 08-19-2010 at 09:00 AM.
    Quote Originally Posted by Xander Berkeley
    I'd better make hay while the sun shines.

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

    XLR8N Jeremy is right...I have my suspicions about the pistons in there, but it isn't right to assume anything.

    There aren't any casting numbers on the heads on that my bud is running. They are aftermarket pieces. All GM heads however, have a casting number that IDs the heads. Again, XLR8N was correct, they are as I think you know, on the top side of the head usually in between the rocker arm studs. You posted the 624 casting number, so I'm figuring that you can get the others.

    Man, there are lots of different ways we can go, I think you ought to get the numbers off the rest of the heads you have, and we can go from there. Hopefully you'll realize that we should be after more than a "sound", and start looking at making this thing built to make good power where you need it.

    This may strike you...I have an old muscle car. A few years ago it had an sbc with a set of 624 heads on it. It was likely UNDER 8:1 static cr, UNDER 7:1 dynamic cr (another discussion), and was waaaay over cammed. Still though, had a decent carb/intake, ignition, exhaust, etc. The exhaust setup was mid-length 1-5/8" headers w/ 3" collectors to 2-1/4" smooth bent pipe, glasspacks before the axle, then 2-1/4" smooth bent full tails.

    Anything can sound good...this engine was a dog....squeaky belt and all...




    Exact same engine...but with open headers...

    http://s812.photobucket.com/albums/z...=openpipes.flv

    So what I'm saying ultimately, is that it is going to sound good no matter what...it is an SBC!! We want it to run like a raped ape too.
    Last edited by SUBURBIAN; 08-19-2010 at 09:45 AM.
    1996 GMC K1500 SUBURBAN SLE
    355" L31 : DELPHI MPFI : 2.25" THRUSH DUALS : RCX SUSPENSION LIFT : RCX STEERING STABILIZER : RCX 2.2 SHOCKS : MOOG EVERYTHING : SMITTYBILT NERF BARS : OPEN GT4'S : DICK CEPEK DC2'S : 295/65/18 DURATRACS

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

    Quote Originally Posted by SUBURBIAN View Post
    So what I'm saying ultimately, is that it is going to sound good no matter what...it is an SBC!! We want it to run like a raped ape too.
    Shane,

    you are supposed to want it to sound like a stock 350 with dumped flowmasters but be able to walk away from anyone in your town!
    Last edited by XLR8N; 08-19-2010 at 09:41 AM.
    Quote Originally Posted by Xander Berkeley
    I'd better make hay while the sun shines.

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

    Quote Originally Posted by XLR8N View Post
    Shane,

    you are supposed to want it to sound like a stock 350 with dumped flowmasters but be able to walk away from anyone in your town!
    I'm a little to old fashioned for that! haha , I drive like an old lady in town.


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

    Quote Originally Posted by SUBURBIAN View Post
    XLR8N Jeremy is right...I have my suspicions about the pistons in there, but it isn't right to assume anything.

    There aren't any casting numbers on the heads on that my bud is running. They are aftermarket pieces. All GM heads however, have a casting number that IDs the heads. Again, XLR8N was correct, they are as I think you know, on the top side of the head usually in between the rocker arm studs. You posted the 624 casting number, so I'm figuring that you can get the others.

    Man, there are lots of different ways we can go, I think you ought to get the numbers off the rest of the heads you have, and we can go from there. Hopefully you'll realize that we should be after more than a "sound", and start looking at making this thing built to make good power where you need it.

    This may strike you...I have an old muscle car. A few years ago it had an sbc with a set of 624 heads on it. It was likely UNDER 8:1 static cr, UNDER 7:1 dynamic cr (another discussion), and was waaaay over cammed. Still though, had a decent carb/intake, ignition, exhaust, etc. The exhaust setup was mid-length 1-5/8" headers w/ 3" collectors to 2-1/4" smooth bent pipe, glasspacks before the axle, then 2-1/4" smooth bent full tails.

    Anything can sound good...this engine was a dog....squeaky belt and all...




    Exact same engine...but with open headers...

    http://s812.photobucket.com/albums/z...=openpipes.flv

    So what I'm saying ultimately, is that it is going to sound good no matter what...it is an SBC!! We want it to run like a raped ape too.

    Now that I like! What size cam was in your malibu!?!? That would my ideal set up! I have long tube headers on my truck with 2.3" true duals and glass packs before axels.. Pistons , I dont know , I know the engine runs real smooth , it doesn't tick but takes a bit of oil. I already have the valve seals to replace them in my basement. I'll be going outside right now to check the casting numbers! thanks

    guys!


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

    You should do a pressure test on all cylinders if it is using oil. Sure, it could be the valve seals but not always the case.
    Quote Originally Posted by Xander Berkeley
    I'd better make hay while the sun shines.

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

    The engine that takes a bit of oil...is it the engine/block you'll be using for this buildup?


    That cam is a generic "268" copy. It was a blue racer/crane grind advertised as a 284, but really had specs closer to what everyone knows as a 268. It had a little more overlap, and seat to seat duration, so it might be argued that this was intended to be a little hotter than a "268" cam. You heard the idle, that was at around 700 rpm. Made plenty of vacuum, and pulled pretty good after like 2500 rpm...up to 5500 or so...but it isn't just the camshaft that determines where your engine makes power, it is the whole combination of parts, and how well they match.

    I swapped heads on this engine, and the powerband broadened out, both down low and up high. The torque came on quicker, was more intense, and stayed on longer. It was pulling well over 6000. Crane advertises this cam with a range of 2000-4800...and I let off the gas at 6300 too chicken to push it any further. Goes to show what matching the rest of the combo well will do.

    Numbers at .050"...
    218/218
    .450"/.450"
    on 110LSA

    This combo should have bever really been put together, but would have responded waaaay better to a smaller cam than the one that was in it.

    When I took it apart, 3 of the lobes were going flat, and the timing chain had so much slack in it, I am surprised the thing ran as good as it did. Kind of goes to show that even with things out of wack and ****eyed, an SBC will run.
    Last edited by SUBURBIAN; 08-19-2010 at 11:19 AM.
    1996 GMC K1500 SUBURBAN SLE
    355" L31 : DELPHI MPFI : 2.25" THRUSH DUALS : RCX SUSPENSION LIFT : RCX STEERING STABILIZER : RCX 2.2 SHOCKS : MOOG EVERYTHING : SMITTYBILT NERF BARS : OPEN GT4'S : DICK CEPEK DC2'S : 295/65/18 DURATRACS

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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)

    yes it oil burns blue for 5-10 seconds when i start the engine after it's been sitting for a while. And yes it's the block I plan on camming since it's only seals.


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

    Quote Originally Posted by shane_k1500 View Post
    yes it oil burns blue for 5-10 seconds when i start the engine after it's been sitting for a while. And yes it's the block I plan on camming since it's only seals.
    It sounds like seals. If you plan on installing this cam into the shortblock with out rebuilding it you should test it so you dont waste your money.
    Quote Originally Posted by Xander Berkeley
    I'd better make hay while the sun shines.

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

    Quote Originally Posted by XLR8N View Post
    It sounds like seals. If you plan on installing this cam into the shortblock with out rebuilding it you should test it so you dont waste your money.
    Agreed...if for nothing more than insurance and a baseline for comparison.
    Can you compression test all 8 cylinders?
    1996 GMC K1500 SUBURBAN SLE
    355" L31 : DELPHI MPFI : 2.25" THRUSH DUALS : RCX SUSPENSION LIFT : RCX STEERING STABILIZER : RCX 2.2 SHOCKS : MOOG EVERYTHING : SMITTYBILT NERF BARS : OPEN GT4'S : DICK CEPEK DC2'S : 295/65/18 DURATRACS

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

    Quote Originally Posted by SUBURBIAN View Post
    Agreed...if for nothing more than insurance and a baseline for comparison.
    Can you compression test all 8 cylinders?
    yes , I'll back back to you guys in about a week! Stay on standby! I haven't had time lately since my other truck burnt a tranny and the engine seized! bad luck huh!? here are some pics of my two trucks! Check out my other thread!

    http://www.fullsizechevy.com/showthr...-ton-4x4-PICS*
    Last edited by shane_k1500; 08-19-2010 at 06:24 PM.


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

    Other engine has an 882 head


    -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!

  19. #59
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    Re: Whats the biggest cam I can put in my stock 350 (carb)

    882 heads have more potential than 624 heads do, but won't help a bit if you're trying to bump compression up and run some cam. If you are going to use what you have, the 882 heads might be a better choice than the 624 heads. They might have bigger valves, and are the supposed best of the light casting late iron sbc heads.
    1996 GMC K1500 SUBURBAN SLE
    355" L31 : DELPHI MPFI : 2.25" THRUSH DUALS : RCX SUSPENSION LIFT : RCX STEERING STABILIZER : RCX 2.2 SHOCKS : MOOG EVERYTHING : SMITTYBILT NERF BARS : OPEN GT4'S : DICK CEPEK DC2'S : 295/65/18 DURATRACS

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