Choosing a new Camshaft for a Stock Chevy 350

Discussion in 'HardCore Corner' started by gifu, Jul 2, 2009.

  1. gifu

    gifu

    Messages:
    936
    Location:
    SF Bay Area, CA
    Funny, I'd have thought this had been discussed. Maybe I stink at searching.

    Anyway... here's the deal. I have a FJ46 (extra-cab, flat bed, SOA, NV4500, Orion, 4.11's, 35's, probably weighs 4800lbs) with a stock GM Goodwrench 350. Running a Performer intake with Quadrajunk on top. The truck crawls just fine (NV4500->Orion), but getting up the hills on the freeway is embarrassing.

    Someday, I plan to swap a diesel, but in the meantime... I want to get some more horsies out of this engine. From what I understand, the stock cam in this motor is pathetic. I starting looking at new cams. I know _what_ the cam does... but I only know enough about cams' numbers to confuse myself.

    So, I'm looking for advice on cams. I want the most power, best economy, smooth idle that I can get... that's not asking much, right?

    I started by talking to Jegs and Summit. They didn't give me much info. I then called the manufacturers. I've heard good things about Crane... but they are in the process of being bankrupt, sold, and reopening. So, I called Lunati and Comp.

    So... here are some comparisons. First, is what I _think_ my stock cam is. Second is the suggestion I got from calling Lunati cams. Next was suggestion from Comp. Last is a run-of-the mill from Edelbrock.

    GM Goodwrench
    * Advertised Duration (Int/Exh): 260/268
    * Duration @ .050 (Int/Exh): 194/202
    * Gross Valve Lift (Int/Exh): .383/.401
    * LSA/ICL: 112


    Lunati
    * part #: 60-1000
    * Advertised Duration (Int/Exh): 250/256
    * Duration @ .050 (Int/Exh): 207/213
    * Gross Valve Lift (Int/Exh): .437/.454
    * LSA/ICL: 112/108
    * Valve Lash (Int/Exh): Hyd/Hyd
    * RPM Range: idle-5000
    * Includes: Cam Only


    Comp Cams
    * Part#: 12-231-2
    * "extreme 4x4 cam"
    * duration (@.050) 206/214
    * lift .432/.453
    * lobe separation: 111
    * RPM range Idle to 4600 RPM
    Edelbrock
    * Operating RPM Range Idle-5,500
    * Duration at 050 inch Lift 204 int./214 exh.
    * Advertised Duration 278 int./288 exh.
    * Valve Lift with Factory Rocker Arm Ratio 0.420 int./0.442 exh. lift
    * Lobe Separation (degrees) 112

    From what I can tell... these are fairly mild cams? Maybe a bit more aggressive then an old school "RV Cam", but certainly not enough to create a loping idle that would suck in crawling situations.

    OK... so... suggestions, comments, ideas, past problems, past projects that turned out well? Let'm rip...
  2. inkpot

    inkpot SILVER Star

    Messages:
    8,328
    Location:
    Chandler, Az.
    Howdy! Can't really give you numbers off the top of my head, but I would stick with something pretty close to the RV type cam. You want something that lists like the Edelbrock as "idle to 5000". If it starts pulling at 1200 - 1500 rpm, your going to be on slipping the clutch all day. With 4.11s over 35's and an NV4500 overdrive, you should be in peak torque range from around 1800 - 3000. That will have you running pretty smooth at hiway speeds. Are you sure that the cam is the problem? Could it be a fuel supply or carb issue? If you are running the big old Delco Remy dizzy with the coil in the top, check the centrifical advance weights. I found mine were rusted shut in the retarded position. John
  3. gifu

    gifu

    Messages:
    936
    Location:
    SF Bay Area, CA
    I agree... the low end torque is what I need. Though, honestly... there's NONE there now, I don't think I could make it any worse.
    with the Orion and NV4500 (92:1 or something), I could have a 4-cylinder engine and it would still crawl. What's missing here is any sort of highway cruising power.
    The carb is rebuilt by a local fuel shop. The dizzie is a new HEI from Jegs. Before I start tearing into it, I do plan on at least checking the compression. What's acceptable compression for a stocker 350?
  4. Alz Toy

    Alz Toy

    Messages:
    398
    Location:
    SE Mo
    Here's what I can tell you based on MY exp. When I got my Cruiser, it had a cam simular in numbers to the Edelbrock in it. Ran OK, but seemed lacking to me, as it didn't seem strong in any one area. Bought into the Comp hype, and bought the next size bigger than you listed, based on Comps recomendation after talking with them. It does make the power, but mainly from 2500 RPM+. rev's pretty easy so its responsive. The bad part, it makes the valve train noisey as hell due to the fast aggresive ramp rate. Slam 'em open, and slam 'em shut. Comp told me they tried to get as close to roller cam action as they could with a flat tappet. I have new valve train parts with the cam, but I'm tired of the racket, so I'm going to option #3. After talking to Harold Brookshire, designer of the Lunati Voodoo series cams among others, I'm going with the same Lunati you listed, but cut as a single pattern cam for more bottom end. Don't know how accurate Desktop Dyno is, but of all the cams I ran thru it analyzing strong low Rpm torque. the Crane Cams 260 Energizer was stronger than anything I looked at showing at 380 +/- from 2-3000 RPM's. To get an idea of how fast the ramp rate is of cams you are looking at, take the numbers @ .050 and subtract from the advertised duration numbers. Example- Edelbrock 278/288 minus 204/214 gives you a lobe intensity of 74/74. On the Lunati- 250/256 minus 207/213 gives you 43/43, so its a faster ACTING cam. HTH, Al
  5. Enigma

    Enigma

    Messages:
    7,024
    Location:
    Pitt Meadows,BC
    x2 or whatever on the 'RV' type cam. I think, or guesstimate as it's been many moons since I last rebuilt the 350 in my fj40, that I was running 10.5:1 with a similar engine as yours ('69 2 bolt main 350, bored .030 over, performer intake, RV cam, quadrajet, HEI ignition, 3 speed tcase, sm465, stock open 4.11's, and 35" tires.
    You should not have any problems with hills in your setup, there must be another issue somewhere. Mine makes buttloads of power all the time, too much at some times even (tore 3 transfer cases in half).
  6. gifu

    gifu

    Messages:
    936
    Location:
    SF Bay Area, CA
    remember... right now... I have a stock cam. I do not have an RV cam. I'm blaming my Hecho en Mexico cam for the lackluster performance.

    Alz Toy... So... the Lunati might be a good ticket? But the lift is more then the edelbrock, with a shorter duration (at least, on the exhaust). Wouldn't that lead to the same valvetrain racket that the Edelbrock was causing?

    What about converting to a roller-lifter set-up? Is that worth the extra$$? Maybe not for the low-end torque i'm looking for... but it sounds neat, eh?

    EDIT: ok, retrofitting a roller cam is really expensive. never mind. It just sounded neat. Keep It Simple Stupid.
  7. gifu

    gifu

    Messages:
    936
    Location:
    SF Bay Area, CA
    Al, you said, "Example- Edelbrock 278/288 minus 204/214 gives you a lobe intensity of 74/74. On the Lunati- 250/256 minus 207/213 gives you 43/43, so its a faster ACTING cam."

    which one are you saying is faster acting? The one with the larger lobe intensity number? Or smaller? Since those are degrees, and the Lunati has a smaller lobe intensity number, does that mean it ends up with a steeper curve? Wasn't this what you thought was causing the loud valvtrain.

    sorry if i'm asking questions backwards or dumb questions... i'm still wrappin my head around cam numbers. Just read three articles explaining... so i'm stating to get it. But differences between all these cams seem so... small, it's amazing they make such a big difference (at least in regards to each other... they all seem heaps more aggresive then the stock cam numbers, at least in gross valve lift.)
  8. Mace

    Mace rock scientist.. Staff Member s-Moderator

    Messages:
    18,044
    Location:
    Las Vegas
    No aftermarket cam is not going to give you more low end power.
    They will add power higher up in the RPM range.

    What about shifting out of overdrive?

    Exhaust restrictions?

    There are lots of options before you start chenging out cams. The goodwrench box motor should have plenty of power for you..
  9. gifu

    gifu

    Messages:
    936
    Location:
    SF Bay Area, CA

    Last Rubicon trip, I was sitting in third gear going up I80 at about 48MPH. Yeah, it's sorta steep... but my that's just silly.

    My buddy has the same engine in his FJ40, and his is just as anemic. Probably only getting 150hp at the wheels. Maybe less. I'm no speed demon, believe me... but this is the wimpiest 350 I've ever driven.

    No cam will give me more low-end? Huh... but... I thought that's what RV cams did?
  10. Alz Toy

    Alz Toy

    Messages:
    398
    Location:
    SE Mo
    Smaller number, quicker ramp, larger number lazier ramp. This is one of the reasons the " old school lazy ramp " cams went alot of miles and made good power, without lobes going flat, also the oil had more zinc in it than is allowed today ( thanks EPA ). The Lunati is a ASMETRICAL design, which means it opens fast, closes slower. The Comp is a SYMETRICAL design which opens /closes fast. Give this man a call, at one time he owned Ultradyne Camshafts, has worked with Comp designing the High Energy series, Lunati with the Voodoo series, and various racing teams. Harold Brookshire, 662 562 4933. You will get a camshaft education that makes sense. Ron Iskendarian of Isky Cams is anotherone you could talk to. Questions are good, thats how we learn. I just perfer to go to the horses mouth. My .02, and HTH. Al PS- lookup the spec's for a truck, then a 'Vette. Both use " stock cams ". Notice any difference in the numbers?
  11. cruiserbrett

    cruiserbrett Moderator

    Messages:
    2,357
    Location:
    San Diego
    call schneider cams in SD. they have been grinding cams forever and will easily answer any questions better than phone sales rep. they ground a blank 2F cam based on the inputs I gave. I am sure they have LOTS more profiles for a chevy V8. PS, if you find a local place that grinds cams its worth the trip to check out the grinding lathes they use to cut the lobes...

    dont forget good cam lube for cam break in. you need it or modern oil will ruin the flat tappets and the lifters.


    Schneider Racing Cams

  12. VETTE60

    VETTE60

    Messages:
    1,256
    Location:
    Pollock Pines,CA
    you need to remember that you should be matching an intake manifold with the cam. the cam alone will not give you what you need. you are looking for more low end torque and really need a combo set up. there are a few things that will get you quicker horsepower like headers, but a package would be your best bet. (cam, lifters, manifold, carb) or even snatch a fuel injection set up off a newr 350.

    I have the same tranny, and love it, but the gears are too far apart. that is why they went to the NV5600 which is a six speed, but just has closer ratios. the shift from 3rd to 4th while loaded pulling grades on the highway is just a bit too far apart, which is where the torque comes in. I decided to go wih a 383 build to get that low end torque, but that is not a cheap fix...
  13. gifu

    gifu

    Messages:
    936
    Location:
    SF Bay Area, CA
    will the heads bolt right on? what about the intake manifold? Will it fit? Valve covers? What else is involved with vortech heads? can i just get used ones off a wrecked vortech?
  14. brokenparts

    brokenparts

    Messages:
    3,890
    Location:
    Hillsboro, OR
    I went with vortec heads for my project. I picked them up rebuilt on craig's list for like $350. You will need vortec style intake and centerbolt style valve covers. This is a very common swap anymore... tons of info if you google it. Comp cams has a neat little desktop dyno to download and play with that allows you to match up components. I went with a 268h comp cam with my heads.... should be plenty of power. I think I'll be able to get away with that cam because I'll be running a doubler and an auto.

    Watch out for too much lift with the vortec heads though... most say the limit is .475.
  15. pb4ugo

    pb4ugo SILVER Star

    Vortec heads should give about 50hp. I know some people have altered the bolt holes and made the older style intakes work, but center hole VC are required. Yrs & Yrs ago I installed an eldlebrock torker cam(cant' recall the #), I'm sure it's the same as mentioned above, and I really didn't notice any significant increase in power, but it did make my temps go up 10*.

    So your going up in elevation and loosing power? Go figure!!! Not sure a cams the answer.

    I'd do gears. I'm running the same hecho en mexico(230hp,woohoo!!) w/qjet & headers & 4:88s w/ plenty of power.
  16. 4x4Poet

    4x4Poet

    Messages:
    309
    I, too, think you've put the "cam" cart before the "compression check" horse. You're obviously right that you need to make sure the 350 is worth investing in a cam upgrade (or head upgrade, etc.) before forking over your hard earned $$.

    Somebody should be able to answer your question asking what the compression should be for a Goodwrench crate motor. I'm guessing it's the same for hyd flat tappet 350s:

    Hope for 160
    Expect 150
    Pray for at least 140.

    Otherwise, I'm pretty sure the Lunati voodoo cam with .437/.554 lift @ 0.50 has something of an RV cam's supercharger effect:
    The intake opens a little less than the exhaust while the exhaust closes a little slower (as mentioned above). This supposedly allows the exhaust pulses to create a bit of vacuum in the cylinder as the exhaust valve "slowly" closes that helps draw in the new charge. The 112ยบ LSA helps ensure a smooth idle. I'm probably making a mistake in my "analysis":rolleyes:, but the slight, "supercharger" effect does help this, otherwise, idle-up power range cam act a bit like a higher rpm range cam. In short, I think it makes for a good truck engine cam.
  17. redneckrick32392

    redneckrick32392

    Messages:
    1
    well if you want more overall power id fix the carburetor issue. i had a quadrajet on my 350 chevelle and it was emberassing too. i upgraded my intake carburetor and distributor to hei and its made my engine feel like a completely different motor. the throttle response is amazing. summitracing parts are dirt cheap. i got the 600cfm street and strip carb($250) and stage 2 intake for lower to mid power range. the cam may be a hair cheaper but the fuel is where i think you should start
  18. Bret

    Bret

    Messages:
    1,982
    Location:
    CO
    GM 350 Crate Engine Build - Chevy High Performance

    Has some food for thought, some of it applies some doesn't. Before you get too deep into it look into swapping to fuel injection, maybe a 6.0l? It all starts pretty harmless and before you know it you have $4K tied up in a motor when you could get a later model FI motor for less than $2K. My 383 has a very mild cam (smaller than the HT383) but it does very well. It supposedly is running a little over 300hp, but over 450ft/lb from around 2K.
  19. baxter650

    baxter650 SILVER Star

    Messages:
    1,561
    Location:
    Grand Forks B.C.
    Could always try changing out your 1.5:1 ratio rockers to 1.6:1s
    Will give you a little more valve lift and a little quicker valve action but won't change any other of your cams characteristics.
  20. baxter650

    baxter650 SILVER Star

    Messages:
    1,561
    Location:
    Grand Forks B.C.
    If you are going to call a cam co. have all your engine, drivetrain info on hand.
    Tire size, gear ratios, wheeling weight, bla bla bla, the more info you give them the better they can help you.

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