RV cam in a 10.2:1 compression sbc?

Discussion in 'Engine Topic' started by Michael Sammy, Jun 23, 2019.

  1. Michael Sammy

    Michael Sammy Member

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    I have a 400 sbc that has 10.2:1 compression. Would I be able to run a RV cam in it to get that low end torque up? I have been reading conflicting arguments online where some people claim that it works fine without detonation, while others are saying there will detonation issues with today's premium gas.

    Also, does anyone know of a good roller rv cam? I have bad luck with wiping cam lobes due to issues with getting RPM up fast enough or engine stalling out. Happened to me twice lol, so looking to go roller so I do not have that issue again.
     
  2. 1980RS

    1980RS Veteran Member

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    If you want to keep detonation down make sure the cam is on a 114° LCA. A 106 or 108° will make more bottom end but then it will hurt driveablity a bit plus your idle will not be as good either. Crane makes some nice street and RV cams that work well in 400's.
     
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  3. tom3

    tom3 Veteran Member

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    Running a Performer Plus cam in my 350 with 9.8:1 or so on 93 octane gas with no problems. Running 1.6:1 rocker arms. Timing sets at 14 degrees before with that cam too. Edelbrock does sell a 400 version of that cam, flat tappet though.
     
  4. Lowend

    Lowend Administrator. .a car, a man, a maraca. Staff Member Lifetime Gold Member

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    10.2-1 with iron heads and a low duration cam is asking a lot of pump gas.
    Isky makes some very nice "mellow" hyd roller cams
    Without knowing the rest of the combo specs (heads, converter, gears) I can't make a great recommendation
    The Isky RR-265/272 is probably a good starting point
     
  5. Michael Sammy

    Michael Sammy Member

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    The heads are iron 76cc heads. They are the 1972 factory heads with just larger valves and some porting work done by a machine shop. The converter is a 2200-2500 stall, and Currently has 4.56 gears.

    The gears are going to be changed out for 2.56 soon, so I was looking to swap the cam to an RV cam so it could have the low end torque, but guess it's not going happen with that compression ratio.

    Wish I knew then what I know now. Would have gone a different route and used dished Pistons so I could run a nice set of sbc aluminum heads and get a 9:1 compression ratio.
     
  6. Proximity_Alert

    Proximity_Alert Member

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  7. jeff swisher

    jeff swisher Veteran Member

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    I have done it many times with the 350" engine ..Lots of compression and smallish cams but small chamber heads were the key.
    Smaller chamber heads are less detonation sensitive .. at least in my testing.
    Just because a cam has a 114LSA does not mean it will close the intake valve later than another cam on a 110 LSA.. you need to look at intake valve closing point, if you want less pressure in the cylinder you need to close the intake valve later.

    I ran the 268H in many engines with as much as 10.87 compression ..ran it in that 10.87 for many years and nearly 100,000 miles 225 psi cranking pressure. very happy at 38 total timing and 91 octane.

    But 58cc chamber head.
    76cc heads were pigs in my testing.
    Another thing i did to all my builds was rough up the entire intake runner during porting to keep fuel atomized.
    And all sharp edges were removed from the combustion space. Blend the sharp edges on the edge of the chambers and valve reliefs etc.

    To take an old engine with no trick intake runner finish and sharp edges and large chamber and start building large amounts of cylinder pressure would be a trial and error thing more than likely.


    The finishes and prep are key to making it work that could be why you get conflicting reports as to if it works or not.
    No idea how large your cam is now but I would not be afraid of a 220@ .050 cam.

    On the flat tappet failure i have not lost a cam since the 2007 era when ZDDP was reduced and I did not know about it.
    I run crower cam saver lifters now for my hydraulic and Howards direct lube solids for the solid flat tappet.
    Molly paste on cam lobes and lifter face and Gibbs /Driven break in oil and no other additives.
    All lifters spin in the holes. I do lube lifter bodies with the break in oil also.
    Engine is prelubed before firing it up.

    Some cam lubes will run off the cam if you let the engine sit for a few days before starting it.. the molly paste stays on it and does not dry out
     
  8. DesmoEd

    DesmoEd Veteran Member

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    I had Comp's 270HR in my 10.1-1 355ci Camaro motor when it had the TH350 automatic and it had tons of low end tq

    Motor was strong right off idle, done by 5500rpm, never had any issues with detonation running premium but I am running alum heads.

    I would not waste the time running a flat tappet cam, go hyd roller and don't look back
     
  9. Zspoiler

    Zspoiler Veteran Member

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    If you are going to run an "RV" type of cam .I wouldn`t fun any thing higher than 9:1 compression .So you can run pump gas.Otherwise you somewhat limit things of what you want to do.
     
  10. cadillac_al

    cadillac_al Veteran Member

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    You don't hear of many 400's that are low on torque. I'll bet the cam companies could give a decent recommendation.
     

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