Performance street SBC build

Discussion in 'Engine Topic' started by jakob stevanus, Nov 8, 2021.

  1. jakob stevanus

    jakob stevanus New Member

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    Hi I have a 70s 350sbc I am swapping in my 78 Camaro for the current 305. It is a z28 with 4 speed t10 and 3.73 posi rear end . Looking for advice on pistons , heads and cam looking to make high 300s in hp and good driver aswell . Maybee occasionally a track day . O will be sending block to machine shop to be bored .030 and just. Need to decide on parts I also have airgap performer for it and street Demon 650

    Thank you .
     
  2. sandlapper

    sandlapper Veteran Member

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    Suggest bore only so far as it takes to clean & straighten bore; if it's perfect at +0.020" then leave it there.
    NPR supplies both shelf pistons & rings in +0.010" & up
    Most of the other old line suppliers offer shelf pistons & rings beginning +0.020"

    Thicker cylinder walls are more stable, cool better, seal w/ rings better and are more efficient.

    For +20 years, all OE have gone to thin metric ringpacks; well-proven win-win. You should do likewise when you choose pistons & rings.
     
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  3. jakob stevanus

    jakob stevanus New Member

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    So don't bore .03 if i don't Have to ? . Any suggestions on brand pistons and rings . Heads and cam ? This is my first build car wise . Have done dirt bikes and Harley's the past 10 years .
     
  4. G72Zed

    G72Zed Veteran Member

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    I really like the Mahle Power Pak piston kits they sell, 4032 forged with metric ring pack.

    Will you be getting it decked as well?

    Upper 300 hp level is easy to achieve. Many choices for Heads and cam, 100's actually. The GM 602 crate make 375-390+ HP, all with only Vortec Iron heads, 9:1 CR and small hyd. FT cam. It uses a dual plane as well.

    What's the budget ?? that will denote some direction on options.
     
  5. jakob stevanus

    jakob stevanus New Member

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    Only decked if I need to , budget Is around 3500 give or take 500 after machine shop work . I have carb and intake already / ignition . So mostly heads , cam , pistons and rings , billet water pump and looking at roller rockers. I was looking for mid to high 9s in compression. Any thoughts on flat top wisco pro Street with 64cc heads should give me 9.8.1 it looks like . Are thee promaxx aluminum heads any good or flowtec . No clue on cams for me . I have a dp air gap new intake . Also not sure on intake head cc size 184 cc or bigger , etc thansk
     
  6. jeff swisher

    jeff swisher Veteran Member

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    I will second the Mahle Power Pak piston kits.
    The cast pistons today are not what they were 25 years ago.
    I used to always run cast in my sbc stuff 11 second 7500rpm deals but the last couple I put together for myself with the same stuff but new cast all died.

    You can get aftermarket heads that are ready to bolt on and then there are the same part number heads that may have extremely tight guides or sloppy guides and you can get a good or bad valve job.

    Would be nice to have the money left over to buy aftermarket heads and have a reputable shop go through them.

    Your HP goals are not high.
    Your 1978 305 engine could donate the heads.

    Yea probably very small valve 1.72-1.50's
    Now I will say this for giggles.

    Buddy bought a 78 Nova 305 2 barrel engine was in it and he wanted to go quicker.
    He had planed on AFR heads but that would bo down the road a bit and I needed to get his car built and make it go straight.
    Took the 350 he found and had it bored .040" over as it took that much to clean it up.
    Decked it so the pistons were .005" down the hole and ran .039" head gasket.
    Flat top cast pistons USA made 345NP Not a Hypereutectic.

    I bowl ported the 305 small valve heads and lapped the stock small valves and back cut them with a
    Radiused back cut. 110 seat pressure springs.

    Chose a 280H cam [email protected] .050 .480" lift 110 LSA stock rockers and pushrods.
    Local cam grinder made the cam for me.

    Here is where I got sporty with the '78 Nova.
    9" Ford was hung out back with a couple extra leafs from a Ford truck tucked under it and 3 of the long springs shifted forward under the spring eye and front 1/2 of the leaf spring pack was clamped together.

    TH 350 trans and 4.57 rear gear.
    Topped those tiny valve heads with a 12" tall tunnel-ram and 2 1405 edelbrock carbs with stock jetting.
    22 initial timing and 41 total as those heads had some slow flame travel.

    First pass he ever made down the strip was this thing and it went 12.8 et.
    At the end of the night with more tire hook it went 12.51 at 111 MPH.

    Converter stalled to 2200 rpm and shifts were made at 6700 rpm
    Not bad for junk 305 2 barrel heads and an old school cam grind.

    Your goals can be reached with about any head out there.
    I do not know your skill level but to take valves out of a head and lap them is a no brainer.
    Bowl porting is not something hard to grasp either.
    Plenty of books and videos out there.

    Save the extra money for tires and fuel.


    Buddy forgot the idea of AFR heads and I built him some ported 601 heads 1.94-1.50 valves and stepped up the cam to a 292H [email protected] .050 on a 110LSA.
    Car went 11.94 at 115 MPH.. his shift points were too high and I feel ET could have been much better if he would have shifted before 7400 RPM OH well his car. 1.6 60 foot times 275-60-15 MT drag radials.
    91 octane pump gas no power adders, 3300 lbs.

    That should give you some ideas.
    If you like aftermarket heads some here will for sure chime in.
    I have built a couple with the Edelbrock 5089 heads and those had some tight guides that needed fixed but other than that I liked them.
     
  7. jakob stevanus

    jakob stevanus New Member

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    Thannk you for that info I will definately consider all points . I have decent mech skills with bike motors mostly Harley and I do lots of car work minus have never done a car engine I can't weld also etc , I should mention the 350 I bought has a set of the 193 swirl heads on it now but I hear they are not good at all . My 305 is not stock to 78 can't remember year it is ill check the casting #s tonight as well as the casting number on the heads off of it . It had a 350 from factory as it is a z28 with a 4 speed
    t-10 and 3.73 posi rear end. First gear is a 2.64 :1
     
  8. jakob stevanus

    jakob stevanus New Member

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    I can weld also **
     
  9. muscl car

    muscl car Veteran Member Lifetime Gold Member

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    Doesn't take much to get a car such as your Camaro to get into the 12's and have plenty of power on the street
     
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  10. jeff swisher

    jeff swisher Veteran Member

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    Nothing wrong with the swirl port if you are in to bowl porting they work very well.
    Leave the vane in them and they will work just fine.

    I would use whatever head you have without any cracks and pick the one that has good guides that needs nothing.

    If all the valve stem tips sit at the same height chances are very good that all the guides are fine.
    Almost all the old school heads (cast iron) i have ran never needed guides.
    I have only had 2 that needed guides.
    3 if you count the recent 601 305 heads I just removed after 13 years and over 200,000 miles of hard use.
    Those heads already had over 200,000 miles on them when I got them.

    Seeing worn guides in aluminum heads has kept me away from aftermarket heads for my personal builds.
    I drive a lot of miles and wish to keep the engines together as long as possible.
     

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