302 rebuild kit question

Discussion in 'Technical' started by bryson123, Jul 11, 2018.

  1. bryson123

    bryson123 Member

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    hi all my dad and I are rebuilding a maverick and just got the word that the motor is done from the machine shop!!! So it’s a 302 that they bored 20 over etc. decked all the good stuff and I am trying to order a rebuild kit. I have one in mind but have a few questions about it before I proceed.
    https://m.ebay.com/itm/SBF-FORD-289...GINE-REBUILD-KIT-CAMSHAFT-PISTON/132446556500
    This is the kit. It says that the compression will be estimated around 10.3:1 or less. My questions are is this compression to much to run pump gas in California? I am shooting for around 400hp will be utilizing aluminum heads as well. Any feedback would be sweet!!
     
  2. groberts101

    groberts101 Member Supporting Member

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    It's never wise to final size a cylinder bore without the piston on hand to actually measure for proper clearance.

    And those uni-position pistons have 8cc valve reliefs which will prohibit anything close to 10:1 unless you have the block milled for a 0 deck height and run very small heads with around 54cc chamber volume.
     
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  3. bryson123

    bryson123 Member

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    Dang wish I saw this earlier. My machinists says that with the block how it is at stock deck height I should be around 9.3 if I chose to do a 54.5cc head. If I were to zero deck the block would I run into clearance issues?
     
  4. Maverocket

    Maverocket Bob Williams Supporting Member

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    With the cam you have listed piston to valve clearance shouldn’t be an issue, but you always want to check. You won’t get anywhere close to 400hp with those cam specs. More duration, higher lift and tighter lobe center will be needed to hit your hp target. With that comes the need for upgraded valvetrain components.
     
  5. bryson123

    bryson123 Member

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    ok, thankyou for all the advice would you say this would be a setup for mid 300hp then?
     
  6. Maverocket

    Maverocket Bob Williams Supporting Member

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    A rough guesstimate would be 260-300 range depending on parts combination. I’m not a pro engine builder but I’ve worked with SBFs enough to have a good idea.
     
  7. Krazy Comet

    Krazy Comet Tom

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    With a good set of AU heads, free flowing exhaust, etc I'd think at least 300, maybe 325-330.

    With similar spec roller cam(TF Stage 1), Twisted Wedge heads, flat top pistons without valve reliefs, 1 5/8 headers 2.5" full exhaust, etc, etc, my T-Bird would produce approx 335Hp. Dunno exactly how compression specced out but it had 170 Lbs cranking. That was on a std bore 5.0.
     
  8. bryson123

    bryson123 Member

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    so let me go over the complete list of what I plan on using with this motor. I had already ordered the kit above and have recived It so will be using everything there. I will be using a Weiand stealth intake, and Holley 650carb reccomended by a neighbor. Stock crank. With long tube headers. As for heads I do plan on using aluminum heads but to be decided on exact ones due to my current dilemma of making more power with the pistons I have. As well as using a good set of rocker arms Sorry for all the questions still learning here hahah.
    So if I were to try and squeeze more power out of the parts I have would it be best to have the decking milled down to zero deck? And then use a 54cc Head? I have already had the block at the machine shop for awhile and would hate to have it there longer but if the only way is to have it milled etc then so be it!!!
     
  9. bryson123

    bryson123 Member

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    Just for everyone’s info this is for a 71 302 block!!! Going into our maverick haha
     
  10. baddad457

    baddad457 Member

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    I did the math and came up with 9.78 to 1. That's with a 54 cc chamber, 8 ccs for the piston top volume and 9 ccs for the gasket.
     
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  11. baddad457

    baddad457 Member

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    You're already at close to zero deck with those pistons. 1.605+ 1.5+ 5.095 = 8.2. Nominal deck on a 302 is 8.206 If the block hasn't been decked already, you could have just a clean up pass done to square things up. I would mock up the crank and a rod and piston in the block and measure the clearance before going farther here. At least you didn't make the mistake of buying 1.585 pin height pistons like many do. Make sure and inspect those lifters before dropping them in the holes. The bottoms should be slightly convex (domed) I would also invest in a set of ARP rod bolts for the stock rods.
     
  12. bryson123

    bryson123 Member

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    Thats all I had done to the deck was just a clean up pass to prep for aluminum heads. I do plan on investing in all arp hardware As well as new pushrods. Honestly I’m sure we would be satisfied with 350hp since this is the first motor we have ever built. I see some conflicting ideas that this can would not be adequate for my goals. I might be able to contact the company and see if I can swap the cam for another what would be the cam specs that I should be looking for keeping in mind that this will be a Manuel t5 that will be driven on the street/ once and awhile track days. As for heads at the moment i was thinking of the AFR 65s with the 58cc chambers or the canfield heads with 54cc chambers what do you guys think about this? Would i be better of with an even smaller chamber size to reach my goals?
     
    Last edited: Jul 19, 2018
  13. Maverocket

    Maverocket Bob Williams Supporting Member

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    Larry, the stage 1 TF cam is a step above the one posted. It’s also a roller instead of a flat tappet which offers more lift under the curve. This particular flat tappet grind is tailored to factory iron heads with poor exhaust flow.
     
  14. groberts101

    groberts101 Member Supporting Member

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    You're right. Depending on where he's at now for deck height.. over 10 to 1 can be had with either a 0 deck and thinner .036 head gasket.. or minus .005" deck height and .030" gaskets with 53cc chambers. Whatever heads are chosen I'd still mill for more compression because it never hurts a longer cam on the street and still allows better octane tolerance to some degree because the combustion space is more compact in such smaller motors like this one.

    Cometic head gaskets are pricy, at nearly half the cost of that entire rebuild kit, but customizable for bore size and thickness and fully reusable as well. Only caveat is the deck and head finish should be a bit smoother than normal to avoid fretting between dissimilar metals. Quality head bolts will typically diminish that tendency though.

    Cam is very old school tech.. nearly 50 years or more.. nothing special at all by todays standards. Look at someting with that same @.050" numbers but having shorter seat timing because that denotes more agressive lobe designs.. more average valve lift throughout the curve. Like Howard's or Lunati voodoo or comp cams extreme energy lineup. They'll all smash that old cam by 15-25 horsepower and make better average torque across the entire rpm range the motor will see. Those will need to be PTV clearance checked for sure but I'd lay small cash that lazy little slow ramped elgin.. or whatever it is.. will never be close enough to the piston to ever worry about contact unless severely floating the valves on a missed or unexpected downshift. But that's what rev limiters are for.

    I'd also lay small cash that timing chain won't stay tight for long either. Good durable long lasting parts cost bigger money. Whatever you do.. do NOT forget to balance that rotating assembly! Good luck with the project!

    Here's a 4.030" x .036" SBF head gasket.
    https://www.summitracing.com/parts/cgt-c5511-036/overview/make/ford

    Comp cam
    https://www.summitracing.com/parts/cca-cl31-238-3/overview/make/ford

    PS. didn't know Canfield was still making cylinder heads but aren't their exhaust ports raised up a bit? I'd probably stick with the AFR 165's and have them milled slightly for higher compression.
     
    Last edited: Jul 19, 2018
  15. greasemonkey

    greasemonkey Burnin corn

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    What head gasket are you using? They do make diffent thicknesses. And just an FYI. If you were to use a better performance piston it probably wouldn't be in the bore as deep. Cheaper rebuilder pistons are generally moved down in the hole to accommodate compression.
     

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