302 rebuild kit question

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

  1. bryson123

    bryson123 Member

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    there are so many mixed opinions here haha
     
  2. bryson123

    bryson123 Member

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    Did you say earlier that a double pump carb wont help my situation? I read in an article that it is what i should probably lean towards?
     
  3. groberts101

    groberts101 Member

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    All I was getting at was that if you're in a taller gear and quickly go WOT the booster signal of mech sec's will drop away more quickly(2bbls immediately open on each side of the manifolds center plenum divider) than a well calibrated vacuum secondary would(with only 1bbl initially used until actual airflow demand opens the other bbl). The motor will struggle a bit harder and longer to rpm into its sweet spot in certain driving scenarios. The dual-plane will help a bunch but you just need to learn how the motor needs to be driven, most efficient and responsive powerband, to avoid bogging or lugging it, is all. These cars are lighter than many other old cars and along with the 5 speed the 650 double pumper will work just fine.

    I'm using a rpm air-gap dual plane on my deal too but it's a bigger wider 351W manifold that's been cut up and welded on for my hi-port conversion. My little 302 has a slightly smaller cam than yours but should still easily pass 400 horsepower. This is the one I plan on using for mine. If I wasn't going to be using an automatic trans I'd likely lean towards a mech sec 750 one model up from yours.

    https://www.holley.com/products/fuel_systems/carburetors/hp/street_hp/parts/0-82750
     
  4. bryson123

    bryson123 Member

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    So I just had to take the piston to deck clearence again and for some reason I got .028. I’m really confused now because I don’t see how this is possible... i has the rods resized but not enough to make that big a difference is there something wrong with me and my setup or is it all good?!?!
     
    Last edited: Jan 20, 2019
  5. bryson123

    bryson123 Member

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    Tell me if I’m wrong but could it be I have a 8.229 deck block?? Because the difference would then be 8.229-8.206= .023 and then add .006 for the piston depth if it was 8.206 which = .029 down?
     
  6. groberts101

    groberts101 Member

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    What year is the block? Casting number will tell you that. You must be talking about the mid-70's smog motor run where Ford increased deck height to further kill compression? 1974-1976 casting numbers IIRC. My block was a taller '74 casting which has finally ended up cut to 8.165". All the castings are similar.. just milled to different deck height spec's to make it cheaper for Ford to adjust things back then.
     
  7. bryson123

    bryson123 Member

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    Ok that’s what I thought I am not home at the moment as I moved back for school but he is going to get the block taken care off. Here is my other question I am assuming it is going to HVe to be milled now... should I have them zero deck it?
     
  8. dyent

    dyent Member

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    for all the hassle, trouble you had, could have purchased a crate motor with a 2 year warranty and driving it.........
    David
     
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  9. bryson123

    bryson123 Member

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    That’s true haha but the knowledge I’ve learned from this and experience has been worth it. That’s the main reason I got this car and decided to do the motor myself is for the skills learned
     
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  10. bryson123

    bryson123 Member

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    Plus even with the machine work and having to block the deck now I’m still way under a crate engine.
     
  11. groberts101

    groberts101 Member

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    Yes cut the deck to 0 for best results. Be sure to measure multiple piston to deck heights at each corner so you know the correct amount which needs to be milled to reach a nominal deck height of 0.
     
  12. bryson123

    bryson123 Member

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    Ya I measured every piston and they all came out to .028
     
  13. groberts101

    groberts101 Member

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    Here's what I would do. Nix cutting the block and trade your 5.090" rods in towards a set of 289 AFTERMARKET rods which are .025" longer at 5.115. That will take up all but .003" of that extra deck/piston clearance without more machine work being necessary(some people hate having their cars in paint jail and I feel the exact same way about machine shops!).

    Even at .003" piston/deck height I'd still go for a MAXIMUM 4.030" bore gasket with no more than .040" compressed thickness to get those last few cc's of compression out of this little motor. You'll be just shy of 10:1 but about as close as you'll get with those pistons and milled 54cc heads.

    BTW, my "math" comes out to a 8.223 deck height assuming no stacked parts height losses or gains.
     
  14. bryson123

    bryson123 Member

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    I see your point but I preset had the rotating assembly balanced also the rods had been pressed with arp bolts and resized. My issue with that is I would then have to have them pressed out and rebalanced and the arp bolts and all that work is scrapped. I don’t mind the machine work cause it would be cheaper than replacing the rods I think. But I will ask machine shop maybe I could mill heads down even more? I mean if they had to deck the block I would just have to take the rotating assembly out. Then this block would be really prepped for the aluminum heads
     
  15. groberts101

    groberts101 Member

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    I get that but the 289 rods or barely 5 grams more than the 302's weights and wouldn't require a second thought to just run it. Bigger thing is that they are all balanced relatively the same. But you are most certainly right, there are pro's and con's to each way you go here. Too bad you didn't get a little more experienced direction before you chose the parts combo but at this point it's basically best case to just follow the best route to end up with as strong a running combo as possible. We've all been there, for whatever reason just making due with what we have, all part of the whole learning process.

    As for milling the heads more and not worry about the piston being in the hole?.. no bueno. Plus you can only go so close to the intake seats during the milling process and there are other geometry and flow loss issues that crop up when you try. Here's that cool math link again. Maybe go play to get your final numbers straight before any machining takes place.

    https://www.eaglerod.com/

    PS. you should seriously consider degreeing in that cam before finalizing head gaskets on this deal. What clearances you take away on head stack height could potentially bite you in the rear later on when it comes to piston/valve clearances. Then you're into piston notch flycutting after another full disassembly. Easy to just rough check even without the cam in place simply by mocking heads with 2 checking springs(I/E) up and checking PTV clearances @TDC. If it is substantial well over .150"+.. you have plenty of wiggle room to tighten compression up. Remember you will be subtracting that .028" deck cut, around .040"-.050" head mill, and any gasket thickness reduction you may be considering shooting for.

    PSPS. the real beauty of those expensive cometic gaskets(I seem to keep pushing like a stock owner would,LOL) is that they can be made in almost every thickness between .027" - .120" to help you dial in piston to head clearance to stay out of trouble during TDC piston rock.

    https://www.summitracing.com/search/make/ford/engine-size/5-0l-302/engine-family/ford-small-block-windsor/brand/cometic?SortBy=BestKeywordMatch&SortOrder=Ascending&keyword=Cometic Head Gaskets&N=4294951343+4294951339+4294951337+401528+4294924325+4294884142
     
    Last edited: Jan 21, 2019

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