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Chevy Rods

Discussion in '"Stock" Alpine' started by Alpine Addict, Nov 25, 2020.

  1. Alpine Addict

    Alpine Addict Platinum Donor Platinum Level Sponsor

    I am planning to install Chevy rods on my 1725CC engine.

    Does any one have a source for purchasing the Chevy rods?
     
  2. puff4

    puff4 Gold Level Sponsor

    I would think Summit Racing would have them, no?
     
  3. Bill Blue

    Bill Blue Platinum Level Sponsor

    Probably not. As I recall, the desired part is a six cylinder item, usually rebuilt. Not likely a "racing" supplier would have them. Eight cylinder rods? Count them by the hundreds.
    Maybe NAPA.

    Bill
     
  4. sunalp

    sunalp Platinum Level Sponsor

    I got mine on Ebay. I think the seller was Jamsi. I had my machinist check them out before I bought them
    and they were fine. Cost about $150 for the set of six. Still have two!
    Cheers!
    Steve
     
  5. Tom H

    Tom H Platinum Level Sponsor

    Looking at Jan's Tedder Project in Issue 14 of the Marque, he used rods from a Chevy 5.7 liter V8 . might be easier to find.
     
  6. jumpinjan

    jumpinjan Donation Time

    Why? You have to do a lot of expensive machining. And the benefit is what????
    The rods are what they call the 5.7 rod. It's used in the 6 & 4 cylinder chevy engines. Typically, you can find them in the Mercurser 4-cyl. boat engine too. Its the same are the 4-cyl car engine. Yes, my article that I wrote has some good info.
    Jan
     
  7. alpine_64

    alpine_64 Donation Time

    Manley do aftermarket chev rods that are lighter and stronger and not to expensive either.

    If you are doing the chev rod swap.. What pistoms are you planning to use? Custom or off the shelf?
     
  8. Tom H

    Tom H Platinum Level Sponsor

    Jan, As you say, the rods are called the 5.7 rod. I assume that means it's from the Chevy 5.7 liter ( 350 cu in) v8 engine. Is that not correct? Is it not likely to be easier to find these V8 rods at common auto parts places than 4 or 6 cyl?

    Tom
     
  9. spmdr

    spmdr Donation Time

    AA, yup, do tell more. OEM, or aftermarket rods? OEM or aftermarket pistons? What RPM are you planning?
     
  10. Barry

    Barry Platinum Level Sponsor




    Tom,

    In this case, "5.7" refers to the connecting rod length (center-to-center) rather than to the engine displacement. Some (not all) SBC connecting rods are 5.7" in length, but the width of the "big end" of a SBC connecting rod is too narrow to be used with a 1725 crankshaft.

    The connecting rod in question is from a Chevy 250 cubic-inch "straight six" engine (or a Chevy 153 cubic-inch "four banger" engine) and has a 5.7" center-to-center length and a 2.000" rod journal diameter and has a greater big end width that is compatible with a reground 1725 crankshaft. The crankpin diameter of the 1725 crankshaft can be "ground" to reduce the diameter from 2.125" to 2.000". With a "good" crankshaft, "offset" grinding can increase the stroke from 3.250" to 3.3125".

    I have not done a "Chevy rod 1725 engine", but I remember stuff.
     
  11. spmdr

    spmdr Donation Time

    Hey, ...I JUST noticed this thread is in "STOCK " Alpine ..... ??????
     
  12. Bill Blue

    Bill Blue Platinum Level Sponsor

    The "stock" forum is also for those who do not mind improvements. A Chevy rod engine is a definite improvement. Just ask the owner who has one.

    Bill
     
  13. spmdr

    spmdr Donation Time

    ...MY favorite kind of "stock". Just checking.

    ...It looks like "Stock" covers ALL the ground, ...with a Stock (Sunbeam) engine....?

    ...on the Street?
     
  14. Bill Blue

    Bill Blue Platinum Level Sponsor

    Yes, since "improvements" are considered stock, I contend the DuraPine is the best stock Alpine on the road.:) It certainly is improved.

    Bill
     
  15. husky drvr

    husky drvr Gold Level Sponsor

  16. Tom H

    Tom H Platinum Level Sponsor

    The definition of the "stock" category on the forum is :
    For those striving to preserve the period look & feel of their car (but don't mind improvements in carb, brake, wiring, etc.).
    I think "tweaking" mods to the basic engine such as bored, stroked, Vizard mod to head, electric fans for radiator, etc, still fit what most of us think of as "Stock".

    Barry, thanks for the clarification about the Chevy "5.7" rods. One small correction to your comment: "The crankpin diameter of the 1725 crankshaft can be "ground" to reduce the diameter from 2.125" to 2.000". With a "good" crankshaft, "offset" grinding can increase the stroke from 3.250" to 3.3125". Theoretically, you could offset grind the crank by 0.125". In my engine I offset ground the rod journals by 0.050" , yielding a stroke increase from 3.25 to 3.350, along with a bore increase of 0.037" (to a common 82.5 mm), yielding a displacement of about 1819 cc. I bought new custom-made pistons from Venolia, plus a Vizard mod to the head, and a Weber 32/36 carb. All in all it seems to have made my Alpine a reliable car with excellent power at highway speeds (with an OD).

    Tom
     
  17. Bill Blue

    Bill Blue Platinum Level Sponsor

    WHAT!? I smell a conspiracy to mitigate the wonderfulness of the car that resides in my basement, or South Carolina, depending on your definition of "car".
    Proof of my claim? Usable power that no Alpine has shown been able to exceed, as shown by the 20-80 acceleration time. Not even Tigers, which surprises me. Economy of 30+ mgp at interstate speeds (70 mph, no air) and the statement by one guest driver that its the best Alpine he has ever driven. Even better than Miatas.

    Bill
     
  18. Tom H

    Tom H Platinum Level Sponsor

    Bill, No conspiracy" here. I think most of us have absolutely no doubt about the performance of your car. Some may puzzle that it was not quick enough to avoid getting rammed from the rear, of course :D. But I'm not in that camp. But clearly discussion about your car belongs in the Modified section. Heck, it's so modified that even you don't call it an Alpine, but rather a Durapine.

    Seriously, Bill I'm still not sure what is more impressive; the original concept, design, creativity, and quality of work you put into the original Durapine, or the rising from the ashes, Phoenix-like, to tackle the task and build the new creation. Looking forward to seeing Durapine II on the road.

    Tom
     
  19. Barry

    Barry Platinum Level Sponsor




    Tom,

    You are correct about the increase in stroke. I correctly calculated the increase in the crankpin radius and then incorrectly forgot to double it to determine the increase in stroke. The fly in the ointment is that many engines no longer have the original 2.125" crankpin diameter which decreases the possible increase in stroke. IMO, the small increase in stroke / displacement is a lot less important than the huge decrease in rotating mass with the Chevy rods and a rebalanced crankshaft.
     
  20. spmdr

    spmdr Donation Time

    When it come to ROTATING Mass, the Flywheel is a VERY BIG nut to crack, rods not so much.

    For it's displacement, the Alpine has a LOAD of RECIPROCATING Mass.

    It's the stock rods/bolts that have problems with the reciprocating mass.

    ...and YES, I know there are other engines that make the Alpine look, well, ... not so bad.
     

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