Long Rod 300 Build

Discussion in 'Small Block Tech' started by Duffey, Mar 6, 2018.

  1. Jim Nichols

    Jim Nichols Well-Known Member

    Duffey, If you use your old rockers with the shaft oiling I still would exchange them with a rebuilt set from Delta Cams or Rocker Arms Unlimited.
     
  2. Duffey

    Duffey Well-Known Member

    I've considered that, however the iron head 300 I bought had the heads redone 10k miles or so before the car was wrecked. The rockers have just barely perceptible play when I work them back and forth (not up and down). Is there other things I could check for? I kinda just assumed they would be easy to replace down the road if I ever really wore these ones out.

    I wonder what all rocker arm configurations work under stock valve covers?
     
  3. Jim Nichols

    Jim Nichols Well-Known Member

    Roller rockers with posilock jam nuts would probably hit. Some have used thicker sandwich style gaskets successfully. T/A carries them. I think the 340 stock valve covers look OK. Chris used SBC with adapters for his build. He wanted the finned OFFY's but they were $300. The Chevys had the same look for half the price including adapters.
     
    Last edited: Mar 21, 2018
  4. Duffey

    Duffey Well-Known Member

    Jim, I agree I shouldn't bog down other Jim's thread with questions about my build it they aren't related to interchange. I will start an actual build thread for my motor when I hear back about the condition of my block, because the title of this thread as well as many posts would be quite misleading.

    I do have a question related to something already discussed in this thread though--how much did it cost Chris to get his connecting rods bored and sleeved for the smaller wrist pins? I'm just wondering after you pay $200 or so for the Ford pistons and rings and the work needed to use them, how much more you would need to just get custom pistons...

    I suppose then a lot of people would urge you to go with the nascar rods, but I feel like the cap screw 350 rods are probably more than I need anyway. I'm mainly looking at the benefit of determining my exact compression ratio, not having to go so large on the overbore, and ease of installation (I feel I may have a hard time getting a shop to go the sleeveing method, even if I trust it).
     
  5. Jim Nichols

    Jim Nichols Well-Known Member

    Duffey, I don't know the cost, but his machinist is a friend. He may have got a deal. I'll ask him.
     
  6. Jim Nichols

    Jim Nichols Well-Known Member

    Duffey, Chris said it went pretty quick and price wasn't specified for that, but he thought it wouldn't be much. Another alternative is to have the pistons bored and reamed. I personally like the Hyper pistons better for a street motor as you can have tighter clearance to the bore and not have the looser cold piston rattle of the forged. I think Bruce chamfered the end for insurance but a straight sleeve would be fine. My guess under $150 to sleeve the rods vs $800 or more for custom forged pistons.
     
    Last edited: May 14, 2018
  7. Duffey

    Duffey Well-Known Member

    Ok, that's not too bad at all. Any chance you could get the particulars from him? Diameter of sleeve, material, procedure, etc? Me thinks I will have to have a "fabricator" machinist make the sleeves and my automotive machinist install them. I'm tempted to just go ahead and order the pistons and rings now...
     
  8. Jim Nichols

    Jim Nichols Well-Known Member

    I think he used DOM tubing that was close to pin size and bored rod for interference fit. I don't know Bruce. After tubing is pressed into rod it was drilled out for pin interference fit. I remember he said .004 to rod. Probably 1.0" DOM OD .049 wall .902 ID. I usually like .003 pin interference fit. Mic the pin hole, there is also .938 OD .095 wall .748 ID. That size would probably slip right in without boring the rod. Buick pin size .940, Ford .912. Any competent machinist can do this. Just a steel spacer bushing. I know he heated the rod and froze the bushing for easier press fit.
     
    Last edited: May 14, 2018
  9. Jim Nichols

    Jim Nichols Well-Known Member

    You could also stake the bushing like these oil galley plugs:
     

    Attached Files:

  10. Duffey

    Duffey Well-Known Member

    Thanks a bunch Jim, I guess as long as the shop has a rod reamer they shouldn't have a problem.
     
  11. 300sbb_overkill

    300sbb_overkill Well-Known Member

    Would be $699 for the AutoTec pistons with pins and rings, would have to change the bore diameter and compression distance and possibly the dish volume which should all be included in the price. The price went up because they are having the Buick .940" wristpins made now instead of selling them with the .945" LS wrist pins. Because the Molnar aftermarket rods have the .940" Buick size in them.

    If you used different rods that didn't have the Buick wristpin size you could get away with getting a set of LS inverted dome AutoTec pistons for $550, just change the wristpin size, bore diameter, compression distance and dish volume to what you need. all the changes should be included in that price. These don't include the rings though just so you know.

    Improving on the HRM 300 stroker build, a set of sbc small journal aftermarket 6.00" rods would of saved a lot of deck milling to use the 307 olds pistons and they would of had MUCH better rods than the factory cast ones. Something like these;

    https://www.ebay.com/itm/SIR6000SBL...014603&hash=item590be6cff7:g:A70AAOSwO4Ra6eE7

    Of coarse the wristpin hole would need to be opened up .053" from the sbc .927" size to the .980" for the 307 Olds wristpin size.(I think you can get the Olds pistons as hypers if I recall correctly?)

    If you go with the sleeves, then make sure the wristpin holes on the rods are generously chamfered on both sides and after the sleeves are installed they need to be swedged using a press with the same angle dies on both sides to hold the sleeves in.(skipping this step they will almost certainly fail)

    Mild steel should be fine for the sleeves, IIRC they used around a .005" press fit and then honed the inside to size afterwards.

    Its your lucky day! Look what I found;

    https://www.ebay.com/itm/Small-Chev...147452?hash=item25f5f337fc:g:3zcAAOSw3K1ay47f

    Now you don't have to sleeve a set of rods, just have the above ones the holes opened .046" IIRC the Ford pistons have the .912" pins and the ones in the link have .866" holes! They are only .010" shorter than factory sbb 350 rods too! Of coarse the big end needs to be narrowed from .940" wide to .845" wide. Take .078" off of the non-chamfered side and .017" off of the chamfered side, good to go.

    I can't imagine anyone putting an offer in on those rods so you can probably get them for less than $200! I would start at probably $175. GL

    NOOOoooooooooooooo, don't do that!:eek:
     
  12. Jim Nichols

    Jim Nichols Well-Known Member

    That picture is not the best example. I meant to stake the bushing itself, not the cast rod. I do believe with .004 interference it won't go anywhere.
     
  13. Jim Blackwood

    Jim Blackwood Well-Known Member

    Those rods Derek found look pretty good. One of the better options out there I'd say.

    You need to pay particular attention to the ring package and spacing though, otherwise your piston choices just went to H*ll. The primary advantage of a custom piston in this scenario is that you can specify wrist pin size and location. If you look at the pistons below, this is with a 1.25" compression height. Look at the space between the wrist pin and oil ring. Venolia likes a 1.2-1.3" CH meaning there's just .050" there to play with. Now, the wrist pin size, going from .750" to .940" means you'd exceed the 1.2" spec by .040". So a non-standard ring package will be needed to stay out of the ring package with this rod/piston/block combo and the Buick wrist pin. The 300 block is .644 shorter, so the maximum rod length to stay in spec with this piston, a Buick wrist pin and a 300 block is... 6.316". Sorry. To use that rod you'll need a custom piston with a tight ring package. Or, you can put the wrist pin through the oil ring. Also look at the weight of those 3/4" wrist pins below. I screwed up with the teflon buttons but compare the pin weight to the 200 grams or more for stock Buick. Of course you can get lighter pins in the Buick diameter, but not that light.

    A word about piston materials. First and foremost, there are at least a couple of alloys used in making custom forged pistons and with different rates of expansion. The newer alloys expand less with heat. So I'm not sure that Hypers really enjoy any advantage there. Before placing an order it'd be a good idea to ask the piston maker(s) that exact question. Is there something inherent in the metalurgy of cast aluminum that makes it more thermally stable? Maybe, but I've not seen the proof.

    Now a 6.4" rod with a 3/4" wrist pin may not exist and I'm not completely convinced that small a diameter wrist pin is the best idea anyway, so the best bet is going to be to look for a 6.3" rod. Chances are you won't find a standard piston to work with it, so look for a deal.

    Jim
     

    Attached Files:

  14. 300sbb_overkill

    300sbb_overkill Well-Known Member

    Jim, he was planning on using sbb 350 factory 6.385" rods with the off the shelf Ford cast pistons, that's what all the sleeving the wristpin hole talk was about.

    The 6.3750" rods I posted are only .010" shorter with an already smaller hole that can simply just be opened up for the Ford off the shelf pistons with an already engineered ring placement.
     
    Last edited: May 16, 2018
  15. Jim Blackwood

    Jim Blackwood Well-Known Member

    Is that going to work? Seems kinda tight. What's the CH on that piston? (Also is there a forged version of that piston available?)

    Jim
     
  16. Jim Nichols

    Jim Nichols Well-Known Member

    Jim, Same piston Chris used in his build. 1.2" compression height.
     

    Attached Files:

    300sbb_overkill likes this.
  17. Duffey

    Duffey Well-Known Member

    Yeah I had forgotton that the standard bore on those are 3.780, I remembered them being 3.800. After I hear back from the machine shop and confirm .030 over will work I will order them.

    Come to think of it, didn't Chris have a set that he wasn't able to use?
     
  18. Jim Nichols

    Jim Nichols Well-Known Member

    Yes, He did. My guess is he has got rid of them by now. They were the uncoated 1.19 compression height.
     
  19. Duffey

    Duffey Well-Known Member

    Well those are the ones I was going to order anyway, but my guess is shipping would probably make it more than what I could get them from Summit for if he is trying to recoup his investment. If he even did still have them...

    I've been snagging bearings as I see them pop up for cheap. Still need rings/pistons, rod bearings, and the seals for the bottom end. Is there a good place to get the seals?
     
  20. Jim Blackwood

    Jim Blackwood Well-Known Member

    Well I guess if they work they work. You say he used the 340 or 350 rods with those? What did he end up with on the deck-to-piston dimension?

    Duffy, are you going to snag those rods Derek found?

    Jim
     

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