A guide to building the lil guy. The Mighty 300

Discussion in 'Small Block Tech' started by Joe65SkylarkGS, Oct 27, 2009.

  1. Jim Blackwood

    Jim Blackwood Well-Known Member

    I have the DXF file now but I've misplaced my waterjet guy's email address so I might have to go by there Monday. These spacers will be used to bolt a 300 blower intake to the 340 block, which will later be used on the 300. The plan right now is to cut down a 2bbl intake and modify it to mount an Eaton M112 directly to it in the lowest reasonable position.

    Scored a set of Carillo take-outs for just under a C-note. Very light at 530 grams. The big end has a 2.021" bore so the rod journals will need to be ground for those inserts, which I don't have yet. Should be about a 1.900" diameter. My rod journals were 10 under anyway so this should get me back to std for that size and I can get the clearance set tight. I could also consider a slight offset grind but for less than .080" additional stroke I'm not sure it is worth it. The width will have to be cut down about .050" on the big end. Pin diameter is .827" I could also de-stroke it a little to make the engine slightly oversquare, but again probably not worth it.

    If you followed the piston discussion in the TA 300/340 head thread below, based on my past experience with Venolia I think I can say with some assurance that I could get about a 450 gram piston made, and use about a 80-90 gram wrist pin. With that light a reciprocating assembly I am looking into what it takes to zero balance the crank. That would make it possible to use a SBC flywheel and simplify the damper choices. If those pistons can be made with about a 30cc dish that matches the head chamber the TA Rover heads could be used, and make use of the squish areas. I'll be calling Venolia before long to ask.

    Using a SBC flywheel significantly reduces the cost of the build. Probably by about $300. Only one bolt hole has to be slightly elongated for it to match up. I have an aluminum one on my 340 right now, it has a counterweight bolted on the back side. With a $300 or more price difference in the flywheel, a $300+ difference in the bellhousing compared to 215/Rover engines, and about a $200 difference between using the HTOB and an external slave on the clutch, that is enough to offset half the additional expense of the TA head bare castings or pay for the custom forged pistons outright. Unless Mallory metal has to be used to balance the crank. We'll see.

    Jim
     
  2. Jim Nichols

    Jim Nichols Well-Known Member

    Jim, Will you adapt the starter to work with the Chevy 153 tooth flywheel or use the Buick/Jeep 160 tooth ring gear on a 168 tooth Chevy flywheel?
     
  3. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    Are you sure that isn't a 2.015" housing bore size?

    Would be for the Honda rod journal size of 1.889", the same size gsjohnny uses in his dragster IIRC.
     
  4. Jim Blackwood

    Jim Blackwood Well-Known Member

    Very likely Derek I just measured one and got 2.0085" on a quick check. Who knows where the seller came up with that 021 number? They'll likely as not need to be resized so no big deal. Is Johnny running a forged crank? These are nice rods anyway, I'll inspect them closer next week and maybe post a photo. Lots of these available for around $100-$150. With that price the money can go in the pistons and the whole shebang comes out not a whole lot over 1100 grams for piston, rod, pin and rings. The 6.2" rod length makes for an easy fit between wrist pin and ring package. So that call to Venolia is drawing ever nearer.

    I would love to know what it would take to zero balance one of these but no answer so far.

    Jim, on the flywheel I'm not entirely sure. The flexplate I have off a SBC is 167 teeth and the SBB 160 tooth ring gear is about 5/8" smaller in diameter. So that one can be cut down, which is pretty simple on the lathe. No idea if the 153T will be large enough. Until I do, better safe than sorry I guess. But when I look at aluminum SBB flywheels for $600 and 2nd hand SBC for maybe a couple bills or even less, well I just need to know.

    I just got the test pattern for the intake spacers and it looks right on so Ken will run these in 5/8" aluminum plate probably this week or next. That should let me make a new blower mount that will bolt to either the 300 or the 340 (with spacers). I'm still evaluating if it is a worthwhile effort, but I think that at least in the long run it will be. Not so much short term.

    Jim
     
  5. Jim Nichols

    Jim Nichols Well-Known Member

    Jim, I'm the one who helped figure out the Chevy flywheel for Chris. I thought it might be easier to use the 153 tooth flywheel and starter. Chevy uses both 153 and 168 tooth flywheels with no changes to block. The difference is in the starter. I'm thinking a little machining of starter mount may work. You can get a custom Billet steel flywheel like Scott did for his LS4 for around $400.
     
  6. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    With the 2.008" housing bore size, you have your choice of 1.850" or 1.889" bearings! With the extra .140" of stroke you can get an extra 12 more cubes if you wanted to.

    With the rods being 6.200", they will actuate away from the cam more than rods that are longer so cam clearance shouldn't be an issue if you went with the extra stroke.(just putting it out there if someone else might want the extra stroke)

    The 2.015" is only the 1.889" bearings available for them and the 1.976" housing bore size only has the 1.850" bearings available for them.

    As for balancing, you might be able to get it internal balanced at the weight you posted with a standard stroke? Would of been a bit easier with a later crank that used the cap screw rods, because the rods were heavier they drilled less weight out of the crank for factory balancing.

    Andy's bob weight came out to 1,640 grams and had to have heavy metal added for balancing with a nut and bolt rod crank, but he has an extra .125" stroke and a 1.005" overbore. Rods weighed around 535 IIRC and pistons without pins weighed 500 grams. Pins were a little more heavy because we got the thick wall pins for him because he wants to run boost. Even though they were "super charger" wrist pins that were heavier than the non s/c pins, they were still lighter than factory sbb wrist pins.
     
  7. Jim Blackwood

    Jim Blackwood Well-Known Member

    The interesting thing Jim is that I am currently running Chris' aluminum flywheel, which has a Buick ring gear and it works fine with the chevy mini starter. I installed the ring gear myself and used the starter recommended on this forum. So I don't know which of those two starters it would be but I do have the order paperwork close at hand so should be able to get a number off it. Do you know which flywheel he used? When I got it, it had apparently already been turned for the Buick ring gear. I simply heated the ring gear and dropped in into place.

    Jim
     
  8. Jim Nichols

    Jim Nichols Well-Known Member

    He used the Jeep 225 V6 ring gear and they must have taken it off to reuse on the cast iron Chevy flywheel because they are cheaper and easier to find. The Chevy starter you used must be for the 168 tooth flywheel. Chris used a similar Chevy starter. The smaller 153 tooth flywheel starter has the mounting bolts in a different position to move the starter in as they both use the same block pad. I am thinking with the Buick flywheel size inbetween you could mill the starter base or the block surface for an off the shelf Chevy starter. Maybe you can find a 153 tooth Chevy flexplate to experiment with. I think the Mini starter Scott used was for a 153 tooth flywheel.
     
    Last edited: Oct 3, 2018
  9. Jim Nichols

    Jim Nichols Well-Known Member

  10. Jim Blackwood

    Jim Blackwood Well-Known Member

    There is no milling required, the chevy starter bolts right up on both SBB and BBB engines (not sure about the 215, sounds like the V6 may be the same). Works just as intended, with the Buick flywheel. Lots of guys here are using them. The only question here is if the 153 tooth flywheel is large enough in diameter to take the Buick ring gear. As it is 7 teeth less I rather doubt it.

    Jim
     
  11. Jim Nichols

    Jim Nichols Well-Known Member

    Jim, You are missing my point. I've used the 168 tooth Chevy starter on Buick V6 and V8 too. That is why I recommended it to Chris. I think it may be possible to use the Chevy 153 tooth flywheel with just the one hole slotted without changing the ring gear. The matching starter is moved in to match. Any milling would just be the difference in dimensions between the Buick and Chevy mounting pad. The 168 tooth starter you and Chris use has a different mounting pattern than the 153 tooth starter as shown in the link above.
     
    Last edited: Oct 3, 2018
  12. Jim Blackwood

    Jim Blackwood Well-Known Member

    OK, I get it. I'll take another look the first of the week. The question is whether to modify the flywheel, the block or the starter. I'm thinking the flywheel may still be the best choice.

    Jim
     
  13. Jim Nichols

    Jim Nichols Well-Known Member

    Jim, Do you know the bolt on balance weight in ounces on your flywheel? I think it would be easiest to just mill the top of this starter mounting block to fit. mini starter.jpg
     
  14. Jim Blackwood

    Jim Blackwood Well-Known Member

    Maybe, but then you have a custom starter, and for such a frequently replaced component that may not be a good approach.

    I used to know the weight but I've forgotten. It depends in part on how far it is mounted from the centerline. But roughly a 2" square patch of 1/4" steel plate is in the ballpark if out by the rim. It corresponds to the size of the cavity in the cast SBB flywheel.

    Jim
     
  15. Jim Nichols

    Jim Nichols Well-Known Member

    300sbb_overkill likes this.
  16. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    That would be ok for a sbb 300 with a standard stroke if someone wants to use longer than a 6.125" aftermarket sbc rod but I wouldn't go that way using a sbb 350 crank because of the potential extra cam clearance issues.

    There are aftermarket small journal(2.00") sbc rods available up to 6.125" long. I wouldn't recommend using the factory sbc rods because they are to short @ 5.7" for 265 to 350 or 5.565" being the sbc 400 rod length because there will be piston to counter weight interference issues with a rod that is shorter than what the factory used for a sbb 300.(5.963" long)
     
  17. Jim Nichols

    Jim Nichols Well-Known Member

    I was thinking the basic street rebuild using 6" rods and Keith Black pistons. I priced reconditioned cast rods at $320. Speedway SBC forged rods at $210. Of course the pin hole would need bored and big end milled to the same width as the stock rod. Also found 6.25 H beam rods that would be perfect for the forged pistons in 305 SBC or 2.3 Ford pin height.

    https://www.speedwaymotors.com/Smal...eel-I-Beam-Rods-6-0-Inch-Press-Pin,32646.html

    https://www.summitracing.com/parts/uem-1749h-std/overview/make/buick

    https://www.ebay.com/itm/Eagle-Rods...914772&hash=item1a1f871379:g:z04AAOSwal5YIeVs
     
    Last edited: Mar 6, 2019
  18. Jim Blackwood

    Jim Blackwood Well-Known Member

    Jim, those pistons you linked to are hypers.

    Jim
     
  19. Jim Nichols

    Jim Nichols Well-Known Member

    Yep, To go with the cheap rods from Speedway. For the longer 6.25 rods I would go with the forged ones Derek suggests with pin height of 1.54 to 1.58. Dish or height as needed for 10.5 compression. For a mild street build I don't think forged pistons are necessary.
     
    Last edited: Mar 6, 2019
  20. Jim Blackwood

    Jim Blackwood Well-Known Member

    No, they usually wouldn't be unless redline is going to be over 6 grand, and then you might as well use the stock cast rods also.

    The advantages of a custom piston go way beyond just higher strength and lower weight though. The ability to specify the compression height, dish volume, squish, ring package, skirt type, crown thickness, and pin size among other things, means it can be fine tuned to match the rod and the head, which is worth another couple hundred dollars on any serious build, especially in cases like with this engine where there is not a wide range of choices available. Any change in rod length means a corresponding change in piston design. If the factory had used forged rods then for the most part we wouldn't be discussing it because those would be the rods of choice. But they didn't, and the wealth of very good aftermarket rods means we're using anything and everything. No uniformity in rods naturally means no uniformity in pistons. And since there is not a proper uniform piston either, you can't very well start at that end and then buy rods to match. The ideal forged piston doesn't exist and even if it did the rod to match it wouldn't. So it's cheaper by far to buy a take-off rod that will work and match the piston to it than to buy a custom piston and a custom rod. After all, if you're buying forged rods why would you put anything less than a forged piston with it? (Provided you could even find a matching hyper) Yes you can probably get the CR right and there's not much squish area in the 300 head but there is some. Might as well use it, but then the dish has to be right. Of course the TA heads are completely different in terms of squish and volume, so that means starting all over on the dish volume.

    I do wish we had a simple established combination that was cheap and ticked all the boxes, but to paraphrase gramps, wishing ain't gonna get anywhere.

    Jim
     
    Mart likes this.

Share This Page