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

    Buick did some cool things with metallurgy. Far as cranks go, if you are going that far you might as well consider using the 350 crank at 3.8" stroke. Easy 340-350 cid depending on overbore. With a turbo that'll make some really decent power. However, you have to cut 1/2" off the mains to do it. I have a crank sitting in the lathe right now waiting on me to do just that. Using a parting tool to make the cuts it takes about 4 hours to cut down the 5 journals on a basic 15" engine lathe but it's necessary to take light cuts due to the chatter. It's possible a better machine or tool could do that quicker. Bring it down to within .030" and send it out for grinding to finished size. Chamfer the oil holes of course.

    Then you have your choice of rods and there are a BUNCH of really good NASCAR take outs on ebay for under a C note. Pick one you like. Rod length can be anywhere from 6" to 6.4" and work fine. I have 7" rods in my 340 which has about a 9/16" taller deck than the 300 and I'm not into the ring package, though I did use 3/4" wrist pins. The two current builds use a 6.2" rod, right in the middle of that range. At this point Derek would usually suggest offset grinding the crank pins for even more displacement which you could do, or leave it and opt for more clearance at the big end, which you are likely to need. Then comes the money, for custom forged pistons, but consider this: For about $400 more than an off the shelf cast or hyper you get to specify everything about the piston, it is stronger and lighter, it fits like it was made for the engine because it was, and over the life of the engine that $400 is nothing. I'll be looking at slipper style pistons this time around for even more weight reduction. And speaking of weight, those rods are a bunch lighter than stock, the pistons are a bunch lighter, so why in heaven and earth would you ever consider a 200 gram stock wrist pin? Just doesn't make sense when you can use one that's half that weight. So now you have a free revving short block with great power potential. What it needs is the air to do that. Heads or turbo? Tough choice. A cheap turbo might just fit the bill. Or... you know those TA Rover heads are "only" $1600 bare.... Know what else? You can buy titanium valves on ebay for cheap. Maybe beehive springs and retainers, take the weight out of the valvetrain. Now that old school flat tappet cam doesn't need such serious spring pressure to get into the upper ranges and the lobes can last. And for how much? Well, with all the money you saved I betcha you could find a deal on a turbo! just sayin...;):D:)

    300sbb_overkill likes this.
  2. sean Buick 76

    sean Buick 76 Buick Nut Staff Member

  3. Golden Oldie 65

    Golden Oldie 65 Well-Known Member

    Point taken. Maybe it's best I just leave the original engine sitting on the pallet leaking oil where it has resided for the past 14 years. Thanks for the info. I won't be bothering you with any more questions.
  4. Jim Blackwood

    Jim Blackwood Well-Known Member

    Really? Give up just like that? Nobody's saying you HAVE to go big. Just mentioning some of the possibilities.

    Now the 300 is a great candidate for turbocharging. Yes you can use the stock rods, crank, heads and pistons. Sean, didn't you get something like 700hp out of a bone stock 350 with turbos? And if I remember right that was without a rebuild. The 300 is basically the same engine.

    Buick engines were renowned for making torque and being reliable and very durable in an age when the gas we used was like throwing gravel down the intake. You have a 140K mile engine where the Chevys of the day were smoking at sixty. So maybe it just takes a little different approach. Use your turbo to overcome the breathing issues of the head. That's completely practical, and if you plumb in a decent sized intercooler you can really boost it hard. The turbo is easy on the internals but if you could find a set of forged pistons for it that'd be a bonus. If not, a set of cast or hypers will still let you make lots of power, they just may erode if you go too far. (good reason for an EGT gage). So your baseline is a bone stock rebuild with the cheapest turbo setup you can find. Well that'll run pretty good. Well enough that you will be happy with it? That's entirely up to you. But...

    Add an intercooler and you can run more boost and get more power.
    Add forged pistons and... same same
    Add cheap NASCAR toake-out rods and gain peace of mind plus rpm potential
    etc, etc.

    Only you can decide where in that spectrum you want to be. One more thing though, with today's clean gas your 140K engine can potentially go double what it did originally.

  5. Jim Blackwood

    Jim Blackwood Well-Known Member

    Here's something, titanium valves in 2.02 and 1.6", cost around $250/set. Of course the intakes had to be cut down and the stems will have to be cut, re-grooved, and fitted with lash caps. Then fit to the heads in the next photo, bare TA-Rover heads, $1600. The seats need cut and the guides reamed to match, along with very light hand porting. Beehive springs will finish them off nicely. Below that, the 340/350 crank with the mains cut down to 2.530", ready to go to the grinder. Lathe time was 3 hours, next one I do will likely be a little less. Next, Carillo and Pankl custom forged rods in 6.2" length for $85 a set. Will require the rod journals to be cut down to around 1.85" and .040" off the width of the big end. Pin diameter is about .780". Finally, the block, prepped and ready for paint, in this case silver Cerokote ceramic.

    Not a bad start on a 300 build, and not terribly expensive. Pistons will be around $7-800, plus the usual extras.


    Attached Files:

    Last edited: Oct 25, 2019
    300sbb_overkill and Footbag like this.
  6. sean Buick 76

    sean Buick 76 Buick Nut Staff Member

    Good stuff!
  7. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    If your rods have the 2.008" housing bore you have the choice between 1.850" and 1.889" rod journal size because they make bearings for both of those sizes with that housing bore diameter.

    If it has the 1.976" housing bore diameter then the only choice bearings are for the 1.850" rod journal size.

    The 2.015" housing bore only have bearings for the 1.889" rod journals.

    Which size housing bore do yours have?
  8. Mart

    Mart Gold level member

    So Jim,
    Those bare rover heads came with pressed in seats, unfinished, and pressed in guides, also unhoned? Can you specify valve & stem in any size you wanted, even 6mm stem?
    Imagine the bare 350 heads will be the same.
    Last edited: Oct 26, 2019
  9. Jim Blackwood

    Jim Blackwood Well-Known Member

    The Carillo rods are 2.008" bore size
    The Pankl rods are 1.976"
    So it sounds like I should use the 1.850" journal size for both sets of rods, that way the cranks will both be the same. I think I have the bearing number for the Pankl rods (1.976") but need the bearing numbers for the Carillo (2.008"). The pin bore (about .828") and big end rod width (.890") are the same for both. Small end is .050" narrower than stock.

    The guides have just enough metal left in to finish ream them to 11/32".

  10. Mart

    Mart Gold level member

    My pankls were the 1.976 bore. I bought the calico coated bearings, $165 These are the extra clearance, rod jrnls were ground to 1.851
    You can get uncoated for $120
    I also had the rod jrnls ground .001 high. They make STDs,. 001 under, and
    .001 over size bearings so you might get away with future polish or light fuzz of jrnls if needed.

    Attached Files:

    Last edited: Oct 27, 2019
  11. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    So I have a set of the 2.008" housing bore size 1.850" bearings and the part# off of them is CB1664H it also says that they are standard. The H might be for the coating that it looks like these have?
  12. Jim Blackwood

    Jim Blackwood Well-Known Member

    Thanks Derek. So just to put both bearing sizes in one place,
    For the 1.976" big end and 1.850" pin: Clevite #1798H
    For the 2.008" big end and 1.850" pin: CB1664H

    Good information to have handy.
  13. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    Some of the nascar take out rod sellers on eBay mention that they also sell the bearings for the rods they sell if you have a hard time finding someone that sells them.

    IIRC all of the 1.850" bearings are the hard high performance bearings only. I believe that you may be able to get the P series "soft" bearings I think they are for the 1.889" journal size that also has more under sizes than the 1.850" journal size.

    1.850" has -.001 std and +.001 sizes.

    1.889" probably has the -.001, std, +.001 as well as -.010" -.02", -.03 and I think also -.040" under sizes.

    If you're going to run a flat tappet cam that can fail sending metal through the oiling system, you would probably be better off with the "P" series "soft" bearings incase of a cam failure that can possibly take out the crank with the hard bearings.

    The "soft" bearings have better imbedding capabilities that may save the crank.(surface heating the crank would be good insurance as well with either bearings, especially using the "hard" bearings while running a flat tappet cam)

    With your lathe you can make your own billet roller cam blank if you wanted too? If the roller lifters failed and sent that through the engine it wouldn't matter if the crank was heat treated or not because those needles would more than likely take out the crank anyway?(unless they took out the oil pump first?)
  14. Jim Blackwood

    Jim Blackwood Well-Known Member

    Hmm... so I might need a bearing number for the 1.889 journal and 2.008" bore size and hopefully I can get the P series bearing. I'd rather use that for the engine with the Carillo rods and grind the crank to the larger size. On the other engine it sounds like I'm pretty much stuck with the H series bearings.

    It doesn't look like the bearings are hard to get, even Amazon had a listing for a set of the 1798H. But I haven't seen a P series for that yet.

  15. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    Here is a Federal Mogul Toyota rod bearing number for a 4 cylinder with the 2.008" housing bore size, would have to buy 2 sets;


    Overall length for the above is listed as .783"

    The Honda Federal Mogul number is also from a 4 cylinder so 2 sets needed;


    The above overall length for the above is listed as .767"

    Both of the above are for the 1.889" rod journal size.

    I can't guarantee that the tangs will line up? The Honda would probably be the best bet seeing how they seem to refer to the 1.889" size the Honda bearing size?
  16. Jim Blackwood

    Jim Blackwood Well-Known Member

    Looking up those Honda bearings I've run into a lot of part numbers and options so I think I will wait and talk to Dustin over Thanksgiving since he'll be responsible for the machine work and clearances. There may be particular bearings he prefers to work with. It's about time we had a confab to set some of the details.

  17. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    If you can find the Honda bearings locally you could bring a rod there to do a test fit?

    Or maybe gsjohnny can chime in, I think he runs Honda bearings but not sure which ones?
  18. This rod looks like a good candidate for a stock stroke 300 build providing you check deck clearance. it's .050 longer than a stock rod and typically the stock piston is about that far in the hole. you could easily change the pin height of the new pistons when ordering to accommodate a shorter deck if needed. my thoughts would be a standard bore forged 3.8 piston which would be a .050 overbore and these rods for a good rotating assembly that would stand up to a build utilizing the new Rover aluminum heads


  19. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    There are 2 different sources that say the factory sbb 300 rods are 5.960" and 5.963" that I know of. Which makes them .040" to .037" shorter than 6.00" that would work great for how much in the hole the of the self sbb 300 pistons are.

    The problem is, most if not all of those off the shelf pistons need to have the wristpins press fit while the above rods are for full floating pins.

    Also, those would need to be altered to fit a sbb 300, the big end thickness and the wristpin hole size. IIRC all of this has already been discussed earlier in this very thread and a whole lot more but some of the links may be outdated by now?

    They use to sell press fit 6.00" rods but the last time I looked for them I couldn't find any. There is also a 6.00" I-beam style rods for a few hundred $$ less that are still forged so still a WAY better than factory rods option.
  20. I wouldn't use a press fit rod. the aftermarket forged turbo 3.8 pistons come bushed and the rod can be honed for the correct clearance. i'd correct the pin size if ordering and at the same time adjust compression height.

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