Destroked 400 SBC / SBC 350 Main Crankshaft in a 400 Main Block

Let's go, we got a lot of work to do to get this new motor back together. This is an aluminum brodix 400 main block. My crankshaft is a Bryant billet crank with 350 mains. In order to make this work, we have to use spacer bearings to make up the size difference. Essentially, they take a 400 main bearing that is .010 undersize and modifiy it to be the spacer bearing so a 350 main bearing snaps right in. Not the most ideal setup, but this has been done for years to have a de-stroked 400 block. Big bore, small stroke gives a great rod angle.
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Thomas Racing Service: Jeff Thomas No Prep Struts

[tommywicker]

Used to build destroked 400s back in the mid 80s to early 90s, nitrous and supercharged before I got into Pro Modified. Badass set up and my all time favorite small block.

[thmike]

MAN that alu block looks The roller bearings are sick! I think I heard some people even do it on the thrust. Funny the original video about your thrust bearing mod, is how I found your channel in the first place. Cool stuff john

[circut]

Stay with the 350 mains . Increasing the size of the journal will increase the crank speed inside the bearing ( you don't want to do that ). Stay with what you are running .it will serve you better in the long run.

[willybill]

I loved my 377 i built back in the day I had no idea what I was doing at the time but it was very impressive for what it was

[ss]

Have the same block. 100 lbs lighter than my GM 350 block….it’s a beautiful sight sitting between the wheels

[brucefrye]

Looks good John. And by what I saw in the video looks like you've done this a time or three as any of us racing on a budget. And that block is nice a really nice peace. ✌

[breal]

Built one back in the 90s for my street raced/driven vega wagon i had. Dont remember what crank and rods etc but i know had 6 inch h beams, the compression was supposed to be around 13 to 1 had the biggest solid cam that crane made that i could run nitous on, pg w brake and a 5000 stall, and 9 inch on homemade 4 link bars that attached basically in stock location. I ran so many bottles of nitrous thru it never missed a beat. take off on the converter let go trans brake, Hurt many feelings here in north florida with that car, on the track and on the street, drove it everywhere, drove from my place to daytona beach for the turnkey rod run no probs Damn i miss that car. Oh best times before i got rid of it was 9.42 at SGMP they didnt care i didnt have all safety equip that likd it would put on a show with the front 3 ft off the ground and me shifting at 8500

[YerkitRacingChannel]

Just put together my rotating assembly on my channel. Missed the other video of you modding the thrust bearing though. Wish I had seen this one before I put it together. Hopefully they will live a long life the way it is! 🙏

[zAvAvAz]

i am placing 3/8" thick 4.185" bore size sleeves in 350 block gm small block chevy with stock crank for 383 cubic inches stock stroke. Now if i use a 4" crank i can get 440 cubic inch for a nice daily low rpm'er. Although rod length is not optimal. If i use a 3.625" that gives me a 399 cubic inch with a great rod ratio. If i use a 3.75" crank this gives me a 413 cubic inch. A 3.8" yields a 418 c.i. And a 3.9" stroke makes a fine 429. Just imagine a 4.1" stroke = 451 c.i. Imagine a 4.15" stroke = 457 c.i. And last and not least 4.2" stroke = 462 c.i. And now complete fantasy 4.25" stroke = 468 cubic inch small block. The most bore size to fit any kind of gasket and chevy standard bore spacing heads would be 4.190" And that is only almost 2 cubic inch difference and not worth it. Shall it work in a 350 with modifications? we shall hopefully see. Maybe it would be worth it to try and put a 4" crank in a standard over bore size 4.030" resleeved block for 408 cubic inches instead. Just a really bad rod ratio i believe. Although people get away with 5.565" rods in the 400, so why not? A 4" stroke in a stock 9" or 9.025" deck 350 block gives 408 cubic inches the biggest rod of 6" with a 1" piston has a the best rod ratio that can fit on a stock deck height 408 cubic inch, 4" stroke, um 350. The ringland is through the pin bore on this. So for street daily driver how would this be and go like? The rod ratio for 6" rod and 4" stroke is = 1.5:1 still better than the stock 400 sbc. And with a 1.15" piston and 5.85" rod the ratio comes to = 1.4625:1 that is just under the stock rod ratio of the 400 sbc being = 1.484:1 with a 5.565" rod and 3.75" stroke.

[tonydowns]

Love that aluminum 400 block John, Great informative video as always.

[pookadookalook]

Inspired to make my next build in this direction holy smokes

[garylucier]

On that block, look at the oil pump, and the feed area of the block from the pump, and make sure the pump and block are blueprinted same pattern, same match-up.

On my block factory the feed from pump is a circle hole, but the pump is an actual oval, so we needed to match it by drilling out the block, boom 5-10 free HP gain just getting rid of a factory engineering issue, and what a difference in quantity of flow volume it achieves.

[sendit]

would a new crank not be just as cheap as getting the old one welded up and turned sometimes saving a couple hundred is not worth the time and trouble and welds never last as long then you could just buy the right main size with the stroke you want but I am a big fan of the 364 or 421 depending on your application

[garylucier]

I see an Aluminum MY BROTHER! VERY NICE.

[oldmanintheshopbuiltnotbou]

looks nice john now youve got to polish up the heads

[davidmcnerney]

That things pretty. Nice everything swapped over easily. Should be worth it.

[sonofmontezuma]

In my day that was called a 377 hi rev engine we used to gobble up all the 400 out of station wagons and impala’s & caprice cars, ertel made cheap piston’s, king and federal mongol, TRW, speed pro made the spacers, in a light car with 1st design off road camshaft car made easy high 10’s all motor

[robertdouglas]

Looks like the Hot Rod is going back together! 🤩🤩

[freddiemoralez]

Thanks for the update 👍😀. And God bless all 👌

[mikemontgomery]

Hope you make the weekend. I think your buddies from Ohio are planning to come down to take some N.C. money !!!