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dow23tee 04-25-2007 05:20 PM

chevy big block 366
i jusy got a 366 c.i. bigblock chevy,just wanted to know how much it can be bored? looked up casting number,says heavy duty truck block thick wall cylinders,casting no. is364779.the stock bore is 3.935,can i find pistons for this,.090 or .120 over,and can it be bored out to a 396, thats 4.094.which is alot.worried about locating pistons if it cant be bored out to396,any help would be appreciated thanks dave

runn141 04-25-2007 05:41 PM

they are no good for performance, very good for towing. id like to get one with the 5 speed from a c60 dump and put it in a 3/4 ton chevy. that would be the ultimate pickup.

Bumpstick 04-25-2007 05:44 PM

From what I have heard and understood the 366 truck block can be bored out to the 396/402 bore size... Its basicly the same block just was machined to be the smaller bore size but keeping the long stroke for torque...

Someone else may have more input on this and since I have never done this myself you may want to investigate it more...? 04-25-2007 08:08 PM

The ONLY thing 366 BBC's are good for, is to pull the crank out and the rods out, list the four bolt caps on Ebay and sell the rest to the scrap yard for the going rate..

The cranks are steel and with a rebalance make great 396-427 based engines. The rods are usually the better 3/8 bolt type. Install good bolts/resize and you have a great rod..

The pistons are all wide 4-ring and weigh a ton.

curtis73 04-26-2007 12:21 AM

agreed. the 427t has a bit of potential, the the 366 is a boat anchor. Save what's good and scrap the rest. Huge stroke, heavy tall pistons, extra rings, tiny bore... its like the 305 of the BBC world, but worse.

BogiesAnnex1 04-26-2007 09:21 AM

This depends on what you want it for. Unfortunately the 366 doesn't lend itself to inexpensive hop ups. The max safe bore is .125 which with the stock crank makes a 390. Not bad but considering the size of the the tall block it's awfully big and heavy for its displacement. For a working truck or a boat it's a good answer, for a hot rod it isn't.

The "T" blocks use an industrial piston that has 4 rings and makes up for the taller block with piston crown height. and of course weight For a hot rod you can make these into long rod stroker motors, but the 427T is a better place to start. Still if you have the bucks it's something to consider.

Then the heads on it are not good for a performance engine. By the time you put all the effort and cost into this, you'd find yourself much further ahead to trade it for something else. But don't under-rate its value, there're good for trucks, boats and industrial uses, so it does have some core value as a trade.


Super Streeter 04-26-2007 07:23 PM

The 366 has one overwhelming virtue,it is nearly indestructable.One setup for a for going fast and looking cool would be to swap a set of large oval oe even rectangular port open chamber heads on that shortblock to get the compression down to about 6.5:1,then add an 8-71 or Megablower to it with a mild blower cam and a pair of 750 carbs.If you spin the blower to make 12 psi of boost and use the right parts it will be a very strong running combo,and look like a killer too.Best of all since it is a short stroke bottom end with good internals{most 366's dont have a steel crank,but do have 4 bolt mains and truck rods} the engine will withstand about 6000 rpm which is more then enough to make scary power when you add 12 psi of boost to the mix.Dont get worried about how much blower you will need,the 366 isnt much bigger then a 350 smallblock,so you wont have to turn that blower too hard to make 12 psi,but if you tried that trick with a 350 smallblock with stock internals you would be picking your crankshaft out of the oil pan in pieces.

I would add a cam kit with about 235 degrees of duration at .050" on the intake and maybe 5 degrees more on the exhaust with a 114 seperatrion angle and 106 intake centerline.A good hydraulic flat tappet with about .510" lift and the correct springs{shim the intake springs to add about 15# over the reccommeded setting to compensate for the boost}.Use 2" primary tube headrs and I wouldnt be afraid of using a set of open chamber rectanglular port heads since the blower will make plantly of low end torque despite the way too large intake ports.

Another hot setup would be to kep the longblock as it sits,and freshen up the stock heads with a good valve job and new springs.Add a cam kit with about 220 degrees duration @.050" on both lobes and .500" lift and freshen up the rest of the valvetrain.Add a Torker intake with spacers,and a 750 carb and add a big shot nitrous plate to it with 300 hp jets.

I have worked with both of these combinations,and they both worked real well for a street car.The blower setup has been running in a 56 Chevy prostreet car that has been on the road for over 10 years with no hassles.It was running mid 12's on pump gas with a 4 speed and was so mild you could drive it anywhere{it literally sounded stock} the car has air condtioning and everything.That setup used stock peanut truck heads and a cam like I described and used a megablower to make about 7 psi of boost.With the better heads,less compression and more boost it should have been about a second faster but I dont think the driveline would have handled that anyway.

The other combo was run both on raw horsepower and nitrous.We ran it on motor in a 68 chevelle with a performer intake and spacers and and Isky 280 cam kit and with a powerglide,2000 stall onvertor and 4.10 gears it was a low 13 second car on street tires.One of the local inner city street racers ran this combo with the torker intake and 350 hp big shot and had an 80 malibu running 10.80's and it sounded so stock you thought it was a dead 305 with headers under the hood.The really neat part of that one was that he had a stock Grand national 10 bolt with 3.42 gears and a th400 with a cheapie $99 2000 stall coinvertor and he would drive the car everywhere.You can make a lot of money on grudge night with a combination like that.

So dont discount that 366 as a boat anchor just yet.It may not be big on power,but it is ready for any power adder you can throw on it.

Good luck.

KA67_72 04-26-2007 07:30 PM

I have one that can go standard bore. 366 pistons are expensive. I'll probably never mess with it, but I was thinking of milling the tops of the standard pistons off and sticking a spare cast 454 crank in it. There would only be room for three rings. This would make it almost a square engine which are supposed to be the best for supercharging. I'd turbo it and see what it would do before pushing the bottom end out. I also thought about boring it to 4.00, put small block pistons in it and milling out some rods. Just some ideas.


runn141 04-26-2007 08:33 PM

putting big valve open chambered heads on that small bore might not work. wouldnt it be like 2.08's on a sb267 with a 3.500 piston, might hit the deck.

Super Streeter 04-26-2007 10:02 PM

Yup,you would have to notch the bores a bit to make it work right.With the cam I nentioned it would be close,but I dont think 2.19" valves would hit,they just wouldnt breath well.I migh be more concerned with the 1.88 inch exhaust valves since the exhaust side of the chamber might hang over even more.Stock 2.06" valves like the large ovals come with fit well though.

66GMC 04-26-2007 10:18 PM

Sorry ... but rectangular-port heads would be a "negatory" :nono: in my opinion.

I read an article that compared oval port heads to rectangular ones, and it became apparrent that the rectangular ones were at a distinct disadvantage until you got WAY up in the RPM range.

That was on a 454.

On a 366 I'd imagine that you'd have to be up in the 8000 rpm range to get any benefit out of them.

My advice:
Buy a rusty old 73 - 87 truck with a 454 for about $500.00, and spend another few hundred on a pair of 781 or 049 large oval-port heads ... and start with something that has some potential. 04-27-2007 08:36 PM

66 GMC has the right idea. I do it regularly. Old Michigan Suburbans with the fenders flapping and the doors rotted off are great for 454 blocks and 400 turbo trans. I have bought them for as little as $50.00

As for the rest of the previous ideas. Not very practical. Just a very expensive HEAVY motor that any good running small block would walk all over.

Super Streeter 04-27-2007 08:53 PM

You are right 66,the rectangular ports are way too big,but the fact is that you cant get a tall deck blower intake in anything but rectangular port.The one I described has a rectangular tall deck intake on peanut port truck heads and it runs strong,but I bet it would be stronger all over if it had ports that matched.

As for the 454.You are right there,but I havent found too many good running 454's for $500 latley.With the price of scrap,a bigblock suburban is worth more then $700 if you brought it right to the shredder,so most never get sold for less then a grand and even thise are usually hashed to death.If he could find one for a grand he could yank the engine and trans and still get more then $400 for the corpse as long as he could tow it there himself.If that were the case,a hotter combo would be a set of closed chamber big oval ports on the stock shortblock.With 049 heads the engine will have about 7.8:1 compression,With closd chamber 100 CC heads it will have about long as you are talking about basically stock small valve stuff,the closed chamber wont give up any flow to the open chamber setup.If he gets lucky and get a 454 out of an early 70's 1 ton,it will have the big ovals on it and he can yank them and use them later if he ever got better pistons,or just sell them to make some of the money back..

runn141 04-28-2007 08:17 AM

[QUOTE=Super Streeter] With the price of scrap,a bigblock suburban is worth more then $700 if you brought it right to the shredder.

what exactly do they pay for car bodies out there? the best you could get around here is $10 a hundred for a car body, a suburban wouldn't bring much more than $300. im just curious :)

PsychoBandito 04-28-2007 05:39 PM

steel right now is worth ~65cents a Pound, so figure your 'Burb weighs in at 3000 pounds of metal, thats 1950$ but because of the the finish, and that sorting and nah nah nah, 700$ is still a great deal.

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