340 stroker

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KB9GIB

KB9GIB

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Hello and thanks in advance for any information. Son is building a 340 the motor we have doesn’t have no internals. so we was thinking of doing a stroker the block needs 30 over bore. This will be 90% cruising car. so with out braking the bank what kit (brand) would you go with? I think you for all your help. KB9GIB
 
I used a Scat rotating assembly. No matter what kit you buy take everything to the machine shop and have it checked and fitted to the block. EVERYTHING ! A "cruising" car does not matter, you want it right the first time and it will last a long time.
 
Cast crank Scat kit would be the way to go IMO. You have options of flat top or dished pistons and whether the rotating assembly is balanced by Scat or by your builder. Figure about $1500-1700 for it depending on sales and who you buy it from.
 
OK rotating assembly straw man chosen
now to pick your heads so you can pick the cc of your pistons
You may have do do an iteration on the above drill a few times cuz you also have to factor in your head gasket
cruzing build for available pump gas then back it down a notch
trans/ gears/ chassis etc would help
is this a Saturday night Cruz? or a Chicago to San Fran Cruiser?
 
KB9GIB said:
Hello and thanks in advance for any information. Son is building a 340 the motor we have doesn’t have no internals. so we was thinking of doing a stroker the block needs 30 over bore. This will be 90% cruising car. so with out braking the bank what kit (brand) would you go with? I think you for all your help. KB9GIB
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Scat rotating kit, 9000 series will be enough.
Keep it 9.5 compression if you can so that he doesnt have to have a PhD in tuning. Jmo
 
KB9GIB said:
Hello and thanks in advance for any information. Son is building a 340 the motor we have doesn’t have no internals. so we was thinking of doing a stroker the block needs 30 over bore. This will be 90% cruising car. so with out braking the bank what kit (brand) would you go with? I think you for all your help. KB9GIB
Click to expand...


4” Scat cast crank, forged piston, balanced. Good to 500-550hp.

But you need to lock down the heads you are going to use first. You need to know the combustion chamber size of the heads so you can choose the right kit with corresponding pistons.

Most aftermarket aluminum heads are 62-65 cc’s. I think new steal heads are similar.

The stock heads are much more. IIRC, 68-72cc’s typically for X’s and J’s.

After you pick heads, pick the stroker kit with forged piston to run as close to 9.5:1 as recommended before. Like 9.2-9.5:1.
 
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What year is the block and what is the VIN number? Been looking for my original block since 1995 and you are close to where I bought it from...
 
Divenut said:
Whoa! The thread made it to 6 posts before the " sell the 340 and build a 360" response.... folks are getting slow on the draw. LOL! ;)
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The Block is 68 and if that’s the right year for your car I will check the vin. And the cubic inch is really not a issue because most of his driving is cruising to cruise nights in a 72 Demon. I would have just built the stock lower end but it was a Barr block.
 
the cubes will determine your heads.
i.e. stock J or X will not compliment a 416 so a 372 may be a better choice.Big power and much more efficient.
 
KB9GIB said:
The Block is 68 and if that’s the right year for your car I will check the vin. And the cubic inch is really not a issue because most of his driving is cruising to cruise nights in a 72 Demon. I would have just built the stock lower end but it was a Barr block.
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Yes, my block would be a late 68 casting for my 69 GTS convertible...
 
ir3333 said:
the cubes will determine your heads.
i.e. stock J or X will not compliment a 416 so a 372 may be a better choice.Big power and much more efficient.
Click to expand...

It’s a street motor. Not going to make big power. But looking for very streetable, easy to tune, small geared, understressed etc...

IIRC, the 372 kits are more uncommon and less options to them. Same price or more.

I’m sure he can make 1 hp per cubic inch with the 372 and stock X or 2.02 J head. And the same with stock heads and a 416 with a tick more cam. And the extra stroke will make the street-ability the same. Just have a free 44 HP more.

Does the original poster have heads right now? Cores or already built?
 
Donnie514 said:
I used a Scat rotating assembly. No matter what kit you buy take everything to the machine shop and have it checked and fitted to the block. EVERYTHING ! A "cruising" car does not matter, you want it right the first time and it will last a long time.
Click to expand...
Why do you say that did your kit have a issue, reason i ask if i recently just got a kit and it was balanced by them. I sent the pistons with my machinist though
 
MoparMark91 said:
Why do you say that did your kit have a issue, reason i ask if i recently just got a kit and it was balanced by them. I sent the pistons with my machinist though
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I purchased the scat kit and paid for the balance and once it arrived I had my machinist eg engine builder check the rotating assembly for balancing and it was out 17+ grams out had it in with in 2 grams. And wrong bearings supplied as to they weren’t chamfered on the conrod bearings no clearance between rods per journal. Don’t take anything for granted and think it’s correct have a good machinist builder or yourself go through everything. It saves a lot of pain and cash in doing it twice.
 
chamfered bearings- good catch- now pinfit, hang and align the rods/ pistons check everything-
and check all heads
 
Here is the 340 Block numbers. if someone can tell me anything I would appreciate it. are if it belongs to your car let me know. Thanks KB9GIB

22A378B9-AFF8-4A49-B208-216C7730B05F.jpeg


427DA062-7AEF-4435-85D7-FADDAEDEBB7F.jpeg
 
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I have a 340 stroker. Making 418 cubes (.04 overbore and 4 inch stroke)
I went forged crank and forged pistons from Molnar. I mainly street blast but didnt want to have to redo it if I broke a crank

Dont listen to the sell the 340 clan.

Dont skimp on heads he will likely get addicted and want more power
 
For a cruise, a stroker is kindof a waste of money. Cuz what you are gonna get is a mountain of motor-home torque, enough to roast tires in two gears....... in a cruiser. A 360 will do that with 10% more gear, a 340 with 15% more gear.
You could put that money into the heads instead and have a nice combo with a torquey cam.
For a bunch of extra torque, go with a 360 and you can drop 10% or more rear gear, and drop one cam size.

As to the 340; with lightweight flat-top hypers you might be able to drop a 318 crank into it for almost zero dollars. Then a set of closed chamber heads, tight-Q,and you got a nice cruiser. With a modest cam, and a modest cruiser-gear you might even get her into the 20s mpgs. Perhaps even mid 20s with a spread-bore metering-rod carb.
That's my kind of cruiser.
 
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