small block compression?

[1BAD68]

I currently have 7.73:1 compression in my 318 and its a dog in the low rpm range, looking at the KB167 pistons they'll give me a 9.3:1 ratio.
Will this give me a big improvement in torque ie: is it worth spending the money on them?

[Plumcrazy]

Those pistons would be an improvement over what you have.   However I just don't see them giving you a "big improvement" in torque. For that you need an engine with more cubes and a longer stroke.   Which for a small block means at least a 360 or a stroker crank in the engine you have.    

[firefighter3931]

  You need to increase the displacement to see any "significant" improvement in torque. 

The old adage ; "there's no replacement for displacement" holds true....But "big" smallblocks (strokers) can make excellent power 



Ron

[1BAD68]

a stroker would be great but i spent the last two weeks thinking about doing that and after pricing out all the parts which wasn't that bad (about $1300) and the engine shop quoting $250 for a balance not including any heavy metal which he said can easily add several hundred to it, its way over my budget not to mention my stock heads wont help it.
I'm just looking to make a little more power with my stock (rebuilt) 318 for now. Meanwhile I'm going to find a 340 or 360 that I can stroke later (kits are actuially cheaper) as extra money builds up.

[firefighter3931]

What cam are you running in your 318 ? A cam swap will definately perk it up assuming the current stick is mismatched. 



Ron

[1BAD68]

right now its a Comp 260/440
I was thinking of getting the MP 268/272 - 450/455

[firefighter3931]

right now its a Comp 260/440
I was thinking of getting the MP 268/272 - 450/455

The Comp magnum 260 is a descent cam for that combo...maybe a little on the big side. Did you degree the cam in or just install it lining up the dots ?

What converter and rear end gearing are you running in this car ? What tires ? Intake ? headers ? exhaust ? carb ?


Outline the whole combo so we can see what you're working with. 




Ron

[1BAD68]

It has about 7000 miles on a .030 over rebuild, has an Edelbrock Performer w/Edel. 600 carb, Comp 260/440 cam zeroed, 2200-2800 stall convertor in a A904, 3.55 sure grip, Flowtech headers, 2 1/2" dual exhaust, 26" tires.

[firefighter3931]

It has about 7000 miles on a .030 over rebuild, has an Edelbrock Performer w/Edel. 600 carb, Comp 260/440 cam zeroed, 2200-2800 stall convertor in a A904, 3.55 sure grip, Flowtech headers, 2 1/2" dual exhaust, 26" tires.

That seems pretty well matched. Ok how have you got the ignition set up ? Base timing ? Total timing and at what rpm ? A lazy ignition curve can really hurt performance. If the cam timing is off (retarded) it will also make it sluggish. If the cam wasn't degreed in then it could very well be installed in a retarded position.

What head gaskets did you use when it was rebuilt ? The felpro blue's will knock down the static compression.



Ron

[1BAD68]

timing is 12 initial, 34 total at about 2400 rpm, head gaskets are the blue FelPro's.
It has power once timing is all in around 2500 but below that its really sluggish.

[firefighter3931]

timing is 12 initial, 34 total at about 2400 rpm, head gaskets are the blue FelPro's.
It has power once timing is all in around 2500 but below that its really sluggish.

Well, it could use more initial timing for sure. Try bumping it up to 18* at idle and see how it responds....i bet you see a big improvement in off idle power.

The felrpo head gaskets are thicker than stock so that is not helping the static compression ratio issue. Another option would be to degree in some advance on the camshaft timing. Does your timing chain set have multiple keyways ? Of course this would require opening up the front of the engine and a new gasket set....

I would start off by experimenting with the timing curve. Generally speaking....low compression motors respond very well to lots of spark lead. 

Check to make sure that your carb linkage is properly adjusted and that you are getting full throttle when the pedal is fully engaged. Have a look and make sure the secondary throttle blades aren't getting hung up etc....



Ron

[1BAD68]

I checked the throttle blades over the summer and all was good.
I'm still kind of leaning towards a stroker being that my engine is out and on a stand ripped apart.
I'm having an issue with balancing the assembly ($$)

[firefighter3931]

I checked the throttle blades over the summer and all was good.
I'm still kind of leaning towards a stroker being that my engine is out and on a stand ripped apart.
I'm having an issue with balancing the assembly ($$)

If you're worried abut a few hundred dollars for the balancing costs then how are you going to pay for the new cylinder heads ? 

How much $$ to you have to play with here ? 



Ron


Ps. I like the stroker idea but it's not cheap and you don't want to 1/2 azz it  A stroker needs good flowing heads as well as more intake/carb then you currently have. 

[Plumcrazy]

One outside possibility may be a defective torque converter.   If the stator clutch in the converter is slipping you will lose the torque multiplication the converter normally provides from a dead stop. 

[1BAD68]

If you're worried abut a few hundred dollars for the balancing costs then how are you going to pay for the new cylinder heads ? 

How much $$ to you have to play with here ? 



Ron


Ps. I like the stroker idea but it's not cheap and you don't want to 1/2 azz it  A stroker needs good flowing heads as well as more intake/carb then you currently have. 

I have enough I'm just cheap and dont want to spend it all at once, I also cant stand not having my car ready when the weather gets nice.
If the stroker kit supplier internally balances the rotating assembly, what is left to balance in the engine?

[firefighter3931]

If the stroker kit supplier internally balances the rotating assembly, what is left to balance in the engine?

Once the rotating assembly is balanced you are ready to go. The forged crank balancer is designed for an internal balance....and you will also need a neutral balance torque converter.


Here's a very good thread you should look at....baicly the same type of build you are contemplating :

http://www.dodgecharger.com/forum/index.php/topic,283.0.html



Ron

[1BAD68]

Thanks for all the info Ron, I had a chance to sit down and talk with a friend of mine last night that rebuilds diesel engines and I've decided to build the stroker.
I have 5-6 months before I'll be driving it so upfront costs wont be so bad.

[firefighter3931]

Good call on the stroker.  Even a very mild 402 build set up preoperly will run very strong and outpower a stock/warmed up 440. One of our members has one in his Cuda and it runs very good...i've driven the car and can personally attest to it's power. 


Ron

[kamkuda]

Good call on the stroker.  Even a very mild 402 build set up preoperly will run very strong and outpower a stock/warmed up 440. One of our members has one in his Cuda and it runs very good...i've driven the car and can personally attest to it's power. 


Ron

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