Heaviest valve springs without machine work (Hemi)

[6.5hp Shinebox]

Running the Black mamba Sr cam with 26lb springs .....valve train is Stock parts, 22mm mikuni carb



Wondering what are the heaviest springs I can use? In a hemi predator head 27mm/25mm 5.5mm stems

 

[TheDullCarbide]

I would definitely recommend aftermarket pushrods. 26lb is the heaviest stock diameter spring available. Beyond that is the 37lb large diameter single or the 32, 36, and I think the 65lb dual spring setups. All of the said springs would require different retainers and some modification to the spring pockets in the head. As for the modifications, I've heard people who have done them with a dremel tool but I don't know what actually needs to be modified.

With 26lb springs you won't be able to rev high enough to take full advantage of that huge cam.

 

[6.5hp Shinebox]

I would definitely recommend aftermarket pushrods. 26lb is the heaviest stock diameter spring available. Beyond that is the 37lb large diameter single or the 32, 36, and I think the 65lb dual spring setups. All of the said springs would require different retainers and some modification to the spring pockets in the head. As for the modifications, I've heard people who have done them with a dremel tool but I don't know what actually needs to be modified.

With 26lb springs you won't be able to rev high enough to take full advantage of that huge cam.

So valve seats need cut & heavy duty valve train...... in order to run heavier springs alright I'll do some hunting try an find some what of a guide to go off of..

 

[TheDullCarbide]

So valve seats need cut & heavy duty valve train...... in order to run heavier springs alright I'll do some hunting try an find some what of a guide to go off of..

The springs have nothing to do with the valve seats on the combustion chamber side of the head. What needs to be modified is where the valve spring sits on the rocker arm side of the head.

 

[ole4]

26lb springs work fine with the senior and stock rockers. The jr is more critical of valvesprings due to faster opening and closing ramps.

 

[6.5hp Shinebox]

26lb springs work fine with the senior and stock rockers. The jr is more critical of valvesprings.

Correct....but the 26 lb springs are weak an need more rpms before I hit valve float