Can I run 64cc 187s on a stock LO3, stock computer with out having negative compression issues?
how can I?

Can I install 1.6 magnum rocker arms on a stock LO3, stock computer with out negative issues?

1990 305 tbi LO3 automatic

can I do BOTH?
Im looking a buying new heads, both possible sets have 64cc, onE has all this:
Pressure tested to ensure no cracks or leaks
3 angle Valve job / performed on Serdi or Sunnen machine
CBN milled to ensure straightness within .0015" and correct finish
All machine work performed on the latest state of the art equipment

• Machined with 16 BRONZE THICK WALL GUIDES, not the flimsy guide liners

• Heads are assembled with 2.02 Stainless Steel one piece intake valves

• Heads are assembled with 1.60 Stainless Steel one piece exhaust valves

• Heads are assembled with hardened valve keepers

• Heads are assembled with new valve seals

• Heads are assembled with new .550 lift valve springs

• Heads are complete and ready to install

ABOUT $506


AND THE OTHER SET HAS SMALLER VALVES
1.94 / 1.50 valves

• Heads are thoroughly cleaned and inspected

• Pressure tested to ensure no cracks or leaks

• Guide work performed / replaced with new guides as necessary

• Valve job / performed on Serdi or Sunnen machine

• CBN milled to ensure straightness within .0015" and correct finish

• All machine work performed on the latest state of the art equipment

• 64CC combustion chambers - improved performance

• 1.94 / 1.50 valves

• All parts are thoroughly cleaned and inspected before assembly

• Heads are assembled with new valve seals

• Heads are assembled with new valve springs

• Heads are set up for UNLEADED FUEL

• Heads are complete and ready to install
• ABOUT $368

 

No. With stock pistons you need 57cc just to make 8:1 C/R

With a stock cam, probably. You will also have no positive issues either...

 

Stock LO3 heads have 58cc chambers. If you switch to 64cc you'll drop compression about half a point (from 9.2 to about 8.6).

Stay away from heads with 2.02" intake valves on a 305. They won't fit very far down the bore before contact happens (about .420" lift, if memory serves). And they'll be severely shrouded up to that point. 1.94" intake valve is about as big as you want to go on a 305.

The stock LO3 cam is what's referred to around here as the "peanut cam". Very short duration, very little lift. You can run 1.6 ratio rockers with it no problem in most cases.

 

Damon, what will the result of the lower compression be or mean?
will I just have to use different gas?

Supervisor, are you saying installing 1.6 rockers arms will make no difference to performance if I install them?
Was your no for 64cc No dont do it, or no for No it wont hurt to install the 64cc?

 

less compression=less performance in most cases

 

True. Less compression usually means lower performance (and reduced need for higher octane fuel). But if the heads flow considerably better than what you're replacing they can completely offset and overcome the power lost to the lower compression in some cases. For instance, installing 64cc Vortec heads in place of stock heads on a 305 will reduce compression but the better flow and combustion chambers typically more than overcome the slight loss of power due to reduced compression.

1.6 ratio rockers can add some power but expect no miracles- the difference is usually slight. And they run the risk of causing the pushrods to contact the pushrod holes in some factory heads since they achieve the higher ratio by moveing the pushrod cup closer to the rocker's fulcrum.