84cc vs 88cc heads

[my73charger]

I will be buying some Eddy heads this winter for my car...hopefully.  I currently have stock heads in about the 87cc range and my compression is around 10.3:1, my question is, would I gain much compression if I go to an 84cc head?

[firefighter3931]

Yes, you will gain a small amount of static compression due to the smaller chamber. Definately go with the 84cc closed chamber edelbrock heads....better quench with a flattop piston. What pistons are in the motor ?

Ron

[my73charger]

Actually I have Speed Pro forged domed pistons.
spacer     
TRW-L2295F30

$49.95
Estimated Ship Date:  Monday
   overview    Warnings    Application         Show All    
Brand:   Sealed Power
Product Line:   Speed-Pro Power Forged Pistons
Bore (in):    4.350
Piston Material:    Forged aluminum
Piston Style:    Dome
Compression Distance (in):    2.029
Dome Height (in):    0.140
Dome Volume (cc):    12.10
Valve Reliefs:    Trough
Wrist Pin Style:    Floating
Pin Diameter (in):    1.0939
Top Ring Thickness:    1/16 in.
Second Ring Thickness:    1/16 in.
Oil Ring Thickness:    3/16 in.
Quantity:    Sold individually.
Notes:    Approximate compression ratios: 11.34:1 with 78.5cc and 10.34:1 with 88cc head.

Piston, Forged, Dome Top, 4.350 in. Bore, 1/16 in., 1/16 in., 3/16 in. Ring Grooves, Chrysler, 440, Each

[Chryco Psycho]

you will actually lose compression going to 84 cc heads , the Alum absorbs heat more than steel & actually needs to have a 78 cc chamber just to get the same effective combustion heat , the other problem is the eddy heads do not position the valve in the same place so you need to carefully check your piston to valve clearance  . In your case this may work out well as the 84 cc head will drop your compression .6 so you will now have 9.8:1 which may help with running pump fuel , a friend has exactly the same combo with the 2295 piston & the 84 cc heads he runs on 87 octane fuel with no hint of detonation 

[firefighter3931]

Those will be fine with the 84cc heads as long as the cam isn't too big. The resulting static compression is ~ 10.5:1 and will run fine on pump gas. What are the cam specs and the rest of the build ?

Ron

[my73charger]

Ok,

this is my cam:

Brand:   Competition Cams
Product Line:   Competition Cams Magnum Hydraulic Cam and Lifter Kits
Cam Style:    Hydraulic flat tappet
Basic Operating RPM Range:    3,000-6,200 RPM
Intake Duration 050 inch Lift:    244
Exhaust Duration 050 inch Lift:    244
Duration at 050 inch Lift:    244 int./244 exh.
Advertised Intake Duration:    292
Advertised Exhaust Duration:    292
Advertised Duration:    292 int./292 exh.
Intake Valve Lift with Factory Rocker Arm Ratio:    0.501
Exhaust Valve Lift with Factory Rocker Arm Ratio:    0.501
Valve Lift with Factory Rocker Arm Ratio:    0.501 int./0.501 exh. lift
Lobe Separation (degrees):    110
Intake Valve Lash (in):    0.000
Exhaust Valve Lash (in):    0.000

Advertised Duration 292/292, Lift .501/.501, Mopar, Big Block

As for the rest of the build

It is a 1967 440 and crank.  I used the stock rods and bored .60 over.  The block was already bored .30 when I got it so the bore was to true everything up.  Completely balanced and I used ARP studs.

RPB Performer Intake
Holley 750 Carb (planning to jet up to 850)

[firefighter3931]

The comp 292/501 is fine with that piston and the 84cc closed chambers. If you were running a bigger cam with .550 lift then there could be piston to valve clearance issues. Use the felpro .040 compsite head gasket and don't forget to order a set of ARP head bolts. That will be a nice upgrade over the iron heads  

What headers are you using ? You might need to make a few mods depending on the brand. TTI's will fit no problem.

Ron

[my73charger]

I have Hedman Headers right now.

Thanks for the help.

[firefighter3931]

I have Hedman Headers right now.

Thanks for the help.

You're welcome  

The headmans fit good as well....this is going to be an easy swap !   Send a pm to Mike (Runner) on this board. He just installed E-heads on his engine with the Headmans and reported that they fit great....one minor mod to clearance a single tube and it was good to go. He'll help you out on the header mod.  

Ron

[my73charger]

Any recommendations as to the rocker arm assembly?

[Runner]

if your not wanting to spend alot of money and want adjustable rockers, go with the crane iron rockers, but id get a set of smith brother adjusters.  if your wanting rollers, then id go comp pro mamnums.   alot of people love the harland sharps, but they are spendy.     you can bolt factory stamped steel arms on if you want to save some coin.

[RallyeMike]

If he runs stamped rockers with this combo, are std push rods ok? My old MP book from a million years ago called for the MP adjustable push rods when using stock rockers with cams similar to that grind.

[Chryco Psycho]

probably not , the way to increase lift on most cams is to lower the base circle so the pushrod becomes too short

[firefighter3931]

if your not wanting to spend alot of money and want adjustable rockers, go with the crane iron rockers, but id get a set of smith brother adjusters.   if your wanting rollers, then id go comp pro mamnums.     alot of people love the harland sharps, but they are spendy.        you can bolt factory stamped steel arms on if you want to save some coin.

If you wanted to upgrade the crane ductile iron 1.6:1 rockers would be the most economical way to go. The added rocker ratio will increase valve lift. The factory rockers/pushrods work fine with the E-heads and i'd probably run those to start off with. When you decide to upgrade to a solid cam (you will) then upgrade the valvetrain.

Ron