781 heads for big block (valve Rotators)

[454 blazer]

I have a pair of 781 heads that are already cleaned up and ready to go on , i belive there are some shims that go underneath the valves ? If so does anybody have a Part# from summit and the springs i would require? As im runnung rectangle heads and as Mr 4x4 High says they dont wake up until 2,800 rpm,Im running a 270 comp cam 4x4 extreme energy cam, holley 750 double pumper , ali intake (matches heads) headman headers and flow masters .Any suggestions would be appreciated.Thanks in advance.P.S i have a large oval port RPM Edel intake that will match the 781 heads.

 

[GMC500]

1st thing, you need a bigger cam
270 is pretty mild on 454 cid motor
I am running Lunati Voodoo 60203 and I am planning to upgrade to a little bigger cam
http://www.summitracing.com/parts/LUN-60203/

regarding the rotators
you need to replace them with rotator eliminators like these
http://www.summitracing.com/parts/HRS-96045/
http://www.summitracing.com/parts/LUN-86603/

and you need to use whatever springs recommended by your cam manufacturer

are you planning to sell the rectangle heads ?
or do you have another set of 781s available ?

Ahmed

 

[454 blazer]

Hi Ahmed,
The cam is a 270 duration which is no far of what you will be ordering, i ran a 280 comp cam for a couple of years and it was great at high RPM but at low RPM it was weak , you can see it on youtube.com just type in 454 blazer.thanks for the summit racing link,i will order a set,ive been told the 781 heads deliver much better torqe than the rectangle port heads, so i may experiment in the coming weeks.Are you looking for a set of rectangles ? By the way do you own a blazer or a pick up ?

 

[GMC500]

yes 781s are very capable and more suitable for this usage


this is my rig

 

[rcamacho]

A 280 duration cam will idle rough on a dual purpose BBC due to valve overlap. Idle vacuum may also be an issue with the brakes without a reservoir.