454 big block in blazer Question

[454 blazer]

Hi guys its been a while, im just in the middle of a big block rebuild , ive brought a couple of large rectangle port heads as my 781 heads require some strange spring set up , trying to get parts here is tuff! so as i said ive got large rectangle ports and a matching intake,is ther any problem fitting these heads to my block as i think they are gen VI heads for a 502 , someone mentioned that the water holes are different ? is this true ? They do seem a lot bigger than the peanut port head water holes, will i have any future cooling issues? Im thinking to put a 292 cam and lifters in also to liven things up a little

 

[80' 427]

The heads won't work without work and that cam is huge for a 4x4. The only thing your 781s need is a .100 thick spacer that comp sells to remove the rotator. You do know that it will not be happy below 3500-4000 right.

 

[454 blazer]

Hmmm, thanks 80 427 , didnt no about the spacers , ive been given a garantee that the heads and intake will lay down some serious rubber, my blazer doesnt see much more than the street once or twice a week , just wanted something a bit quik of the lights , but as uve pointed out this is gonna be laking in the tourq deppartment. what cam would be a bit more realistic then, thanks again.

 

[80' 427]

Whats the rest of your combo? for example, converter, transmission, gear and tire. Also what do you use it for?

 

[454 blazer]

Th350 (overhauled) 3000 stall converter and 33,s i ran a 280 cam with the small peanut ports ran very well went to up grade the heads , and found the cam was stripped on a couple of lobes , ive put new cam bearings , mains and conrod bearings just to be safe , oh and new piston rings. i just use it aruond the streets and a couple of times in the dunes.As i say it ran great , the pull was amazing , ive been advised a 292 , but i think you are right its gona be to high , also i dont no wether this makes a difference but ive got a gm performance intake whitch is a high rise , apparently good for low down tourqe. I just like raising a few eybrows when i set of from the lights!!! LOL.

 

[80' 427]

I guess you using it a little harder than rock crawling. I would just get the spacers for the 781s that comp sells to get rid of the rotators or the new brodix race rite O ports. I just bought a set and they have great low lift and upper end flow. The 280 comp is fine but I would consider GM performances hard faced lifters that they sell, or better yet a hyd roller.