Older 454 Block with NEWER Fuel Injected Heads?

[savatreatabvr]

I have a 1973 Chevy c20 454 that needs rebuilt, I've got a chance to buy a pair of newer (not sure what year?) heads off an fuel injected 454 for a good price. Can I use these heads on my older 454 block and will my older intake manifold bolts on to the newer heads? If for some miracle this does work will I run into any tuning issues? I don't have my 454 torn down yet so I don't have anything to compare the new heads to.

[68post]

What year are the new heads ?

[jetmech85]

I'm pretty sure if you stay with '90 and older heads you won't have any problems.

[savatreatabvr]

Originally Posted by 68post

What year are the new heads ?

(Not sure what year)! The guy doesn't know either, he just said they came off a fuel injected 454 that spun a bearing at 2000 miles. Awful low miles on an engine to spin a bearing, I may 2nd guess this guy, lol!

[68post]

You need the casting numbers off of the new heads to determine their age.

[Bigstevex4]

The only differance i know is you need a differant intake that matches intake ports and you can put a carb on it. I know the make them for small blocks. But have never done it for what its worth.

[bnoon]

Don't do it if you want any performance. Fuel injected heads will be peanut ports, not the larger oval port heads from a '73 454.

For what it's worth, intake port mismatches when using the stock oval port heads actually make very little difference in power at lower power levels. You can even use rectangle port intakes on oval port heads and still make 500 horsepower with no difference going to an oval port intake at 500 horsepower on the same setup.

[anubisani]

the heads make not work on the block if the water ports are different the block will have the small circle the heads may have the elongated hole depending
on the year

[donut]

x2, I think I've read that you can change the head gasket to allow gen 6 heads on a mark iv block. (or something like that).

More info needed. I also believe the late model heads had a non-adjustable valve train.

[anubisani]

Originally Posted by donut

x2, I think I've read that you can change the head gasket to allow gen 6 heads on a mark iv block. (or something like that).

More info needed. I also believe the late model heads had a non-adjustable valve train.

GEN 5 & GEN 6 have the elongated holes and yes there is a special gasket you can use

[savatreatabvr]

Originally Posted by bnoon

Don't do it if you want any performance. Fuel injected heads will be peanut ports, not the larger oval port heads from a '73 454.

For what it's worth, intake port mismatches when using the stock oval port heads actually make very little difference in power at lower power levels. You can even use rectangle port intakes on oval port heads and still make 500 horsepower with no difference going to an oval port intake at 500 horsepower on the same setup.

I didn't know I could use rectangle port intakes on oval port heads, that just opens up a whole new head search.

[68post]

Just saying that the engine was fuel injected means that three different generations of cyl head are included. If they're new enough to be true Vortec heads I'd want them over any of the older peanut-port heads.