289 heads on 302

[88mudder]

I have an H.O marine application 302, late 70's i believe, forged pistions, mild cam, 4bbl, carb spacer, headers etc. It still has the stock heads, just a mild cam stock lifters, springs, and pushrods.

I have a set of mildy build '65 289 heads, comp heavy duty springs, push rods, lifters, and a nice cam.

The plan was to do a 289 head swap since both cams are hydraulic flat tappets. Can i just swap the 289 heads, pushrods, and lifter combo onto my 302? I heard this increases compression and adds some nice power. Should i do this since its free? Will it make my engine run like crap or improve? Thanks for reading.

 

[baddad457]

The heads and pushrods, yea. The lifters? NO! You cannot reuse flat tappet lifters on a different cam. Nor can you mix the lifters on the same cam. The 289 heads should boost the comp ratio by about 1 or 2 full points depending on what it is now.

 

[COPPERHEAD85]

I have 289 heads on the 302 in my truck,work great.

 

[88mudder]

I have 289 heads on the 302 in my truck,work great.

thanks, i am going to tackle this project in an afternoon soon.

 

[88mudder]

The heads and pushrods, yea. The lifters? NO! You cannot reuse flat tappet lifters on a different cam. Nor can you mix the lifters on the same cam. The 289 heads should boost the comp ratio by about 1 or 2 full points depending on what it is now.

So pretty much just swap the 289 heads onto my engine as well as the 289 pushrods and leave the lifters on? Will i notice a power gain and is this worth it?

 

[COPPERHEAD85]

I don't think you need to swap push rods.
Like baddad said it will up the compression.It depends on what CC the chambers are on the 302 now and what CC the 289's are.

 

[baddad457]

So pretty much just swap the 289 heads onto my engine as well as the 289 pushrods and leave the lifters on? Will i notice a power gain and is this worth it?

Wait, what parts are you calling "lifters" ? I think you may be confusing lifters with the rocker arms. The lifters are the cylindrical parts that the pushrods are plugged into at their bottom ends. Rocker arms are the parts that the upper ends of the pushrods are pushing against that transfer the motion of the cam to the valves. The rocker arms need to stay with the heads they're on, unless you're going to replace them with roller rockers. The early 289 heads used different rockers than the later 289 heads, of which these rockers were carried on with the 302 heads until the 77 model year. Beginning in 78 the switch to pedestal rockers was made on the 302/351W.

 

[88mudder]

Wait, what parts are you calling "lifters" ? I think you may be confusing lifters with the rocker arms. The lifters are the cylindrical parts that the pushrods are plugged into at their bottom ends. Rocker arms are the parts that the upper ends of the pushrods are pushing against that transfer the motion of the cam to the valves. The rocker arms need to stay with the heads they're on, unless you're going to replace them with roller rockers. The early 289 heads used different rockers than the later 289 heads, of which these rockers were carried on with the 302 heads until the 77 model year. Beginning in 78 the switch to pedestal rockers was made on the 302/351W.

Thanks for the clarification i think i got it now. Im debating if i should do this, the engine seems to have lots up power up to 5 grand and now that my kickdown is set the truck moves out. The 289 heads i got are freshly built with comp heavy duty rocker arms and springs, small 289 chambers. Thanks for the help!

 

[88mudder]

Is it worth posting the head casting number on here to see if anyone can help me figure out what year they are from? I know for fact the 289 is out of a '65 , early 5 bolt bell block only had them for a few years i heard from a guy.

 

[baddad457]

If they're original to that 289 then they're the better early heads with hardened pushrods, the good cast rockers and pushrod guide slots in the heads.

 

[88mudder]

thanks all