GT-40P heads on a 289?

[BroncoKelley]

I finally found the misfire issue and some other info about my 73 ranger I picked up 2 months ago. Apparently 2 of the intake valves stuck in the guides causing the piston to hit the valve, bend the pushrod and in turn blow out the lifter. Anyway, I also found out that the truck has a 66 289 in it with .060 pistons and not a 302, the heads however, are the 54cc heads. I got a set of GT-40P heads laying around and was wondering if anyone has installed them on an older block and if there are any issues in doing this. This seems the cheaper route to go now as it will probably cost me $500+ to get the 289 heads done.

 

[Broncobowsher]

P-heads have different spark plug angles that generally interfere with the exhaust.
The chamber size is larger, compression ratio (and power) will drop.
If the valves hit the piston hard enough to blow out the lifter, it probably damaged the piston as well.
Pistons are the same for a 302 as a 289, difference is in the crankshaft and rod length.

 

[BroncoKelley]

I have hooker headers on it and have some 90 degree spark plug wire ends so I don't think there will be an issue-there is only 2 cylinders that it may be close. The mark on the piston was barely noticeable and the rocker arm was off to the side when I pulled the valve cover, I think that had more to do with why the pushrod was bent.

 

[G's Baja Bronco]

my only concern would be the CC's, see: http://i580.photobucket.com/albums/ss241/cantbuytime/Stang/CylinderHeads.jpg
more cc's is less power and compression.

I am running the gtp's on a 91 5.0l ho engine, it came with the E7TE's (62 to 65 cc's) and now with the F7ZE (58 to 61 cc's) I gained a little compression and power.

looks like 289 heads where either 63 or 52-55 cc's, is you have the 52's you will loose some power, if you have the 63's you will be about where I am at.

 

[BroncoKelley]

my only concern would be the CC's, see: http://i580.photobucket.com/albums/ss241/cantbuytime/Stang/CylinderHeads.jpg
more cc's is less power and compression.

I am running the gtp's on a 91 5.0l ho engine, it came with the E7TE's (62 to 65 cc's) and now with the F7ZE (58 to 61 cc's) I gained a little compression and power.

looks like 289 heads where either 63 or 52-55 cc's, is you have the 52's you will loose some power, if you have the 63's you will be about where I am at.

Well anything would be better than what I have now which is no power. The casting on my current heads is C6AE, the GT-40P heads are the later ones with the 58-60cc heads. How is the header and spark plug clearance?

 

[G's Baja Bronco]

I am running MAC GT40P shorty headers for 91 GT stang, it was easy since I did a frame off.

 

[John Marinan]

A 60 over 289 isn't going to last very long, might want to replace the whole thing.

 

[Ranchtruck]

The valves probably stuck due to gummed up gas deposits on the stems. I'd clean out the tanks and make sure you're starting with good gas and a new filter.

I've had pushrods drop out a few times from that on engines that have sat for a while, but never had the pistons catch the valves.

Might also want to check the timing chain slack by turning the crank and watching the rotor in the distributor.

 

[BroncoKelley]

Well, I have decided to pull the 289 and go with a 351 (I know, bummer!). There's a guy close to me that builds small block fords and sells them out of his garage just by word of mouth and craigslist. He has built some 5.0 motors for a few of my mustang buddies and his stuff just works. He has a 351 truck short block 40 over ready to go with a good torque cam. He is willing to take the 289 off my hands in trade!

 

[G's Baja Bronco]

nice deal, you will love the extra torque My Brother does on his 73!