new heads? or new engine?

[calpolymustang]

The heads on my 289 have to be replaced because one of the valve seats loosened up, and i really dont feel like putting any more money into stock heads.

I'd like to know if you guys recommend i get new heads, or a 5.0 with 50-75k miles. I dont want to change the transmission or the gearing.

Heads would be 58cc, so my compression would drop. Maybe 1.90/1.69. Would I loose much bottom end by having large valves on a small motor? And with this route...i still have just a 289.

The engine would need the balancer/flywheel/waterpump conversion, but what I'm mainly worried about is straining the engine on the freeway (3400rpm seems like a lot for a roller cam).

Any ideas?

 

[65ShelbyClone]

Your current cam looks pretty mild. I don't think bigger valves would hurt the low end that much, especially not with a 3500 stall converter. The old school of thought would say that my combo would have terrible low end(single plane, aluminum flywheel, 3.50s, 1.90/1.60 heads, 650 carb, etc), but it is actually very good. It's all in the cam.

I guess it comes down to how cheaply you can get the 5.0 and the matching damper and flexplate versus the cost of whatever heads you are looking at.

 

[calpolymustang]

Summit has World WindsorJr heads for $820

58cc 1.94/1.60 with 180 runners

With the 5.0, its $150 for flexplate/dampner then additional money for the oil pan and pickup.

 

[67rcks]

The engine would need the balancer/flywheel/waterpump conversion, but what I'm mainly worried about is straining the engine on the freeway (3400rpm seems like a lot for a roller cam).

Any ideas?

Maybe I'm missing something but head swap is straightforward and you don't need to make any changes in the lower engine.

 

[calpolymustang]

Sorry...
With the 5.0 swap... I would need the balancer/flywheel/waterpump conversion, but what I'm mainly worried about is straining the engine on the freeway (3400rpm seems like a lot for a roller cam).

 

[D.Hearne]

First of all, a roller cammed motor can handle sustained rpms better than a flat tappet can. I don't know what gave you the idea it couldn't. Second, you'd be happier with a milder stall converter. A 3500 stall with what you're running it with is a huge waste. You'd be much happier on the freeway with a something in the 2000 rpm range for stall. I'm running a converter with about this behind my 331 with a Z303 cam ([email protected] duration .587 lift hyd. roller) High rise dual plane intake, same transmission, rear is a 9" with 3.50's, tires are 26.5" tall. I can lightly powerbrake it and lightem up the 295's on demand. Go to a lesser stall converter along with the heads, your wallet will stay full longer.

 

[calpolymustang]

Thanks for the info.

I'm not looking forward to spending more money on the tranny, and still have the stock-rpm converter. Its in great condition (only a few years old) and has only been on the shelf for a few months. If i dont keep the 3500, ill go back to the stock conveter