289 Rebuild Suggestions

fasttback · Jan 5, 2007

Well...since my cam bearings were cracked I will have to pull the motor. Since the motor will be out I wanted to freshen it up a little (according to the po it was rebuilt 10,000 miles ago). I will look into this as I tear apart the motor.

So for now, I was just planning on cleaning the motor installing new cam, main, and rod bearings. I will check clearances on all of the typical locations and inspect the cylinder walls for cross-hatch and ridge conditions. Also, a new timing chain, oil pump, oil pump shaft, ARP rod bolts, and windage tray will be installed.

Is there anything else I should consider for the bottom end without dumping a ton of money in it? It's a mild motor with a .480" lift cam 224 (0.050) duration, 9.5:1 compression, single plane, 625 Demon, 351W heads 1.9 and 1.6 (stage III ported), tri-y's, 2.25 exhaust.

rbohm · Jan 5, 2007

since this motor was rebuilt recently, i would not worry about the cylinder bores except to clean them up with atf and some lint free white towels. use a set of moly rings as they break in quickly and last a long time. as for the rest of the block, clean the oil passages as completely as you can with either brass, or plastic bristle brushes. same with the crankshaft oil passages. if you havent already, replace all the bolts with arp bolts and studs(use the studs on the mains).

ga289stocker · Jan 5, 2007

Sounds like we have similar combo's expect for the 351 heads, ever ran her down the 1/4?

fasttback · Jan 5, 2007

rbohm said:
since this motor was rebuilt recently, i would not worry about the cylinder bores except to clean them up with atf and some lint free white towels. use a set of moly rings as they break in quickly and last a long time. as for the rest of the block, clean the oil passages as completely as you can with either brass, or plastic bristle brushes. same with the crankshaft oil passages. if you havent already, replace all the bolts with arp bolts and studs(use the studs on the mains).

Thanks. Will add some moly rings and more ARP bolts/studs to the mix.

fasttback · Jan 5, 2007

ga289stocker said:
Sounds like we have similar combo's expect for the 351 heads, ever ran her down the 1/4?

Not the 289, but those heads were once on a similar 306 motor with a .512, 252 (0.050) solid cam. I shifted at 7200 and went through the traps at 101 mph in 3rd gear, but I'm too embarrassed to tell you the time. Since it was a street car, I had no drag suspension or suspension tuning for the drag strip and IT SHOWED.

I plan to run the current setup this spring with some modifications to the suspension. Hoping 13's?

302 coupe · Jan 5, 2007

make sure to have the rods resized if you change bolts. Also, I have heard that changing to main studs can cause distortion/misalignment of the caps. I.E.-it's best/safest to only change said components if you have the tools to remeasure alignment/clearances, or you are willing to have a machine shop do it.

68RustBucket · Jan 6, 2007

Those heads might not be a good idea. The compression on 289's is usually bad enough, depending on the pistons used. Even bran new flat top pistons will bring the CR up to ~9.5:1 with 58cc heads. I'm not sure what the combustion chamber size of 351 heads are, but I can't imagine they are the same size as 289 heads. Might want to check up on that first.

fasttback · Jan 7, 2007

68RustBucket said:
Those heads might not be a good idea. The compression on 289's is usually bad enough, depending on the pistons used. Even bran new flat top pistons will bring the CR up to ~9.5:1 with 58cc heads. I'm not sure what the combustion chamber size of 351 heads are, but I can't imagine they are the same size as 289 heads. Might want to check up on that first.

Yea...that's always been a problem with the 289s back in the day. Since the heads were lying around the garage since the 1980's I thought I would use them. The heads are C9s with just under a 60 cc chamber. The compression ratio will be around 9.3-9.4:1 with flat tops. Because of this I'm running a bigger lobe separation (112 degrees) to help out.

This will be a big upgrade from my E6's, which surprisingly ran well with 8:7:1 on the 289.

68RustBucket · Jan 7, 2007

fasttback said:
Yea...that's always been a problem with the 289s back in the day. Since the heads were lying around the garage since the 1980's I thought I would use them. The heads are C9s with just under a 60 cc chamber. The compression ratio will be around 9.3-9.4:1 with flat tops. Because of this I'm running a bigger lobe separation (112 degrees) to help out.

This will be a big upgrade from my E6's, which surprisingly ran well with 8:7:1 on the 289.

If you can, get them suckers milled down another ~2cc and you'll be golden. I'm guessing they aren't the original pistons, considering you had a CR of ~8.7:1 with E6's. They probably have 64cc chambers, so 58cc chambers would be fantastic.

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