Engine: Flat Top 289 Pistons

[345 DeSoto]

Where would one purchase .060 over 289 flat top pistons and rings?

[r1lark]

Try Phil at Fairborn Studebaker. He is one of the best vendors out there for engine parts. Basically, a flat top 289 piston would be an R1/R2 piston.

The flat tops should give you around 10:1 compression ratio. I believe there are also shallow dish pistons available that give a boost over the standard 289 pistons, but not quite as high as the flat top pistons.

[swvalcon]

I would think 10.-1 compression with cast iron block and heads would be pushing the limit on today's fuel on a hot day. Unless you like mixing race fuel or turning the timing back and then you may as well just stay stock. If you could more in the 9-1 range you would be better off. I had a 75 corvette that was close to 10-1 with a 4 sp and sometimes you had to back out of it because you could hear it start to ping pretty good.

[Bud]

There are half dish pistons available for the 289 engines which is what I would recommend for use with modern fuel. I have flat top pistons in my Avanti and on a warm day, it will detonate on pump gas. I've slowed down the spark advance rate which helps, but doesn't eliminate the problem. Pistons are available from several of our Studebaker parts vendors. Check with them for parts availability and price. Bud

[t1003nl]

Before you do anything, measure the cylinder head chamber volumes, the piston dish volumes and piston drops of your current parts. Calculate your static compression ratio based on your actual parts. Then recalculate based on 0.060" oversize bore and removing the dish volume. If you decide to go with half dished pistons, verify what the actual dish volume will be on the new parts. A stock 289 piston dish should be around 19cc's. A half dish should be 9.5cc's. I have a set of half dish pistons in my garage and the dishes measure 14.5cc's. Be careful with cylinder head chamber volume. I have had untouched, factory heads measure 5-6cc's larger than spec.

Summary thoughts...measure everything FIRST, then order parts. Know what you will be getting and confirm the final compression ratio will be what you want. Do not assume your heads will be at nominal factory spec. I'm running a '64 289 at 9.7:1 measured static CR using 93 pump octane fuel with no issues. I set basic timing at 12deg BTDC and I have 35deg all-in with mechanical advance. It runs great.

[SScopelli]

Do not forget the other factors..

1) The Head gasket thickness plays into the final compression ratio as well..
2) The heads you are using... If you are porting out your 570 heads and cleaning up the chambers, then it may be the same as the 582 heads..
3) if you use the 582 heads with flats, will probably bring you to 9:1.
4) Spark Curve...

[PackardV8]

Do not forget the other factors...

For true. Measure the thickness of the head. IIRC, the blueprint dimension from rocker cover rail to head surface is 3.5625."

Many Stude heads have already been milled once or twice. Occasionally, I find a pair someone has milled .060" or more.

jack vines

[JoeHall]

Around 1990, I bought a 63 Cruiser and rebuilt its 289. I bought new, OS pistons from an elderly Mr. Snearly, in Colorado. I noticed his pistons were flat tops, and called and asked him about the difference. He assured me they'd be OK, so I took his word for it. That motor ran great; excellent MPG, and was the zippiest 289 I ever had. I don't know if they were R1 pistons or what, but they worked great in that car, and on regular gas. I do not recall the car running hot, and drove it around 9,000 miles before selling it a couple of years later. Wish I'd kept the motor.

[345 DeSoto]

I take it 582 heads refer to the casting number...or part of it? The casting numbers on my heads are 535976...

[Bud]

The number 582 is the last 3 numbers of the casting number in between the center 2 exhaust ports. That head was used on supercharged R engines and the 259, 289 powered Champ pickups. They will give you around 8 to 1 compression on a normally aspirated engine with shim head gaskets and around 9 to 1 in the R engines. Most of the 259 or 289 normally aspirated engines had 555, 294 or 570 heads on them depending when the engine was produced. The 56 engines used a lower compression head, but at this point, I can't remember the number. Bud

[Quentin]

I take it 582 heads refer to the casting number...or part of it? The casting numbers on my heads are 535976...

you have a low compression head according to the bob johnstone list. 1956-60 head, 7.5:1 compression. You can do flat tops no dramas with that comp ratio, should take you to 9:1 or thereabouts.

[345 DeSoto]

My 976 heads are 58cc, and give me 7.5:1 CR and have not been milled. The head gasket appears to be a thick fat flat steel. Going with the same gasket, what CR will the 1/2 dished pistons give me...approximately.

[Colgate Studebaker]

If you decide to go with flat tops, I have a set of pistons that I bought from Jim Pepper that I'm not going to use. I paid him $200, so taht is what I'd need for them. Bill

[JoeHall]

If it were me, with those heads, I'd go with Bill Van Alstyne's flat tops, if they are the right size.

[StudeRich]

I would refer to Bud's Good advice, and NOT use Flat Top Pistons.

There are half dish pistons available for the 289 engines which is what I would recommend for use with modern fuel. I have flat top pistons in my Avanti and on a warm day, it will detonate on pump gas. I've slowed down the spark advance rate which helps, but doesn't eliminate the problem. Pistons are available from several of our Studebaker parts vendors. Check with them for parts availability and price. Bud