TxHawk

Sorry, I was just thinking of the extra cost of shipping if you were to buy parts here.

tomas_wallin

Thats true - but I have kept that in mind...

Does anyone know what the freight (somewhere 2-6weeks) is for a pair of heads?

I think a prop would cost ~$125 with a rather quick delivery.

Lee-way

Well riddle me this? How are you going to change rod bolts without getting into the bottom end of the motor? Wouldn't it be wise to change out the crankshaft and pistons if you even decide to go that far? Just speaking from experience. I did some Rand D work to a 330 hp motor just to see how much stress she would hold up to and running it at 5200 rpms is where the crankshaft let go. It was exciting, nothing like trying to break a motor.

dyno

I'll run my cast cranks at 5200 all day long....good machining and ARP bolts go along way! SuperV runs his to 5700 never had a crank problem engines were built in 1994.

tomas_wallin

Yeye, But I don't have to change anything just because I remove the oilpan and change the rod bolts...
Perhaps I should balance the crank etc? Or should I leave it as is?!

Pat McPherson

Hey Dyno,
Did you change the rods? or are you using the stock 3/8 bolt rods?

ECeptor

I did a search and could not find the thread. I'm sure you've done this many times already but I'll ask anyway - any chance of you listing the specs of your engine? Heads, Pistons, Cams, Intake, Carb, etc...

Whiteknuckle

Ditto post #24 from Dyno. I'm running 3/8" ARP Bolts. Engine has been balanced and line bored. Remember these are not the cast cranks out of a 1955 Packard. Modern metallurgy and machining makes them much better than the old stuff. Are they has good as a good forged crank? no, but they can get the job done if you use your head!

KAAMA

Back in the mid 1980's my friend had a 30' Scarab with a pair of Merc 330hp engines. We wanted to upgrade the engines a bit. Back then, aftermarket heads were pretty much non-existant. The engines already had the "049" GM large oval port castings which is a very good casting. We had larger stainless steel valves installed in the heads with some bowl/pocket porting as well plus bronze guide liners installed and cut, spring seats machined for larger springs, 3-angle valve job, and had the heads resurfaced. We DID install new forged pistons over using cast ones. New higher duration flat tappet hydraulic cams. New aluminum hi-rise dual plane intake manifolds and new Holley carbs.

My friend couldn't afford it all at once. So, he tried doing things as wisely and strategicly as he could. The boat had through the prop hub exhaust, so the first year he modified the exhaust to exit through the transom above the water line by installing aftermarket exhaust manifolds (GIL) and new aluminum hi-rise intake manifolds. By just doing that the engines picked up 400rpm each. The second year he had the cylinders re-bored completly refreshend the bottom ends with cams and the next year after that he did the heads, and carbs.

However, the things we were concentrating the most on were the rods, cast cranks and the squareness of the blocks while playing particular attention to the main saddles of the blocks.

The stock cast cranks had to be cut .010" for both rods and mains. The rods were shot peened, and recondtioned using the new 3/8" ARP rod bolts. The main saddles of the blocks were align honed to make sure that everything was correct, fitted, and spun nicely. The rotating assemblies (pistons, rods, cranks, dmapers, flywheels) were balanced so that nothing was fighting each other or would cause any vibrations that would lead to any failures. Proper machine work and fit is paramount to the life of an engine. He ran that boat for hundreds of hours and didn't have a failure because he did it right the first time. Engines ran up to 5500rpm. Cast cranks worked fine----even at 10/10. Everyone told us they would fail----and back then we didn't even run any oil coolers, just straight conventional 40w Valvoline oil.

formula31

Dont ask the oil question, thats almost as bad as politics or religion. Ive always has good success with a straight 40 wt. Since I am pushing more hp now on seasoned engines I am going to run Mobil 1 15-50 this year.