What's a good cam for my olds 455?

[Hamjet]

As long as we're talking about our Oldses.....my family used to go water skiing with a hydro from '68, to '76 all the time, and the engine in the boat was a '67 425 Olds. This engine is exactly the same as a 455, save for a shorter stroke and a factory forged steel crank, and it absolutely would turn 6500 all friggin' day long if you wanted it to....................but not at first.

We seized two engines prior to getting the Mondello treatment. Stock 2 bolt mains caps were line-honed (after cap cutting) to the tight side for good bearing crush. Vertical oil clearance of .0025". Cross-drilling and tuft-riding done to the crank. Stock Olds rods were polished , shot-peened, sps bolts, re-sized, again, on the tight side for good bearing crush,( verticle oil clearance again .0025") and Mondello side ground the rods to give .022"rod side clearance for the pair. Oil slots were machined into the rod thrust sides .005" deep by 1/2" wide.

Mondello oil restrictors were used in the center three main-to-cam oil holes. An Aviad 12 qt oil pan and high volume pump with a 3/4" pickup were used.

Jahns 11.0:1 forged pop-ups, with floating pins were used. Of course, everything went off to the engine balancing shop prior to assembling.Bearings were Clevite 77, rings were Sealed Power Moly/ductile iron at stock widths.

Camshaft was an Isky hydraulic, ( sorry, I don't remember it's specs, but it wasn't real big ). Lifters, springs, pushrods, retainers, locks, all Isky in the kit.The cam was degreed and set 2 degrees retarded from Isky's lobe center. ( ALWAYS check your cam timing, my experience has shown that most cams are off, usually too advanced). Cloyes True-Roller timing set. The heads were ported/polished,heat cross-overs plugged in both heads, and ran Mondello guide plates and small block Ford 1.6:1 roller rockers.( 425 Olds heads have screw-in studs from the factory, that have a shoulder, or, "positive-stop". Replace these with small block Ford or Chevy 3/8" screw-in studs to make it adjustable). Polished stainless valves and bronze guides, ( I'm sure Kevin meant bronze, not titanium, in his post). Intake valve faces ground to 45 degrees, not the stock 30 degrees, for better top end breathing

Externally, induction was an Edelbrock O-4B single carb Hi-Rise with a box stock 800 cfm double pumper Holley. Ignition was a Hunt magneto. Exhausts were Nicson wet logs with aluminum O/Ts.Headers may have freed up some more power, but this WAS a ski boat, so we didn't use 'em.

It sounds like a lot, but it isn't, this was an everyday v-driven ski boat, thrashed often by a lead footed father and his two teenaged sons (one of those teenagers being me).

This is really BASIC stuff. That Olds turned 6500 at will,without any engine problems, and suprised many a 427 Chevy owner( the big Chevy at that time).It idled nicely, and pulled skiers all day.I did all the assembly on this engine back then, and, continue to build engines for a living today.



Perhaps, the real problem is turning 6500 with a JET PUMP. Most stock pumps will limit rpms to around 5500. Guys DO rework their pumps looser to turn high rpms, but this can get expensive, and you lose bottom end power and response out the nozzle.



Bottom line, DON'T write off the big Olds. They are plentiful, and with a few bottom end modifications and the RIGHT parts, they do their thing.

Spike,

I am a big fan of Olds 455's and agree with you that you can make them live and if properly set up they can make good HP.

My problem I have with one of my Olds motors, wants me to make an anchor out of it.

I have thrown big $$ at it, done all the mods and imported the best parts I could find.

The same journal gets thrashed every time. I have rebuild the motor a total of 4 times and the same journal (No5) gets beat to sh#t. New crank every time (used), new I beam rods, clearances as per Mondello's and Bill Trovato etc.

Do you maybe have any suggestions.

Sorry for hi-jacking your thread Gerfguy, but maybe it is something that we are missing and can help.

Wikus

[ezobens]

Cam selection should be based on load, maximum RPM expected and power goals, not how it sounds at idle. In a marine application, exhaust plays a big part as well- If you have logs that dump out the transom and under the water, you need to me more concerned with reversion than if you have over the transom exhaust.
My CVX-20 was running the popular Comp Cams hydraulic 455 Olds 'Perfect for Jet Boat' cam but with the exhaust under the water, I had a horrible time with exhaust reversion at idle/low speed.
It would suck in the rubber flappers just sitting at idle in the water- Not good.
I ended up with a custom cam that that has minimal overlap and fits my power requirements nicely.

There are a lot of choices out there- Just make sure you go with what you need for your application and not for how it sounds idle. Most of your boating isn't done at idle anyway-
Just my 2 cents.
Elm

[Fuli]

Spike,

I am a big fan of Olds 455's and agree with you that you can make them live and if properly set up they can make good HP.

My problem I have with one of my Olds motors, wants me to make an anchor out of it.

I have thrown big $$ at it, done all the mods and imported the best parts I could find.

The same journal gets thrashed every time. I have rebuild the motor a total of 4 times and the same journal (No5) gets beat to sh#t. New crank every time (used), new I beam rods, clearances as per Mondello's and Bill Trovato etc.

Do you maybe have any suggestions.

Sorry for hi-jacking your thread Gerfguy, but maybe it is something that we are missing and can help.

Wikus

Gerf, I used the Earson JB 200. When I was not blowing up my 455. Worked well with Ka heads and a dual plane intake. After my fourth engine rebuild, It sank on the shore at Lake Powell.

I will always love the Olds Elephant engine, but not in a boat, ever again.

[Spike Morelli]

Wilkus,
Oh my, four times #5 beats itself to death! I can't really say, over the phone, so to speak. But, if you use a different crank every time, and use a different rod every time, and have no problems elsewhere, at very least, you know where to concentrate your search.
I was thinking about the problem....if you rule out clearances, poor components or machining, as you indicate, what about this...................your firing order is 18436572. This is a longshot, but could your ignition be a factor? Because #6 fires just before #5, if it crossfires in the cap, or induces a pulse thru the wires to #5, that #5 cylinder can fire too soon, hammering the piston and bearings and rod. Any spark plug damage to #5 plug as well? Something to think about. Maybe not an issue. It's the only weird outside thing I could think of, save for actually tearing the damaged engine down for a more educated report.

[Hamjet]

Wilkus,
Oh my, four times #5 beats itself to death! I can't really say, over the phone, so to speak. But, if you use a different crank every time, and use a different rod every time, and have no problems elsewhere, at very least, you know where to concentrate your search.
I was thinking about the problem....if you rule out clearances, poor components or machining, as you indicate, what about this...................your firing order is 18436572. This is a longshot, but could your ignition be a factor? Because #6 fires just before #5, if it crossfires in the cap, or induces a pulse thru the wires to #5, that #5 cylinder can fire too soon, hammering the piston and bearings and rod. Any spark plug damage to #5 plug as well? Something to think about. Maybe not an issue. It's the only weird outside thing I could think of, save for actually tearing the damaged engine down for a more educated report.

Spike,

Thank you for the reply, it is something I will definitely look into. I busy assembling the motor as we speak. I have gone with Eagle H-Beam rods this time, Cryo Treated Clevite bearings and was at the machine shop, checking the machinists work as he was grinding the crank etc.

New block which was magnafluxed and all the oil galleys checked. If this doesn't work I am going to import a sub assembly from either Mondello or Bill Trovato. I am stuck on the Olds and just loves the way they look and sound.

Wiikus

[200VEGAS]

do you guys ever use the msd ignition so you could use say a 5000 or even 4700 rev limiter and use an impellor that will be pushing hard at that rpm? i had several olds 442's growing up and they were so awesome, and so much torque. stock, they ran out of power at about 4700 and if you didnt shift, they just quit pulling. im talking about 68 and 69. after 71, no compression just killed even the 455 w-30. my father had one

[Spike Morelli]

Wiikus,
Keep on keepin' on with that big Olds. I've read many things about Cryo-treating engine parts, and I want to endulge in it myself on some current projects. Come back on here to let us know how things turn out for you.
Personally, I think engines are a lot of fun.....it's all about the engine when it comes to a performance boat, otherwise, all you have is a fancy canoe! Hey! Good boat name......"Fancy Canoe"

[sixpac]

Wilkus,
Oh my, four times #5 beats itself to death! I can't really say, over the phone, so to speak. But, if you use a different crank every time, and use a different rod every time, and have no problems elsewhere, at very least, you know where to concentrate your search.
I was thinking about the problem....if you rule out clearances, poor components or machining, as you indicate, what about this...................your firing order is 18436572. This is a longshot, but could your ignition be a factor? Because #6 fires just before #5, if it crossfires in the cap, or induces a pulse thru the wires to #5, that #5 cylinder can fire too soon, hammering the piston and bearings and rod. Any spark plug damage to #5 plug as well? Something to think about. Maybe not an issue. It's the only weird outside thing I could think of, save for actually tearing the damaged engine down for a more educated report.

if it was spark induced or crossfires in the cap causing # 5 to get beat-up what would be the correct coarse of action to stop the problem ?

[Spike Morelli]

if it was spark induced or crossfires in the cap causing # 5 to get beat-up what would be the correct coarse of

action to stop the problem ?

IF , and this can happen, but If you crossfire in the cap, it may be caused by a hairline crack in the cap between the two electrodes, or it can happen if there is a carbon trail allowing an arc to jump between the terminals in the cap. In either case, I believe you should be able to see either with the naked eye by inspecting the distributor cap real good. Sometimes, even bad spark plug wire boots side-by-side can spark across to each other. You can see this kind of stuff when you put a car on an oscilloscope to tune it, but when was the last time you've seen one used, and boat shops may not even have one. Sometimes, an ignition is updated to a capacitive discharge style box for a hotter spark, going through a stock distributor and factory style plug wires, and the voltage is too much for the cap or wires. The obvious fix is to upgrade the cap and wires to a heavier insulated dielectric cap, and heavier insulated ( larger diameter ) wires.
Check out photos of drag cars and boats from the sixties, all running hot magnetos. Those mags put out way more zap than a stock battery ignition and most used 7mm Delco wire core plug wires, and put out lots of horsepower even under heavy fuel loads and boost, without crossfiring, but things were starting to change.
Then the seventies come in, and for smog reasons, cars are tuned to run lean, and start to misfire, so the factorys begin to go electronic, with Lean-Burn, H.E.I., etc, and now, spark plug wiring begins to get heavier insulated with 8mm wires to contain the higher voltage potential. Hot rodders were starting to use the new ignitions over the old "dual-point" set-ups.

Today, we can run really hot ignitions that are breakerless, and capacitive discharge, such as the popular MSD line. ( Personally, I prefer the simplicity and reliability of a scintilla vertex , or Schiefer/Cirello magneto on my projects ). Plug wiring can be 9mm or larger to contain the voltage. Big wires don't make any more power, they just are necessary only when your ignition requires it, such as high voltage. ( It's like the old saying, "..if your car doesn't ping running regular gas, using super won't make any more power"), so if your engine runs good using 7mm wires, 9mm wires won't make it run any better.

Bottom line, if you're crossfiring in the cap ,or inducing voltage through your plug wires,,,,#1- get a new cap and wire set, #2 -separate your plug wires away from each other with looms running all the way from the cap to each plug, and #3- if your ignition has been upgraded, get an even heavier cap and better wires. Again, this all may be a longshot as to the #5 bearing pounding, but it could happen. Ford recognised the possibility of inductive crossfiring in their 15426378 firing order, with 7 and 8 being the likely culprits, and separate 7 and 8 wire at the loom on the left valve cover by placing the wires at opposite ends through the loom from the factory on their V-8s. Now, lots of Ford guys will loom their left side wires 5678 front to back just like the cylinders are, and never have a problem, but even with a stock point and coil ignition, Ford engineers knew it could induce a misfire under the right conditions, so they separated the wires in the loom. It's in the Factory shop manuals. It's, less likely in GM's 6-5 firing, being that the cyls are on opposite sides of the engine, making it more likely to be in the cap, and for most people, this never happens, but it could where any two cylinders sucessively fire. Anyway, it's food for thought, and easy and cheap to remedy.

[Spike Morelli]

Spike,

With 11:1 comp, did you have to run high test? What comp is regular good up to ?

Gerfguy,
Yes, we always ran high test. Everybody did, that had a hot boat back in the 60's/70's, but today may be a different story because of the lower octane gas available.
I don't know at what comp regular unleaded is good up to. Because of all of the variables in each engine, such as head chamber shape, ignition timing, engine temp, cam overlap bleed-off, etc, it's a matter of having used a certain combination with good success, but 9 to 1 is safe usually, some combinations can run a little more. With today's better manifolding, ignitions, cams, and such, many engine builders are getting big power from 9 to 1 comp engines, than we got in the sixties.

[Spike Morelli]

I found a photo of the 425 Olds engine from my family's ski hydro, the one that I had outlined how it was built. I know, you can't tell by the photo, but this Olds hauled.

[keith69ranger]

for cap and rotor use brass components, aluminum breaksdown and promotes crossfire on loaded engines. saw lots of SBC kill offshore raceboat engines in key west back in early 80's, plugwires would just be tied together and laying on manifolds. salt spray contributes also.

[Hamjet]

Wiikus,
Keep on keepin' on with that big Olds. I've read many things about Cryo-treating engine parts, and I want to endulge in it myself on some current projects. Come back on here to let us know how things turn out for you.
Personally, I think engines are a lot of fun.....it's all about the engine when it comes to a performance boat, otherwise, all you have is a fancy canoe! Hey! Good boat name......"Fancy Canoe"

Spike,

I finally got the motor assembled and had the first test fire today. I took my time collecting and importing the parts on this one and it was well worth it. I must say she sounds damn sweet. Oil pressure cold is @ 80Psi and drops down to 60Psi, temp is 180 degrees F @ 15Psi in the block. Had to run in the new cam (292 Iskey from Duane (HTP). The 10Qt oil pan is also a huge improvement from the 8Qt I previously ran. Next is installing the drive shaft and then off to the lake. Will post some pics when I get a chance, had some stuff done to the hull as well.

My boat's name is "Prawn Star" my nickname - my name is Wikus like the character in District 9 (Wikus van der Merwe) who calls the aliens "F#cking Prawns" my friends thought it appropriate.

Wikus

[hulltruth]

Cut your losses sooner then later and get chevy.You will be money ahead in the long run.Or you can dump a few more thousand into and wish ths whole time you had cut your losses sooner.

[Hamjet]

Cut your losses sooner then later and get chevy.You will be money ahead in the long run.Or you can dump a few more thousand into and wish ths whole time you had cut your losses sooner.

Let me guess, you probably can't afford to run an properly prepared old skool Olds engine, chebby is so everyday.

Wikus