What's a good cam for my olds 455?

[gerfguy]

I'm not sure what info is needed to get a answer here but I will give you what I got. I have a 21' sleekcraft jr executive, "c" impeller in a jacuzzi 12yj. 455 with "J" heads & hardin logs. It will have a performance products intake(not sure of a carb yet). I'm looking for low to mid rpm power & either a lumpy or deep sound at idle. What would be a good cam for this type of application?

[Stv Euro]

Get with Mondello in Cal. Engle Cams builds the cams and they will ask you a couple of questions and get you set up.

[sleekcrafter]

Mondello's is over priced and outdated tech info. Summit has an off the shelf cam, http://www.summitracing.com/parts/HRS-510041-12/ Or if you want to go custom grind, Bullet Cams has done thousands of jet boat cams http://bulletcams.com/ Jet boat shops such as Hi-Tech Performance, and Jetboat Performance, can set you up as well with cam packages.

[rev.ronnie]

Tough to go wrong with a Comp Xtreme marine cam, or a custom grind. Talk to Chris Pagett at comp, tell him Cedar Machine sent ya.

[Spike Morelli]

Gerfguy,
I'll throw my two cents in here. It sounds like you are warming up your engine, however, you aren't saying if you are going to rebuild the Olds and do the necessary modifications to it to make it live. If you are bolting on external stuff, keep your cam selection on the decidedly mild side. Oldses were built for torque, not revs. They will rev reliably, but require a few mods. The gentleman who advised you to contact Mondello is on the right track, he builds engines, and, Oldsmobiles are a specialty of his. Or, talk to an engine man of your choice with Olds marine engine experience.
I'm sure that enthisiasts that recommend a grind to you mean well, but do any really make a living building engines? Probably not.
Joe Mondello , sadly, passed away a few weeks back,.....his son Bernard Mondello, builds engines in Corona, California, and can get you squared away, should you care to ask him. Mondello Racing's phone number is (951) 371-1432

[gerfguy]

Spike, the engine was rebuilt acouple years back & has lass than 20hrs on it,so I'm doing just like what you're saying "warming it up" I am in contact with a couple of marine engine guys so I get the right cam. Thanks!

[Hamjet]

Gerfguy,
I'll throw my two cents in here. It sounds like you are warming up your engine, however, you aren't saying if you are going to rebuild the Olds and do the necessary modifications to it to make it live. If you are bolting on external stuff, keep your cam selection on the decidedly mild side. Oldses were built for torque, not revs. They will rev reliably, but require a few mods. The gentleman who advised you to contact Mondello is on the right track, he builds engines, and, Oldsmobiles are a specialty of his. Or, talk to an engine man of your choice with Olds marine engine experience.
I'm sure that enthisiasts that recommend a grind to you mean well, but do any really make a living building engines? Probably not.
Joe Mondello , sadly, passed away a few weeks back,.....his son Bernard Mondello, builds engines in Corona, California, and can get you squared away, should you care to ask him. Mondello Racing's phone number is (951) 371-1432


Spike, the engine was rebuilt acouple years back & has lass than 20hrs on it,so I'm doing just like what you're saying "warming it up" I am in contact with a couple of marine engine guys so I get the right cam. Thanks!

Gerfguy,

Spike gave you sound advice, changing the cam on your Olds is going to destroy the motor if you do not do the necessary mods on the now renowned oiling restrictions, poor oil drain back from the heads, spun rod bearing due to incorrect tolerances and the limitations of the factory rods on the 455 Olds engine. I have been there trust me.

Add an oil cooler to the setup to keep the oil at a reasonable temp and run the correct oil for your application.

There are a lot of discussions on how to prepare your Olds to make it last, and by ignoring to address the short comings of the Olds your project will end up in tears and wasted money.

Wikus

[RLP]

I tell ya the comp cams 280 magnum will work GREAT.
That C impeller seems a little small,the B would be better.
Unless ya got lots of performance mods to the 455 dont turn it up to much.
The Xtreme marine by comp will work great also im sure.
I know the 280 magnum is an car type cam,but does a great job in the all around use jet with the 455.
Have use this cam in 5 other 455 jet builds and works GREAT!
The last was 19ft same pump but B impeller and the 455 and would turn 5,600 with a fresh pump.

[gerfguy]

I bought this boat last year witch came with a brand new rebuilt pump. If it wasn't already rebuilt I would have gone in a different direction with it altogether but its brand new & I'm not messing with it. I'm not sure what a "c" impeller is good for but it staying in for now.

[thompy]

the yj pumps have a large spread of impellers, i had a sb in mine and belive it was an E, they were like 1300 for a new imp about ten years ago, these are high volume low pressure pumps like the panther pumps

[sleekcrafter]

I bought this boat last year witch came with a brand new rebuilt pump. If it wasn't already rebuilt I would have gone in a different direction with it altogether but its brand new & I'm not messing with it. I'm not sure what a "c" impeller is good for but it staying in for now.

The jacuzzi will get to a point, where the boat does not go any faster, but the engine/pump will over rev. The 21 sleek is rather large for "C" impeller.

[clayolie]

i have a 76 sleekcraft 19' with a nicely built 455 w/ c heads. jucuZzi yj12 pump that i blueprinted myself. comp cams has a specific cam for and olds 455 in a jet boat application. 5000-7500rpm i believe. ordered it from auto value. boat runs great but it it does cavitate off the line if you have your pump set for topend.

[Stv Euro]

Ok. Back to me again. I am running a Engle cam built FOR Olds jet boats for Mondello. You guys are talking about turning 5600 RPMs: That is a bomb on the water. My impeller is an A2 cut for a Berkley and will turn 5000 RPMS with the entire engine built. The bottom end is all forged and tons of time put into the "C" heads. Spend your money on the top end b/c of the cold water entering the engine it kills valves and you will break valves. I have S/S valves with titanium guides and roller uppers. Don"t get discuraged just remember the olds will NOT turn 6500 rpms like the Chevy but they still run great. Thats just the way it is!

[Spike Morelli]

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 basically the same as a 455, save for a shorter stroke and a factory forged steel crank, and it absolutely would turn 6500 whenever you wanted it to....................but not at first.
We seized two engines prior to getting the right info from Joe Mondello of Mondello's Porting Service, and Larry Ofria at Valley Head Service . Stock 2 bolt mains caps were studded, line-honed (after cap cutting) to the tight side for good bearing crush. Vertical oil clearance of .003". 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 .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. Oil was Valvoline Racing 20/50.
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 ). Anti-pump up lifters, springs, pushrods, retainers, locks, all Isky in the kit.I do remember degreeing the cam , and set it 4 degrees retarded from "straight up", for a bit more top end power. ( ALWAYS check your cam timing ). Cloyes True-Roller timing set. The heads were ported/polished,heat cross-overs welded closed 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 guide liners, ( 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. 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.
Ignition was a Joe Hunt Scintilla vertex magneto with centrifugal advance all in by 2200, standard 7mm AC Delco Packard 440 wire core wires, Champion plugs one step colder than stock. M/T valve covers received two breathers each, in addition to the oil fill tube, which had a breather replacing the cap, to relieve all crankcase pressures at high RPM.
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.
For a photo of this engine, check out post #26.

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.

[gerfguy]

Spike,

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

[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. :mad:

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.246492

[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

[GIL_CV21]

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.

sure BBC's and BBF's are good power, parts are cheap, easy to work on but their like A--holes everybody has one . I'll keep my 455 . Gil