cracked block :-(

Well i missed the two lower drain plugs on my pcm 454. so time for a new motor....

It currently has square port heads which according to the specs I find for it. Indicate that it's a 7k+ rpm head. I have found a few low mile good complete "peanut port" truck heads which are great for torque and quit pulling around 5k rpm. I know pcm says to keep the motor below 4500 or 4200 and thats all my 650cfm carb will spin a 454.

Was going to try to get some opinions from fellow boarders. Should I clean up a suburban complete motor and be out the door for under a grand? Or rebuild the current set up with a new block for a lil over 2k? Even if I do all the work myself and just farm out the machining on a new long block it'll be 1k in parts/machine work only.

I've had the parts guy at scoggin dickies and three local motor builders suggest I go to a peanut port for the torque for my application.

If they're right why in the world did supra put in a high rpm motor for a low rpm application?

I would go with the stock truck motor and see how it goes. If you are not satisfied with it
you can always spend the extra grand in the off season and change it.

you gotta remember, there is no difference in a naked block of a marine engine and a street engine. the difference is in the cam shaft and a couple of of other things. cruising rpms on car engine are between 1500 and 2000. on a boat they are more like 3000 to 4000. an outboard even goes to 5500. your cam shaft is not gonna last very long if you are runnin a street engine in a boat.

so just take your suburban engine and marinize it. cause remember, when GM builds a block at a plant, they dont know if its goin in a truck as a chevy 454 of if its goin in a boat as a mercruiser 454.

Do marine engines have marine pistons ? or are they the same ?

According to pcm they don't touch anything including the cam.
Just the accesories and water neck.
I will prob put the same cam thats in my motor into the truck/suburban motor.
I wish roller cams weren't so much.

I'm thinking throw a gasket set and new paint on it. Maybe change the cam and bearings and see how it runs.

where were the cracks? could you visually see them?

This is on one side. The other side has crack a little bit smaller.

http://i123.photobucket.com/albums/o287/cowwboy4/DSC00912.jpg

I'm concerned that I could have a similar problem on one side of my block. I'm hoping it's not cracked, but there is a distinct line. Is there any way to repair a crack?

My machine shop told me that there is a special marine stamping on the block and that certain parts are beefed up to account for the increased stress and RPMs these engines are designed to run. He only runs marine BBCs in his race cars because they are "beefier."

There are some "marine" according to the "rat motor" building book I got. I know according to my buddy who used to build motors at mercruiser and the techs I talked to at pcm they don't order anything special. It may have been older stuff was that way but when I talked to the scoggin dickies guy he couldn't find anything marine, block wise.

Since a marine engine does not build pressure in the water system you can use jb weld on an external crack. If the water is getting into the oil or cylinders you will have to have a new block/engine.

I ran a 3.0liter in an i/o for several years after patching with jb weld.

^^^^^^ I have had success using JB type bubble gum for many years too on an external crack. Worth a try before retro-ing a new block/engine.

Maybe the 454 was chosen for its low-end torque.
But they're definitely leaving a lot on the table.

"Marine" = higher nickel content. Not all boat blocks are marine, but some are.

That crack doesn't look "JB Weldable" to me..

That crack is in my block not SS's.
I know mine is toast.
I wish mine was a external crack.

By Nick McDonald (lsukuntryboy) you gotta remember, there is no difference in a naked block of a marine engine and a street engine.

I'm not all sure about that. Years ago we had a Mustang short block in a 1988 Mastercraft Prostar 190..... thinking exactly like you are. When it came time to water test, we dropped the trailer in the water & bumped the boat in reverse..... it went right back up on the trailer. Tried it again but this time put the throttle in forward..... and the boat backed right out on to the water. We ended up buying a Nautique prop for the boat.... reverse pitch. Initially we worried about wearing the gears on the opposite sides, but apparentely it wasn't an issue.
Come to find out the marine Indmar / Ford 351 spins backwards than a car engine. I'm not sure what makes it do that.... ignition? Cam?

Good luck on the engine build. I think I'd try JB welding it, since it's not in the cylinder or exhaust..... looks like a water jacket? If it works, great. If not, then your rebuilding & not out any more money.

Bill,
That is a camshaft issue, not a block issue. Camshafts come in reverse and forward rotation.

If you really want to technical about it GM, Ford and Chrysler all had marine blocks at one time or another, most having four bolt mains and increased webbing at the bottom of the block... The marine blocks are also often referred to as Mexican blocks since many have an M on the block and many marine blocks were used in mexican production vehicles due to possible octaine issues with good old Pemex. AMC probably had the biggest difference when it came to regular versus marine blocks...

(Message edited by wakeboardsam on March 30, 2009)

Blasting and painting all my accesories now, getting ready for when I get the motor decided and built. Down the road resale would it matter what colors it was painted? I was thinking chevy orange on the block/heads and everything else either black or hugger green (bright green).
Just trying to get things to stand out and look a bit different.

IMO resale would be better keeping it all stock
and painting it stock. I would be skeptical on a
motor built at home with no warranty. Better to have it look OE.

Most of the brackets had been painted a few times judging by the layers removed from the blasting. Most engines you get rebuilt will be chevy orange. The block/heads will be painted that color. Thats just what the shop that will be building it paints them. Just was thinking on my water pump bracket, motor mounts, exhaust, alt bracket, pulleys, etc....
The intake will be black just like the factory did.
Looks to be the colors those pieces were painted previously was silver, maroon, orange, then finally black. So pick a color for the OE color.

i agree with michael. if i saw a street job'd looking engine, i'd be concerned about what was in it. keep it clean and simple, the engine speaks for itself.

you gonna clean the bilge, replace fuel lines, etc? my wiring harness and control/battery cables were grimy too.

All black just like the new ones come. It would look good with different colors but that would be one more thing that would need constant cleaning. Let those colors get dirty and it would look like crap IMO. Black motors hide the dirt in the hard to reach places. Some nice aluminum valve covers would be cool or some aluminum pulley's. Aluminum intake (dual plane) would look nice and preform good. Comp cams can set you up with a marine application cam. Just explain what your doing with the boat. Oval port heads would be a better application. Sell those square port heads on craigslist or some thing (hot rodders).

Got the replacement motor in today.
It's a oval port 2 bolt main out of a 85 suburban.
Everything looks great just looks like it had a leak near the front of the oil pan.
Now to re-gasket everything, replace the valve seals, paint it and throw her in.

Get rid of that intake. They rob the horsepower.

Thats kind of what I had been thinking after looking at the monstrosity. Would my square port intake work on it or do I need to go find a different one?

Get a new one/used for the oval port heads. Some thing like a Edlebrock Preformer RPM (dual plane). Roller rockers are a good idea too.

I am looking at a Performer 2.0 locally for a good price. I'm loving the blast cabinet at work right now. Makes cleaning up all the mounts and covers so much easier.

I have been thinking of ways to do a quick drain system. I am eyeing the kit that skidim sells. A guy at the auto parts store suggested getting the rubber plugs that expand when you tighten on their center screw. Maybe put those in place of the freeze plugs? Just wanting to make sure this is the last time I have to replace a motor from freeze damage.

Daniel
The best way to insure no freeze is to fill it with 50-50 antifreeze. I think you are in Texas and you may still use your boat late in the season. A block heater will work for the spotty cold snaps. Remember freezing to a boat engine is like tornadoes to a trailer park it happens fast and often.
Good Luck with your repair.

Oklahoma but close enough.
It will get used throughout the year so need something that will be fairly easy and quick to do. Maybe set up a hard wire 110 system tieing my battery tenders in with a block heater.
Just remove the raw water intake so it drains the tranny cooler and then plug the boat in.

Bill, I knew transmissions are tuff, but Damn, I didn't think they were that tuff!

I agree on all black. 351W in my boat after head/cam/intake job and fresh paint:

Intake just came in today. So hopefully tonight I'll get all the new bolts from the hardware store and get it mostly together.

"after head/cam/intake job and fresh paint" and a couple of Budweisers.

Lil more progress

"after head/cam/intake job and fresh paint" and a couple of Budweisers.

More than a couple!!

Looking good

Finally got her in.
Started it for a minute but didn't have the cooling lines hooked up yet so only made sure it fired then killed it.

Wow... what a cherry picker. So very glad that it's not me in this situation (for once!) Good luck!

It's one left over from my dads old wrenching days. I had to extend it out as far as it would go and welded all the joints to help it out.
I got a nice air over hydraulic cylinder that helped out the process.
Is not a fun ordeal and hope to never do it again.

On a marine engine there is no H2o pressure, unlike a car and you can pull the motor, pre-heat the block and if you know what you are doing, weld it up. You ahve to weld about 1' outside of each end first and then together or you'll get weepers. There is no pressure on the block, unlike a cat/truck, and this has been done alot on blocks that have freeze cracks. If it is on the intake side near a water port, you need a block but on the outside of the block, no problem at all.

I didn't think a weld would hold up on a cast iron block... Or is that the "if you know what you are doing" part?

You can weld on the cast iron block and get it to hold. Like TKO said, you really need to know what your doing though.


So whats a good way to clean up the yard after getting oil on it?

I guess the salvage yard had pulled the oil sending unit off the motor before I got it. I thought I had checked all the open bolt holes to confirm the weren't oil or water passages. But I missed one. It pumped out most of the engines oil before I could shut it back off again and made quite the mess on my side yard.
I am thinking I should name the boat the "Juan Valdez".

Doesn't he ride a burrow and make coffee? LOL

oops.. Not juan valdez, the "exxon valdez".

hahahah oh man that's a good joke, but sorry to hear it daniel. Looks like you're recovering well. What year/model is the boat again?

Took her out for the first time with the new motor. ComeS out the hole harder then before. My buddy trae was brave enough to board behind it even with 3ft white capped rollers. First time I had rollers come over the bow and that's in a old school pirata no ballast! But had great results. Wohoo

awesome news, great to hear you've got her running again

Wow that is so awesome! You guys really knocked that repair out of the park!!! Now back to the good times!

Mikey, the deposit was already put down for the cabin for memorial day the weekend before I found out the block was broke. So had a deadline and still have to work on the trailer and stereo a lil bit.
I wishs I had video of the waves. I am still shocked my big ole boat was taking roller over the bow.

looks great! What distributor did you go with?

It's the HEI that was on the boat when I got it.