451 went boom

[carrman]

Well my much troubled 451 ended its career two weeks ago. Got on the freeway, and she began misfiring. Looked in the mirror and I couldn't see behind me the coolant was going out the exhaust so bad. Wrecker ride to the garage where I get it worked on. After sitting a day, the oil became overfull. Pulled the heads and found what you see in the pics:

From what we can tell so far, I broke a piston and in turn broke the block. Consulted a good machine shop, and will have the heads inspected for reuse. Owner looked at pics and knew right away what happened. The ring gap on the top rings was insufficient for a Keith Black piston, and it expanded and broke out the ring land you see in the pic. A year ago, when I broke one of my built iron heads we'd found that one of the rods hadn't been resized and the bearing was getting ready to spin. We rectified that With new bearings and resizing of the rod, but even then on start up I had to crank for a few seconds before I activated the choke so that you wouldn't hear rod slap on start up. In addition, the engine always made a "wah wah wah wah" sound until it was completely warmed up. In short, my machinist was a crook stealing from his business, his customers, and doing shoddy work. I got screwed. So now here I am with really bad choices. I can sleeve the bad bore, and have a new shop check all the clearances and fix whatever is still screwed. Or, I can put a low mile RV 440 in, utilize the 440 Source heads, my oil pump, water pump, and XE268H Comp cam and runs that. That's probably my best choice as I don't trust that 400 block anymore, but compared to the 451 this 440 will be a slug. Last option, walk away from the car and sell it for whatever I can get for it. I can't afford to rebuild engines once a year. This sucks.

 

[ideologist]

Where are you located? Probably safer to salvage what you can and get a new engine or new block.

 

[carrman]

Medford Oregon

 

[ideologist]

I've seen some engines in NorCal, I'll check around for you

 

[Rustyrodknocker]

If the rv 440 is complete I would run it that way. They are low perf but run great on **** gas. Adding heads will not likely do much. Unless you add a turbo! Then of course you need proper ring end gap for that too.

I wouldn't hesitate to sleeve it and buy one piston.
But my advise is questionable. If I had a forged piston with that damage I wouldn't be able to resist welding it up and re cutting the ring groove. If that worked.. I would have to try it out.

 

[70bigblockdodge]

You will never be happy with that RV engine till it comes apart. Compression will be in the toilet, not just low. Quench and advantages of the aluminum heads will be negated by pistons so far down in the bore you will get a echo. IMO stay with combo you already own, I would sleeve it and correct any "errors" from previous build. Is this the same piston that suffered from the leak in the iron heads?
Makes me appreciate how lucky I have been with machine shops. Also appreciate my "self assembly warranty".

 

[twostick]

If you already have the RV 440, that's the easy button solution. The pistons are no further in the hole than any other smog era 440. With iron heads on it you're looking at about 7.8:1 compression. The Source heads should get you closer to 8:1 so it should perform decent enough for you with that cam.

If you are going to use the old oil pump, take it completely apart and inspect it. No telling what kind of trash went through it while the engine was eating itself.

What is the rest of the current combination? Compression ratio, induction, ignition, rear axle etc?

Kevin

 

[carrman]

Edelbrock AVS2 800 CFM carb, FBO ignition box, Edelbrocl Performer intake 2.76 rear gears. Current ratio is about 10:1. Comp Cams XE268H, Duration 268/280, Lift .477/.480. This thing was putting 451 hp, 528 ft lb of torque with the old iron heads.

 

[twostick]

If the distributor hasn't been recurved, get that done.

I would install the cam 4 degrees advanced to help low end torque given the compression reduction.

Unknown intake, iron or aluminum? If it's an iron Thermoquad spread bore intake, it's as good as a plain Performer would be. The RPM would be a step up but I'm not sure how much of a real world improvement you would see over what you have, especially with exhaust manifolds.

If you have an 8.75 diff, I'd find a set of 3.23 gears. That should equal or maybe even improve the butt dyno compared to what you had with the 451.

Kevin

 

[moper]

Take the heads, cam, and whatever else performance oriented you have on the 451 and use the RV shortblock. I'd wager you will have very little seat of the pants feel difference because at that point the only difference is the .080 of bore, 1-1.5 points of compression, and about 50 lbs. That cam won't care about the compression loss.
Given the damage to it and history, I'd sell the block for whatever you can get, and use the proceeds to buy the gasket set.

edit - also be aware of the balance on the RV engine. It "should" have a neutral balance and use an unweighted convertor. But just in case I'd get the convertor, or a picture of it if possible, with the engine. You can stick any weights needed on the one you have.

 

[carrman]

Currently running an Edelbrock Performer on the 451, I don't have an intake currently for a 440. My mechanic helping with this mess has some iron 440 intakes to use. He hates "Frankenstein" motors like my 451, and with all the trouble I've had doesn't trust the block any longer. I guess what I want to know is if I use this RV 440 with my heads and such, and I going to be stuck with a 200HP slug? The Source heads are 82CC closed chamber heads. Shouldn't that get me to a decent compression ratio?

 

[LocuMob]

Currently running an Edelbrock Performer on the 451, I don't have an intake currently for a 440. My mechanic helping with this mess has some iron 440 intakes to use. He hates "Frankenstein" motors like my 451, and with all the trouble I've had doesn't trust the block any longer. I guess what I want to know is if I use this RV 440 with my heads and such, and I going to be stuck with a 200HP slug? The Source heads are 82CC closed chamber heads. Shouldn't that get me to a decent compression ratio?

I stuck a used .484 purple shaft into an RV 440, slapped my 440Source heads on, and beat the snot out of it. That lasted til I broke a connecting rod. Ugh. Different low compression 440, another used .484, iron heads, I think 452's, and tti headers this time around. I put a higher stall convertor, 26-2800, and it goes like a sonuvabitch after 2500 rpm. I have a 3.55 rear gear. It's a slug in the hole engine, but it pulls hard in the cams power range. They aren't terrible for pennies on the dollar.

 

[moper]

Currently running an Edelbrock Performer on the 451, I don't have an intake currently for a 440. My mechanic helping with this mess has some iron 440 intakes to use. He hates "Frankenstein" motors like my 451, and with all the trouble I've had doesn't trust the block any longer. I guess what I want to know is if I use this RV 440 with my heads and such, and I going to be stuck with a 200HP slug? The Source heads are 82CC closed chamber heads. Shouldn't that get me to a decent compression ratio?

Oh right - B wedge block... SO you need an RB intake. Look on your Facebook Marketplace. I've bought a few off there recently for under $200. You don't have a Frankenstein engine. It's a 440 in a 400 block. Only thing different is the pistons and well - they're broke anyway. The 440 will have a real measured compression around 7.8-8:1. The XE268 you have will run very well with that. The heads will help raise that by about a point too. You won't feel much for a difference dropping maybe a point of compression. It might sound s little less snappy at the tailpipe. And it might change the idle a little to make it a little more noticeable. So slug - no. Snappy - a little less. But it won't break rings and the devil block will be gone for a lot less than rebuilding another rebuild or starting over.

 

[Rustyrodknocker]

Take the heads, cam, and whatever else performance oriented you have on the 451 and use the RV shortblock. I'd wager you will have very little seat of the pants feel difference because at that point the only difference is the .080 of bore, 1-1.5 points of compression, and about 50 lbs. That cam won't care about the compression loss.
Given the damage to it and history, I'd sell the block for whatever you can get, and use the proceeds to buy the gasket set.

edit - also be aware of the balance on the RV engine. It "should" have a neutral balance and use an unweighted convertor. But just in case I'd get the convertor, or a picture of it if possible, with the engine. You can stick any weights needed on the one you have.

This reminded of something, If you do run the rv motor as a temp, (which is precisely what I have done) don't use the rv converter with 2:76's

This is what I have, and worse yet I bought the converter new because the one that came with the motor had a chipped tooth. I was unsure if I could use my original converter and thought I would play it safe. The higher stall of the rv converter and the high gears, I can't stand.
I'm guessing the concept is to get the sub 200 horse smog motor making some power to get the heavy rv moving. Probably fine for a 3/4 ton pickup with 4:10's
I'm planning on having the Transmission done this summer and this reminded me to get rid of that converter.

Separately, does anybody have expierience with sleeveing? That may be a cost blow out vs a different block.

 

[BIGBARNEYCARS]

Does Keith Black even make a forged piston for the Mopar big blocks? Personally I'd go with TRW Forged Pistons that will keep you @ about 9 to 1 when your + .040 over. Also I'd make a day trip up the Wildcat Motors up in Sandy, Or. a half hour east of Portland. I'm pretty sure they can fix you up with a thick wall 440 with a forged crank produced in the late '60s. And you might wanna call 'um first to make sure that have a block and crank. That'd be where I would start (and have), Jer

 

[Davea Lux]

You are lucky that the parts that broke off the damaged piston did not take out the head. Be sure to pull the valves from that cylinder and check the seats for damage from debris that went out the exhaust. Does the bore have a hole in it or has it cracked? A hole is usually more reliably repaired with a repair liner than a crack because a crack expands the size of the bore and that can cause problems getting a tight leak proof seal on the repair liner and cracks tend to keep growing. If this was the same cylinder that failed with the iron heads, the piston may have had microscopic damage (cracks) that caused it to fail after the heads were replaced. I agree with you evaluation about this engine not being trustworthy. If you still want a 451, I would start with a fresh block. That of course means a fresh build and it probably would make more sense to start with a 440. You can toss the truck rotating assembly in favor of an after market high tensile steel setup on the crank and rods that will be much stronger and much more reliable on a performance build. If that is not financially feasible at this time, install the truck block and run it as is until you acquire the funds to start over. You will have a low performance setup with the RV engine, but you will have the vehicle mobile.

Dave

 

[70bigblockdodge]

I've had doesn't trust the block any longer

The block did nothing wrong.
You had really, really ported iron heads and they cracked, that what they do. That's why really ragged edge iron heads are drag race only pieces. Second failure is wrong ring gap, no other explaination for broken piston at normal rpms. I know you don't trust the block and now it has major problems with the crack/hole which is from sticking the piston in the bore.
If you can't hear the RV engine run then your at a fork in the road. And your going to have to rering and bearing while you add you HP parts. Is fix my junk and not add a new block into the mix.

 

[CBODY67]

I have a NOS 440 MH short block. Pistons are .125" "in the hole". Rated compression ratio is 8.2CR. My original plan was to put my NOS Stage IV heads on it, or the small chamber heads off of my '67 383 (with MP porting template work), which should be about 9.0CR, the way I figured it.

I put both a NOS Purple Shaft 284 cam and a Comp HE268 cam in it, checking their specs with a dial indicator on #1 cyl's lobes. Surprisingly, the 268's "under the curve" area is probably equal to or a bit more than that of the Purple Shaft 284. I was surprised. BTAIM The "HE 268" predates the later XE268 by about a decade, I believe. When I bought it, it was their most popular street cam for most V-8s, before the later versions were any where close to being available.

To me, the term "slug" is relative. Some "slugs" might need a bit different driving style, by observation, to best use their available performance. Just as "highway gears" and "looser converters" take a different technique UNTIL road speed is equal to or above where the converter is mostly in its most efficient power transmission (locked-up hydraulicly) mode. Until that happens, you get "soggy" throttle response at highway speeds. Much "tighter" throttle response when above that rpm.

Just some thoughts,
CBODY67

 

[carrman]

The RV 440 is a known quantity as my friend who had it ran it before pulling it.

 

[pomonamissel]

i've got 400 block and 440 blocks . the 400 just needs a piston then you have all you need for that 451 and it must be a long rod motor (6.75) c/c ? and you say your going stealth heads . so it just lower end to fix . i think a forged piston would be best in that motor . cast pistons crack n break easier that forged or billet pistons . those kb's are quite , i'm just not a fan of them .