The Dodge Challenger Message Board

Hi
New year and new problems occurred.
I was bored by strange sounds from my engine and I decided to check the compression pressure.
On two cylinders my engine has only 40 PSI and on remaining 6 - 150PSI - so I disassembly the engine and I found two broken pistons (my poor English don’t let me describe it very precise, but part of pistons between two top rings was tore out plus one ring on one piston was broken). It looks very strange because everything inside is new - new cam, lifters, bearings, timing chain and of course pistons (bore also is in good condition).

For me now, the most important thing is, what pistons I have to buy now?

I want to keep compression ratio at level of 10:1 or 10.5:1. Head volume is 90cc (I have ‘452’ heads) and I can’t find pistons to meet my expectations. My old pistons are: totally flat top with zero deck height with casted 'B-278'.

This year I really want to drive my car not only to spend whole evenings and weekends in garage that is why I want buy this pistons and rings very urgent.

Do you have any suggestion?

Thanks
Jarek

I forgot to add that my engine is 440 c.i. from '77
Jarek

Go here.

http://www.hughesengines.com/www/hughesengines/general/pistons/bb_pistons.asp

Go for the KB pistons with the "quench dome" which is a raised 'D' portion on the crown that fills the quence area in the head. Cost you $314 for a set. You might have to use a 20thou steel head gasket to get the right dome-to-head clearance.

Oh! I forgot to add that your problem was probably caused by too tight a piston-to-cylinder clearance.

Or (less likely) gapless piston rings that have not been cut to spec.

Correction! A too-tight piston ring clearance is the most likely cause of your problem according to something I just read.

Maybe do you know what is head volume (cc) of STD cylinder head '452' and what is height of combustion chamber? At last I want to be sure if my heads were milled or not.

The honest answer is I don't know!

Hi
Head volume of '452' is 92cc (I found it in a book which I have bought 2 years ago) - so my head are not milled. Now I am wondering why somebody put distance washers between rocker arms and heads. Maybe pushrods are too long? Mine are 9.3" (and hydraulic lifters are 1.9")
I am still not sure what I have and that is why I ordered pistons from Summit Racing (KB 237) with flat top. I hope they will be fine.

Yaro

I want to repeat my question:
what is length of pushrods in 440 engine?

I don't think you asked that before did you? Anyway. That is easy to answer! The center-to-center length of the standard 440 rod is 6.768-inches.

Thanks Dave,
but pushrod or connecting rods?

Doh!
Sometimes my brain misses gear as you can see! You wrote pushrods and I read Connecting rods. Dave's brain works in mysterious ways!

I don't know what the length of the pushrods are. But the whole point of hydraulic lifters is that it does not matter as long as there is a little pre-load on the lifters when the valves are completely closed.

Go to http://www.cranecams.com/hydlfaq.htm and have a read about lifter pre-load. You should be able to then check if your pushrods are too long or not.

I installed new pistons (Keith Black 237 – flat top) and they were taller than the deck height at TDC (about 0.07”). The originals were level. There was some interference with the head so I ground the head a bit to eliminate it. The heads are 452's from 1977. There were no any collision between pistons and heads (I checked it many times) Anyway, I buttoned her up and now the motor runs with a hell of a loud, rapid, metal on metal clanging sound.
I do not thing that is piston slap because this noises are ”too gentle”.
Finally, when you turn the engine off the motor is making “knock-knock, tuk, tuk”, like we were making popcorn for a couple of minutes then dies down.
It is not a engine run on.
For that matter, you only have to crank the motor a few second cold and you hear that strange noises. I have checked lifters preload and it is set according to spec.
So that's the story. Actually the car runs fine with an even rhythmic pulse from the tailpipe so valves aren’t getting bent. It just makes a hell of a racket. Anyone experience this after similar engine work?? I swear there's no contact pistons with the head. I also swear I double checked everything so nothing was left loose.
Should the pistons be above deck height?
Why lifters is making “knock-knock”?

Jarek

Did you changed valve covers Jarek? Cause with cast alu (if I'm right) you hear a gentle rattling noise out of the engine bay. Just a suggestion.

That the pistons are above deck height doens't matter, mine are also above the deck. It just gives a higher CR! Does your flat top has valve notches? Cause with my 340 the previous owner had installed the pistons upside-down. With the valve notches at the wrong site, so the valves had hit the pistons just a little. Right now I have notches on the bove sides of my pistons. I quesse that would make some noise too.

Did you took your engine out of the car? When throwing in my 340 last year we broke one of the bolts that connect the flexplate so we toke another bolt...one which was thicker. When starting up the engine it constantly hit the dust shield in front of the trans. But that wasn't gentle anymore!

Pistons have a nothes, I installed it according to instruction, my valve covers and rocker arms are stock and I didn't took block from engine bay and I checked engine mounts. Everything seems to be OK but it isn't.

Hans didn't mean the engine mounts. He was talking about the bolts that hold the torque converter to the flex plate. If you don't use the correct bolts it makes a loud clanking noise like the one you describe.

Were the pistons KB hypereutectic? These pistons seem to need larger than forged type, ring end gap. I've heard of breakage occuring (where you state) if the ring gap is tight as has already been said here. I ran a set on an 11sec 440 motor they were no problem but I can remember thinking that the ring gap was excessive (even though I followed the instructions) when I installed them.

I would pull one of the heads off and just check everything, then put some modleing clay or plasterseen on the slug,put the head back on and wind it over by hand,pull the head back off and inspect.

I was sure that pistons didn't meet heads, but I wasn't right - but nobody is perfect -(.
At Tuesday I decided to disassembly the top of engine and after that I saw that edge of each piston hit into cylinder head.
Using drill and "polishing stone" I cut edge of each combustion chamber to fit this bloody, too high pistons into head. And at Saturday I started the engine and I heard beautiful, clear sound of 440. Now I can start my Holiday.
Yaro

Hi guys;
I just purchased a 72 w/a built 440. Last week the motor died on me just cruising down the street. When I turned it over it was banging in one cylinder Tunk, ker Thunk, Thunk an so forth. Thinking the piston was hitting a valve, I towed it into the shop & pulled the valve covers. Two rockers were in pieces and two rods were bent like pretzels. The other rods were all nicked or had a groove and were damaged. Compression was:
Left 155/165/170/170
Right170/160/190/175 190 was the bent rods. My mechanic tells me the cam is too hot (too much lift) and is mismatched with the pistons and torque converter. He wants to rebuild. Can you give me some advice?
Here are the specs on the 440 bored 30 over:
Crane Cam #644561 Intake @ Cam 336 @ Valve504 Exhaust @ Cam 352 Valve528 Rocker Arm Ratio 1.5
Spring Requierments: Closed 120# @ 1.875
Open 318# @ 1.372

Arias Pistons Compression 11:1 0 dome/flat top 2 pocket 40/32 Aluminum 4 1/2 stroke
4.350 bore 6.768 rod length 8.175 compression displacement

Isky valve springs Height 1.60" 400# per inch 135 closed/395 open.

Torque converter stall speed 1400-1500.

Intake valves Manley #11890/ Exaust #11891

In talking to Isky today they feel that the springs are within the correct range. If they were not stiff enough the piston would hit the valves. The cause of failure was probably over reving/red lineing by the prior owner or someone test driving the car before my purchase. I haven't had it running long enough to enjoy it. I'm most concerned with mismatched components. Other than changing the cam & pistons (total rebuild) or an engine exchange what are my options? Higher stall speed on the torque converter? 2000+? How do I make it streetable?

Thanks for your help!
Barry B.

The guy is not bullshitting you. That's for sure.

That is a pretty wild cam to use on the street. You could make it work but it is a serious street/strip cam. I don't think the valve lift is that bad but the valves open early and close very late which could lead to the pistons hitting the valves at high rpm (valve float) or if the heads or deck have had a lot shaved off them.

Depending on your intended use this cam may well be too wild for you.

To use this cam you need 4:10 (or bigger) axle gears and a 10 inch convertor with a stall around the 3000-3500 range. Maybe even more.

But using a milder cam may mean the static compression ratio is a little too high for the gas you use. Unless you have alloy heads?

Hope this helps.

When you say the 'rods' were bent and marked did you mean the pushrods?? Sounds like the valvetrain geometry is getting out of whack when the engine is running and the lifters are pressurised. Although I have also heard about this sort of thing happening when the owner has been clueless about how to set valve lash with adjustable rockers. (You reading this Jeff-B?)

Yes I ment the push rods. Will the motor hold together with street use (no red lining)and the low stall converter I now have or will it just be a matter of time before I bend them again? If I go to higher stall speed can I avoid a rebuild or exchange?

The converter is not what did the damage. That only effects how it drives. Was it trying to pull away hard at idle? What idle speed did it have?

Find out for sure what did the damage. Why are there marks on the push rods? there should not be any marks. They will only bend if the valve lash is set wrong or if the valves are hitting the pistons or they are the wrong length or something like that. The do not bend just because it is a high output engine. They bend when something is not right!

Get the piston to valve clearance checked first. Make sure the pistons are not damaged.

Are the valves OK?

Are the rockers made by Crane. If so change them because they break all the time. Never use rockers with springs to keep them apart on the shaft.

It sounds to me like the Engineer looking at this for you knows what he is talking about. But he also has a buisiness to run so he will try to sell you as much as possible. Ask him what you need minimum to get this running again.

I do not know the idle speed before it broke, but it was not trying to pull away. The bent rods were from the cylinder where the piston was hitting the valve. The compression check was after the damage & my guy tells me it is unlikley the pistons or valves are damaged with those compression readings and to pull the heads for a visual will not tell us if a piston has a hairline crack on it's side. The rockers are adjustable, but not identified on the build sheet. The pushrods are identified as 1633B. When you say, "valvetrain geometry is getting out of whack" what do you mean? The marks on the rods are all in about the same place & look like a ring or notch. He reluctantly has said that replacing all the pushrods & the broken rockers will get me back on the road, but he will not guarentee the work.

If you are sure the pushrods are not catching anything then just replace the damaged bits and see how it goes. That is your best option.

I don't see how you can tell that the piston was hitting the valves without pulling the head off and physically looking for marks on the piston. I think he is now bullshitting you. Also why ony one piston? Or am I missing something?

It sounds to me like the only thing that has happened is the rockers broke. This has happened in the past with Crane roller rockers and sometimes (but much more rarely) with other makes. Are yours a gold color? Are they roller rockers?

When I said the geometry could be out of whack i mean that with very large lifts the tip of the rocker can come off the top of the valve stem if it is not set up right to start with. Look at the wear pattern on the valve stem tip. See if the wear from the rocker is bang in the centre and does not go near the edge.

Also the pushrods can hit the heads in some cases. When you said there were marks on the pushrods i was trying to think what sort of marks they were and how they might be caused. However from your description now it sounds like they could be scribe marks for setting lash or a join from the manufacturing process?

You have to realise that it is very difficult for me to think about what could be wrong with your engine without seeing it myself! I have to rely entirely on your description. Also I have limited experiance in engine building.

If it were my car i would have pulled one head off and checked the piston tops for marks. No marks on the pistons mean the valves never went near. Then I would replace the broken parts and make sure it is set up correctly with the valve lash. Then suck it and see. If you were happy with the way it drove before then don't change anything else.

if the pistons hit the valves hard enough to damage anything the valve would bend.The copression in the cylinder is good.It sounds like the rocker broke first and then the free push rod hits the rocker shaft and bends. It happened to me on a 340.

I am awaiting parts from crain to replace the OEM pushrods & adj. lifters. We will r&r, adjust the valves and hope when we start it there are no thunking noises. Thanks for your help & please email with any further advice.

Barry. You need to go to 'Edit Profile' in the left frame under 'Utilities' and add your e-mail address to your details there. Otherwise we cannot e-mail you.

The pushrods the experts at Crain sent were 1/2" too short and for rollers, so I returned them and they will have to custom make them. I have adjustable OEM rockers. The motor is for real. The previous owner put 7K into it & I have the build sheet and all the reciepts.
The pushrods were Isky 1633B & valve springs Isky 8005-A. Intake valves are Manly 11890 & exhaust 11891. Anyone have an engineering degree out there? The engine builder probably cleaned up his inventory on this one. I just want to make it work so I don't have to worry about blowing it up. Any of you experts have any ideas?



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09-18-2002 09:02 PM