RB Deck Clearance

[Doorkicker]

Hi all and thank you in advance...you guys have been a huge help.

I have a 440 short block and the deck clearance is 0.172... I'm pretty sure it's a MH motor but that seems like a big number to me. Anyway...

Here is my question... Is the deck height the same (generally speaking) on all RBs and the clearance is for the most part defined by the rod and piston length and compression height of the piston? Assume stock.

Where I'm going with this is, if I put a stroker in it will I still have the same deck clearance? I'm under the impression that the late (1977) Mopar 440s were low compression dogs by design and they did so by shortening the rod and or pin location in the piston, or some combination, but the actual block for all intense and purpose was the same.

I feel like this is a pretty stupid question, but I just needed to check.

 

[GTX JOHN]

The change in deck is from the change in pistons exclusively.

 

[R/T Boy 67]

Echo

 

[Doorkicker]

The change in deck is from the change in pistons exclusively.

Thank you!!!

 

[Doorkicker]

Echo

Thanks! I'm literally going to sleep better knowing that

 

[Doorkicker]

@GTX JOHN @R/T Boy 67 .... Follow up. If you had this short block, would you drop in a stroker to get the compression up?

 

[Kern Dog]

That totally depends on your wallet and goals for the car.
Higher compression pistons would cost less than half of a stroked crank, rods and pistons.
For example, in a stock 440, a set of TRW (Now Speed Pro) Six Pack pistons sat .025 in the hole compared to .076 that the stock pistons sat. This was a ‘77 440 from a New Yorker.

 

[pnora]

If MH the cam is also going to be a negative. On a budjet rebuild you may only need pistons and rings as said. Depending or bore size and wall condition you might just get by with a basic piston, ring, bearings, and gaskets. What crank is in it?

 

[Kern Dog]

My machinist told me that the iron used in most Mopar engines is really hard. He said the Chevy blocks are easy to bore since they are much softer.
My point is…. In many cases, you can get by with a dingleball hone and new rings. My guy always measures bore taper and said that anything over .004 taper should be bored over.
The 383 In Jigsaw had minimal taper but had one cylinder where some water sat in it. This necessitated a bore job. It was for the best though. It allowed me to get the compression ratio where I wanted it.

 

[pnora]

My machinist told me that the iron used in most Mopar engines is really hard. He said the Chevy blocks are easy to bore since they are much softer.
My point is…. In many cases, you can get by with a dingleball hone and new rings. My guy always measures bore taper and said that anything over .004 taper should be bored over.
The 383 In Jigsaw had minimal taper but had one cylinder where some water sat in it. This necessitated a bore job. It was for the best though. It allowed me to get the compression ratio where I wanted it.

The one thing I will add is cylinder ridge. Of there is any ridge it needs to be removed. Reason is the pistons up higher in the bore should also be raising the top ring. If there is a ridge the rebuild will have a short life.

 

[Doorkicker]

That totally depends on your wallet and goals for the car.
Higher compression pistons would cost less than half of a stroked crank, rods and pistons.
For example, in a stock 440, a set of TRW (Now Speed Pro) Six Pack pistons sat .025 in the hole compared to .076 that the stock pistons sat. This was a ‘77 440 from a New Yorker.

Thanks @Kern Dog.
Well, I'd like to go far with the motor. And figure if I'm going to tear it down, might as well go for it. Your point on money isn't lost on me. Definitely got me thinking.

What would be your target CR with aluminum heads (i was thinking 10.5:1, but dunno) and do you think a stock cast crank can take it?

 

[Doorkicker]

If MH the cam is also going to be a negative. On a budjet rebuild you may only need pistons and rings as said. Depending or bore size and wall condition you might just get by with a basic piston, ring, bearings, and gaskets. What crank is in it?

It's a cast crank, stock. It was just bored .030 and I have a cam for it...XE275HL-10 (231 & 237 @.050, 525 lift). Yes... It looks like the 'new' pistons were basic flat tops that sit pretty low.

 

[Kern Dog]

I've read that the cast crank is quite durable and is good up to "around" 500 HP.
Most people (Myself included) have not driven a car with that much power. My own 440 based 495 might be close to 500 at the flywheel but I don't know for sure.
I went with a 4.15" stroke back in 2004. A stock stroke 440 is still a potent setup. The additional torque that the added stroke provides does allow me to use a taller axle gear and still have great acceleration.

 

[Doorkicker]

I've read that the cast crank is quite durable and is good up to "around" 500 HP.
Most people (Myself included) have not driven a car with that much power. My own 440 based 495 might be close to 500 at the flywheel but I don't know for sure.
I went with a 4.15" stroke back in 2004. A stock stroke 440 is still a potent setup. The additional torque that the added stroke provides does allow me to use a taller axle gear and still have great acceleration.

@Kern Dog you really got me thinking.

Ok... Two potentially stupid azz questions.

Stupid question #1-- if I were to just swap out pistons and the short block is in the car, and i have clear access to the bottom of the engine...am i crazy for thinking i can change the pistons with the engine in the car? Ok, stupid question #1.5... so you find it easier to extract and reinstall the engine with or without the transmission attached?

Stupid question #2-- if an RB has a deck height of 10.725. Do i simply add rod length 6.768, half the stroke of 3.75 (1.875) and the compression height of the piston (i.e., KB237) 2.067 to get the deck clearance? Based on my example here... That's 6.768 + 1.875 + 2.067 = 10.710. which take that from 10.725 would result in a deck clearance of 0.015.

If #1 & #2 are correct assumptions, I'm just going to grab a new set of positions as suggested. I think.

 

[66Satellite47]

The "deep" deck height is the result of the late model low CR design. The blocks are very close across the years for height. Rod length should be the same I presume LY rods. Change the pistons to get to around .020 deck height. I can't imagine how to do the job without pulling the motor and doing the work on a stand.

 

[beanhead]

RV blocks had notoriously deep pistons, as well as big bore chamfers...and best of all the decks (typically) aren't very 'square', meaning you don't get the same measurements from one piston to another. The last one I did (still going strong) had to be cut around .005 on one end and IIRC like .015 on another end, to get all eight pistons at the same height. That said, they ran like that for ages so it all depends on how **** you're getting about it

 

[Kern Dog]

I am not an engine builder....but I have built some for myself.
You can do the math but the most accurate method is a "Mock Up" where the engine is partially assembled and measured.
My machinist has set the crank and then pistons 1,2 5 and 7 to measure for squareness. Like Lloyd/Beanhead was stating, some blocks have decks that are taller at one end of the block or another.
I had a 383 that was that way. He had to machine it to clean up the surface but also to square it up.
You theoretically can leave the engine in place but whatever it saves you in labor for removal will make it much less convenient during assembly.
I have removed many engines while leaving the transmission in place but they have always been automatics. Last year when I pulled my 440-493 for a refresh, I pulled the engine, trans and K member all at once. This was partly because I have a 5 speed manual and I wasn't confident in mating the engine to the transmission without great difficulty.

 

[gkent]

Follow up. If you had this short block, would you drop in a stroker to get the compression up?

You don't need a "stroker" to boost compression, just a new set of pistons. If you want to go the cheap route, throw in some pistons from the late 60's - You "could" even use a good set of used, standard bore slugs that someone might give you for the cost of shipping. Just do a quick dingle-ball hone so new rings have something to seat against. This route - I wouldn't even bother worrying about balancing the thing. Talk about a cheapo weekend job !!!

 

[Doorkicker]

You don't need a "stroker" to boost compression, just a new set of pistons. If you want to go the cheap route, throw in some pistons from the late 60's - You "could" even use a good set of used, standard bore slugs that someone might give you for the cost of shipping. Just do a quick dingle-ball hone so new rings have something to seat against. This route - I wouldn't even bother worrying about balancing the thing. Talk about a cheapo weekend job !!!

Yeah... I figured I need pistons to get CR, but I was thinking while I'm in there, might as well go big. Or....is that overkill? I'm looking at a 440source stroker, which is a great price for everything, no doubt. But a swt of pistons is about a third of the cost. But with that stroker i get soooo much more than just pistons. I think it's really a budget thing that I'm struggling with.

 

[gkent]

I built a 526 stroker using the 440Source kit. Honestly, you need to give yourself a budget of at least $6k. And even then you'll probably spend more. The thing is it doesn't end with the motor. Everything else needs to be beefed up to handle the extra power. So when they say "go big or go home" they're not talking about horsepower, they're talking about MONEY !!