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Mild 400 build on a budget

Garys1969RR said:
I think you can get a lower end balanced for around $100. I would try to get the piston up near the deck, no more than .050 below deck. Most of those low compression 400s just don't have much power. A few do, if built right, as has been shown, with good flowing heads. But even those will still produce more torque and power with a compression increase.
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I called a few local shops that have good reputations, and just the balance runs around $200. But they won’t just do the balance, they also require the crank to be cleaned and magna-fluxed, which I totally understand why they do that and agree it should be done. By then the price tag is up to about $500. Again, I know why they do it, and ideally I would love to have this done. I’m just weighing the expense against the benefit. But, I want to hear ideas and opinions about this, which is why I posted the question to start with.
 
I too have looked into aftermarket heads to raise my C/R on my 400. From what I have read is the 75cc aluminum heads will raise compression about 1 point, but they will perform like the stock cast 452 heads power wise. Something about the aluminum not producing the heat to burn the fuel like the cast heads. I hope what I read is wrong, as I would like to go the 75cc head myself. Since $$$ is limited, I would look at the biggest bang per buck. I also remember you stating your heads are shot. I see your dilemma.
 
oldbee said:
I measured carefully & used one of those “ball”(?) hones, 500-600 grit(?) & have had no problems.
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I almost got a couple of those ball hones in various grits, because I liked the thought of being able to reverse the direction and knock off the peaks created by the coarser grits. But I read several posts about how they could be tricky to use and possibly cause problems. The hone I’m using is the Lisle 15000. I got it off eBay at a reasonable price, with an assortment of stones in various grits, most of them new. I watched a lot of YouTube videos about it and liked it because the stones are 4” long, and I think, if done carefully, will minimize any chance of tapering or egg-shaping the cylinders.
 
XCELLR8 said:
I too have looked into aftermarket heads to raise my C/R on my 400. From what I have read is the 75cc aluminum heads will raise compression about 1 point, but they will perform like the stock cast 452 heads power wise. Something about the aluminum not producing the heat to burn the fuel like the cast heads. I hope what I read is wrong, as I would like to go the 75cc head myself. Since $$$ is limited, I would look at the biggest bang per buck. I also remember you stating your heads are shot. I see your dilemma.
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Hughes Engines talks about this in an article regarding cast iron vs aluminum heads. In short, at least the way I understand it, even though I’m raising my compression almost 1 point by using the 75cc heads, the aluminum dissipates the heat from combustion faster than cast iron, which reduces cylinder pressure to effectively lower the compression ratio by about 1 point. But, since I’m using a cam that builds significantly more cylinder pressure than the original cam, I should still be seeing a performance increase over what I started with. The bonus is that this head still flows better and is lighter than the 452’s, so I still come out somewhat ahead by getting the Eddy heads I think. For about the same money as what I’m going to pay just to get my stock heads usable, I can get the Eddy heads that flow better and are lighter, and they claim burn better, but I doubt I see any real benefit there. But if I ever have to submit to emission tests, that might help some then.
 
good plan
I've had no problems with a rigid hand hone depending on how much ridge/ taper out of round you have- Chryslers have good blocks, it may not be worn much- spend some time with a internal mic or a dial bore guage
hone with coarse hone then finish with fine grit either ridged or bottle brush
Cam looks good for what you are doing-- NOT ANY BIGGER what's the seat duration--get the right springs on the new heads
If going for pistons- I helped design the KB reverse deflector pistons for the 440 with John Erb at United- he's retired
I really suggest you use them- get 0 deck with a .040 gasket or down a little with a shim gasket so you end up with .030-040 piston to head
this is the best thing you can use for your build
if using open chamber heads use the quench dome pistons with the slab off on the spark plug side, or a dish on the spark plug side
you want to push the combustion chamber at TDC over next to the plug- not shaped like a pancake- where id preignitions on the side away from the plug
light is better than heavy ask around you might not even notice the out of balance
stock rods with Direct Connection SPS bolts or your rods may have good bolts in them already- just reuse
won't UEM comp you some pins? Stock Chrysler pins are heavy
Should run better than a 400 chevy- eat your heart out bow tie guys
 
"I’m using a cam that builds significantly more cylinder pressure than the original cam" - there is no fix with the stock pistons- none
stock 400 cam is also around 204 @50 Magnum cam 10 degrees more problem with stock is that seat timing is large due to lazy ramps
Stock cam has relatively wide spread-which cuts overlap and makes intake close late- it's an emissions thing
HR should solve that problem
 
Which 440 pistons are you referring to that has the reverse deflector? Will a 440 piston work in a 400 with a stock 400 stroke crank?

The Tech that I spoke to at UEM didn’t offer anything. He acknowledged I’d have to get heavier pins to make the KB240’s work and that was all.

How much lighter do you think I can go and not have problems with the balance?
 
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A reverse dome piston has a small flat dome opposite the spark plug. It rises up above the deck at TDC , and sticks up into the flat part of the combustion chamber on a 452 type head, also referred to as an open chamber head. This increases chamber turbulence at TDC, and helps with the combustion process. You can't use these pistons with some heads, such as the E Street or Performer RPM head with a closed chamber. They are made to work with the 452 or 906 type head. Dont think 440 pistons will work in a 400, although I've heard someone tried it. There are 400 pistons made with a quench dome.
 
A reverse dome piston has a small flat dome opposite the spark plug. It rises up above the deck at TDC , and sticks up into the flat part of the combustion chamber on a 452 type head, also referred to as an open chamber head. This increases chamber turbulence at TDC, and helps with the combustion process. You can't use these pistons with some heads, such as the E Street or Performer RPM head with a closed chamber. They are made to work with the 452 or 906 type head. Dont think 440 pistons will work in a 400, although I've heard someone tried it. There are 400 pistons made with a quench dome.
 
Right, I was just curious exactly which piston he was referring to in case it was one I didn’t look at because the weight wasn’t what I needed.
 
We designed the piston for the 440 but KB makes similar for 400 and SBM
if you use the 84 cc closed chamber head you can use a piston with a D Dish on the spark plug side
running pistons down the hole with any head and your motor will run HOT and then ping so you retard the timing and it runs hotter and does not make a much power so you step on the gas and burn more and run hotter yet- WILL IT NEVER STOP= NO it just gets worse
you can make it work racing with good gas but not on the street with street gas
get the right piston
looking for the answer on underballancing- how much is not enough
 
gary wrote
You can't use these pistons with some heads, such as the E Street or Performer RPM head with a closed chamber.
Actually you can if you mill off enough of the quench dome to get the quench/ clearance you want
Early KB made the CH too low requiring block decking to get quench right
There is no easy answer to get it right with the Open Chamber smog head.
 
400Magnum said:
I’m putting together a mild 400 for a 78 Magnum and would like to get feedback on my plan. The goal of this rebuild is to stay on a very limited budget and have an engine with decent performance and be reasonably affordable to drive. This will be a cruiser, go to the occasional local car show, drive to work on nice days, and once in a great while take it for a long road trip. It will never be on the track.

The engine has been rebuilt before, but needed going thru again for various reasons. The pistons were sitting very low in the bore when I disassembled the engine, on average they measured 0.152” below the deck. I don’t have the budget to take the block to a shop to get decked, so I’m just going to have to live with that.

My 452 heads are shot, all the valve guides are worn and the exhaust seats are eroded. I’ve called several shops in the area and they’re all quoting me close to $1000 just to get new guides and seats. If I have to spend that much money, then I’d rather get Edelbrock or Stealth heads for about the same price with 75cc chambers, build my compression up a little and save some weight. With the right thin head gaskets it gets me into the 8.1 range versus 7 for the 452 heads.

I bought my cam years ago when I was making decent wages. It’s the smallest hydraulic roller retrofit cam the Crane makes, .429”/.452” at 204/214. This cam builds pretty decent cylinder pressure, so I’m hoping the low static compression ratio won’t be as much of a problem as it normally would be. Crane says the static compression should be in the range of 8-9.5, so I’d just be getting there with the aluminum heads.

The rest of the build is pretty much stock. Stock replacement pistons and rings, stock rods, etc. I will be using an Edelbrock Performer intake and a Street Demon 625 with the composite body too.

So I’m just wondering how well you all think the combination of low compression pistons, cam, aluminum heads and intake, and carb will work together for my goals?
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Just my two cents, but I would focus on spending money on the bottom end. Get new pistons to come up close to zero deck. You should be able to find a decent set of 452 heads for a couple hundred bucks to get you by. It is a hell of a lot easier to do a head swap down the road then it is to go back through the bottom end.
 
oldbee said:
I measured carefully & used one of those “ball”(?) hones, 500-600 grit(?) & have had no problems.
Click to expand...

I did the same on a 360 magnum block. Finished the cylinder walls with a 320 grit ball hone. 165lbs compression all around now.
 
What about using a closed chamber factory head to bring the compression up ? I would think a set of 516 heads with hardened seats would be a cheaper alternative than aluminum. Ya, they have a smaller exhaust valve, but something to consider. I built a low-budget 400 years ago with a set of 915 heads and it ran really well.
 
scot said:
What about using a closed chamber factory head to bring the compression up ? I would think a set of 516 heads with hardened seats would be a cheaper alternative than aluminum. Ya, they have a smaller exhaust valve, but something to consider. I built a low-budget 400 years ago with a set of 915 heads and it ran really well.
Click to expand...

I’ve looked for any and all cast iron heads. The only decent ones I can find are on eBay, and by the time I pay for shipping, and then get hardened seats installed, which also requires new guides, I have what I’d pay for new Eddy heads. I can’t find anything local, except for rebuildable cores, which is what I already have.
 
The 440 Source aluminum head is only 72cc chambers, but it's aluminum. Geez, I would think you could find a set of 516s for cheap, they are pretty common & not a HP head. Your engine is 8.2:1 compression...pretty weak. A 516 head would put you about 9.2:1, which would be good.
 
Those are 906s and are not going to help your compression ratio out at all. Pretty much the same CC as a 452. I'll take a look at my stash...I may have a set of closed chamber BB heads. Compression is going to help you out more than any flow.
 
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