400BB Heads Question

[Davea Lux]

Cant you tell by my ridges that they dont come all the way up?

View attachment 499954

View attachment 499955

Run the #1 piston to TDC using the timing mark as a guide. Clean off the accumulated carbon. Find a metal straight edge and place it centered on the bore for #1. Start sticking feeler gauge probes under the straight edge. until you get a tight fit. This will give an approximate measurement of how far down the hole the piston resides. On a 400, they are nearly always ninety thousands or more down. If you want a real accurate measurement, rent the bolt on dial indicator from your local parts house.
A 7.5-8.0 comp ratio is not likely to support any significant boost in performance because the combustion dynamics are just not there. You need something in the neighborhood of 9.0-9.5 to gain good performance with an appropriate cam.

Dave

 

[70bigblockdodge]

They can run okay with stock pistons. You just have to be very careful to not over cam it because it will be unforgiving.
Very sharp cliff to fall off cam wise.
Here is a example of the difficultly in building some compression in these.

This is basically using a flat top piston with no valve reliefs at .005 down in the cylinder, a felpro style gasket and a informed average of the CC's that uncut 452 heads usually have. Just barely making 9:1.
@Davea Lux if I found a .090 in the hole 400 that would be a good one. Probably a 72-73 magnum/HP version.

 

[badvs3vil]

Run the #1 piston to TDC using the timing mark as a guide. Clean off the accumulated carbon. Find a metal straight edge and place it centered on the bore for #1. Start sticking feeler gauge probes under the straight edge. until you get a tight fit. This will give an approximate measurement of how far down the hole the piston resides. On a 400, they are nearly always ninety thousands or more down. If you want a real accurate measurement, rent the bolt on dial indicator from your local parts house.
A 7.5-8.0 comp ratio is not likely to support any significant boost in performance because the combustion dynamics are just not there. You need something in the neighborhood of 9.0-9.5 to gain good performance with an appropriate cam.

Dave

I have a dial indicator and will check it tomorrow when I finally pull the block out.

 

[70bigblockdodge]

Here is your engine give or take a few ten thousandths on the deck measurement.

Good news is no need to pay for premium gas, it will run on any swill you can get to lite.

 

[Luke Pokrajac]

Lunati voodoo 256 would be great for this 400.

 

[70bigblockdodge]

Lunati voodoo 256 would be great for this 400.

That would be a good one.
I would also recommend as a cheap alternative either of the Summit cams SUM-6400 or even the larger 6401 if you want to push your luck. It has a 114 lobe separation for good manners. Duration is a bit high for low compression, but you could always advance it 4-8° to increase cylinder pressure.

 

[badvs3vil]

but you could always advance it 4-8° to increase cylinder pressure.

I am really curious about this. I would do this via the timing gear?

 

[70bigblockdodge]

I am really curious about this. I would do this via the timing gear?

View attachment 500101

You can advance 4° using the keyways, one is advanced, one straight up and the other is 4°retarded.
Done correctly you need a degree wheel, cheap one at Summit works good you just need to fab something toake sure it does not slip, or mark it to indicate slippage.
For fine tuning you need a offset dowel pin kit. You drill the pin hole in top gear and use eccentrics to change relationship. There is also a expensive timing chain out there with 9 different keyways in it. Once you get the hole drilled in the top gear (drill press recommended) it is not a big deal to change the timing. There are a million videos on YouTube about degreeing a cam so you can sort that out. 2 degrees or less will have no effect. Advance only with low compression to build cylinder pressure by closing the intake valve earlier after BDC.
Btw is that a new chain or the one that came out. Very tight if used, it a good one.

You need one of these kits

 

[badvs3vil]

You can advance 4° using the keyways, one is advanced, one straight up and the other is 4°retarded.
Done correctly you need a degree wheel, cheap one at Summit works good you just need to fab something toake sure it does not slip, or mark it to indicate slippage.
For fine tuning you need a offset dowel pin kit. You drill the pin hole in top gear and use eccentrics to change relationship. There is also a expensive timing chain out there with 9 different keyways in it. Once you get the hole drilled in the top gear (drill press recommended) it is not a big deal to change the timing. There are a million videos on YouTube about degreeing a cam so you can sort that out. 2 degrees or less will have no effect. Advance only with low compression to build cylinder pressure by closing the intake valve earlier after BDC.
Btw is that a new chain or the one that came out. Very tight if used, it a good one.

Yeah that's what I found in it when I tore it down.

 

[70bigblockdodge]

Yeah that's what I found in it when I tore it down.

I'd reuse that. It has advance keyway and tight

 

[badvs3vil]

Ok so the heads have been dropped off at the machine shop. He told me quickly that he can tell the engine was from a scrap yard because the heads have those solder over heat things, which were both melted btw. He also said the heads have never been off that motor before. He did say that these heads do look good though.

Since that are being worked on, I went ahead and got the block out today. I also cleaned up a piston and cylinder using a Scotch-Brite Scouring Pad and some WD40. Below are those pics. Anybody see anything that I should pay more attention to on here? How does it look to you?