410 Build up - Questions and Research.

[Yellow Truck]

Kevin,

I'm going with either Edelbrock or Survival heads. The real decision between them seems to hinge on not being able to get anyone at Survival to sell them to me. I wrote twice and got no reply. Then I called and spoke to a very nice man who builds engines there, but he couldn't work with me to take an order.

I'm also going back and forth between replacing everything (including changing to another block) or keeping my crank and rods and changing out the rest.

I have a little bit of time since the the two blocks are going to a machine shop for evaluation next week, but when I have the results, including the final bore size, I'll need to get out the credit card. That requires someone on the other end of the line!

[jayb]

The mods to the Holley intake will definitely help your build; I think that anything over 400 HP will benefit from those modifications.

A little more on those little square stubs coming out of the manifold.  Any cast aluminum part has to have some way to be fixtured in order to be machined.  Those square things are basically datum points to fit into some kind of fixture.  Every cast part has to fit on a fixture for machining.  In some cases, you can do this without adding additional material to the casting, but if there aren't any clear, flat surfaces to index to the fixture, you need to create some.  That is what those square stubs are for.

[ScotiaFE]

The head dilemma should be between Survival (aka Felony) and BBM.
I have no actually data to back this up, but I think they are pretty close in the giddy up factor.
The Edelbrock's are not in the same class.

Full disclosure: I do own a set of Edelbrock's and a set of BBM's and would not mind owning a set of Felony's.

Edit: Words from the gent's who actually developed their respective heads.

http://www.network54.com/Forum/74182/thread/1428150539/Aluminum+cylinder+head+suggestions

[Barry_R]

Pretty much luck of the draw on the phone these days.  Best shot is to call around 10 or 10:30 in the AM or late afternoons.  My cell - the 2489310358 number - is good 'til late in the evening.  Just too many guys, too many projects, and not enough "Barry".  Texts and email are answerable really late and really early - might be a good way to handle questions as well.



The guy you spoke with is very, very technically capable, quite capable of taking down information, but sometimes reluctant to close the deal on making a sale.  I think he's scared to goof anything up, even though I am 100% confident that he wouldn't.

[Yellow Truck]

Barry,

Thank you for the reply. How busy you are is a reflection of how big the built up demand for good FE parts is, and how welcome your work is. Nice problem to have.

I am sorry that I don't remember his name, but he was very helpful up to the point he couldn't help any more. I will try again - I need help building the order for parts I need, and some advice on what I don't need (can re-use) to get where I want to go.

Howie,
As always, thanks for the helpful suggestion.

[Yellow Truck]

Beginning to get feedback on the two blocks, but in talking to the machinist he said something that sounded a little odd and I thought I'd ask people who know more than I do. I was asking him to confirm the deck height and if it needs to be decked, to tell me the amount that would come off to square it to the bores. He said that if you run a longer rod you can run higher compression. To be clear, he was not saying that a longer rod will make higher compression (obviously it will), but that the characteristics of the piston movement in the bore results in a lesser tendency to detonate.

Anyone have experience with longer rods tolerating a higher CR without running into detonation issues?

[ScotiaFE]

It's the piston that will set the deck height.
The formula,  D-(H+L+T)=d
D = Deck Height
H = Compression height of the piston
L = Connecting Rod Length
d = Deck Clearance

An engine with a zero deck clearance and a quench of about .040"
will do more to prevent detonation, along with a good cam pick and a good curve on the dizzy.
Along with a good gear set and the best fuel you can find.
Bigger engines tolerate more compression and bigger cams than smaller engines.
Cam up and don't lug the engine down and keep your foot in it.

[Yellow Truck]

Howie,

I don't know if I'm misreading your post, but deck height is the distance from the center line of the crank to the top of the bore. It is a measurement of the block, I think you are mixing it with deck clearance, which is influenced by piston compression height.

I asked the machinist for a measure of the deck height so I know what we have to play with when I come back here for some suggestions on the build.

On the economics side of stroker kit vs keep my crank and rods, I will need new pistons, and I have a friend that wants to buy my 1U crank, so it looks like the economics for a new rotating assembly is closer to keeping what I have than I expected-
Keep the old assembly (prices are approximate):

• forged pistons - $700
• inspect the rods - $100
• rings and bearings - $200
• balance the assembly - $450

Total of $1,450 Canadian.

Buy a Prison Break kit:

• buy the kit $1,995
• neutral balance my flywheel $100
• sell my crank and rods to a buddy -$300

Total of about $2,300 when converted to Canadian.

I'll give up drinking for a month to make up the difference!

[ScotiaFE]

Ya I'm probably mixing something up.
Stock deck height of an FE is 10.17"
 

[jayb]

The difference in compression you can run with a long rod vs a short rod is not going to be significant.  I wouldn't worry about any differences there.

[My427stang]

The difference in compression you can run with a long rod vs a short rod is not going to be significant.  I wouldn't worry about any differences there.

I agree.  Better to focus on tight quench, good blueprinting and matching parts.  Run 6.49 rods on a stock crank and 6.70 for a stroker

A good read here too

http://cochise.uia.net/pkelley2/DynamicCR.html

[Yellow Truck]

Thanks Ross, that link answered the question about how rod length would affect CR. It is not obvious until you think about the dynamic compression ratio.

[Barry_R]

There are a whole bunch of factors that play into fuel quality tolerance that are not readily addressed in dynamic compression ratio calculations.  The DCR stuff is a valid "cross check" and a useful directional tool.  But it is definitely not a number you should  be trying to optimize simply for the sake of "hitting the number".  Its good data but not the only factor - I think a couple folks here have touched on that.

Consider an example with a big cam and 11:1 compression running on pump gas.  Even when the DCR is in the safe range, at some point in the power band you will still have a 11:1 compression ratio engine.  Probably right around peak torque of +/- 4000-4500 RPM.  If you're in a Mustang or a Cobra the odds are that you'll sweep past that point pretty quickly with minimal load on the engine and never experience a problem.  But in a heavily loaded truck or a boat you might be "parking the motor" at that RPM under a heavy load and it'll eat itself up.

Rod length and bore diameter both have significant impacts on fuel tolerance, but it might not be in the way you'd expect.  They are supporting a function of time - the time required for excessive cylinder pressure to initiate a pressure induced secondary flame front and resultant detonation event.  Consider that a shorter rod will essentially pull the piston away from the head more quickly it will thus allow pressure drop to happen before the secondary combustion front has the time to develop.  Same benefit for a smaller bore - the smaller diameter takes less time for complete combustion to spread across the chamber & cylinder.

You should also consider combustion chamber shape when working on fuel tolerance.  More modern chamber designs will not reflect on most flow bench numbers and will not show up on a DCR calculation.  But a current chamber shape will help to homogenize mixtures and steer the combustion process past a more centrally located spark plug.  This in turn means a reduced timing advance requirement, more power, and improved tolerance for poor fuel.

Lacking the OEM benefits of electronic fuel and timing management we need to be a little more conservative about some things.

[NIsaacs]

There are a whole bunch of factors that play into fuel quality tolerance that are not readily addressed in dynamic compression ratio calculations.  The DCR stuff is a valid "cross check" and a useful directional tool.  But it is definitely not a number you should  be trying to optimize simply for the sake of "hitting the number".  Its good data but not the only factor - I think a couple folks here have touched on that.

Consider an example with a big cam and 11:1 compression running on pump gas.  Even when the DCR is in the safe range, at some point in the power band you will still have a 11:1 compression ratio engine.  Probably right around peak torque of +/- 4000-4500 RPM.  If you're in a Mustang or a Cobra the odds are that you'll sweep past that point pretty quickly with minimal load on the engine and never experience a problem.  But in a heavily loaded truck or a boat you might be "parking the motor" at that RPM under a heavy load and it'll eat itself up.

Rod length and bore diameter both have significant impacts on fuel tolerance, but it might not be in the way you'd expect.  They are supporting a function of time - the time required for excessive cylinder pressure to initiate a pressure induced secondary flame front and resultant detonation event.  Consider that a shorter rod will essentially pull the piston away from the head more quickly it will thus allow pressure drop to happen before the secondary combustion front has the time to develop.  Same benefit for a smaller bore - the smaller diameter takes less time for complete combustion to spread across the chamber & cylinder.

You should also consider combustion chamber shape when working on fuel tolerance.  More modern chamber designs will not reflect on most flow bench numbers and will not show up on a DCR calculation.  But a current chamber shape will help to homogenize mixtures and steer the combustion process past a more centrally located spark plug.  This in turn means a reduced timing advance requirement, more power, and improved tolerance for poor fuel.

Lacking the OEM benefits of electronic fuel and timing management we need to be a little more conservative about some things.


Awesome explanation, especially about "Parking the Motor" a problem I had for 20 years running 428's in trucks. Being a good mechanic but not a hot rod mechanic I could never fix the problem only run reduced timing and cold plugs, Thanks!

Nick

[Yellow Truck]

Thank you Barry. That is the best "in one place" explanation I've seen. I've been trying to put that together for some time.

I should have the actual number for my block today - I'll know what it needs done in terms of bore and deck height, and then I can try to reach you to get a part list going.

I was talked out of a simple cam replacement, which has made this a much better learning experience, and I hope will get us a better result.