Timing with Hypereutectic pistons

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vc318

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Hi Guys,
Looking to build a 318, the deck is currently being hot tanked and honed to .040", and milled to zero deck to suit KB167 pistons.
I'm hoping to find a set of aftermarket heads, that once cc'd, will give me a compression ration of 10.1:1
The car is 3000lbs, will be getting a 2400rpm stall and built 904 with a TF2 Transgo
The camshaft I am hoping to use is the XE268H.

My question relates to the pistons I am purchasing. They are the Keith Black 167KTM-040, reading the fitting instructions [ame]https://www.uempistons.com/installation_instructions/kb_installation.pdf[/ame]
on page 2 it states

"NOTE: Hypereutectic piston engines will require 2-4 degrees less total
ignition timing. One key to top performance is to have all cylinders
longing for the same timing numbers. Equal air flow, fuel mix, quench,
chamber temperature, swirl, and compression at each cylinder work to
this end."

Now when I dial in this camshaft, do I need an adjustable timing keyway set to degree the cam in less from what the cam card suggests? Or are they referring to the timing with the distributor?

Sorry if its a silly question

Cheers
Andrew
 
That has to do with the design of the piston, the material specifically. It "reflects" heat a bit better than plain cast pistons so the burn will be a little hotter. Honestly - I'd ignore that...lol. What you cannot have, in any way shape or form, is pinging or detonation. Those pistons are like tool steel: strong, but brittle. Pinging and detonation are like hammering on a chisel. Parts tend to chip off... 4° of timing more than likely will not make or break that piston. Steady detonation eventually would. Make sure the top ring gap is per the KB specs, and don't sweat the timing unless it pings. Given the static ratio and the cam, you might have to play with the timing curves and carb jetting to keep it out of detonation and ping.
 
Cool, thanks for the feedback guys, I have a 600cfm holley here I am going to put a kit through, I'll use it to run the motor and cam in but eventual goal will be to try out the Fitech Injection with timing control to avoid the dreaded detonation and pinging
 
If you get the quench tightened up, she will make plenty of torque at 32 to 34 degrees power-timing, and will stay out of detonation.
FYI;If you go aluminum heads and tight Q; I run 10.7 Scr on 87E10 with 8.7Dcr, detonation free, at 900ft elevation, and 205*F minimum water temp..
You need to get the pistons up close to the top,tho.
 
And FWIW.... I have destroyed forged pistons with detonation caused by excessively advanced ignition timing in a race when the distributor got whacked. The hypers are a bit more easily damaged, but as Moper said, you gotta keep out of detonation with any of them. And you can detonate with any fuel and ignition system!

And as said, cam timing is not ignition timing. Advanced cam timing helps low end torque and raises DCR.

Pay very close attention to the ring gap info on the KB's.
 
moper said:
That has to do with the design of the piston, the material specifically. It "reflects" heat a bit better than plain cast pistons so the burn will be a little hotter. Honestly - I'd ignore that...lol. What you cannot have, in any way shape or form, is pinging or detonation. Those pistons are like tool steel: strong, but brittle. Pinging and detonation are like hammering on a chisel. Parts tend to chip off... 4° of timing more than likely will not make or break that piston. Steady detonation eventually would. Make sure the top ring gap is per the KB specs, and don't sweat the timing unless it pings. Given the static ratio and the cam, you might have to play with the timing curves and carb jetting to keep it out of detonation and ping.
Click to expand...

What Dave said ^^^^^^^ X 1000
 
Thanks guys.
Also just need some clarification on page two, it mentions the piston to wall clearance for a 4.000" bore....what specs would I use for a motor that is 3.950"? Is it a requirement to check on an freshly machined over bore? Would the machine shop to that anyway?
 
3.950" is essentially the same as 4.000" so use the 4" number. The machine shop is responsible to set the piston to bore clearance properly; they ought to ask to have your new pistons in their hands when they bore the block. But it is your job to doublecheck their work especially if you are assembling the engine.
 
vc318 said:
Cool, thanks for the feedback guys, I have a 600cfm holley here I am going to put a kit through, I'll use it to run the motor and cam in but eventual goal will be to try out the Fitech Injection with timing control to avoid the dreaded detonation and pinging
Click to expand...

Back up the bus, there young fellow.
I'm assuming;
this is for a street car?(2400TC)That you have an Early A,(3000lbs),
that you have limited mechanical knowledge,and
That for some as yet unstated reason,you are targeting 320hp,
So......................computer controlled ignition timing can break an engine every bit as quick as a regular distributor. Maybe even quicker.
And, IMO, at your power level, EFI is just bragging rights. What I mean is;A carb is just fine with an XE268 cam. The 2400 is probably gonna have to go, unless you are thinking of running big-number rear gears, like 3.91s, or if you don't mind coming outta the gate a bit soft, or are running skinny tires, or real crappy street suspension.What I mean is; if it hooks, the 2400 will drag the revs down into the soft part of the engine's powerband. If it spins and the revs get up to mid to high 3000s, where the torque starts, then it don't matter much what stall you run.
But then I'm thinking; if you are targeting 320hp, you will not be wanting to just spin skinny 245s;heck you can do that with a stock teener. So, I got to thinking, I wonder what this guy(you) are thinking? Then I thought, I wonder what his plans really are? He (you) seems to be all over the place.
On the one hand, he says 320 hp; but he's confusing ignition timing with cam timing.Then, he's concerned about skirt clearances, but the machinist hasn't asked for the pistons to "hone the cylinders out .040". And he wants to run a 2400TC with an XE268.
Ok, a picture is starting to form in my head. I think this guy is a little "green".Am I right? That's ok, we all started out green. So, how about you tell us a little about yourself and your car, and how you intend to drive it, before you spend your life-savings on a disappointing combo.
 
First off 10/1, on a teener is hard to get.
If you really are gonna Zero-deck it,then you will need to run closed chamber heads,
and and a thick (.035,minimum) head gasket.
This is because, the math says 10/1, on a 3.95 x 3.31 teener,is a total chamber volume of 73.85cc.Since the pistons will have 5cc eyebrows, and the gasket (FelPro.040) is about 8.5cc, and the deck is Zero cc,that leaves just 60.35 for the heads, and almost the only way to get that is with closed chamber heads.Couple that with,the 320 hp goal, and your heads just became very, very,expensive.

A cheaper, easier way to a 10/1, 320 hp, with a teener, on the street especially, is a long-arm crank.
Say a 3.58 stroker..This requires a total chamber volume of 79.88, and heads+deck of 66.4cc
Or a 3.79 stroker....This requires a total chamber volume of 84.56, and heads+deck of 71cc.
Or a 4.00 stroker....This requires a total chamber volume of 89.25, and heads+deck of 75.75cc

Another reason to think this through, is that the XE268, while not being super-soft off idle, that 2400TC could make it seem so. "Could", being code for "will", IMO.
To get the off-idle torque up,you can go to a shorter period cam,(thus increasing the Dcr), or you could go stroker. The long-arm will do three things for you;
1) plenty more low rpm torque, and
2) allow a longer period cam. before dropping the Dcr into the basement, and
3) make Scr and head selection(with bigger valves, and more flow), much easier.
These pluses,lead to a dynamite street engine, with tons of low-speed torque, a very strong midrange, and a lot of higher rpm power potential. With this new-found torque, you can step down a cam size or even two, or not, making the 2400TC do-able, and 3.55s( or even 3.23s) also doable; making hiway touring a possibility again .
So here's how that might play out,(remember I'm talking a streeter here);
The money you didn't have to spend on rear gears and a TC, will buy you a stroker pkg.
The money you didn't have to spend,maxing out the teener heads, will buy you a nice set of iron street-ready heads.
The money you didn't have to spend on machining costs, will buy you a Suregrip and some fat tires.
If you chose your stroker kit,and heads wisely,(and there's some really smart guys on FABO to help you with that), you will end up with a really killer 3000 pound streeter, that you can lite up the tires with, in maybe three gears; and still drive a 12 hour day, to three states over, for a weekend car show. I call that a win,win,win, winning combo.
Well that's my opinion, anyways.

Oh yeah, the engine cubes math out to; 351,372,and 392;if that make the decision any easier.
Oh yeah, another thing, none of these will make 320 horsepower........Unless you seriously
choke
them
down.
 
AJ/FormS said:
Back up the bus, there young fellow.
I'm assuming;
this is for a street car?(2400TC)That you have an Early A,(3000lbs),
that you have limited mechanical knowledge,and
That for some as yet unstated reason,you are targeting 320hp,
So......................computer controlled ignition timing can break an engine every bit as quick as a regular distributor. Maybe even quicker.
And, IMO, at your power level, EFI is just bragging rights. What I mean is;A carb is just fine with an XE268 cam. The 2400 is probably gonna have to go, unless you are thinking of running big-number rear gears, like 3.91s, or if you don't mind coming outta the gate a bit soft, or are running skinny tires, or real crappy street suspension.What I mean is; if it hooks, the 2400 will drag the revs down into the soft part of the engine's powerband. If it spins and the revs get up to mid to high 3000s, where the torque starts, then it don't matter much what stall you run.
But then I'm thinking; if you are targeting 320hp, you will not be wanting to just spin skinny 245s;heck you can do that with a stock teener. So, I got to thinking, I wonder what this guy(you) are thinking? Then I thought, I wonder what his plans really are? He (you) seems to be all over the place.
On the one hand, he says 320 hp; but he's confusing ignition timing with cam timing.Then, he's concerned about skirt clearances, but the machinist hasn't asked for the pistons to "hone the cylinders out .040". And he wants to run a 2400TC with an XE268.
Ok, a picture is starting to form in my head. I think this guy is a little "green".Am I right? That's ok, we all started out green. So, how about you tell us a little about yourself and your car, and how you intend to drive it, before you spend your life-savings on a disappointing combo.
Click to expand...

I guess I should've elaborated. It is a 1966 VC Valiant. Stock diff ratio is 3.23, which is what it has.

The 318 I have has already been bored .030". The machinist has my short motor. He found .003" cylinder wear and suggested taking it out .040". Without doing this, he was concerned there may be an issue with blow by.
We discussed pistons, I mentioned the KB167, he asked for a few figures, including compression height of the pistons and was able to tell me how much the block needed to be milled as well as what was required in terms of machining the stock 318 heads. He has asked for the new pistons also.
As recently as yesterday, I have found an aftermarket option for the heads which I will be purchasing
http://www.ebay.com.au/itm/Mopar-Ch...225767?hash=item1eac450ea7:g:XCkAAOSwezVW06YY

With the chamber volume of 65cc, it should put me in the 9.4:1 range just by using the heads with the KB167 pistons, without even factoring in the work done to the block.
Since finding these heads available, with the valve sizing (which i think is a typo on the ad) I may even be able to run an xe274 cam, and according to the CamQuest program, that needs a 2200rpm+ stall.
How much the cam and valve sizing does/doesn't hurt vacuum with that compression ratio, I'll see. But there are options to work around this.
I also have an Edelbrock LD4B I am using.
Car is 100% a street car, it will run 98 Octane fuel, it's not a daily driver, it's a weekend cruiser/whenever I wanna take it out for a thrash.

I agree that Fuel Injection won't make it immune to detonation or hurting the engine, or even make it have greater HP, but the Fitech system is so cheap, it makes sense to use it, with all the benefits of correct AFR's in correlation to coolant temp, cold starting and constant self tuning of the AFRs for near perfect combustion under all engine loads. Why spend $$$ building this motor to only run it with a carb? Definitely not for "bragging rights". Why should how much power you have dictate whether or not you use fuel injection??

I'm using this motor because it's free and 360s, 340's are expensive and hard to come by in Aus. Forget stroker motors, too much needs to be done in terms of getting it street legal here. The year of this vehicle does not need to meet emissions in Australia.

I trust what the machinist recommends, he has been in the industry since 1975 building street and race motors. He didn't laugh at my ideas or what I have planned, he explained how MY goals can be achieved. He thinks its great that I'm going to build the motor myself.
And he certainly isn't sitting behind a computer screen taking the piss out of people and their ideas.
I appreciate the help other users have given in the thread. Thankyou.
There may be some other people out there that had the same questions I had hence starting this topic but lets not ASSume that.

Andrew
 
Seeing as this has gone off track anyway, here's what I do on a daily basis
Any Left hand drive vehicles that come to where I live in Australia, need to be stock and in roadworthy condition bar the radio.
If it gets converted to right hand drive, it's open to whatever mods you want as long as an engineer signs off on it.
All these cars below are street legal.
I'm green to building a pushrod v8 but not mechanics or the industry. I get to speak to guys that build high end v8s and what has and hasn't worked for them.
This is only a small part of the work I do. For every Dodge/Chrysler I inspect, I inspect 10 mustangs and corvettes.
I work for the Government here and we are the last step for getting these cars on the road
Got a heap of other cars if you're interested
Enjoy!

- 572ci 800hp - $250k to build
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LS1 auto on airbags
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- biggest street legal tyre car in my state
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