School me in the ways of intaking fuel and air...

Hey Matt, it was gooid to meet you at Pines, and it sucked to see you out so early after all the effort you put in. Like you say spend some time to get it running right without the time pressure. You'll get there.

I hope to see you at another rally soon Peirce-Neige maybe?

-Martin

Hey Martin,

Good to meet you too! Sorry I was a bit distracted... I think by Sat. morning I'd had 9 hours sleep in the previous 3 nights! Was getting to the end of my ability to focus... Maybe a good thing the car wasn't really running, we might have crashed when I fell asleep behind the wheel!

Seeing you still rolling through Bancroft with that "camber adjustment" was just badass!

PN is out, we're expecting baby #1 in Feb!... But there is a plan to run next year sometime, might try to run Bear as a shakedown and then Pines.

Al, Fuel injection??? what is this technology you speak of?

Matt

Fuel injection is only $153 away (not including the fuel pump, and injectors, and regulator, and fuel lines, and ignition module, and wiring harness, and time to tune the whole thing, etc...)

http://www.diyautotune.com/catalog/megasquirti-programmable-efi-system-pcb22-kit-black-case-p-128.html

Still probably only makes sense to use a megasquirt on a car that already had fuel injection so you don't have to worry about the other crap required to make the system work.

Quote
JonArmstrong
Fuel injection is only $153 away (not including the fuel pump, and injectors, and regulator, and fuel lines, and ignition module, and wiring harness, and time to tune the whole thing, etc...)

http://www.diyautotune.com/catalog/megasquirti-programmable-efi-system-pcb22-kit-black-case-p-128.html

Still probably only makes sense to use a megasquirt on a car that already had fuel injection so you don't have to worry about the other crap required to make the system work.

vieleicht ein besser wahl:
http://www.k-data.org/kdfi-v1-3-with-enclosure.html

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Too many wires and graphs for me!

We have a FI tank, pumps, and all the bits, could easily do it too. I will hold on to the stuff. The stock FI system made another 10 hp over that anemic Hitachi thing... no other engine changes.

But, I mean come on, triple carbs mon! What is cooler then that? Somebody can say, "i got twin DCOE's" or "I'm running 4 R1 carbs on my civic.." But I have the unique advantage of saying "Dooodes, triple carbs FTW mon!"

Oh and sad to say, but thinking about the way it was running, I think the choke may have been stuck on... It would only make any power near full throttle, and that Hitachi is dual venturi. I wonder if the choke was stuck half closed the whole time. Was too tired to think that morning as to what the problem was. Not sure if that makes me madder or sadder.

Did I say, "damn carbs"

Matt

Alright, two steps forward, three back...

Trying to get this thing finished before Sept 20th and in the car to test!

Compression/head shaving questions.

Long story short/recap

78mm bore
83mm stoke
1.4mm head gasket
37 cc combustion chamber
4.5 cc piston dish and recess below block

Cam from Delta cams, longer duration, more lift, nothing crazy.

The tripple carb set-up

I had a head "milled" (2 years ago, ran the motor, look to above posts for a recap) and I thought I spec'd 1.5 mm to come off that should have bumped me up to 10.5:1 range.

I cc'd the combustion chamber just before I planned to bolt it all up again this past weekend, and it's still in the 37 cc range, giving me about 9.12:1; only over stock by 0.12

I'm pretty sure they just skimmed the head... not the big whack I asked for. SOOOO

I took it back in today, and one of the guys measured the head height and said .080" had already come off, but that is like 2mm and should have dropped me to 11:1 or higher. However he measured to the cast section on the upper side where rubber valve cover gasket meets, is that a typical place??? There are a couple of machined bosses in each corner of the head that seem like a more standard measurment, and they stand about 2 mm off that cast section...

Anyway even if he's right, somebody milled it before me, or they did mill 1.5 off, whatever, who's to say I shouldn't take another 1.5 mm off to get up to 10.5:1?

Need YANK! must have COMP...

Edited to add more numbers...



Edited 2 time(s). Last edit at 09/03/2013 11:53PM by Mad Matt F.

Okay, let me try to explain this better, and maybe somebody can undestand my ramblings...

I did not cc the head before sending it to the machine shop the first time.

I took the known compression ratio, the bore diameter, and figured taking 1.5 mm off would bump me up from 9:1 to approx 10.5:1.

Since having it milled, and since having it run (sort of), I have now cc'd the head and come up with 37 cc. If I use that number to caluate compression ratio, including having cc'd the dish in the piston, and factoring in the head gasket, I get a calulated compression ratio of 9.12:1

So I took the head back to the machine shop, assuming that they (big, well known and respected shop in town) likely didn't understand my terrible French (J'essaie, J'essaie), and only skimmed the head.

The guys in the shop measured the head, checked a book look-up and said what I believe to be (again my poor French)
"Tu es fou! on ne peut pas prendre plus loin, quelqu'un déjà moulu il est pratiquement .08"!"
or loosely translated,
"you idiot! we can't take anymore off this thing, it's already been milled to the ground.."

however, that would lead me to believe, that calculated compression should be a tad more then 9.12:1...

I'm not thinking the shop is wrong, but either I missed something in translation, or perhaps the measurments are off somewhere.

My question about "where to measure head thickness" comes from the fact the valve cover "rail" is still raw casting, and to me that doesn't seem to be the place to measure to, as it undulates enough I can feel it! and there are these 4 bosses, or lands, or whatever at each corner of the head that are machined on top, and seem like a more accurate place to measure too... as seen in exhibit A below. (not the subject head, but another one, that has been only slightly skimmed, and cc's within a 1/2 cc of the one in question). If they are where the measurements are to be taken, it would make complete sense, and I still need to take off 1.5 mm...






Edited 1 time(s). Last edit at 09/05/2013 12:29AM by Mad Matt F.

I don't know of a "standard" way for measuring head heights. I usually check the manual or reference a known head that hasn't been touched.
In the case of the Justy head, measuring from the valve cover sealing surface seems mostly legit. Though the machined bosses serve no purpose that I can see (maybe that is where they are supposed to measure and their manual is wrong...)

Have you tried putty/clay in the head to see what your running clearances are? This might give you a better idea of how much you can actually take off.

Bugger the theoretical thickness Matt you moose-molesting maniac!
Get a cheap-ass graduated pipette and see the cc, si?

You didn't take the known comp really, did ya?

because to do that you woulda already had the graduate pipette you silly Goose.
And would have said " I measured the combustion chamber volume, calculated the actual gasket volume using the super convenient formula John told me (dia x dia x .7854 x height), measured the cyliner volume using same sooooper easy formula, did me sums and got xx:1"

But NOOOOOOOoooooooooooOOOO, you din't do that, did ya?

Now you have to, and then you have to say what your intake valve closing ABDC is, then we can talk.

Ya must know somebody at a hospital or a lab who can borrow a disposable pipette of min 50cc...just borrow mind you.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

oui man, I took the comp... 37 cc post the initial skim

actual measurements:

78mm bore
83mm stoke
1.4mm head gasket
37 cc combustion chamber
4.5 cc piston dish and recess below block


my pipette was a syringe I found in the park

I checked valve clearance and they didn't tap my 1/2" /3cm blob of home made playdough so that doesn't seem to be an issue

my concern has only been that given the head thickness measurement I'd be taking off 3.5 mm to get a bump of 1.5 compression points. and that seems wacked. And as I don't know what I'm doing I'm afraid of se screwing something up.

Quick look says all that comes out to 11.0:1

Be nice to know rod c-c and gasket bore dia

And INTAKE VALVE CLOSING ABDC

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

Quote
john vanlandingham
Quick look says all that comes out to 11.0:1

???

What am I missing?

CC of piston stroke = 396.8 cc

CC of combustion chamber = 48.5
head = 37
head gasket (80mm/1.4mm)=7 cc
piston dome and block =4.5
445.3/48.5 = 9.18 (better then the online caluator I used, but that's likely pi sig digits..

Quote
john vanlandingham
gasket bore dia

oops, yeah... sorry, above 80mm bit bigger then the cylinder bore.

Quote
john vanlandingham

rod c-c

who needs real numbers???? you should see the stuff I make up in my head.

Rod centers = 13cm

Quote
john vanlandingham
INTAKE VALVE CLOSING ABDC

Hmmm that's tricky I THINK this is my cam...

Valve Opening = -2.4 'BTDC
Lobe Center = 108.2 'ATDC
Valve Closure = 26.4 'ABDC
Duration = 204 Crank Deg
Max Cam Lift = .20673 IN.
Net Valvelift = .3101 IN.
Lobe Area = 16.34 IN. *Deg

Exhaust
Valve Opening = 29.3 'BBDC
Lobe Center = 109.4 'BTDC
Valve Closure = -2.4 'ATDC
Duration = 206.8 Crank Deg
Max Cam Lift = .21142 IN.
Net Valvelift = .31713 IN.
Lobe Area = 17.35 IN. *Deg



Edited 1 time(s). Last edit at 09/08/2013 09:39AM by Mad Matt F.

John,

as per our discussion, that is for sure the cam specs.

Also fixed my math... 9.18:1

cheers



Edited 1 time(s). Last edit at 09/08/2013 09:40AM by Mad Matt F.

Deck the block a crap-ton, then shave the tops of the pistons down until they are zero-decked?

Although since you only have three pistons, it might be cheaper just to actually GET flat-top pistons.

---

Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.

Quote
Pete
Deck the block a crap-ton, then shave the tops of the pistons down until they are zero-decked?

Although since you only have three pistons, it might be cheaper just to actually GET flat-top pistons.

I had thoughts along this line the pistons are 0.3 mm below the block deck. I could take the block down till they are a bit proud since the gaskets are so thick. But then I'm stuck with that and I'm short on blocks. I have spare heads...

What is the advantage of decking the block vs head for pinging issues? I don't really understand how one is better then the other.