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

Posted by Mad Matt F 
Pete
Pete Remner
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Re: School me in the ways of intaking fuel and air...
September 08, 2013 11:58AM
Just speaking purely of theory here, every engine's gonna be different, but if you shave .080 off of a head, you're removing a thin slice out of the combustion chamber, while if you shave .080 from the block, you're removing an entire cylinder diameter's worth. We're assuming here that the pistons you have sit down in the hole at TDC, which a shocking number of modern engines do...

And then if you deck so far that the pistons are proud of the deck and have to shave them down again, you're not gaining any more compression except what you're removing from piston dish.

Where things get different is if the deck is thin, where the head bolts thread into, crap like that. But one dude on the Audi forum started with a 10-valve engine which had massively dished pistons and super thick decks, and shaved something absurd like 1/4" from the deck and the piston tops... Worked just fine after he figured out how to keep the cambelt from flapping in the breeze. But his machining time was cheaper than a set of pistons so he went for it.



Pete Remner
Cleveland, Ohio

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



Edited 1 time(s). Last edit at 09/08/2013 12:01PM by Pete.
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john vanlandingham
John Vanlandingham
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Re: School me in the ways of intaking fuel and air...
September 08, 2013 02:57PM
Quote
Pete
Just speaking purely of theory here, every engine's gonna be different, but if you shave .080 off of a head, you're removing a thin slice out of the combustion chamber, while if you shave .080 from the block, you're removing an entire cylinder diameter's worth. We're assuming here that the pistons you have sit down in the hole at TDC, which a shocking number of modern engines do...

And then if you deck so far that the pistons are proud of the deck and have to shave them down again, you're not gaining any more compression except what you're removing from piston dish.

Where things get different is if the deck is thin, where the head bolts thread into, crap like that. But one dude on the Audi forum started with a 10-valve engine which had massively dished pistons and super thick decks, and shaved something absurd like 1/4" from the deck and the piston tops... Worked just fine after he figured out how to keep the cambelt from flapping in the breeze. But his machining time was cheaper than a set of pistons so he went for it.


Very good advice, just one correction. LOTS and lots of modern like real current things have pistons dead flush...It's mainly older things (like my 1.7 V4 Saab (Ford) that are down the bore in the V4 case 2.2mm and US Pintoids are 1.2mm down, old Volvos are 0,4mm down BUT later B230 are dead flush...---so even at nominal 8.0 the miserable fuckers would ping like crazy..
First V4 I zero decked '+' 004" or 0,1 the comp came out at 10.8 and that would run fine on regular... In the years since '87 I've done them +.004 and bigger bore (more cylinder volume) and had on paper 11.3 and then they want SOOOPER---but that's with a cast iron head...

Zero deck--or .004-.006" / 0,1- 0,15mm out is NICE...

It takes some very careful measuring but chopping the block is a great idea..

Of course you gotta check the bolt UHL and confirm they don't bottom----that was a DNF at rocky Mountain 1988 for me---

Being a little short 3 cylinder POS a machine shop should be tooooooooooo bad.....here in Sleezattle a inline 4 is about $80 to surface the block, so logically it should be 25% less.
And yeah every motor is different but the gas and detonation are the same...

Of course the hot thing--pun intended ---would be to weld up the chambers and machine out some quench pads, brou ha! ha!!!!

Wanna see some kick ass piccies of that on a nice motor?



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.



Edited 1 time(s). Last edit at 09/08/2013 03:00PM by john vanlandingham.
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Mad Matt F
Matt Follett
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Re: School me in the ways of intaking fuel and air...
September 10, 2013 02:51PM
return trip to machine shop yielded the realization that yes those lands are the place to measure to.
1.3 mm coming off. Damn the torpedoes.
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Pete
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Re: School me in the ways of intaking fuel and air...
September 10, 2013 07:20PM
MAN THE DECKMASTER, FULL SPEED AHEAD!



Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.
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Mad Matt F
Matt Follett
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Re: School me in the ways of intaking fuel and air...
September 23, 2013 11:34PM
I'm a friggin idjit...

Go back to the top of page three... Where we tried to run Pines with the mighty triple carb set up, and had no luck due to being short on time. All along I figured main jets were way to rich, but I never actually took the bowls off and checked -

wait for it,

wait,

come on...

think "what did he miss?"....

IF THEY WERE THERE!!!!!!!!!!!!!!!!!!!!!!!

Two carbs had the mains floating in the bottom of the bowl! The other is missing completely!

FAWK!

If all goes well I'm planning to tune the beast this weekend, and tonight I popped to fuel bowls to "see what I am starting with" First bowl off and the jet fell out on the table. I thought "hmmm well, maybe, but there were still two other cylinders that would have pulled it through a bit"

Open the next one, same friggin story!

Open the third, NOT EVEN IN THE BOWL!

Free carbs are exactly that, free carbs... However, while ticked we wasted so much time, and money 2 years ago, I go forward with up lifted spirits, and dreams of kicking 2L butts.

smiling smiley

Night.
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Robert Culbertson
Robert Culbertson
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Re: School me in the ways of intaking fuel and air...
September 24, 2013 12:11AM
Ha! That would explain the raw fuel in the exhaust.

My dad once forgot the entire carburetor for his flat track bike once. Got in a hurry at work and loaded the bike and gear.... minus one key component.
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john vanlandingham
John Vanlandingham
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Re: School me in the ways of intaking fuel and air...
September 24, 2013 10:09AM
Well it just glows to schmoe ya.
Basics first..

New carbies, quick peek and write down and stick on wall about eye hgt.. That way you see it so often you kinda recall everything ,
THEN when its time to try you go "Whaaaas goin on? Jetting jetting OH YEA!"

Basics basics

First things first



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.
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Pete
Pete Remner
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Re: School me in the ways of intaking fuel and air...
September 25, 2013 07:47AM
And it ran at all...



Pete Remner
Cleveland, Ohio

1984 RX-7 (rallycross thing)
1978
Silence is golden, but duct tape is silver.
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Mad Matt F
Matt Follett
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Re: School me in the ways of intaking fuel and air... or the Justy build page...
September 28, 2013 12:27AM
Alright, getting there...

But of course I got side tracked... and decided to build a header. A friend gave me a 4AGE header, and while it had a wierd extra tube, I figured I could use it. So a few cut wheels later, and voila





My question, since I am such a metalurgist, and pro welder...

I hacked the flange off the stock cast manifold, and hope to use it to hold this thing in place...

After boring it out to fit the 1.5" tube with a hole saw, my first thought was to bevel the inside edge of the flange, so the weld pool would hold it in place if it cracked, and not weld the ouside edge.



But then I thought maybe that's not enough. I could get a ring to fit the outside of the pipes, weld that on and then let the flange be loose al-la bike pipes. Or I could weld both sides and hope...

thoughts?
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john vanlandingham
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Re: School me in the ways of intaking fuel and air... or the Justy build page...
September 28, 2013 01:07AM
Is that a fawkin PINK BLOCK?

I knew you guys were RED up there but PINK?



John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

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CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.
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Mad Matt F
Matt Follett
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Re: School me in the ways of intaking fuel and air... or the Justy build page...
September 28, 2013 01:10AM
Come on John...

it's ORRRanGE!

phone camera...
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john vanlandingham
John Vanlandingham
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Saab 96 V4



Re: School me in the ways of intaking fuel and air... or the Justy build page...
September 28, 2013 11:27AM
Quote
Mad Matt F



My question, since I am such a metalurgist, and pro welder...



thoughts?

OK you can claim its "Canajian Orange"eye rolling smiley or whatever..
Whay is clear even to a non-deist is the Rally Gods has blessed this project---look at the light slant in , and I betcha if ya listen theres a faint angelic choir, singin Kyrie eleison in the background,
Verily, that photo is PROOF that Gawd means for you to be happy.
It is written!



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.
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john vanlandingham
John Vanlandingham
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Location: Ford Asylum, Sleezattle, WA
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Rally Car:
Saab 96 V4



Re: School me in the ways of intaking fuel and air... or the Justy build page...
September 28, 2013 11:32AM
Whaddya have to loose with the cast iron probably brittle thing welded to steel?

However--a smrat guy, always worry what could go wrong when you guys cook up "brilliant" solutions might make and save a tracing of the flange while that's loose and tracing is easy so that if cast iron does what cast iron nealy always does---except when Bogu has blesst you which obviously is the case---then for us normal guys we'd have a tracing and go get a flame/water/plasma cut for a steel flange.....for when us unblesst, the inevitable happens.



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.
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Mad Matt F
Matt Follett
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Re: School me in the ways of intaking fuel and air... or the Justy build page...
September 28, 2013 04:09PM
I didn't set that shot up. .. But I'm happy with the results. I think it speaks to the shear awesomeness of the justy.
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Robert Culbertson
Robert Culbertson
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Re: School me in the ways of intaking fuel and air...
September 28, 2013 09:28PM
If you have some steel flat bar, you can trace one out and hack away at it with drill, hole saw, and torch.
If you are handy with a torch you can try brazing the flange to the header. I have brazed a few cast manifolds up and they are still working fine. If you braze you can do the inside and the outside of the flange, creating more support for the cast flange area.
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