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174 cu in Engine Pistons
Posted by: teddbrown ()
Date: February 19, 2015 11:02AM

Been working on the 174ci large bore engine and am at a decision point. The Clarks Full Fin Cylinders have been used by the Aircraft guys for awhile... so much so that they have their own Clarks parts number. Nothing replaces cubic inches and I don't want to modify the case and heads to get there (Even more cost).

CURRENT: The pistons the aircraft guys had made are forged and cost well over $100 each just to have made, when you factor in $85 cylinders, that engine gets expensive quick. Can't blame them as they build for durability/No Fail. They are also cut to lower compression which I want to stay at about a true 9.3 (stock heads) to 9.5:1 (Cut to step) using a flat top piston.

PLAN: Have cast pistons made that can drop in just like stock without any modifications...basically a Corvair piston to fit the large bore. (The cost of forged is not even close)

WHERE I AM AT: Contacted piston maker, submitted design and already got my quote and he said he can pull the trigger when ready. The rings are standard GM rings and will be much cheaper than Corvair rings. Catch is I have to purchase 240 pistons and they wont make any less.

BEFORE I DO ANYTHING: I need to know if anyone is interested? Pistons will be about $35 each estimated costs (wanting to keep around $200 per set). You will order your own cylinders from Clarks directly and Rings can be sourced from Rock Auto, FLAPS, etc. The only down side is the cost of the Cylinders, but Clarks Full fins are the bomb and I would not even attempt with them.

IF YOU ARE INTERESTED.....PM ME. I'm not dropping 7K on pistons to have my kids sell as scrap when I go to the old folks home. I will go forward or just build a couple engines and let it go.

Ted Brown
Anderson, SC
www.corvair-efi.com

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Re: 174 cu in Engine Pistons
Posted by: Zodi Davis ()
Date: February 19, 2015 12:13PM

I don't know who you approached for pistons but it may be worth while to contact Egge in California, I've gotten pistons for corvair from them in oversizes beyond .060 around 180.00 a set with a min. 6 sets.
rings from Frank at Deves rings in L.V.
Once again ,I don't know who you have checked with but can't hurt.

Greg/Zodi Davis
Sierra Vista, AZ.
65" Monza convertible
65"Corsa turbo coupe
66" Corsa coupe 140
66" Monza 140
65"Corsa convertible
62" Rampside
64" corvan
64"Greenbriar deluxe

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Re: 174 cu in Engine Pistons
Posted by: teddbrown ()
Date: February 19, 2015 02:01PM

Thanks for the info:

Contacted Egge before. .060 is max oversized piston mold for Corvair at $224 a set....36 piston minimum. I called today again just to make sure my info was correct....I hate that it was. To make a .105 overbore, they said it had to be a forged custom piston. He told me if he does not have a mold for it, it has to be forged and machined.

Ive called a lot of piston companies...all will make forged pistons for about $100 each. If no one else is interested, that will be my best option.

Rings are not a problem and cheap.

Ted

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Re: 174 cu in Engine Pistons
Posted by: texas yenko dude ()
Date: February 19, 2015 06:39PM

I ordered some from Wiseco last year for YS-199.

I ordered 15 forged flat tops with valve reliefs, teflon skirts, and a bunch of other stuff. +- $115/each

Texas YENKO Dude
YS-070
YS-199
YS-320
Southeast of Disorder


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Re: 174 cu in Engine Pistons
Posted by: RCSmith ()
Date: February 19, 2015 07:04PM

anything available off the shelf in a

90mm with a 21mm pin?

then compression height becomes the issue.




.

Ray C. Smith
'66 Corsa


Bergen County ,NJ

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Re: 174 cu in Engine Pistons
Posted by: chris ()
Date: February 19, 2015 07:45PM

PM sent.

'65 Monza 4 door
4 speed
110hp
Gardner, KS

Heart of America Corvair Owners Association

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Re: 174 cu in Engine Pistons
Posted by: mwr ()
Date: February 19, 2015 11:40PM

If you do end up going forged I've had nothing but great results from both Venolia and Wiseco.

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Re: 174 cu in Engine Pistons
Posted by: afterdarkgames ()
Date: February 20, 2015 06:04AM

So how did the .105 over become the magic number to bore the new full fin cylnders to? Why not go an extra .020 or half mm and use a standard readily availble VW piston?

Im not downing this adventure I am just trying to get find out why the .105 is THE number.

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Re: 174 cu in Engine Pistons
Posted by: RCSmith ()
Date: February 20, 2015 06:32AM

The maximum overbore for these was covered in this thread==

[corvaircenter.com]

Ray C. Smith
'66 Corsa


Bergen County ,NJ

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Re: 174 cu in Engine Pistons
Posted by: teddbrown ()
Date: February 20, 2015 09:03AM

afterdarkgames Wrote:
-------------------------------------------------------
> So how did the .105 over become the magic number
> to bore the new full fin cylnders to? Why not go
> an extra .020 or half mm and use a standard
> readily availble VW piston?
>
> Im not downing this adventure I am just trying to
> get find out why the .105 is THE number.

Because the airplane guys have Clarks Corvair making the cylinders already and Clarks ships them. flycorvair.com I ordered one last month and Mark said they will make as many as I will order. $85 Each.

I figured if a smart guy like William Wynn and others will fly a $30K airplane with a Corvair motor bored to .105 for thousands of hours without a single failure, I might take a chance of driving on the road where my worst outcome is calling AAA. Going to this bore increases 10 HP at the prop according to their website. He is running lower compression pistons for safety (they cant adjust the timing in mid-air). I have talked to this guy and will be attending the next Corvair College in Barnwell, SC. I wanted to run flat tops as with EFI and American Flat 6 (Tom's K )Large Valve 110 heads. I can control knock if it becomes a problem.

Can you bore to 90.5? Im sure as Ray Sedman does it on Stock Cylinders with a torque plate.

My goal was a install large Corvair Piston and Cylinder to give 10 extra cubic inches without any machine work...period.

Ted Brown
Anderson, SC
68 Convert 110/PG/EFI/DIS
61 Loadside 102/PG/EFI/Dist
61 Rampside 4 speed (Restoration starts Nov 2015)
130HP/PG/Honda Engine Project
67 Monza Cpe
61 Greenbrier
**UPDATED** Corvair Fuel Injection and DIS Page

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Re: 174 cu in Engine Pistons
Posted by: teddbrown ()
Date: February 20, 2015 09:11AM

texas yenko dude Wrote:
-------------------------------------------------------
> I ordered some from Wiseco last year for YS-199.
>
>
> I ordered 15 forged flat tops with valve reliefs,
> teflon skirts, and a bunch of other stuff. +-
> $115/each

Wiseco is $952 for 6 ($158 each) with pin and rings. but thanks for the info. Everyone I have talked to is about the same price.

Ted

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Re: 174 cu in Engine Pistons
Posted by: chris ()
Date: February 20, 2015 09:52AM

afterdarkgames Wrote:
-------------------------------------------------------
> So how did the .105 over become the magic number
> to bore the new full fin cylnders to? Why not go
> an extra .020 or half mm and use a standard
> readily availble VW piston?
>
> Im not downing this adventure I am just trying to
> get find out why the .105 is THE number.

For some reason, I also thought the VW pistons don't have the correct pin size to fit the Corvair rod (I may be wrong here). Otherwise, it would be nice since they are easily obtainable/affordable.

'65 Monza 4 door
4 speed
110hp
Gardner, KS

Heart of America Corvair Owners Association

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Re: 174 cu in Engine Pistons
Posted by: teddbrown ()
Date: February 20, 2015 10:29AM

> For some reason, I also thought the VW pistons
> don't have the correct pin size to fit the Corvair
> rod (I may be wrong here). Otherwise, it would be
> nice since they are easily obtainable/affordable.

Your right on point Chris. The VW Pistons (90.5) will make the Cylinder walls thinner, Pin size is wrong and compression height has to be adjusted. The VW stuff is more obtainable and affordable, but machining costs eat that up quick.

I was trying to make an affordable way to increase 10 cubic inches without breaking the bank... in stock cylinders from Clarks and a drop in pistons for about $200 per set. So far I have 4 people that are interested.... that's a long way from the 25 of the 40 sets I need before I invest that kind of cash.

I know the Corvair bunch is a fickle one and I thought getting the price around $200 is the way to go. We talk a thousand, but wont spend a hundred.

Ted



Edited 1 time(s). Last edit at 02/20/2015 10:30AM by teddbrown.

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Re: 174 cu in Engine Pistons
Posted by: afterdarkgames ()
Date: February 20, 2015 12:22PM

teddbrown Wrote:

> Because the airplane guys have Clarks Corvair
> making the cylinders already and Clarks ships
> them. flycorvair.com I ordered one last month and
> Mark said they will make as many as I will order.
> $85 Each.
>
> I figured if a smart guy like William Wynn and
> others will fly a $30K airplane with a Corvair
> motor bored to .105 for thousands of hours without
> a single failure, I might take a chance of driving
> on the road where my worst outcome is calling AAA.
> Going to this bore increases 10 HP at the prop
> according to their website. He is running lower
> compression pistons for safety (they cant adjust
> the timing in mid-air). I have talked to this guy
> and will be attending the next Corvair College in
> Barnwell, SC. I wanted to run flat tops as with
> EFI and American Flat 6 (Tom's K )Large Valve 110
> heads. I can control knock if it becomes a
> problem.
>
> Can you bore to 90.5? Im sure as Ray Sedman does
> it on Stock Cylinders with a torque plate.
>
> My goal was a install large Corvair Piston and
> Cylinder to give 10 extra cubic inches without any
> machine work...period.

I am all for the easy to drop in performance parts with the least amount of machine work possible and know the Airplane guys are using the .105 without failures, I was just curious as to how they came up with the magic .105 number vs something smaller or larger. Was there a formula for minimum thickness vs wear over time or was it just "yep looks good"?

Yes I know the pins are different on the VW pistons but if you are putting new pistons on anyway the rods will be out and can have the little end resized to the vw pin. But it is also another machining bill that will add up eventually and you cant go back to stock parts without replacing the rods.

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Re: 174 cu in Engine Pistons
Posted by: Scott V ()
Date: February 20, 2015 01:06PM

afterdarkgames Wrote:
-------------------------------------------------------
> the Airplane guys are using the .105 without
> failures, I was just curious as to how they came
> up with the magic .105 number vs something smaller
> or larger.

.105 bigger from the stock vair bore of 3.437 is 3.542 = 90mm = ez size to get rings for.

-Scott V.

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Re: 174 cu in Engine Pistons
Posted by: teddbrown ()
Date: February 20, 2015 01:20PM

afterdarkgames Wrote:
-------------------------------------------------------
>
> I am all for the easy to drop in performance parts
> with the least amount of machine work possible and
> know the Airplane guys are using the .105 without
> failures, I was just curious as to how they came
> up with the magic .105 number vs something smaller
> or larger. Was there a formula for minimum
> thickness vs wear over time or was it just "yep
> looks good"?
>
> Yes I know the pins are different on the VW
> pistons but if you are putting new pistons on
> anyway the rods will be out and can have the
> little end resized to the vw pin. But it is also
> another machining bill that will add up eventually
> and you cant go back to stock parts without
> replacing the rods.

Good Question. William Wynn is a real smart guy, but he also does not give up all his secrets... or he don't talk about them to the general public. I plant to go to Corvair College this year and pick his and other peoples brains. I spent some quality time with "real smart machinist" yesterday and I brought all my stuff. after measurements and calculations, he said the stock cylinders are as good as the replacements if they had been bored perfectly on center at the factory like Clarks' does the full-fin replacements. He said once bored (Factory workers on a production line), they follow same bore during oversizing which can cause problems with "holing out" on one side. He measured the Clarks cylinder and he said it was bored perfectly straight...the stock cylinder i carried was off to one side.

I'm sure someone will take exception with his comments. He does machine work for NHRA Top fuel stuff and some other category I didn't even recognize, so I trust his word.

Ted

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Re: 174 cu in Engine Pistons
Posted by: teddbrown ()
Date: February 20, 2015 02:26PM

Just to be clear.... Clarks Corvair already stocks the .105 overbore FF cylinder for the aircraft guys. You have to call to order. The part number is: C11628WW and the cost is 89.00 each. WW is for William Wynn. I just looked at my invoice.


Ted

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Re: 174 cu in Engine Pistons
Posted by: Mlevair ()
Date: February 21, 2015 06:51AM

I sellaftermarket rods that are corvair on the large end and vw on the small end with arp bolts to the air plane guys all the time so they can use vw style pistons in corvair cylinders.

LeVair Performance & Restoration
Michael LeVeque
Anderson,IN
765-617-9307
Mlevair@sbcglobal.net
levairperformance.com

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Re: 174 cu in Engine Pistons
Posted by: dryenko ()
Date: February 21, 2015 06:41PM

Michael, are those rods for the A or B style VW pistons ? C to C length ?

Bob C aka Dryenko
Dobson, NC 27017

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Re: 174 cu in Engine Pistons
Posted by: chris ()
Date: February 21, 2015 10:34PM

Mlevair Wrote:
-------------------------------------------------------
> I sellaftermarket rods that are corvair on the
> large end and vw on the small end with arp bolts
> to the air plane guys all the time so they can use
> vw style pistons in corvair cylinders.


Come to think of it, I thought I remember hearing about that. Nice part about that is you get new rods.

'65 Monza 4 door
4 speed
110hp
Gardner, KS

Heart of America Corvair Owners Association

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