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Getting More Air? A Hot Mod. Discuss here.

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 #221404  by 300maximilien
 
IIRC the OEM bore is around 68MM and when they grt bored out they are 70-72mm. Apparently the Holly Butterfly doesn't seal off the bore properly and a custom oval shape is needed
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 #221408  by grayslater
 
300maximilien wrote: and a custom oval shape is needed
Craig, are you saying that the butterfly is slightly oval in shape? I was starting to come to the conclusion myself from what my brother has made.
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 #221415  by 300maximilien
 
grayslater wrote:
300maximilien wrote: and a custom oval shape is needed
Craig, are you saying that the butterfly is slightly oval in shape? I was starting to come to the conclusion myself from what my brother has made.
This is what I have gathered from all the reading on the subject. Since the closed position is slightly tilted the butterfly must be slightly oval to seal. I have no hard evidence other than what people have posted across the Forums
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 #221427  by grayslater
 
300maximilien wrote:
grayslater wrote:
300maximilien wrote: and a custom oval shape is needed
Craig, are you saying that the butterfly is slightly oval in shape? I was starting to come to the conclusion myself from what my brother has made.
This is what I have gathered from all the reading on the subject. Since the closed position is slightly tilted the butterfly must be slightly oval to seal. I have no hard evidence other than what people have posted across the Forums
I guess I need to take my OEM butterfly from my extra TB and scan it in and see for myself. Let see, where can I fi that in with everything else as of late. Spring is here and I'm busy. :)
 #222919  by CaptainMorgan
 
The holley plate was the correct shape and worked fine, it just isn't available anymore and was only 70mm so you couldn't go bigger without a custom plate.

I've never tried to adjust an IAC before, so I'm not sure if you could compensate for a slight gap in the throttle plate or not. I do know that the system is designed for the plate to completely seal, and if you do that then there are no headaches.

The plate definitely needs to be slightly ovular, and the edges need to be cut to sit flush with the walls of the TB while the plate is closed.
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 #222952  by grayslater
 
I scanned in the original plate and if it's an oval it is very slight. I need to find a set of calipers and take a more specific reading.
 #222993  by CaptainMorgan
 
grayslater wrote:I scanned in the original plate and if it's an oval it is very slight. I need to find a set of calipers and take a more specific reading.
If we really can't settle this them perhaps we'll have to remove a TB at the meet and measure. I'll gladly volunteer to do it if necessary, mine is a 70mm that works perfectly. I'll bring my calipers just in case we decide to do it.
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 #223005  by grayslater
 
CaptainMorgan wrote:
grayslater wrote:I scanned in the original plate and if it's an oval it is very slight. I need to find a set of calipers and take a more specific reading.
If we really can't settle this them perhaps we'll have to remove a TB at the meet and measure. I'll gladly volunteer to do it if necessary, mine is a 70mm that works perfectly. I'll bring my calipers just in case we decide to do it.
Sure, bring the calipers and I'll bring my stock 68mm butterfly. I was talking with Tom last night and I brought up the topic. He thought that the stock 68mm was a perfect circle but that the holley 70mm had some flatened sides??

No word from my brother on the revised butterfly (not a surprise mind you) but I was kind of hoping to have this done before the meet. :roll:
 #223120  by CaptainMorgan
 
Cory it wouldn't surprise me if the factory plate was a circle. The stock TB IIRC isn't the same diameter straight through. It may be that the shape of the TB allows a circular plate at the stock diameter to close fine, but if you bore it straight through then you need the oblong plate.
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 #223127  by grayslater
 
CaptainMorgan wrote:Cory it wouldn't surprise me if the factory plate was a circle. The stock TB IIRC isn't the same diameter straight through. It may be that the shape of the TB allows a circular plate at the stock diameter to close fine, but if you bore it straight through then you need the oblong plate.
I know there is an angular section of the TB and I remember my brother telling me that he had bored it as well (at that given angle). But I see what you're saying.
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 #230739  by 300maximilien
 
grayslater wrote:
CaptainMorgan wrote:
grayslater wrote:I scanned in the original plate and if it's an oval it is very slight. I need to find a set of calipers and take a more specific reading.
If we really can't settle this them perhaps we'll have to remove a TB at the meet and measure. I'll gladly volunteer to do it if necessary, mine is a 70mm that works perfectly. I'll bring my calipers just in case we decide to do it.
Sure, bring the calipers and I'll bring my stock 68mm butterfly. I was talking with Tom last night and I brought up the topic. He thought that the stock 68mm was a perfect circle but that the holley 70mm had some flatened sides??

No word from my brother on the revised butterfly (not a surprise mind you) but I was kind of hoping to have this done before the meet. :roll:
Any new updates Cory?
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 #231105  by Brando26
 
I just visited maxbore.com and found a section saying if the butterfly is oval shaped they cannot do it. Did anyone ever check with calipers? I have an extra TB, but no calipers.
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 #231119  by grayslater
 
300maximilien wrote:Any new updates Cory?
I finally received my latest butterflies from my brother over the 4th of July weekend. After having him increase the diameter an additional .010 the butterfly still dropped in. He thought for sure that I'd have to shave/sand/grind it down to make it fit. The problem being is that it still doesn't seal well enough vertically. Once again this is a double plated butterfly that allows me some (very small amount) of travel to hopefully close the gap. But in my condition, it would appear as though the upper and lower portions of the TB are oval or egg shaped if you will. I don't know if it's that way stock or a condition of that done by my brother? The TB itself is not a straight bore but has a combination of bores. This combination of bores plus the added fact that the butterfly itself does not rest perpendicular to the main throttle bore makes me wonder of the exact shape of the butterfly needed??

It could very well be that with my brother's inexperience in the area may have given me a uniquely shaped bore?? I wasn't confident of a proper seal and did not procede forward with the installation.
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 #231146  by 300maximilien
 
Thank you for the update Cory....not good news...sorry about that.

Since I have not acquired a TB and do not have the funds available to get one or have the borejob done I would be willing to contribute to a fund that would allow someone (Paid Member) to send theirs out to MAXBORE and see what they come up with. For the sake of research for the Club.

I Pledge $20....anyone else up for this??
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 #231178  by Brando26
 
I don't have a problem supplying the tb. I actually have two.. One is perfect, the other has a chip where the wall of the throttle cable guide should be. I imagine we would use the good one. Anyone else donate a few $ for academic purposes?
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 #300541  by 300maximilien
 
I never did get one done from these guys, but there was a post here a short while back from 99mopar here that got one done.

Ah here is the thread.... http://300mclub.org/forums/viewtopic.ph ... re#p295473



And here is a pic of the Maxbore TB. Looks pretty nice to me!

Image
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 #300552  by paintballdude05
 
I'd be willing to send one in for "club research purposes". I have a couple spare 02+ 3.5 TB's kicking around.
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 #300555  by 300maximilien
 
Not sure it would be needed since 99mopar has one done pictured above.....unless you think there would be a difference in the '02+??
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 #300560  by paintballdude05
 
IRC with the pre-02 TB's you could go bigger with for some reason, that would be the only difference.