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another throttle body size/brand question...can't find 52mm, worried 58mm is too big

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Old 10-18-2018, 12:45 PM
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another throttle body size/brand question...can't find 52mm, worried 58mm is too big

I've done a lot of research, but am getting a lot of conflicting opinions. And a lot of the info that I have found is outdated or based on equipment that isn't really available any more. So here goes..

I am building a new TPI setup for my car. I have a GM Performance Parts 350 HO crate engine (Vortec heads, 0.435/0.460, 212/222 @ 0.050"). It's nothing special - stock internals. The car has 1-3/4" headers and 3" exhaust. So far, I've gotten a Vortec TPI base and AS&M large tube runners. A realistic max HP I am looking at is 400 or so. I am having a lot of trouble finding a throttle body. I *want* a 52mm throttle body, but it seems that very few are available now. The only new one that I have found from a known manufacturer is from BBK. But there are a handful of places that still make a 58mm one. And the secondary market for 58mm ones seems a lot better. My questions are as follows:

1) Are there any new 52mm throttle bodies out there that I may be missing? Even the used ones seem to be few and far between, or they are beat up pretty bad.

2) Will a 58mm throttle body cause any issues with a mild TPI build? I realize I don't need one that large, but it opens up a few more options for me. I have read a million articles online, and can't seem to come to a conclusion on this.

Any suggestions would be great. Thanks.



Old 10-18-2018, 12:51 PM
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Re: another throttle body size/brand question...can't find 52mm, worried 58mm is too

No need for a larger tb, gms ramjet 502 uses a 48mm tb.
https://www.summitracing.com/search/...hrottle-bodies
Old 10-18-2018, 12:58 PM
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Re: another throttle body size/brand question...can't find 52mm, worried 58mm is too

I understand that, but I don't know if I want a Summit Racing throttle body.
Old 10-18-2018, 01:01 PM
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Re: another throttle body size/brand question...can't find 52mm, worried 58mm is too

Look into bbk, they use a sealed roller bearing on the throttle shaft vs a bushing. Same thing with holley but holley has a adjustable spring fo blade tension. The bbk is on the stiff side. Nothing wrong with using a 58mm but it’s just not necessary.
Old 10-18-2018, 01:10 PM
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Re: another throttle body size/brand question...can't find 52mm, worried 58mm is too

As stupid as this sounds, I don't like the look of the BBK. I have had the car for over 20 years, and have always wanted to have a TPI setup. I'm trying to keep the look as factory as possible because I have loved the look of TPI engines since the early 90's. And, to me, one of the signature parts of a TPI engine is the plate on the throttle body. I can't get that with a BBK throttle body. Again...I know that is a stupid reason, but this build is as much about keeping the nostalgic/old school look as it is the performance.

That is good to know about the benefits of the BBK one, so I appreciate it. I'll definitely keep it in the running.
Old 10-18-2018, 01:19 PM
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Re: another throttle body size/brand question...can't find 52mm, worried 58mm is too

You could always call tpis and see if they still bore and bush the stock 48 to 52mm.
arizona speed and marine and Lingenfeter all use to offer this service. Placing a ad in the classifieds wanted section here might help you locate one.you didn’t state the year of your car but there are two different linkages 85-88 and 89-92 wrap around cable. You can use the 89-92 on the earlier plenum if you change the throttle cable.
http://garage.grumpysperformance.com...52mm-58mm.546/


you might inquire about this one

https://www.thirdgen.org/forums/engi...erbroc-hi.html

or call or email this company

http://www.maxbore.com/

Last edited by Tuned Performance; 10-18-2018 at 01:36 PM.
Old 10-18-2018, 07:31 PM
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Re: another throttle body size/brand question...can't find 52mm, worried 58mm is too

Originally Posted by Z28 Boy
I've done a lot of research, but am getting a lot of conflicting opinions. And a lot of the info that I have found is outdated or based on equipment that isn't really available any more. So here goes..

I am building a new TPI setup for my car. I have a GM Performance Parts 350 HO crate engine (Vortec heads, 0.435/0.460, 212/222 @ 0.050"). It's nothing special - stock internals. The car has 1-3/4" headers and 3" exhaust. So far, I've gotten a Vortec TPI base and AS&M large tube runners. A realistic max HP I am looking at is 400 or so. I am having a lot of trouble finding a throttle body. I *want* a 52mm throttle body, but it seems that very few are available now. The only new one that I have found from a known manufacturer is from BBK. But there are a handful of places that still make a 58mm one. And the secondary market for 58mm ones seems a lot better. My questions are as follows:

1) Are there any new 52mm throttle bodies out there that I may be missing? Even the used ones seem to be few and far between, or they are beat up pretty bad.

2) Will a 58mm throttle body cause any issues with a mild TPI build? I realize I don't need one that large, but it opens up a few more options for me. I have read a million articles online, and can't seem to come to a conclusion on this.

Any suggestions would be great. Thanks.
wellright off the back. You will never see your combo hit 400hp. 270-300whp max. Instead of looking for a throttle body, you need 24lbs injectors and a tune.
Old 10-19-2018, 06:29 AM
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Re: another throttle body size/brand question...can't find 52mm, worried 58mm is too

Originally Posted by VincentZ28

wellright off the back. You will never see your combo hit 400hp. 270-300whp max. Instead of looking for a throttle body, you need 24lbs injectors and a tune.
I don't know what that has to do with my question, but thanks for the response.
Old 10-19-2018, 06:32 AM
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Re: another throttle body size/brand question...can't find 52mm, worried 58mm is too

Originally Posted by Tuned Performance
You could always call tpis and see if they still bore and bush the stock 48 to 52mm.
arizona speed and marine and Lingenfeter all use to offer this service. Placing a ad in the classifieds wanted section here might help you locate one.you didn’t state the year of your car but there are two different linkages 85-88 and 89-92 wrap around cable. You can use the 89-92 on the earlier plenum if you change the throttle cable.
http://garage.grumpysperformance.com...52mm-58mm.546/


you might inquire about this one

https://www.thirdgen.org/forums/engi...erbroc-hi.html

or call or email this company

http://www.maxbore.com/
Thanks...good point on the classifieds. The car is a '91, but I'm starting from scratch. So I can get whatever I can make work I guess. I've actually read a lot on Grumpy's page...TON of good info on there.
Old 10-19-2018, 07:33 AM
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Re: another throttle body size/brand question...can't find 52mm, worried 58mm is too

Originally Posted by Z28 Boy
I don't know what that has to do with my question, but thanks for the response.
He is trying to help you maximize the return on HP for $$$ spent.
I am with Vincent, you need injectors and a tune. A set of 1.6 Roller Rockers would also be a better place to spend the money.

What he is trying to get you to understand, the throttle body will help very minimally if at all. On a mild 350, it's basically eye candy.
Old 10-19-2018, 08:22 AM
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Re: another throttle body size/brand question...can't find 52mm, worried 58mm is too

Originally Posted by KyleF
He is trying to help you maximize the return on HP for $$$ spent.
I am with Vincent, you need injectors and a tune. A set of 1.6 Roller Rockers would also be a better place to spend the money.

What he is trying to get you to understand, the throttle body will help very minimally if at all. On a mild 350, it's basically eye candy.
I understand that - and I am, of course, planning on injectors and a tune. I never said I wasn't. That's why I didn't know what that response had to do with my question.

As I said in the OP, I'm building a new TPI setup, so I have no throttle body. I have to purchase one no matter what, so I'm looking for suggestions.
Old 10-19-2018, 09:03 AM
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Re: another throttle body size/brand question...can't find 52mm, worried 58mm is too

Originally Posted by Z28 Boy
I understand that - and I am, of course, planning on injectors and a tune. I never said I wasn't. That's why I didn't know what that response had to do with my question.

As I said in the OP, I'm building a new TPI setup, so I have no throttle body. I have to purchase one no matter what, so I'm looking for suggestions.
My advice, save the money and buy a stock unit off the boards or ebay.
Old 10-19-2018, 09:15 AM
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Re: another throttle body size/brand question...can't find 52mm, worried 58mm is too

Originally Posted by KyleF
My advice, save the money and buy a stock unit off the boards or ebay.
Thanks. I don't think I disagree with that...but the issue seems to be finding one that isn't chewed up. A lot of them (maybe even all of them) I have seen are pretty oxidized and in rough shape. I've been looking on ebay for months and months. But I'll keep looking. And I'm still open to suggestions.
Old 10-19-2018, 10:30 AM
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Re: another throttle body size/brand question...can't find 52mm, worried 58mm is too

Originally Posted by Z28 Boy
Thanks. I don't think I disagree with that...but the issue seems to be finding one that isn't chewed up. A lot of them (maybe even all of them) I have seen are pretty oxidized and in rough shape. I've been looking on ebay for months and months. But I'll keep looking. And I'm still open to suggestions.
if you are doing from scratch, you will need the TPS sensor and the IAC for the idle and the housing for the IAC that goes under the Throttle Body. Holley will be the best bet for you if you want it new. The cheaper on would be Professional Products 69701 52mm. They are about 250.
Old 10-19-2018, 10:42 AM
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Re: another throttle body size/brand question...can't find 52mm, worried 58mm is too

Larger than necessary throttle body's will make the vehicle harder to drive. Very minor throttle inputs result in huge amounts of airflow and and it becomes really "touchy" with the gas. You should use the smallest throttle body that will accommodate your planned power as it will be easier to drive.

GD
Old 10-19-2018, 10:43 AM
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Re: another throttle body size/brand question...can't find 52mm, worried 58mm is too

Originally Posted by VincentZ28

if you are doing from scratch, you will need the TPS sensor and the IAC for the idle and the housing for the IAC that goes under the Throttle Body. Holley will be the best bet for you if you want it new. The cheaper on would be Professional Products 69701 52mm. They are about 250.
Thanks for the input. I've looked at Professional Products stuff, and I don't know how I feel about them. I would like to get a Holley one, but they are only available in 58mm. They used to be available in 52mm as well, but they don't make them anymore.

I'm looking for a clean OEM one on ebay right now...I'm going to get one to see if I can clean it up, and also so I have a reference point for how the sensors and linkage came from the factory.

Within reason, I don't mind paying some extra money for one. Availability is the issue unfortunately. Which is why I am considering a 58mm even though I know it is too big for my setup...but I can order a nice new one today. Will it hurt to get one that is too big...that's the question..
Old 10-19-2018, 10:49 AM
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Re: another throttle body size/brand question...can't find 52mm, worried 58mm is too

Originally Posted by Z28 Boy
Thanks for the input. I've looked at Professional Products stuff, and I don't know how I feel about them. I would like to get a Holley one, but they are only available in 58mm. They used to be available in 52mm as well, but they don't make them anymore.

I'm looking for a clean OEM one on ebay right now...I'm going to get one to see if I can clean it up, and also so I have a reference point for how the sensors and linkage came from the factory.

Within reason, I don't mind paying some extra money for one. Availability is the issue unfortunately. Which is why I am considering a 58mm even though I know it is too big for my setup...but I can order a nice new one today. Will it hurt to get one that is too big...that's the question..
As long as you tune it, it's not going to "hurt" anything. It's just going to be even more touchy, which the TPI's already were. You lightly tap the gas on a stock TPI car that's setup right and they violently lurch forward. It's partially because of the throttle cable on the earlier ones, but it's also the large throttle body. It lets in a lot of air for very little throttle input.
Old 10-19-2018, 10:50 AM
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Re: another throttle body size/brand question...can't find 52mm, worried 58mm is too

Just get a used one, disassemble it, and glass bead blast it. Paint or clear-coat to your liking, etc. It's not difficult to make the aluminium shiny again.
Old 10-19-2018, 03:47 PM
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Re: another throttle body size/brand question...can't find 52mm, worried 58mm is too

Originally Posted by Z28 Boy
Thanks for the input. I've looked at Professional Products stuff, and I don't know how I feel about them. I would like to get a Holley one, but they are only available in 58mm. They used to be available in 52mm as well, but they don't make them anymore.

I'm looking for a clean OEM one on ebay right now...I'm going to get one to see if I can clean it up, and also so I have a reference point for how the sensors and linkage came from the factory.

Within reason, I don't mind paying some extra money for one. Availability is the issue unfortunately. Which is why I am considering a 58mm even though I know it is too big for my setup...but I can order a nice new one today. Will it hurt to get one that is too big...that's the question..
I’m using a Professional Products 52mm on my Miniram 388ci making 440whp. Don’t have a problem with it. Hell I got it free. It came on my sons car when we bought it. He has a 52mm Holley on his Holley Stealth Ram making 360whp 358ci
Old 10-19-2018, 04:10 PM
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Re: another throttle body size/brand question...can't find 52mm, worried 58mm is too

Originally Posted by VincentZ28

I’m using a Professional Products 52mm on my Miniram 388ci making 440whp. Don’t have a problem with it. Hell I got it free. It came on my sons car when we bought it. He has a 52mm Holley on his Holley Stealth Ram making 360whp 358ci
That's actually great to know that somebody is using it and having good luck with it. I'll definitely look more into it. Thanks.
Old 10-20-2018, 07:56 AM
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Re: another throttle body size/brand question...can't find 52mm, worried 58mm is too

Look into local "swap meets" if you have those in your area. I was at one a few moths back and there was more than one vendor selling tpi stuff. One guy had a complete TPI set up that was in grat shape for only $250,
Old 10-20-2018, 08:53 AM
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Re: another throttle body size/brand question...can't find 52mm, worried 58mm is too

My advice would be to find and clean a stock 48mm.

...that being said, I have a brand new Holley 58mm that I haven't really up of for sale yet, but is available. It's for an early 85-88 style throttle cable. I used it on my 89, and it worked great, BUT.....I didn't care for the throttle linkage. It was a preference issue, not performance issue. Also, Holley throttle bodies do NOT allow the use of factory throttle body plates. You have to use the HOLLEY plate that it come with. Not what I would do in your shoes, but I'd let it go for a VERY good price. Less than 50 miles on it. Hit me up if you're interested.
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