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NEED INFO: 11mm to 14mm domestic injector conversion flatbody black tops


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#1 Yokohama

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Posted 19 April 2021 - 07:29 PM

I have an 87 with the early style injectors that are both the same CC. I have seen some places selling 14mm top hats made from billet or original units machined for 14mm "domestic" units. Is this doable? Can I get 14mm injectors that will work with these and be the same cc as the stock black top units? Can I have my tophat machined by a shop?
I've also seen it mentioned here about using 14mm to 11mm adaptors and some kind of plugs meant for a RB mixer bores to adapt the domestic injectors.

Any advice I can get would be great. If anyone has done this to the early type injector setup (pre-widebody), what parts did you use (injector part #, etc.)?

I'd really like to modernize the injection system at least in terms of fuel injectors that will last.

thanks!

(Edit: I meant 86)

Edited by Yokohama, 22 April 2021 - 01:50 PM.






#2 ucw458

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Posted 20 April 2021 - 01:38 AM

Stock injectors have a wider spray pattern and work best in these cars.

87-89 uses staged injectors.  Roughly 650/1050cc.  The larger secondary injector comes on around 3k rpm.  83-86 use x2 850cc injectors that pulse at the same time.  You may have the wrong injectors.
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#3 obsolete

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Posted 20 April 2021 - 11:45 AM

Physically making modern injectors fit is not that hard. I showed how to do it here: http://www.starquest...howtopic=157354
Getting the amount of fuel that the factory computer is expecting for a given injector pulse width out of anything other than a factory injector is hard. The Trilogy/LSP aftermarket injectors (low-Z Rochester/Delphi style) are close enough that they work pretty decently most of the time, but there will be times where they're a little too lean or a little too rich. If your factory injectors are shot, the Trilogy or LSP replacement injectors are by far the easiest way to go. To really get it dialed in, you'll need some kind of aftermarket tuning device in addition to the new injectors, though.
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#4 Yokohama

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Posted 22 April 2021 - 01:41 PM

Edit: I put 87, but I meant 86. Sorry about about!

Could I get Rochester/Delphi style 850's (low z) and fit them without modifying the injectors and have the car work OK?

I don't think that Trilogy even offers 850's anymore, correct?

Edited by Yokohama, 22 April 2021 - 01:49 PM.


#5 TexasQuest

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Posted 23 April 2021 - 07:40 PM

View PostYokohama, on 22 April 2021 - 01:41 PM, said:



I don't think that Trilogy even offers 850's anymore, correct?
You can contact Trilogy to see if he can make you some.
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View PostJohnnyWadd, on 04 March 2010 - 10:01 PM, said:

my shaft was big i dont know what your talking about.

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#6 obsolete

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Posted 24 April 2021 - 08:04 AM

He is selling 850/1250 sets for 87-89 models, so I bet he could sell you two 850s: https://www.ebay.com/itm/233975529558

I agree with TexasQuest, you'll have to send him a message. Also, wow, these seem to have gotten a lot more expensive over the years...
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#7 Yokohama

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Posted 05 May 2021 - 12:34 AM

Are there other places that would modify injectors for me that have experience doing this?




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