Holley Throttle Body Component Part Numbers

T

Tom Katzenberger

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Jun 26, 2019
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Guys,

I have a Howell EFI with the Holley Throttle body purchased from Applied about 5 years ago. Does anyone have the part numbers for the components on the Holley throttle body, (IAC, TPS, Injectors, etc.)?

I'm planning a cross country trip and want to prepare for the unexpected. I am the only one with a Howell EFI with EBL and I am trying to put together an EFI parts travel kit.

It appears Holley uses a Chrysler IAC and possibly a GM TPS. I have no clue on the injectors?

Thanks to any one who can assist.

Everyone take care and stay healthy,
Tom K.
 
Most people with the EBL started with a Howell EFI kit. They ordered the EBL already installed into a 7747 ECM and kept the Howell ECM as a spare.

When I was looking for the 80pph injectors to fit my Holley TB, I found the injectors were Holley proprietary and all I could get was the 60pph. As you can see in this link, they now rate that injector at 60pph @ 12psi and 85pph at 21psi. When I got my Holley kit and one of the first with the small injectors, Holley would not tell me the PPH rating of the injectors.

I did get a replacement IAC, but I don't recall if I got it from Howell, or found an identical part. I think I messed up that IAC while trying to figure out my my Howell kit was running so poorly... which turned out to be that Holley changed to 60pph injectors while our application and Howell's ECM was requiring 80pph injectors.

This appears to be the TPS.

I now run a Rochester TB with 80pph injectors. I carry one spare injector only because the TB I bought on Ebay had one faulty injector, so I installed two new ones and kept the good one as a spare.

Instead of buying expensive Holley parts, why not put that money towards getting a Rochester TB with the correct 80pph injectors. Parts are readily available at a much lower cost. I think I paid less than $50 each for the inectors for the Rochester from Rock-auto (but that was over 10 years ago)
 
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If you want the 80pph injectors all you have to do is swap a GM Rochester Injector pod on the Holey TBI unit. Yes, it will take some work with a grinder or a Dremel. All you need is an injector pod, injectors, injector connectors and a base gasket for a 7.4 TBI. Best to get the rebuild kit. I believe I saw a U tube video on it.
 
Thanks guys,

I do want to go in the direction Bruce is talking about for the reasons Bruce states. I will start the hunt for the throttle body. What years and vehicles may have the desired throttle body? I may have to go way back on the Birdfeeder to when the guys were fabricating EFI systems themselves before Howell.

Bruce, do you know what components I will need for the conversion back to a Rochester TB from the Holley? Are their any software issues or concerns or can I just swap them out.

Thanks again,
Tom K.
 
Tom Katzenberger said:
Thanks guys,

I do want to go in the direction Bruce is talking about for the reasons Bruce states. I will start the hunt for the throttle body. What years and vehicles may have the desired throttle body? I may have to go way back on the Birdfeeder to when the guys were fabricating EFI systems themselves before Howell.

Bruce, do you know what components I will need for the conversion back to a Rochester TB from the Holley? Are their any software issues or concerns or can I just swap them out.

Thanks again,
Tom K.
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You will be looking for a 1988-1994 7.4L GM truck. Plan on having the throttle body re bushed as the throttle shaft will be worn. and will be lose. Just plug and play, but the injector harness and TPS harness will need adapters as they are different connector and pins.
 
There are a lot of junk motorhomes rotting away with 454 engines sitting in them. That's where I got my ECM, ESC and throttle body. I got some harness bits and some other sensors, but much of it was already cut up for some reason.
 
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Like Biggamehunter said, the connectors are different between the Rochester and the Holley. Even on different years of Rochester TB they can be different. If you can get pigtails of the connectors with the Rochester you buying that would be great. The Holley connectors are common weatherpak connectors that are easy to find.
 
Thank you everyone for the hot tips. Todd , i'm going to go through the winter and see if I can find the exact one that I was needed. I appreciate everyone's input very helpful
 
If you cannot fine what you are looking for, you can put a GM pod on the Holley. The only thing to change is the injector connectors. Those are all the same for all GM trucks that used TBI.
 
Thank you Biggamehunter.

Todd Snyder gave me a lead on a throttle body close to home. I am waiting for a response in ref to the model number.

Everyone have a great evening.
Tom K.
 
tmsnyder said:
I have one off a 5.7L, the bores are slightly smaller than the 7.4L , you are welcome to it. There is a company, I believe that will bore it out to the larger size, yours if you want it!

Some place like this: https://www.sprperformance.com/services-1
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To clarify, and this is from memory...

Stock SBC bores are 42mm and can be bored out to 46mm, while stock BBC bores are 50mm and can be bored out to 54mm. I don't think I'd try to adapt the 5.7 TBI onto the 455 for my GMC. Maybe my Toronado though.
 
pvfjr said:
To clarify, and this is from memory...

Stock SBC bores are 42mm and can be bored out to 46mm, while stock BBC bores are 50mm and can be bored out to 54mm. I don't think I'd try to adapt the 5.7 TBI onto the 455 for my GMC. Maybe my Toronado though.
Click to expand...

You think that 46mm vs 50mm bore is going to be noticeable on a 455 running the rpms we run?
 
+1 on tossing the Holley. I could never get the tune quite right. I found a Rochester locally from a reliable source, hosed it off with carb cleaner and installed it, reloaded the "stock" 455 tune, and it was nearly perfect. I had to make no tweaks, although I did only because I could!
 
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RF_Burns said:
I'm guessing that would be just like running about 90% of wide open throttle at WOT.
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I almost never run WOT, II avoid it.
Hard to believe it would matter now that I think about it.
I wonder if youd even need bigger injectors

Maybe get slightly better MPG? Probably not since it's EFI
 
tmsnyder said:
For the $250 price of opening up the small block TBI he would be better off putting that money toward the 7.4L version.
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My thoughts exactly. That's why I'm not comparing 46mm to 50mm--a 46mm is going to cost more than a 50mm anyway. I got my 454 TBI for $100. If I was going to invest $250 extra to bore one out, I could bore out the BBC TBI to go with 54mm (now THAT I don't find necessary for my application). So dollar for dollar, I'd be better off comparing 46mm to 54mm, or comparing 42mm to 50mm. There's a 30% difference in cross sectional area there. It'd be hard for me to upgrade a bunch of stuff on my motor and then take a huge step down in breathability from the old Quadrajet to the 2-barrel SBC TBI.

It won't make a difference when I'm cruising, but downshifting to climb a hill with a different cam, headers, air intake and 3" exhaust? Well, I hope it makes a difference. Chevy thought the 42mm was sufficient for everything except their trucks/motorhomes with the 454 (I'm ignoring the handfuls of SS cars here). They weren't building race motors, but rather, they were building workhorses. If they thought it was necessary to make a whole different throttle body for the big blocks, I can only assume they were right.

Granted, finding a 454 TBI for the price of a 350 TBI takes a lot more looking. But there are definitely junk P30 motorhomes getting scrapped every day in this country that have these TBIs with 60k miles on them. It's sad how many fall into disrepair and get scrapped out.
 
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