Author Topic: Can I use this E4M for mild 350 upgrade?  (Read 1777 times)

Offline Backfoot100

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Can I use this E4M for mild 350 upgrade?
« on: May 05, 2024, 05:13:10 PM »
Hello Gents;
New member and admitted Holley fan boy but really wanting to give a QJ a chance.
Here's the deal. '86 GMC Suburban w/350 and 700R4. Acquired 7 years ago. Engine is pretty much stock but added headers and dual exhaust.
Got Cliff's book and rebuilt the carb with one of his kits shortly after I got the ride because it needed it bad. Carb number 17085292. Been running great since then but started having the secondary air doors binding and not closing. I can look into that but not why I'm here.

Looking to do a few minor engine mods. New Brodix IK 180 heads (64 CC chambers) with a used but very clean Performer Air Gap manifold I've had laying around for several years, and a new MSD Street Fire HEI dizzy. Just looking to get a few upgrades so this thing will be able to get out of it's own way a little bit.
Keeping the stock cam for now and wanting to reuse the QJ so I can keep the stock mounting brackets for the A/C, cruise control and tranny TV cable.
Is there any chance that I can rebuild this QJ to use in this application or do I need to look at another option?

Thanks in advance for your assistance.

Offline quadrajam

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Re: Can I use this E4M for mild 350 upgrade?
« Reply #1 on: May 06, 2024, 05:47:29 PM »
Thats a good carburetor. 80s SMAB truck carb. I am running that exact same carb on my s10
with a basicaly stock 350 set-up. Love it.
You might could get by with a stock rebuild since all that is really changing is some more compression.
I cant say for sure because I've never ran a stock q-jet, always modified to the high side of
Cliffs #1 recipe.Heres how I modded mine....
idle tubes opened from .034 to .038, DCR left stock @ .057, kept the stock primary rods 52M
and jets marked 72 but measured a perfectly round .073.  Stock PP spring,  Idle screw holes opene
from .055 to.076, I think I left the idle air bypass @ .052...??.  APT up 3-1/2 turns

AS for the secondary, if your rear pull-off is working ok you can leave it be. I hate rear pull-offs
but thats me. You will however have to change those horrible DP secondary rods out for somthing
skinnier.

QJ


Offline Backfoot100

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Re: Can I use this E4M for mild 350 upgrade?
« Reply #2 on: May 07, 2024, 10:18:33 AM »
Thanks for the info QJ.
I need to get my carb tore down and look at the numbers. When I rebuilt it originally, I just kept everything bone stock and used Cliffs  rebuild kit. I didn't have any idea what I had to start with beforehand because it barely ran at all.

My next question is this.....
Mine has the mixture control solenoid on it. What did you do with that? Or do you not have it?

Offline quadrajam

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Re: Can I use this E4M for mild 350 upgrade?
« Reply #3 on: May 07, 2024, 11:18:27 AM »
I believe my carburetor was unmolested when I got it so those were factory measurements.

As for the electrica connector on top, thats not mixture control it was an emissions modification
to reduce the amount of accelerator pump shot by about half after engine cooling temp got above
170ยบ.  it's grey not blue right? If you had a wire going to it before just dont plug it in. Mostly
found on 85 and 86 truck q-jets.

QJ
 

Offline Backfoot100

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Re: Can I use this E4M for mild 350 upgrade?
« Reply #4 on: May 08, 2024, 06:09:01 AM »
Yes it's a gray electrical connector with two wires. Didn't know for sure if I could just unplug it. Hoping it could be that simple without damage to anything.

Thanks again for the info.