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Discussion Starter #1
Just placed an order for the 142 blower for a basically stock 350 that's in my 68 nova. 411 eaton posi, 700r4 animal trans. My question (for now) lies with the carb. I bought a Holley street demon about a year or two ago and it's basically new. It's the 625. Is there any way this carb would work? I've read both yes (bc it's above the pressure) and no. Holley said they would change it but wouldn't say exactly why and jegs tells me that I can use it and it will work just fine. Haha. So I've returned here to see what the expert think? Tia fellas
 

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I'm not a expert but I'll throw in my .02 cents. The 625 cfm carburetor will work but it's probably too small to be optimal. A lot will depend on the heads/ camshaft/fuel system that you are running. When you start forcing air into the engine it is going to take more fuel to keep it from leaning out. If you keep the small carburetor be careful when you start running it with the blower. You don't want to run the engine lean. To really know ask yourself this question. If you had a 500 cubic inch engine would you put the 625 CFM carburetor on it. In reality the 142 blower displaces 142 cubic inches. It makes your 350 engine think it's roughly 500 cubic inches. I would go with at least a good 750 with a milled top. If you have camshaft/heads you could probably go bigger. Just as a added note. Blower cars really like different grinds on the camshaft. When everything is put in the right place the feel of boost is very addictive.
 

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I ran an old 700 double pumper on my 355 with a 144 B&M blower for years with no issues. Nothing special done to it.
 

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Discussion Starter #4
I thought I'd have to step the carb way up too but Holley was trying to have me get a 650 and after talking to their tech and me suggesting a 750. Also my carb shouldn't let me run lean, I can jet it if need be, 625 is how much cfm the carb flows not the amount of fuel it will deliver. At least that's what I've always known to be true. Also the 350 is a stocker. Still confused if I need a "blower" carb or just my regular street demon will work since it sits on the blower and not under a power hat or anything.
 

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You don't need a blow-through carb for a top mount where there is no added pressure to the carb. With say a Vortech/procharger setup where there's a box or a bonnet you would need a blow-through.

650 seems reasonable for a stock-ish motor and with some tuning you should be okay.

We do expect some good burnout videos once you get it installed and dialed in! :devil:
 

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I have a B&M 144 with a holley 750 vs. ; works great.
The 625 might restrict boost depending on pulley rato, cam , heads etc. These small blowers don't make much boost on an engine with good flowing heads and performance cam. I'd try it and if the boost is real low lke under 4lbs maybe try a bigger carb. I'd also up the jets in the secondary a couple numbers just to be safe.
 

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Discussion Starter #9
Awesome, I'll try the 625 street demon, go up 2 on the secondaries and see how she acts. Possibly thinking about a 1" spacer the help with the vacuum of the blower messing with the power valve...would that make sense? Burnout videos will certainly be uploaded when she's all set up. Basically stock 350, stock cam,heads, with longtube headers.
 

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Discussion Starter #10
Just figured out that I can't boost reference my carb so I guess I'm going to be looking for a cheap option for a new one. Anyone have a link for a cheap boost gauge for my blower and also a cheap rev limiter??
 

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I ran the rear pv blocked on mine and never had a need for boost referencing.
 

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I had a B&M 144 on a pickup many years ago and ran a big pulley at 4-5 pounds. Pretty sure I used a Carter 600-650 just fine. Motor made like 170-185 HP before the blower and 220ish after.

I had a cut down 144 on my Type 1 VW, 1812CC and ran a 390cfm just fine.

These blowers really aren't designed for big boost. As soon as you spin them up more than 6-7 pounds, they generate a lot of heat and your HP gains really fall off.
 

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Discussion Starter #14 (Edited)
After all this I'm ordering the carb. Will build a 383 in a couple years and use it with the blower on that build too so fingers crossed it's my last one. Still want to pick y'alls brains tho. Let's talk spark plugs.... I need two levels cooler then stock to prevent detonation and I'm pretty sure non projected. Anyone have a part number on the needed plugs? Oh and have a Holley street demon for sale now if anyone is interested.lol. Great shape with only a few hundred miles on it. Loved the carb, hate to see it go
 

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Discussion Starter #15
Custom built 750 (flows 820ish) double pumper with boost reference is being mailed out Tuesday for me. Spark plug I think I can figure out, I'm running the accel 576s so I think now I need to run the accel 574s. Here's my big question, where the hell do I get my boot hookup on the weiand intake? I'm confused on this one!
 

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Is that port full manifold vacuum? It should connect up there than and you should be able to tee a boost gauge off of that. My understanding is you want it to a manifold vacuum port, below the blower, so it sees the amount of boost produced in the intake. The supercharger on my truck is fuel injected so it's a little different set-up and I'm also kinda new to the whole supercharger thing.
 

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Discussion Starter #19
I'm actually not quite sure myself. I'm thinking that is where I put the t for the carb and gage tho. The instructions say drill and tap the intake for that but idk what else that port would be for? Ahh FI would be nice! But even with me spending a pretty penny on the custom carb it was still cheaper and I'm on a budget to a point. Thanks for the reply! Hope some others with the 142 chime in! What plugs are you running?
 

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Yes you would drill and tap for it if you didn't already have a full vacuum port. I'm sure what that port's for but maybe someone else with more experience with those will confirm that. Usually with a small amount of boost you go a step colder on the plugs.
 
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