Does anyone want to know how to convert a Qjet?

[Thumpin455]

I have it down pretty good now, and I am taking pics of the latest one as I go through it. If you guys want to know how I will post it. If you dont, well that is ok too. I dont want to argue about ethanol, but I will show you how to run it with a Qjet.

[Stich496]

i like the idea and voted yes, BUT a q jets fuel bowl isn't big enough..
how are you going to open up the inlet and keep the fuel level at float level when on the hammer

[Thumpin455]

I use the small floats and drill the needle seat to .150 to .152. That seems to work pretty good for my 455. If you are trying to make more power than 450-500 then a Holley would be better. If you want a good street carb to run ethanol, the Qjet is what I would use. Right now it just has a Carter electric street pump pushing fuel from the tank, it would run out of gas at the top of first with any carb when I first built this engine. It works pretty good for a mid 13 second cruiser.

[tedly]

Where's the button for "Show us dammit!"

[SpiderGearsMan]

got a batf permit ?

[bad_language]

It just so happens I have a Q-Jets lying around...

[mlcraven]

Looking forward to following this one, I have a QJet in a box somewhere so will hunt it down and break it out.

[Ron Ward]

If it works for a Q-jet, it should work for a Thermoquad as well. Count me in.

Ron

[1trickpony]

I would like to see this. Make sure you explain it for idiots like me
And maybe talk about other modifications you would need to run ethanol (fuel pumps,line,??? I don't know)

[DanStokes]

I clicked "And show us how to make fuel, too. I figured this would include the Q-J mods. Cool Project
Dan

[Thumpin455]

got a batf permit ?

1: You dont need a permit to convert your car to run ethanol.
2: It isnt the BATF that issues them it is the TTB
3: You only need one if you are producing ethanol or ethyl alcohol, methanol does not require a tax permit
4: You can get the permit right here: http://www.ttb.gov/forms/f511074.pdf
5: Yes I have one.
6: What is it to you anyway? I suppose you want a note from my mommy next.

I guess we know who had the no vote.

[Thumpin455]

I will show the fuel production in another thread, right now I will just do the Qjet mods.

Some things you need:

Numbered drill bits. Mine came from CarQuest and they were around $80.
Pinvise. I got mine from Tower Hobbies http://www3.towerhobbies.com/cgi-bin...vise&search=Go

Highly recommended:

Cliff Ruggle's book "How to rebuild and modify Qjets" He also has some good transmission books.

http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Dstripbooks&field-keywords=cliff+ruggles&x=0&y=0

Cliff also provides very high quality rebuild kits that are 100% compatible with ethanol. All of his kits are ethanol ready, so it isnt like they are special. He also provides throttle shaft bushing kits that should be installed on any Qjet rebuild. He also has jets large enough to run E85 so you dont have to drill them.

Some of what I do is detailed in Cliffs book, and the only variables to what he does is how far we open things up. A good place to start is his full race carb recipe if you have a low compression mild engine, it will be quite close with larger jets if your engine has more than 15" of vacuum at idle.

The idea behind this is a driver so you can run the high compression engines from the 60s on E85 which is much cheaper and better for your engine than race gas. If you are building a Qjet for your street strip car, then a 3/8" line is probably all you will need, since stitch is right about high power applications needing more bowl volume. I havent found any problems with 60s, 70s, 80s, and 90s era fuel systems other than needing recalibration.

So now I am off to take some pics and drill some holes. Im doing two carbs right now, one for a friend in Texas, and one for my buddies Figure 8 car in Nebraska. Both are 455s, but one is pretty mild with a stock cam and 10:1, the other is 11:1 with a 238/242 cam in it. Just a small variance in the two.

[Darren N.]

Todd, this was hardly a question for me. YES, please show us how you re-work the Quadrajet AND how you make your fuel.

[Thumpin455]

Ok here goes. This is a starting point for an 400-470ci engine with a decent sized cam and about 11:1. The main changes you would have to make for less or more compression/cam/ci is to the idle circuits, and of course the jets. There are only a few changes from what Cliff has in his book, but I showed what I did today. It is just like rebuilding one and you modify all the same parts, it just depends on how much more fuel it needs as to how far you open things up. Sorry for the blurry pics, the camera doesnt have a macro setting.

First disassemble the carb and clean it up. I like to bead blast them gently to get the crud off. This one came from a boat so it was covered in rust and oxidized pretty bad. It might have even sat outside for a while.



This one wasnt bad since boats dont have throttle return springs and thus they dont have asymmetrical loads on the throttle shaft. Still it is going in a car and I want it to run right, so I do the bushings anyway. To do this you will need to get the kit from Cliff, it comes with a drill bit set up to self guide and open up the bores just enough to fit the bushings. First you need to grind down the bottoms of the screws that hold the throttle plates to the shaft. They stake them at the factory to keep them from falling out and killing the engine. If you dont grind off the protruding part it will break off in the shaft and then you had just as well find another one. Here they are ground off so I can unscrew them.



Then after removing the spring holding the linkage to the secondary shaft, you can pull the primary out, then you drill the bores with the special stepped bit.





I wrapped tape around it to give me a guide as to how deep to make the new bore, you dont want to go too far in.





This is plugging the main jet wells, they tend to leak and did on this one.





Now the meat.

Accelerator pump restriction. I opened it up to .046 Its where the drill bit is sticking out in this pic, kinda hard to see. Also the idle bleeds are .070, some need to be opened more, some less. Not pointed out in this pic is the booster passage, now its .040, it is on the feed side of the booster directly behind the brass nozzle. This actually made a pretty big difference in my first carb, its something I did last week and it worked. The two brass tubes coming out of this piece also get a drill, I made these .046 as well, they will richen the secondary circuits. The passages seem to flow enough fuel as they are, you just need the orifices and restrictions in the carb opened up a bit to flow more fuel.



Idle down tubes. Pull em out and drill the ends to .046. Pulling them out is described in Cliffs book, and he provides new ones in his kits. Simply you use a .090 punch to drive the inner tube down inside the collar, then you use a sheetmetal screw to grab them and yank them out with some dykes and a screwdriver as a fulcrum. This can be a huge pain in the ass, and one on the first carb gave me fits, but its out now.



Then reinstall them carefully. You can see one pressed in and the other sticking up above the housing. These are a big source of idle problems with Qjets, and they are sized to the engine specs, they are small on smaller engines, larger on larger ones. Most often they are plugged with the gunk that builds up in carbs, just cleaning them can often make a POS carb run great.



Idle mix bores. Drilled them to .106 These were of the sealed variety and I had lots of fun getting them out. If you dont do the down tube modification these will have almost no effect. With the down tubes sized right they work just like normal mix screws on a gas carb. The bigger holes make sure you can get enough fuel to let the engine idle correctly.



Drill the needle seat from the bottom to .152, use a check ball and a punch to make a new seat. Be sure to whack it on a piece of wood so you dont screw up the threads. Cliff says the windoed version flows the same as the solid version like this one, and he has new ones already at .150, so if you specify that he will include it in the kit and you wont have to drill and seat it. I forgot when I ordered it.



I drilled the jets from the bottom to .082, there were .074 before, so they should be close, maybe a bit rich. Its ok, you can get jets sized on either side of it. Currently i leave the secondary metering rods out, Im not sure we can get some small enough without turning them down on a lathe or in a drill press with a file. I know it will provide enough fuel for it, but I also know that all the stock rods I have now are way too lean. They need to be quite a bit smaller to work right, but if you can get the right sizes it should work just like normal. The best way to do final tuning is with a wideband O2, otherwise it is very difficult to read the plugs since they come out very clean without the normal discoloration.

Doing this will allow it to run on E85 and idle well. You still need to know how to tune a Qjet and what changes affect what part of operation. They have lots of adjustments and capability, that makes them more complex than a Holley or E carb, but it also makes fuel metering more precise.

[pontiacpower]

I formally request that you write a book Todd. People need to be able to access this information. This engine might get a qjet