3 Movies - 6,000 RPM Nailhead, tach, q-jet and exhaust.

Thought it would be neat to share a few mpegs I took after my fortnightly tune up on 401 powered '66 Electra. They where shot using my digital still camera. The vision isn't great but at least the sound is fairly bad

I realise that it's entirely possible that my cheap tach is far from accurate but it showed a reading of 6,400rpm so I hope I'm not exagerating too much.

This one is my favourite:
I am free revving to show the secondaries opening and captured that incredible 'roar' that the Quadrajet is famous for.



Click here for the Q-jet video (1.4MB mpeg).

This one shows the tach displaying every bit of 6,000 rpm. The only mod I have done to this engine is to add the above 800cfm '76 Quadrajet which features AX rods, a B Hanger and adjusted air valve.


Click here for the Tach video (866Kb mpeg).

I'm not entirely happy with the sound in this video but it's good enough to get a rough idea of how my Electra sounds at the moment. Stock manifolds, 2 inch pipes and straight through mufflers. Sounds great cruising around town but 'raps' a bit when the revs climb.


Click here for the exhaust video (1.2MB mpeg).

 

On the secondaries....

Mine don't open quite as easily or fast...They'll open up that much if I open them by hand, but I don't believe I've gotten them that far open when free revving. Maybe I'm just afraid to throw the rpms up that much on an engine with 138000 miles on it.

BTW, I'll work on your banner tonight. I've been pretty busy lately. And of course I had to go downtown and celebrate Mardi Gras:Brow:

 

Cool videos Bill, I'm very surprised how easily the nailhead motors will rev. Cool man!:TU:

 

Adam, don't sweat the banner. I've gone this long without one so I can wait a while longer.

The secondaries were "liberated" by a little air valve tuning, you'd be surprised by the difference if you do what some of those "how to tune your quadrajet articles" will show you.

 

I've played with the air horn tension a bunch but if I get it too loose, it will bog real bad. It is at the point where the bog is gone, but it's back at stock tension. I'd rather have no bog, though. Do you think it's attributed to the fast that I only have a 350? The 455 (or 401? in your case) yould suck more air and cause the secondaries to fly open like that...theoretically. I played with them today and they only open about 3/8 of an inch when I give it full throttle. I don't leave it there long, but it doesnt looks like it's going any further even if I keep the rpms up.

I hate carburetors...but they're sooooo important to get right. Or else, your car is a piece of junk if it sucks.

 

When you tune the seconadaries to open faster you have to give all that extra some extra gas or you'll get 'the bog'. This is the engine saying "ok, you've given me all this extra air - where's the fuel to go with it?"

What secondary rods and hangers are you using? Do you have Doug Roes secondary rod and hanger chart (I might post it on BuickStreet as it's very handy. Mine are super rich AX rods and the second richest hangers ("B"). That supplies a lot of fuel to compliment all that extra air flow. Try richer rods, they have longer power tips which means that they (the power tip is the thinner part at the end of the rod) are exposed earlier which means more fuel can rush past. The power tips stick down into the jets and a fat rod will block fuel from rushing past where as the thinner tips (richer) will allow more fuel to go past. Being that all metering rods are the same length, the longer the power tip is (the skinny bit on the end) the sooner it will be exposed by any rise in the rod (as it's lifted out of the jet hole). The amount it rises is controlled by the air valve via the hanger so if you get the air valve to open quickly the rod will lift quickly. If the power tip is not exposed by this (because the fat part is still in the jet as opposed to the skinny power tip) the motor will lean out causing the bog.

Also, you might want to check out the vacuum can that allows the seconary air valve to open. There are faster ones and slower ones. With the engine switched off fully depress the vacuum can. hold, and slip your finger off and see how long it takes to fully release. Stock ones will take about 2 seconds to open but there some 'sportier' ones that will release in under 1 second. I was lucky with this carb as mine is one of those and releases quite fast. It's not immediate but it's much faster than others I have seen.

There are mods you can do but they involve drilling tiny holes in the vacuum can inlet and can be tricky if you don't have the correct tiny drills. You're best bet is to just try as many cans as you can until you find one that releases it faster which is in (or about) one second. It should not be immediate or else it won't be able to do the job and the air valve will just flop open. It should be gradual - meaning that it still works. I drove around with an allen key and a small screwdriver flooring it and pulling over, making adjustments and testing, then pulling over making more adjustments and more testing etc. It was a lot of fun - but I used a lot of gas (about 1/4 of a tank) to get it right.

 

I've got fat rods...can't remember the code, though. Where did you get your rods? Maybe I'll look around and see if I can find something close by.

Thanks for the long reply...good info there. I know what you mean by driving around with a screwdriver and allen wrench. You can definitely use some major gas if you do that for very longou:

 

Hey Bill,thats cool i like the way you did that whole thing,wanted to ask you,what do i need to get a video clip on my computer like that?any special software?let me know.

Thanks

 

Ok Bill...

I found this:

http://www.carbs.net/rodshang.asp

What would you recommend as replacement rods for me? I think my current ones are C(?). Also, what hanger would work best?
I see AY, would those be close to your AX rods?

 

You've got a big heavy car like I do Adam so I would say that if the AX rod and a B hanger work well well for me they would be close for you. Things to remember would be that I live in a moderate climate at very close to see level or at most a couple of hundered feet above and that I'm fairly aggressive with the throttle (I'm finding it harder and harder to come up with ways not say "I'm a thrasher" but I really love to floor it regularly).

Try and find out exactly what sort of rods you have and then we can compare. It's fairly easy to find out. Just unscrew the hanger (one screw) and CAREFULLY remove and replace the rods.

There is a table at http://www.hioutput.com/tech/qjetrod.html which is quite good. Also, remember that you can physically bend your hanger to achieve changers. The only difference in hangers is where the hole that the secondary metering rods hang from sits. A higher hole holds the rods closer to to the power tips and therefore they will be exposed earlier. Adjustment of these hangers is explained by Randy Frazier in his well copied article called "Quadrajet Tech" like this...

The entire article is a mandatory read for everyone who wants to play with the quadrajet and can be found at http://www.geocities.com/gtopercy/Pictures/quadrajetTech.html as well as many other places.

There is also a fairly large bad scan of the doug roe metering rd chart at http://www.netspace.net.au/~peterpam/secd.htm (230kb) which I think is from Doug Roe's book.

The best part about tuning the secondary performance on a quadrajet is that it can be done using only one screwdriver so it's pretty easy.

One last thing to note is that my AX rods are so thin on the power tips that I could easily pierce my skin with them - they are that thin. Big difference from the stock rods I removed which where so fat I doubt I could pierce an apple. I should take a photo comparing the two which I might tonight and post here.

 

CZ is what mine are...big fat ones.

I am thinking about going with CC rods with a B hanger. The charts saysthat my CZ rods should NEVER be used for performance:grin: These things are like unsharpened pencils.

 

Whoa! CZ's! You need to unblock that baby and get a higher hanger or modify that one. You will be surprised at the difference. Don't even wait to get home. Replace those suckers in the car park as soon as you buy them and you will feel mucho difference straight away. Then later when everyone's asleep you can out and do the torch in mouth, one hand on the allen key, one hand holding back the linkage while the third hand adjusts the spring back a little at a time. 1/8 of a turn is all you need to make a difference. You should be able to freely swing that air valve whithout feeling too much spring resistance but make sure that it closes fully when allowed to by itself. Have you checked that it (the secondary air valve flap) opens all the way to 90 degrees?

 

Yes I have filed the stop down until it opens to 90*.

Yeah it's real fun trying to adjust that stupid air horn while it's on the car. sometimes I want to just rip the linkage off.

So what do you think about the CC rods? I want to just order them from carbs unlimited instead of hunting around for them like a chipmunk. Also, hanger size...I'm thinking B. N is on it now. This thing is a smogger and you can tell.

 

CC's with a B hanger should really liven the 'ol girl up. I can guarantee it! Can't wait to hear the results. What timing are you running? You upgraded to HEI yet? How is your air valve vacuum release cannister, fast (1 second or less) or the standard 2 second variety?

You know, my carb was manufactured in '75 and was a replacement for a 76-79 Pontiac big block. That is smack bang in the middle of smogsville and yet it has responded to all the tricks. I even discovered that it has the large needle and seat which was a real bonus.

 

My carb was a 76 model for Buick...but the 800cfm variety:bglasses:

I have the 2 second wonder canister. This is on my Lesabre, which I am selling, but I want to make the changes on my Centurion as well. The Centurion has the stock 71 qjet which was also 800cfm. The timing on the Lesabre is about 12*. That's as far as she goes w/o pinging. The timing chain is a bit stretched, so it has a tendency to backfire every once in a while. That's rare, though. When it's warm, it's ok. I leaned out the fuel mixture a little yesterday and I drove it to the city last night. When I got home, it was purring liek a kitten...kind of like what it did before I started screwing with it:grin:

But yeah, I'll go ahead and order a couple sets of rods and hangers. Did you get my PM on the banner?

 

George, what sort of camera do you have again? What sort of files does it make? AVI, MOV or MPEG?

My camera produces AVI's but media player won't play them (FinePix viewer will, it's the software that came with the camera). I found out that Apple Quicktime will play the AVIS' as they come from the camera. I then edit the movie to eliminate any extra footage that isn't required and export it as an AVI. I then use a little program that converts the Quicktime AVI's to mpegs and the size is much smaller but the quality remains the same. It took me all night to work it out but now it's FIGJAM all the way.

 

Yes, I got the PM on the banner but I'm at work (shhh) so I've spent all my 'free' time responding to this thead. I had a look and it looks great. I'll have to find an old gif animator program I think I have Corell gif animator but I couldn't be bothered starting from scratch. I like what you've done and like the idea that I can add the cars as the site progresses. I'll probably host it on my site and pass the link around. Great work bud. You are The Man.

 

One more thing....

I have the PSD format of the file if you want it. It might come in handy if you want to edit it. I used Adobe ImageReady 7 to animate it.

Here is the link to the psd.

HERE

 

Another cheap Qjet trick

I have an old GSXTRA article that talked about the above, and added a little trick. It has a diagram of how to put a little taper on the ends of the metering rods. I tried it out on my '70, and thought I'd test it on the street. The tires went up in smoke, and it took a while to relearn how to launch it. I finally went to 15's with 275's. Whole lotta fun. Dan

 

Dan, don't tease. Tell us how, what, where, I have a spare set of AX rods I'm willing to experiment with. Got a copy of the diagram or the article?

Adam, thanks, I'll download it when I get home tonight. Well done. All I need is a bit of inspiration and I'll take it from there. Not much of an artist myself but I like to edit.