hey guys..

got a feeling that my qjet is too small for my build:

- 455cui .030 over
- Stock Qjet 7040252: .071" jets and .043" tapered metering rods, "DA" secondary metering rods, .135" needle/seat (cliff ruggles sent me that configuration) + secondary hanger "E"
- static CR 10,25 : 1
- Edelbrock heads - intake 2.125 exhaust 1.625
- hyraulic roller cam by mark remmel 232/236@.050 on a 114 - advanced 8°, Lift is .579/.581 with 1.6 rockers.
- stock exhaust manifolds (for now) + stock toronado low rise intake
- timing as for now is 36° mechanical and 44° total


now that i installed the AEM gauge with a wideband at WOT its dropping to 10 A/F and the vac gauge shows around 5" HG


whats your opinion?

 

A later 800 cfm custom tuned Qjet would show improvement, look in Cliff Ruggles book for dyno proof. Also with the adjustable APT, more adjustable choke if converted to electric, adjustable choke pull off, the list goes on, GM did do improvements. Isn't 10 very rich for an air/fuel ratio?

 

10 is rich. The high vacuum reading at WOT is more than likely from the restrictive exhaust and not necessarily too small a carb. Most of those type tests take place on a dyno which is a much different environment then real world.
They also have a pressure test method where you can test your exhaust for restriction but I can tell you from experience that 70 Toronados aren't know for their free flowing exhaust. You have a 2 1/4" pipe at best unless you modified it.
I think you're fine but you should address the richness at WOT.

 

the qjet is already converted to e-choke and i was able to employ APT. also got cliffs book.

the exhaust system is a 2.5" dual exhaust with dynomax super turbos..but with factory downpipe and manifolds (for now)

looks like i need to start working on a set of custom headers -.-

 

Not likely, not sure how you can be pulling vacuum on the intake side when you have restriction on the exhaust side. If anything, with a cam of sufficient overlap, you'll get even worse inlet dilution. If he puts headers on it it'll most likely be worse.
Besides the carb, his most likely problem is the crappy Toro intake. Wherever the bottleneck is on the intake side is where the problem lies. I'll bet if he could put a 1" spacer on it it would bring the vacuum down.
Also with that much vacuum at wot I wouldn't be surprised if it's pulling fuel out of some of the air bleeds, resulting in his overly fat wot air/fuel.

Point of reference, most of the builds I do have either 850's or as big as 950's on them. And even with real good headers and good heads, they typically still pull over an inch of vacuum at wot.

 

461 CI x ~5500 max rpm = 2535500 x .85 (assumed) VE =2155175/3456 =624 CFMs. Your Qjet is more than capable of handling that 461. Thats if your going up to 5500rpms?

What is the base timing and vacuum signal at warm idle and how do the spark plugs "read"??

"now that i installed the AEM gauge with a wideband at WOT its dropping to 10 A/F and the vac gauge shows around 5" HG. This means the secondary side of the carb is rich".

Correct You should see little to zero HGs at WOT" But 10.0:1 AFR is rich of Stoic.

Are you having drivability problems or are you just concerned about the readings your seeing on the A/F and vac gauge?

 

i'll let you know where base timing falls (IIRC 18°) and the vac at idle (around 17" HG). maybe i shot a video for you guys so you can check what the vac gauge, tach and A/F are doing.

i do have drivability problems like lack of power at WOT and it kinda surges at part throttle. i'm also concerned that its adding some vac adv when you can't reach zero vac at WOT? its got an adjustable vac canister but i never checked the vac it needs to start advancing.

as for the plugs..i'll let you know. kinda busy this week. i checked the choke already and it works fine so the secondary air flaps will move at WOT (which they also did while reving it up while in park...so vac pull off is working)

i also found a wet spot around one of the well plugs, gonna put some epoxy on them next week.

 

Seems like your total timing is too much for a high compression motor. My best advice is to go to Cliff's website and post all your info on his contact page. Cliff is a fantastic tuner and loves solving problems, his vast experience with track and dyno work has helped me out of a number of jams. Good luck.


http://www.cliffshighperformance.com/request_form.php

 

Mark you're killing me.
Lets review:
You have a larger engine with a larger cam running through near stock exhaust, at least initially. Crappy log manifolds dumping into stock down pipes and then into larger pipes. There is no scavenging of the exhaust happening, at least in an ideal way. This alone can explain the 5 inches at WOT. You can't put 10lbs of **** into a 5lb bag to be blunt.
I agree a larger carb would show better results but most of your comparisons take place on a dyno with an engine with headers. This is not an apples to apples comparison.
I used to own a 70 Toronado with a 461 and RV cam (basically) and ported heads. It ran 14's all day long in the quarter. Took the engine and put it in a 70 Cutlass and ran mid 12's right out of the box with the only difference being headers. Of course the 800 pound difference in weight was maybe worth a second but not the two plus I gained.

Eightballz you're not under carbed but there is something wrong there if it seems to lose power at WOT. The Toronado intake tract, air cleaner, intake, etc, may not be the best but considering the W34 made 400hp with it says a lot. I think the 8* of cam advance is a little excessive but I can see why you may have gone that route in order to make the idle more manageable in such a big car.
I think you just need to go back to basics and see what's going on.

 

Doing some thinking on this problem over lunch...10.0:1 AFR indicates not enough air or too much fuel, any richer it wouldn't run. I also didnt really let the cam profile sink in.

As with any build all things need to be assembled in harmony. So even though the math shows the 750 Qjet should work there are other things to consider.

Toro intakes reportedly flow decently, but for what application...surely not a 461 high perf build with that fat azz nearly .600" lift cam. Same goes for the exhaust system. Intake, exhaust and possibly carb all too small.

In theory your problem can be related to just an undersized carb. Before going that route do a simple test. As suggested remove the exhaust manifolds and install a 2" or larger spacer under the carb and take it for a spin.

If the above test produces favorable results by the seat of your pants, low to no vac signal at WOT and the AF meter comes closer to Stoic, your heading in the right direction.

I think I see a new intake exhaust and carb in your future.

 

No, you're killing me. What you're saying doesn't make any sense. If it's because it's corked up on the exhaust side like you say, then when it's in overlap all the cylinders will be sharing that much more dirty air, thereby negating some vacuum.

Check out the dyno sheet, 468c.i. cleaned up H heads, W30 intake, Hyd roller 229/234@.050, (real close to eightballs as well) same Qjet as eightballs, W/Z manifolds blowing thru 2 1/4" pipes that were about 5' long with turbo mufflers. Pulled 1.5", not even close to 5". I think I even have the video.

It's mostly the Toro intake, thank you.

 

Once again an apple to oranges comparison. Nothing is close there. Did you supply him the cam for the Toronado?
Mark you have an agenda and frankly I'm sick of your attacks on me, including your PM's.
I'm going to agree to disagree and let you rant.

 

Just curious is the after market Toro/Motorhome intake a good improvement over the stock intake?

 

When was the last time I pm'd you?! Two years, three years?! Be honest, are you still mad at me because I critizied your cam choice and questioned why you didn't spend $100 to have your block sonic checked years ago? C'mon.

Maybe a Granny Smith to a Macintosh, but certainly not apples to oranges. Same size engine, same carb, very similar cam(yes I did his too) same ex. manifolds, an even smaller pipe size, same mufflers, DIFFERENT INTAKE.
Agree to disagree, but it's mostly the intake based on my experience.
Thank you.

 

thanks for your replies..

as far as i know the only aftermarket intake that will fit with factory qjet and filter is the rockwell intake. but unfortunately..the only improvement will be weight savings. its basically a stock replacement made out of aluminum but with bosses for EFI.

 

all right...i promised some videos..here we go:




these videos where shot after i pulled the spark plugs and fixed the missing spark plug washer on #6 (dont ask me how that thing got lost...i have no idea ). i also unplugged the vac adv so it ran only on mechanical.

you can clearly see how much vaccum the engine is pulling at WOT and that theres not a steady reading at part throttle.

i also added some pics of the leaking well plug.

let me know what you think

 

Put some JB Weld on that leaking well plug. Are those plugs a tan colour? Hard to tell on the pictures. Maybe adjust your APT a hair richer and try leaner secondary rods. Have you opened up the secondary air any amount over stock? That may add power and lean it out nicely, Cliff shows that in his book.

 

Any chance your throttle isn't opening up all the way? Just a thought.

 

Now lets see a vid with the exhaust manifolds unbolted or at least the head pipes disconnected and a large spacer added under the carb, even if you need to take off the hood. As cutlassefi points out verify WOT is actually WOT.

 

If you need to update your intake (which is likely) to something with some flow you're in for some crafty modifications. Same goes for headers. You might get away with a drop base air cleaner assembly? Not sure you can modify the engines motor mount height even a little without effecting the trans axle. You might be the first guy to do a cowl induction hood on a Toro (that Ive seen).

Or do this...

 

Yes...Jay Leno's twin turboed LSX powerd RWD 1966 Toro is a great example of how to gain hood clearance.

 

I'm thinking that the secondary rods are too fat. There is also the possibility of the throttle shaft bushings leaking air. Those are the whole reason that I quit Qjets.

 

As said, check for full throttle and check your air valve opening distance. I would think you should go on the bigger side of Cliff's specs. Also get a set CK secondary rods. I have multiple sets CV secondary rods, nearly indentical to the CK rod and nearly every 70's and 80's QJet's I have owned has had them. I would also get a G and P hanger as those two are available new.

 

maybe i try to kill my neighbours ears (i.e. driving w/o manifolds) on sunday. i'll let you know how it turned out and if i burned the inner wheel wells. i also got my old Secondary metering rods "AU" i could try.

btw i found some interesting stuff on the GMC motorhome forums. the idea is to mill the edelbrock perfomer 2151:

I turned them over on my workbench and sat them on the carb mounting surface then measured the distance from the workbench to the
front lifter valley sealing surface and the rear lifter valley sealing surface.

OEM Manifold (my guess is that this is not the correct height for a toronado intake..)
Front: 3.55 inches
Rear: 3.77 inches

Edelbrock Performer
Front: 4.50 inches
Rear: 5.60 inches

Edelbrock Performer that has had the carb mounting surface milled down reducing the height.
Front: 3.76 inches
Rear: 4.08 inches

what do you think?

 

The AU, CK and CV metering rods are nearly indentical and were on a lot of factory carbs. I bet you will see a noticeable difference. Just make sure you have full throttle and check your air valve opening distance. Remember your car is much better than stock now. I am kicking myself for not installing an O2 bung in my exhaust and running a gauge, just for this exact reason.

 

The height on a stock 455 intake is 2 3/4", a Toro intake on a 455 is 2 1/8". The Edelbrock Performer BB intake height is 4 1/2".

Just for comparison.

 

Just disconnect the head pipes at the exhaust manifolds. Easier and should produce the same effect without burning anything up.

 

here you can see the position of the secondary throttle blades at WOT. i guess i need to do some adjustments. in the second video you can see how much travel is left when the pedal is at WOT. i also need to add that i'm running a pertronix ignitor III setup (coil and module) with the delco 7mm wires. are these wires ok for now? and yes the bypass 12v wire is installed. with the voltmeter hooked up to the + side of the coil and - side on the battery i got like 13.8V

 

The secondary setup is a measurement from the air horn and iiirc it isn't exactly verticle.

I think what mark was asking was when you floor the gas pedal does the primary open fully and is it verticle?

If you have the csm there is good section in there on how the primary and secondary should be set up

 

Is the choke opening up far enough to release the secondary lockout on the air valve (top flap). It could be hanging up. I would try knocking out the roll pin and removing it completely. Make a couple runs and see if there is a difference. Good luck

 

need to fix this first with a new spark plug...hope this helps.