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quadrajet tuning for e85 #4020026
02/23/16 08:12 PM
02/23/16 08:12 PM
Joined: Dec 2013
Posts: 3,686
Massachusetts
turtlevette Offline OP
turtlevette  Offline OP
Joined: Dec 2013
Posts: 3,686
Massachusetts
I've been opening up my QJs to clean and check jetting. I'm thinking of a strategy to run fat in the primary but still lean for e85 say about halfway in the middle, then complete the final tuning with the secondary metering.

The reasoning is that the carb has to be completely disassembled to get to the primary jets but the secondary metering rods are very easy to swap. They're on a hanger secured by one screw right on top. I can do it in under a minute. I'm an expert on these things.

So I'll swap secondary metering rods based on whether I'm running e10 or e85.


So hopefully we can build a thread to help each other on this. I'll be playing with it all this spring and summer and will update this thread as I learn things. I have a wideband a/f monitor and will be swapping it between the Trans Am and Corvette. Heck I might even do my 84 suburban and jet boat too. From my research you want 9:1 on alcohol rather than 14:1 and those figures are lower under acceleration.

No politics. This is about true enthusiasts using poor man's race fuel. That's it.

The ta has been running poorly since I acquired it popping thru the carb and accelerating poorly. I found 51p primary rods with 72 jets. Someone must have messed this up as it's way lean. I calculated it needs 78 jets for gas. So I ordered 79 to start then 81 and 83 jets for the e85 tune. I'm trying to collect secondary rods but they're expensive. I'm keeping an eye for used ones on eBay.




Last edited by turtlevette; 02/23/16 08:21 PM.

USA-1
Re: quadrajet tuning for e85 [Re: turtlevette] #4020039
02/23/16 08:21 PM
02/23/16 08:21 PM
Joined: Oct 2004
Posts: 7,975
Cincinnati, OH, USA
bullwinkle Offline
bullwinkle  Offline
Joined: Oct 2004
Posts: 7,975
Cincinnati, OH, USA
Is there a metal float & E85 resistant parts available? Back in the day when I ran Q-jets, even E10 caused damage, requiring a rebuild every couple years.


06 Ram 3500 CTD 4X4(FG Venturi), 93 GMC C3500 6.2, 89 F-450 7.3, 98 XJ 4.0(XG8A), 05 xB(XG3600), 18 Transit 3.7, 03 Merc Grand Marquis 4.6 2V(XG2)
Re: quadrajet tuning for e85 [Re: turtlevette] #4020069
02/23/16 08:40 PM
02/23/16 08:40 PM
Joined: Jan 2007
Posts: 17,501
Clovis, CA
Merkava_4 Offline
Merkava_4  Offline
Joined: Jan 2007
Posts: 17,501
Clovis, CA
I used to have problems with the E85 drying out the accelerator pump plunger.

You gotta drive the role pin out and then take the bowl cover off to get the accelerator pump out.

Re: quadrajet tuning for e85 [Re: bullwinkle] #4020086
02/23/16 08:50 PM
02/23/16 08:50 PM
Joined: Dec 2013
Posts: 3,686
Massachusetts
turtlevette Offline OP
turtlevette  Offline OP
Joined: Dec 2013
Posts: 3,686
Massachusetts
I have several cellulose (nitrophyl) floats I can experiment with. The one in the vette has been submerged in e10 for 20+ years. And I've run a few tanks of e85 thru with no problems. I'm not worried about corrosion at all. I just picked up a nice 79 qj for 10 bucks so even if I destroy a carb, its no biggie.

They make the blue accelerator pump seal now that is alcohol proof. The ta already had it and I put one in the vette years ago.



Last edited by turtlevette; 02/23/16 09:03 PM.

USA-1
Re: quadrajet tuning for e85 [Re: turtlevette] #4020138
02/23/16 09:45 PM
02/23/16 09:45 PM
Joined: Oct 2014
Posts: 1,648
SANTOS, BR
Pontual Offline
Pontual  Offline
Joined: Oct 2014
Posts: 1,648
SANTOS, BR
Plastic float is appropiate. And you need to rake the mains out to get 30 to 40% more flow with the same depression.

Re: quadrajet tuning for e85 [Re: turtlevette] #4020153
02/23/16 09:56 PM
02/23/16 09:56 PM
Joined: Mar 2013
Posts: 775
NY
joegreen Offline
joegreen  Offline
Joined: Mar 2013
Posts: 775
NY
I am a fan of the quadrajet. Looking forward to updates. I was running a quadrajet on my 78 until I swapped to tbi.

Last edited by joegreen; 02/23/16 09:57 PM.

1978 Chevrolet k20
Engine: Delo 10w30xle
Transmission: Castrol transmax dex/merc

1984 Mercedes-Benz 300 turbo diesel
Engine: Delo 400 15w40le
Re: quadrajet tuning for e85 [Re: Pontual] #4020154
02/23/16 09:57 PM
02/23/16 09:57 PM
Joined: Dec 2013
Posts: 3,686
Massachusetts
turtlevette Offline OP
turtlevette  Offline OP
Joined: Dec 2013
Posts: 3,686
Massachusetts
Originally Posted By: Pontual
Plastic float is appropiate. And you need to rake the mains out to get 30 to 40% more flow with the same depression.


I don't think it'll be that much but I'll know for sure when I start tuning. The Corvette actually ran acceptably on e85 with no jetting changes. No lean backfire no bucking and half decent part throttle acceleration. I'm thinking it'll be half of that.


USA-1
Re: quadrajet tuning for e85 [Re: turtlevette] #4020306
02/24/16 06:07 AM
02/24/16 06:07 AM
Joined: Dec 2002
Posts: 40,884
'Stralia
Shannow Offline
Shannow  Offline
Joined: Dec 2002
Posts: 40,884
'Stralia
turtlevette,
my thesis was on flow of air and fuel in an inlet manifold...convinced my workplace supervisor that it was analogous to PF flow in a burner, which meant I could keep my cadetship...

Anyway, using gas, about 10-15% minimum of the fuel ran as a trickle along the manifold floor, at around 10% of the mean speed of the air velocity...snap the throttle open, and that fuel got washed straight into the cylinder and everything went lean until the next equilibrium state was accomplished, and it did once the slow moving fuel film got back to the end of the runner.

Problem with the 70s V-8s is that fuel/air distribution is whacked...the process that I described above, in a dual plane manifold, with variable length/hydraulic diameter/everything runners can have individual cylinders running lean misfire, while another is wildly rich...throw in a transient and stored fuel (capacitance ???) can reverse that, and the new equilibrium can change the lean/rich cylinders.

Can bypass all of that with vaporisation.

And from reading your posts re the Transam, I don't see that you are chasing 12:1 compression and 800hp (made up numbers).

Does the T/A have an intake "warmer" like a lot of the 70s cars had ?

Surely would have EGR.

I'll describe a car that I had in the '90s, a Holden HZ wagon, with 253c.i. V-8 and auto...previous owner had ditched the thermostat, so it had massive valve guide wear (1mm movement of valve head when the unworn stem was in the guide area), and a huge ridge at the top of the bore, numbers 1 and 2 being worst. The cold coolant stopped the additives in the oil forming the tribofilm, and the cast iron wore out.

Replaced the heads, manifold, and carb with a Q-Jet and later series heads, yep 800cfm on 253 inches. Holden did that in the early 80s, to rationalise parts

253 was a rubbish engine, the heads were for a 4" bore, and had overlap on the 3.625" bore.

Anyway...

After messing around with it for a bit, I had.
* Thermostat on the inlet of the water pump (sent that part to Gary Allan RIP)
* The air intake controller rigged up to vacuum with no compensator (the bimetallic strip)...vacuum, full heat, no vacuum, cold air.
* PCV (and there was a lot from the poor ring seal) was routed through a 1/2" (copper, poor choice) pipe wrapped around the exhaust manifold, and covered in kaowool (1990s asbestos)...lead into the standard central PCV port on the Q jet.
* I drilled the EGR valve with an 1/8" bit so that there was EGR at all times, maximum when at high vacuum obviously, only a little at WOT.
* ported the Vac advance to full vac advance at idle, rather than off idle Vac advance.

Results...
* ran out of idle speed adjustment
* used mixture control screws to control idle speed (lots of hot air, and the hot PCV, and the hot EGR meant that the fuel wasn't pooling, it was vapor and didn't play lean misfire until I was really lean at idle).
* had fuse wire inserted in the primary jets (same reason as above).
* IIRC (and this was fuzzy), I strengthened the springs on the secondary flaps to increase the vacuum response on the secondaries and artificially richen them up a tad at W.O.T (I spent a lot of time playing S.U. carbs before I bought a V-8).

I ended up with a machine that would do 30MPG (British), when 22MPG was standard tune, but was an absolute cow to start and run cold.

Pinging was non existant in light running or full W.O.T., but there was a fair bit of knock just at the point that you committed to overtaking.

Pontual can probably confirm how far you can lean an appropriately designed aircraft engine out in steady state (Google Lindburg and the P38).

If you can keep the T/A in vapour phase, you aren't really all that lean

Re: quadrajet tuning for e85 [Re: Shannow] #4020309
02/24/16 06:13 AM
02/24/16 06:13 AM
Joined: Dec 2002
Posts: 40,884
'Stralia
Shannow Offline
Shannow  Offline
Joined: Dec 2002
Posts: 40,884
'Stralia
Just for whoops and giggles, here's a couple of pics from my thesis...all air and fuel adjusted to stoichiometric on the test rig.

Part throttle


W.O.T


Variance in Fuel film speed versus mean air speed at multiple throttle openings.



Imagine that fuel as vapor...

Re: quadrajet tuning for e85 [Re: Shannow] #4020652
02/24/16 01:55 PM
02/24/16 01:55 PM
Joined: Dec 2013
Posts: 3,686
Massachusetts
turtlevette Offline OP
turtlevette  Offline OP
Joined: Dec 2013
Posts: 3,686
Massachusetts
I had to read thru that 4 times before I started to get it. I'd love to look thru the whole thing if its OK. You've got my email. The vette has junkyard 86 tpi aluminum heads so there is no port to the manifold for an exhaust heat crossover and making egr non functional. So I would suspect vaporization/atomization is poor. The Pontiac is stock. I'm going to put an egr block off plate on the ta as I suspect a vacuum leak is coming from there.

The QJ with the massive secondaries favors fuel flow to the rear cylinders under wot and front cylinders during normal cruise. There is a trick in Doug Roes book to make the throttle plate open more than 90 degrees to direct some flow back to the front.

Actually the biggest driveability issue on e85 with the vette is getting it to idle nicely. The later QJ has idle air tubes that prevents a rich idle mixture. There is a way to either drill out the fuel passage or restrict the idle airtube to get rich mixes. With the manual on the ta, if it idles at 1500 rpm who cares? Keeps me from stalling it.

I did a gas tank swap on the vette a few years ago and the rubber liner was absolutely perfect after 40 years of e10 fuel. The tank was starting to rust thru in spots from the outside.


USA-1
Re: quadrajet tuning for e85 [Re: turtlevette] #4021364
02/25/16 11:33 AM
02/25/16 11:33 AM
Joined: Oct 2014
Posts: 1,648
SANTOS, BR
Pontual Offline
Pontual  Offline
Joined: Oct 2014
Posts: 1,648
SANTOS, BR
Originally Posted By: turtlevette
Originally Posted By: Pontual
Plastic float is appropiate. And you need to rake the mains out to get 30 to 40% more flow with the same depression.


I don't think it'll be that much but I'll know for sure when I start tuning. The Corvette actually ran acceptably on e85 with no jetting changes. No lean backfire no bucking and half decent part throttle acceleration. I'm thinking it'll be half of that.




Well, from my experience, and applicable literature if you dont raise the CR, you gonna get about 30 to 40 percent more consumption in a sports appli ation, because of lower BTU, leading to lower efficiency. You can recover efficiency by raising the CR, running colder plugs and retarding a little the ignition timing, sice higher ethanol content fuel have a quicker speed flame. Now if you guys had hydrated ethanol, it could be worst in consumption, but the maneuver for raising CR is even better to offset losses. The issue is around the CR. As you didnt mention raising it, the consumption could go to the ceiling at 30% to 40%, garanteed.

Re: quadrajet tuning for e85 [Re: Shannow] #4021375
02/25/16 11:43 AM
02/25/16 11:43 AM
Joined: Oct 2014
Posts: 1,648
SANTOS, BR
Pontual Offline
Pontual  Offline
Joined: Oct 2014
Posts: 1,648
SANTOS, BR
Originally Posted By: Shannow
turtlevette,

Pontual can probably confirm how far you can lean an appropriately designed aircraft engine out in steady state (Google Lindburg and the P38).

If you can keep the T/A in vapour phase, you aren't really all that lean


Yes, you can go lean, all the way to rough running, when at or below 75% power, or you'll spike the EGT ... and ruin the piston crown if you do agressive leaning at WOT...

Now the rough running issue, is directly dependant on evenly mixture distribution balanciation. The more even feeding is the admission, the leaner you can go, without missfiring a cylinder before the others. If unbalanced the manifold run of the mixture at certain rpms, the leaning (below 75% output) makes rough running, earlier.
But thats fuel conservation focused, obviously not performance focused.

Re: quadrajet tuning for e85 [Re: Pontual] #4021479
02/25/16 01:52 PM
02/25/16 01:52 PM
Joined: Dec 2013
Posts: 3,686
Massachusetts
turtlevette Offline OP
turtlevette  Offline OP
Joined: Dec 2013
Posts: 3,686
Massachusetts
Originally Posted By: Pontual
Originally Posted By: turtlevette
Originally Posted By: Pontual
Plastic float is appropiate. And you need to rake the mains out to get 30 to 40% more flow with the same depression.


I don't think it'll be that much but I'll know for sure when I start tuning. The Corvette actually ran acceptably on e85 with no jetting changes. No lean backfire no bucking and half decent part throttle acceleration. I'm thinking it'll be half of that.




Well, from my experience, and applicable literature if you dont raise the CR, you gonna get about 30 to 40 percent more consumption in a sports appli ation, because of lower BTU,


I don't think it follows BTU content exactly. I feel if I go 15% richer I'll be at a place where drivability is acceptable to me. I'm not shooting for lowest drag racing et. And the corvette again, has run just fine without touching anything. I went Boston to Albany on a tank of gas and came back on a tank of e85. I believe all the negativity about mileage loss and jetting concerns are way overblown.

If I stroke the 301 from a 3" crank to a 3.75 or 4, that'll raise my compression hugely. The vette has the tiny 58 cc heads that have been shaved a few times so I'm already around 11:1

And I really dont care if I blow either of these engines up. I have a rodeck 350+ aluminum sb1 block in storage that's just itching for a home.







USA-1
Re: quadrajet tuning for e85 [Re: turtlevette] #4021500
02/25/16 02:30 PM
02/25/16 02:30 PM
Joined: Oct 2014
Posts: 1,648
SANTOS, BR
Pontual Offline
Pontual  Offline
Joined: Oct 2014
Posts: 1,648
SANTOS, BR
Uuright...

Re: quadrajet tuning for e85 [Re: Pontual] #4029058
03/04/16 02:18 PM
03/04/16 02:18 PM
Joined: Dec 2013
Posts: 3,686
Massachusetts
turtlevette Offline OP
turtlevette  Offline OP
Joined: Dec 2013
Posts: 3,686
Massachusetts
Originally Posted By: Pontual
Yes, you can go lean, all the way to rough running, when at or below 75% power, or you'll spike the EGT ... and ruin the piston crown if you do agressive leaning at WOT...



That's right in line with my philosophy. Lean on primary side (cruise and part throttle) and make up for it when the big bores open.


USA-1
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