Before/After Black racing - learned a few things.

[b4black]

I've been meaning to post this for sometime. It's 103°F outside, so I I just found some time.

I have too many project cars, so my '83 T Type basically only comes out of the garage to do some bracket racing with a Chicagoland GSCA Club a few times a year. And since it is bracket racing, I can't mess (aka tune) with it too much. First time this year we took both cars. My girlfriend races my '02 GS and I drive the '83. First run of the day.....(GS left, T Type right)

Best times for each car! The T Type ran very strong all day, but did slow a little as the day warmed up. Several others runs were in the 14.2's. Best day ever with the car.

I usually run 100 unleaded race gas, but the local station quit carrying it, so this was on 112 leaded. It still knocked some. About 5 leds will light up randomly on the Casper's gauge (it's always done that). Boost would briefly get to 19 psi, but most of the time, it's somewhere below that. (The wastegate isn't opening - I should go back to the stock turbo for now.) I later found out the alcohol injection had become disconnected over the winter. I know I run too rich and I have been trying to dial back the alcohol anyway. Without any, the car leaned up some and ran strong - and consistent. I made it to the semi-finals before the rain came.

The GS by the way runs on 93 pump gas, has an intercooler and 3.2 pulley. Scan tool showeds zero knock, so now it has a 2.9 pulley, and I ran a 14.02 in the heat last weekend. The pulley is about all that I change on this car. Easy!

And that is the approach I am going to take with the '83 for now. Leave the alcohol disconnected, run just 93 pump gas, leave the carb alone, dial back the boost, don't pull any timing with the MSD, and get rid of all the knock. Then gradually work my way back up. One thing at a time. No more juggle alcohol, boost, timing, A/F, octane, etc.


I also put a wide band O2 sensor in. Even without the alcohol, it's very rich - 10 to 11 A/F at times. At 9 psi, it still knocks some. So I disconnected the wastegate and left it open. Still knocks. It's not false knock. It seems to happen just as the secondaries open. I need to do some more driving around to confirm.

I'll keep everyone posted on what I find out. It might be a little while though before I can get at it again. The starter solenoid needed a whack the other day to get going, so I need to fix that before venturing out again.

 

[MNcarbturbo]

Not bad times for it being that hot! On both cars.

 

[charlief1]

If you are interested I've got some info from the 301T guys that might help you Rich. Kevin has been having some issues running rich but has got it pretty much figured out. The secondaries accellerator holes need to be opened up some and I'd bet that the spring pressure is off a little.

 

[canadian nascar]

If you are interested I've got some info from the 301T guys that might help you Rich. Kevin has been having some issues running rich but has got it pretty much figured out. The secondaries accellerator holes need to be opened up some and I'd bet that the spring pressure is off a little.

Hey guys,

How big can the secondary accellerator holes be opened?

the intake brass rods in the carb that support the secondary accellerator holes are .09"
mine were .055 now they are .07 of an inch, the spring is about 1/2 a turn tight and still a little lean bog.

getting 4 sets of secondary rods next week to lean it up

later Kevin

 

[charlief1]

Hey guys,

How big can the secondary accellerator holes be opened?

the intake brass rods in the carb that support the secondary accellerator holes are .09"
mine were .055 now they are .07 of an inch, the spring is about 1/2 a turn tight and still a little lean bog.

getting 4 sets of secondary rods next week to lean it up

later Kevin

Tighten the spring up slightly Kevin. Go to something like 5/8 turn and see how it does before drilling the holes bigger. This is where you have to go slow with a mix of procedures. Set the spring tension first to see how it does and if you don't get results like you want then drill the holes larger. The timing of the secondaries have to be fully explored before going to larger holes in the carb. You can get a bog from the secondaries opening to quick or to slow and that's what you've got to do first.

 

[MNcarbturbo]

S0 should the secondary air valve actually be tightned up and not loosened? I Loosened mine up, didnt notice anything.

 

[b4black]

If you are interested I've got some info from the 301T guys that might help you Rich. Kevin has been having some issues running rich but has got it pretty much figured out. The secondaries accellerator holes need to be opened up some and I'd bet that the spring pressure is off a little.

The problem is not running rich. That can be dealt with by changing the secondary rods. The problem is knock (even at low boost and very rich) so something else is going on. I believe I might have a lean issue when the secondaries open up causing the knock. But I want to confirm that first. I need to figure out what the problem is before randomly trying fixes.

My point was I am trying to eliminate variables and approach this methodically. I see to much try this/try that and you need a bigger turbo. The key to a blown engine is eliminating knock and that is where I will start.

And a couple of posts into this and it's already gone off a tangent. ugh.

 

[charlief1]

The problem is not running rich. That can be dealt with by changing the secondary rods. The problem is knock (even at low boost and very rich) so something else is going on. I believe I might have a lean issue when the secondaries open up causing the knock. But I want to confirm that first. I need to figure out what the problem is before randomly trying fixes.

My point was I am trying to eliminate variables and approach this methodically. I see to much try this/try that and you need a bigger turbo. The key to a blown engine is eliminating knock and that is where I will start.

And a couple of posts into this and it's already gone off a tangent. ugh.

My point was that in 99% of the cases I've delt with the lean "spike" is usually caused by the secondaries opening to fast or not getting enough fuel when they start to open Rich. That was what I was trying to point out here. Changing rods alone may not give the results you want since you have to tune the whole thing and start with the mechanical aspect and then change rods ect. Not trying to piss you off or agrivate you. We used to get different cams for the secondaries so we could change rods, hangers, and cam to change the entire way the secondaries could work.

 

[canadian nascar]

sorry about jumping on your thread .

Kevin

 

[canadian nascar]

sorry about jumping on your thread .

Kevin

I opened up the secondary accel holes and they, the holes, are above the flaps so the fuel is restricted getting down the bore until they are actually opened some. I could see staining of fuel on the under side of the secondary flaps indicating to me restriction of fuel. Cliff Ruggles has info on removing some material on the flaps for better flow. I took a round 1/4 '' file and removed about 1/8'' off the flap inline with the secondary accel holes.

doing this I was able to loosen the secondary spring tension more than 1/4 turn.

 

[b4black]

My point was that in 99% of the cases I've delt with the lean "spike" is usually caused by the secondaries opening to fast or not getting enough fuel when they start to open Rich. That was what I was trying to point out here.

This is helpful. Sorry, I didn't see that in your first post. (I see something about running rich, not lean).

I want to confirm the lean spike, which I think is likely the case. I have pretty much left the carb alone, with the exception of bending the tab to let the secondary air valves open more (which did increase max boost). Spring tension is something I planned to play with, but never did due to the bracket racing. (We typically get two runs, then go right to eliminations.)

It's only going to be in the 80's today, so maybe I'll get that bum starter solenoid replaced.

 

[charlief1]

This is helpful. Sorry, I didn't see that in your first post. (I see something about running rich, not lean).

I want to confirm the lean spike, which I think is likely the case. I have pretty much left the carb alone, with the exception of bending the tab to let the secondary air valves open more (which did increase max boost). Spring tension is something I planned to play with, but never did due to the bracket racing. (We typically get two runs, then go right to eliminations.)

It's only going to be in the 80's today, so maybe I'll get that bum starter solenoid replaced.

See if you can confirm the lean spike and hopefully at what RPM it's at. Typically the secondaries open between 2500-3000 (sometimes lower) and that's when the bog/lean condition happens. If you're really adventurous take the hood and the air cleaner off so you can video the way the carb works under load. That might give you a better idea of what's happening.

To set the secondaries I usually use a light tap to see how fast they open when hit. If they pop to easy then it's a problem and if it's to slow then you end up with the engine reacting really slow. Once you get the spring pressure right then use the diaphram and a vacuum source to hold them closed. Put finger pressure at the back of the top plate and release the vacuum. A 3 count is usually about right but use light finger pressure on it. Almost like a dead weight. Hope that helps you out Rich.

 

[b4black]

Now that the pesky starter is fixed, I did a little testing tonight. With the wastegate unhooked, no knock at all. Not that that is surprising, but it's a starting point. Of course it is slow, but it will build about 4 psi of boost. Next I'm going to try hooking the wastegate back up, but locking out the secondaries to see how it reacts.

 

[charlief1]

Have you got a scanner hooked up so you can watch the O2's? I'm wondering what the mix is doing here.

 

[Scott Adcock]

Rich,

Those are good times and in the heat to boot...We just got back from the track this week (first time out in quite a while) and were in the low 16's, but 60' foot times in the 2.6 range (I'm at a mile high altitude which sucks). Previous 60' times were in the 2.2 range and we have been in the high 15's before, so I know we have some more tuning to do. Timing and knock elimination are the key - so I agree with you, eliminate the knock and run as much timing as you can. Focus on one thing at a time. I haven't fooled with the boost settings, just kept it at about 17-18psi, leave with about 5-6psi and shift at 5,200 -5,300rpm. The secondary air valve is the part that can be tuned with adjustment of the small spring using an allen wrench (PIA). I think I have mine a bit too loose and may account for the bit lazy 60' times.

I am curious to see what you find as the culprit, but looks like the car is pulls pretty hard on the top end for sure.

 

[b4black]

Cliff Ruggles has info on removing some material on the flaps for better flow. I took a round 1/4 '' file and removed about 1/8'' off the flap inline with the secondary accel holes.

I have heard of this before and just did some reading.
"Some "performance" versions of Quadrajets were built with "transition slots" cut into the air valves which made for a smooth transition from primary to secondary operation. If you can find some of these, use them!"

http://bosshosshelp.com/Menu Items/quadrajet/MikeQuadrajet/quadrajet.htm

 

[b4black]

Rich,
The secondary air valve is the part that can be tuned with adjustment of the small spring using an allen wrench (PIA). I think I have mine a bit too loose and may account for the bit lazy 60' times.

I set mine very loose a long time ago. It doesn't bog, but it sounds like this is the cause of the lean spot. I just tighten it up a quarter turn and now it feels like the other carbs I have sitting around. I'll give it a shot tomorrow and see how it does.

 

[b4black]

I set mine very loose a long time ago. It doesn't bog, but it sounds like this is the cause of the lean spot. I just tighten it up a quarter turn and now it feels like the other carbs I have sitting around. I'll give it a shot tomorrow and see how it does.

Made in to the track yesterday. Set everything back like the run at the top, including 110 race gas and no water/alcohol injection, with the exception of the air valve tension adjustment.
Tightened up didn't go well. 10 psi boost max was all it would do. Ran a 15.2 ET. Loosened it back up - 14.4 ET.

Left it alone the rest of the day for bracket racing. Made it to the semi-final and then red lite at -0.011

It will get to 20 psi, but it takes it a while to get there. And the knocking is still there, this time a little more and throughout the run. About 1 LED on the gauge each second or so - no real pattern. I'm usually looking at the boost and knock gauges, but one time watched the wide-band. A/F was about 10.5, so it's very rich as a suspected. (Oh, I did make one run with the alcohol injection on very low and it ran pretty much the same, but with some stumbles here and there. Another sign it's too rich.)

Then when I left, I set the boost back to 10 psi and put some 93 pump gas in (still mostly 110 race gas though). No knock at all and A/F still at 10.5. I'm hoping the knocks stay away once all the race gas is out. Then I will tune from there.

 

[usetaboost]

Hows your o2 doing with all the race gas? do you have cross counts on your scanner?

 

[usetaboost]

Is the knock happening during wot or at part throttle?