Chuck and Ryan's RCR Build

[Chuck]

Front Clip Alignment

When we started driving the GT we quickly noticed the front clip shaking slightly left to right. A way to stop the lateral movement was needed. The solution was very simple. Two automotive rubber door stops were placed on either side of the front clip. An under sized hole was drilled and the rubber stops pushed into place. They are about 5/16” high, just enough to hold the clip snug. They also center the front clip on the spider and eliminate all lateral movement.

The center of the front clip tended to sag a bit in the middle where it meets the spider. This was easily resolved with two automotive rubber door stops, spaced to rest under the center vent. They are about 5/8" high. Undersized holes were drilled and the stops pushed into place with a bit of silicone to make sure they stayed put. Now the seam between the spider and the front remains level and straight.

We found a good selection of rubber stops at the local True Value store.

These inexpensive, simple additions worked very well.

 

[Chuck]

Weber Carburators Tuned. Finally.

Six months ago Ryan and I knew nothing about Weber Carburators, other than the looked cool. After spending countless hours reading every thing we could get our hands on, some valuable guidance from another thread on this web site from people a lot smarter than us, and many more hours working with the carbs, we can finally say they are just about tuned. The GT has reached the point where we can start it up, it spits a couple of times, then settles down within about ten seconds, after which it idles smoothly. It accelerates well and only occasionally spits after it is warmed up. It runs steady through the RPM range withut issues.There is probably some fine tuning that could be accomplished with a dyno, oxygen sensor, or by a knowledgeable mechanic, but for now we seem to have a stable set up. (Hope this public decleration does not jinx it!).

So much has been written about Webers that I am reticent to add more. A write up of the issues we discovered and resolved is ready to post, but unless someone is interested we will probably not post it.

 

[Randy V]

Weber Carburators Tuned. Finally.

So much has been written about Webers that I am reticent to add more. A write up of the issues we discovered and resolved is ready to post, but unless someone is interested we will probably not post it.

Myself - I would like to read what you discovered and resolved.. Please post in the Engines / Induction / Exhaust forum...

Very happy to read that you've gotten her settled in for some good cruising...

Will you be going to the Run & Gun?

 

[Chuck]

Will you be going to the Run & Gun?

Randy:

Not sure. Ryan will be at U of I this fall and he gets a bigger kick out of the track time than me.

How about you?

Chuck

 

[EGLITOM]

Hi Chuck

need a driver ) ??? I already told Fran a german driver in german car ( 917) would be cool, but on the other side i think a german driver in car build by a "Schmidt" is as cool.

TOM

 

[Randy V]

Randy:

Not sure. Ryan will be at U of I this fall and he gets a bigger kick out of the track time than me.

How about you?

Chuck

No toys to play with there this year...

Unless you're looking for a driver that is!!!

Oops - I see Tom's already volunteered his services... :lipsrsealed:

 

[Rob]

Chuck,
Good to hear you've got the webers sorted. Sounds like you got them about where I ended up too. At start up I would get a couple pops. I dismissed this as no concern considering there are no chokes. After running for a couple minutes they were good. At random, every now and then (seemingly no rhyme or reason) I would get a rouge pop, but infrequently. Never did figure that one out. Everyone I would ask said "yep....webers". Anyway...would have liked to have made that go away too, but never got conclusive info/feedback on how to do so.

Enjoy...

Best regards,

 

[Chuck]

Tom, Randy:

You are both just too generous - to offer your services like that. I am deeply moved. I will give your kind offers due consideration. A response will be forthcoming any day now . . . .

Chuck

 

[Chuck]

Rob:

Yup, sounds like our Webers are / were at the same level.

We are still fiddlling. Now we are pulling the plugs after letting it idle a bit, then making 1/8 turns of the mixture screws to lean out the rich plugs. Each tiny change seems to make a tiny incremental improvement.

But the good news is we can actually get out and have fun driving it with rare popping and spitting. Hope it lasts.

 

[Cliff Beer]

Chuck, a low cost tuning tool which is helpful with webers is a exhaust gas analyzer which you can install with a bung in the exhaust system and read the mixture on the display while travelling down the road. It's not as precise as a dyno but it'll give you a rough idea if your running mixture is rich/lean and how the mixture looks on acceleration.

You can buy these things for $200-300 and it's money well spent.

 

[Chuck]

Cliff: Good tip. Any make or model recommendations??? Sources??? Thanks

 

[Keith]

Chuck,
I for one would be very interested to see you post your experiences in sorting out your webers. It won't be that long and I will be doing the same thing...........
Keith

 

[EGLITOM]

IMHO there is only one lambda tool to recommand:

LM-2 Wideband O2 Digital Air/fuel Ratio Meter

the LM2 Basic kit is great for to start with. I´m using this on the racetrack on my motorcycle just temporarely mounted. works great reads fast and reliable.
LM 2 basic kit P/N: 3837, MSRP $349

In combination with a TPS and the RPM adapter you get perfect readouts on the laptop, which allows you to analyze what happens during any load situation. for this you would need the extended kit
P/N: 3806, MSRP $479

TOM

 

[Chuck]

Tom:

When you come over for Run and Gun just bring along the LM-2 and we can fine tune the Webers . . . . .

Thanks for the tip. Just when you think you have all the tools you need you discover another 'must have.' Ugh.

 

[Cliff Beer]

Cliff: Good tip. Any make or model recommendations??? Sources??? Thanks

Hi Chuck, here's a good one - simple and inexpensive.

INNOVATE 3795 DB-BLUE WIDEBAND Air Fuel Gauge LC-1 KIT

 

[Chuck]

Thanks Cliff.

So I am trying to figure out just how badly I need another gadget. Don't have bunge to screw the O2 sensor into, so would likley get the adaptor for the exhaust. Then we could check the fuel / air ratio at different RPM settings, likely while driving, as we strive for the ideal ratio.

Net result would be, presumably, changing the fuel and/or air jets to get the best ratio at mid and upper RPMs as well as the idle jets and mixture screw adjustments at idle to 2500 RPM or so.

But if one changes the jets and idle mixture based on real world driving experience until it runs optimally at various RPMs, how much difference would knowing the air / fuel mixture really make? The air / fuel mixture might affect general tuning, but won't the fine tuning be based upon real road experience anyway?

So am I missing something? Can't see adding another gadget to the collection if it won't really affect the final adjustments.

 

[Al Jones]

The tuning might be a problem as you will only know if it's rich or lean and because of the 180 design,you won't know which bank let alone which carb might be causing the bad A/F ratio. If it's 'out',you'll have to try one carb at a time to see if it makes a difference and if it doesn't,return to the original setting for that one and go to the next. A bit different than a 4bbl with 2 sets of jets and those for high or low speed. Generally,and I know the head hunters are coming out of the woodwork to get me for this, small discrepancies won't really matter at idle ( your best setting by actual running is good here) or low speed/partial throttle as long as your timing is set right. Where you will have a problem and the test equipment will help,is at max throttle opening where you will toast a motor if excessively lean and run hard for an extended period. A bit rich won't hurt you,only drop the top end power a bit. This is my opinion only,so get a couple more thoughts on this. A.J.

 

[Cliff Beer]

Chuck, the 02 bungs are easily found, and also pretty easily welded into the exhaust. As indicated above, on a GT40 with cross over exhaust it's helpful to have at least a couple bungs (so you can move the sensor around a little).

Answer to you question...

The electronic AF meter allows you to quickly dial in the basic jetting from idle to WOT. A lot of folks struggle to get just the basic jetting right.

You can fine tune any way you want. Old school and low budget approach is to change out jets and check it on the butt dyno. That's not a bad way to go however, with four (webers) carbs the AF sensor allows you to quickly get the mixture pretty darn close.

 

[Chuck]

Ok. You convinced me.

Is there any downside to using the tail pipe adapter for the O2 sensor? From the pics it looks like it senses the exhaust gasses some distance into the tailpipe / muffler, and given how short the exhaust system is this would seem to me to be acceptable.

Thanks for the good tips

Chuck

 

[Randy V]

The o2 sensor is a heated sensor on this meter so there would be no problem there Chuck.

The 180 degree pipes will give you false readings as you may have one carb throat rich and another very lean thereby netting an average of "good"..

The only way that I know of to really get a handle on each cylinder would be to drill small holes in each pipe and use thermocouples to read the temperature of each cylinder as it's contributing to the net average read by the tailpipe..

I had planned on just taking laser temps on my exhaust pipes on the Chassis dyno while reading the F/A mixture via my Wideband 02 system. I don't know that this is the absolute best way but I'd rather not wash down one cylinder while burning up the piston in another..