Carrera 2 replica engine for the Ghia - Choices

[helowrench]

Pile and I were discussing the venturi stuff over coffee a few months back. I cannot remember exactly the correlation. Hopefully he will drop by and elaborate.

[FJCamper]

Hi Randy,

What sizes are you offered?

FJC

[RHough]

Hi Randy,

What sizes are you offered?

FJC

Hi Frank,

CSP offers them 1.50", 1.75", and 2.00"

My system has 38mm (1.5") primaries.

http://www.csp-shop.com/products/Produc ... 2529b/det/

Cross section
http://docs.csp-products.com/katalog/?view=403

From my dusty memory on un-merged headers the end of the primary reflects a pressure pulse back up the pipe and a secondary pulse is reflected from the end of the collector. I have no idea how any harmonic tuning works with a merged collector. They seem to be all about gas velocity and creating low pressure at the exhaust port. I would expect a weak (if any) primary pulse and reflected wave from the end of the collector or venturi. I have no idea how the pressure changes work as the area changes inside the collector.

The answer is for me to buy all three and spend a day on a dyno to measure effects. I'm trying to avoid that ...

Randy

[Steve Arndt]

Attached is a pic of my Father's 65 Carrera 2 four cammer engine. I wish he still had it.

[RHough]

Attached is a pic of my Father's 65 Carrera 2 four cammer engine. I wish he still had it.

So the air cooled gene is strong in your family!

Very cool ... how many ways could we screw up ignition with two distributors? How many threads would get started ... "I have a miss or stumble at part throttle. I noticed that the points on one distributor are gapped at 0.025" and the other ones are 0.031" could thin be my problem or if it a dirty jet? I need the answer to settle a bar bet."

Great photo. Thanks for posting it.

[RHough]

Long overdue update:

The 1967cc engine runs! About 2 hours in it broke a chrome-moly rocker stud that left me stranded. Towed home and replaced all the studs with a new set, found the lash cap in the pushrod tube and all was well. Reset the valves at Zero Lash when cold and they clatter when warmed up.

The Dakota Digital gauges are the cats ass. In addition to having Speedo/Fuel/Volt and Tach/Temp/Pressure I can use the digital displays to read: Clock, Volts, Engine Hours, KP/H, Odo, Trip 1, Trip 2, distance to maintenance, A/F Ratio, 0-60 time, 1/4mile Time, 1/4mile Speed, Max RPM, and Max Speed.
The Rancho Pro-Street box is quiet and shifts like ... a new transmission.

I've got a too rich at cruise issue with the 40mm IDF's that is my first priority now than spring is close by. Engine runs 11.5 - 12.0 A/F at cruise on the idle jets (main jet stack pulled out of the carbs). With the main stacks in it goes lean to 16:1 then to 12-13:1 at WOT.

The rich light load mixture says to try #47.5 or #45 idles (Has #50 now)
The WOT is right on so the mains should be good.
The lean spot is the mains coming in too late after the idles quit? So a small Air Jet to kick them in sooner?

or

Trade the 40mm IDF's on a set of 44mm and tune those ...

The car is a beast compared to stock. It turns to 6500RPM with ease in 1 & 2, can't to that in 3rd or 4th legally so I don't know ... Big power and better than stock torque everywhere over 1000 RPM. The CSP Python is a bit loud but not terrible.

[Piledriver]

With the main stacks in it goes lean to 16:1 then to 12-13:1 at WOT.

What's your cruise AFR with it assembled?

16-17:1 at light cruise, 12-13:1 at WOT is goal, set the idle jet based on adjustment range after doing best lean idle, target is 1/2><1 turn, less gets a smaller jet, more gets bigger.

I reread your post a few times and I'm still not sure, but if that's where you are, step away from the carbs, you are done.

Some carbs have separate idle air jets to lean the top end of the idle range (AKA cruise) on Webers its built into the jet, has to be drilled to play with it.
Other than float level (which richens/leans everything a little) there is nothing else to adjust.

Also, I assume your fuel pressure is set to 2-2.5 PSI, much higher and Webers become impossible to tune esp at idle or cruise, they fail used as fuel injection.
The bowls overflow a little, randomly, creating a rich condition that just won't tune out, ever. It will probably work fine under heavy load.

On the collector venturi, try 1.5".

[RHough]

With the main stacks in it goes lean to 16:1 then to 12-13:1 at WOT.

What's your cruise AFR with it assembled?

16-17:1 at light cruise, 12-13:1 at WOT is goal, set the idle jet based on adjustment range after doing best lean idle, target is 1/2><1 turn, less gets a smaller jet, more gets bigger.

I reread your post a few times and I'm still not sure, but if that's where you are, step away from the carbs, you are done.

Some carbs have separate idle air jets to lean the top end of the idle range (AKA cruise) on Webers its built into the jet, has to be drilled to play with it.
Other than float level (which richens/leans everything a little) there is nothing else to adjust.

Also, I assume your fuel pressure is set to 2-2.5 PSI, much higher and Webers become impossible to tune esp at idle or cruise, they fail used as fuel injection.
The bowls overflow a little, randomly, creating a rich condition that just won't tune out, ever. It will probably work fine under heavy load.

On the collector venturi, try 1.5".

Yes, good Holly FP regulator set at 2.5-3 PSI. Float levels checked and set by ACN. It does not sound or feel like a random fuel level issue to me; no random drips and drops from the mains at small throttle openings. In my experience that would show in the wideband readings. It doesn't hunt it is very stable but too rich. #50 idles seem to be 'right' for 40mm IDF's and I have not heard of anyone having to go smaller but everything points to the idles being too big. I can double check FP and float level just to make sure nothing has changed. On the old tired stock 1600 these carbs gave mid 20's for mileage. I'm at a loss as to why the new engine gets 12-13 mpg with the same jetting and FP.

At any legal cruise speed it runs 11.5-12:1 ... On the flat or slight downhill it is way rich. When I tip in just a bit for a slight (4th gear) grade it goes lean. I think it should be 16-17:1 on the flats, leaner on a downhill and slightly richer as the load goes up. If I go to third and put my foot down it goes to about 12:1 which is right where I think it ought to be under heavier load. The way I understand it I should be able to get the lean cruise (with vacuum advance) on the idle circuit then see it go richer with increased load as the main stack kicks in. I don't like seeing the mix got lean when load increases. If I cruise at 80+ MPH I get into the moderate load lean area then richer as I open the throttle more. I just never get there at cruise speeds under 70 and it sucks gas.

Sorry to be so wordy ... if I can figure out a way to pull an RPM/Throttle Position/A/F ratio graph together I'd post it.

Thanks for taking the time to read through this! I'm not running any collector nozzle at the moment. I'll order a 1.5 and see what that does.

R

[Piledriver]

Explaining stuff absolutely clearly is hard work.

Where are your idle screws?

I'm not suggesting this setup as it was absolutely wrong on several levels, but on my 1700 with 44IDF/36s, in order to not have it fall on its face I ran a 70 idle jet and had the screws run in just cracked--- like 1/16th of a turn.---old carbs, bit sloppy, finally ran a loop of fuel hose over the screw heads to get them to stay put.

The idle jet was so rich that if the screws loosened themselves even a tiny bit, throttle response at tip in was all blubbery rich.
But it ran fine, and got awesome fuel mileage.

Didn't have a wideband back then but the motor liked it, my wallet did too.
(bone stock 1700 but with no head gaskets or base gaskets, deck was ~.023". No issues. no carbon buildup either. Ran it to redline repeatedly on every on ramp.)

In any case, before I "fixed" the random self-adjustment, I found the screw settings to have a HUGE effect on the mileage, like 20 MPG vs 45 or 55 on the highway.
On one ... high speed trip to Florida it was higher. I went over a week between fillups commuting to work in my 914.
Seriously.

It's been a long time since I messed with carbs and a distributor, still have them, last used several years ago to break in a cam.

[RHough]

Explaining stuff absolutely clearly is hard work.

Where are your idle screws?

I'm not suggesting this setup as it was absolutely wrong on several levels, but on my 1700 with 44IDF/36s, in order to not have it fall on its face I ran a 70 idle jet and had the screws run in just cracked--- like 1/16th of a turn.---old carbs, bit sloppy, finally ran a loop of fuel hose over the screw heads to get them to stay put.

Wow. It is months since I posted about my tuning challenge.

Idle screws are 3/4 - 1 1/2 turns out depending on idle jet.
2500-3000 RPM 3rd or 4th gear Cruise:
47.5 idles 12.5:1 - HUGE lean hole before main circuit start
50 idles 11.5-12.0:1 - leans to 17:1 as mains come in
52.5 idles 10.8 - 11.0:1 - leans to about 15:1 when mains start

Since 90% of street driving is light load cruise, and the mixture is in the 11-12:1 range the fuel milage is rotten. Best I've seen is 13-14 MPG and as low as 11 mpg (US Gallons)

I have tried every trick I can think of to get the main circuit to start sooner.
Bigger Airs = Earlier Main Start? - With the Airs *out* it is like a 300 AC jet. Still has the lean hole.
Huge main jet (165) - still has the lean hole
F11 - F7 - F2 emulsion tubes - still has the lean hole
plugged the top bleed holes in the F11's - still has a lean hole
28mm or 32mm venturis - still has the lean hole

I can get WOT mixtures from 10.5 to 13.8 with different Main/Air/Tube/Venturi Combos.

Today I'm trying the float levels set to 9mm

I've set the max advance (vacuum hose off) at 28°
I've got an anti pulse valve in the vacuum advance hose.
Distributor vac advance starts @ 2" of vacuum and is full on at 7-10" of vacuum.
The available vacuum from the advance port at 2500-3000 RPM cruise is only 2-3" and I have never seen more than 5" of vacuum signal from the carb.

To get good fuel milage I need a 15-16:1 mixture and more advance to compensate for the slower burn rate. It seems that the maximum vacuum signal from the advance port is at the lean transition from the idle circuit to the mains ... I just can't get that loading on the engine.

Since the HP requirement for cruise has not changed I think the 1600 stocker needed more throttle opening at cruise that put it into the lean cruise sweet spot. The new engine cruises on the idle circuit below the transition.

I think it could use 45 idle jets and be happy *if* I could get the mains to start early enough to cover the lean hole. That leaves me with the issue that I don't have enough vacuum at the distributor to provide advance a leaner cruise mixture will need.

I'm starting to look at EFI systems for the car. The combination of $100's in brass, no choke/fast idle, random plugged idle jets, and no success after months of effort has gotten me to the surrender point.

So a new thread is is order ...

[Piledriver]

Bummer. I oddly never got better mileage than when I ran the 44/36s on a stock 1700.
Of course it also ran great with a distributor discovered to be locked at ~30 degrees advance + vac can...

~huge idles with the screws just cracked worked for me, no flat spot.
I also played with the air jet hole on the idle jets...
Idle circuit controls cruise economy.

You seem to realize you are going to want programmable ignition anyway, considering the capability/cost of a Microsquirt and harness, its a no-brainer.
If you want sequential fuel it can be had with the mod pre-installed.
(All surface mount, so DIY modding not practical for most)

Mario has a nice crank trigger/wheel setup for T4s, and if you dig making stuff, a wheel in distributor (as a trigger setup only) works great and is trivial to set up, its a great way to recycle a 009.

A set of the 38mm Honda VFR TBs are dirt cheap, darn near bolt on (With the rubber boots), and probably flow like 44s with huge venturis..

[RHough]

~huge idles with the screws just cracked worked for me, no flat spot.
Idle circuit controls cruise economy.

You are going to want programmable ignition anyway, considering the capability/cost of a Microsquirt and harness, its a no-brainer. If you want sequential fuel it can be had with the mod.(All surface mount, so DIY modding not practical for most)

Mario has a nice crank trigger/wheel setup for T4s, and if you dig making stuff, a wheel in distributor (as a trigger setup only) works great and is trivial to set up, its a great way to recycle a 009.

A set of the 38mm Honda VFR TBs are dirt cheap, darn near bolt on (With the rubber boots), and probably flow like 44s with huge venturis..

I agree - the change is cruise mixture is directly related to the size of the idle jet. Swapping between 47.5 - 50.0 - 52.5 idles gives the predicable changes in cruise mixture. However trying to trim the cruise mixture a bit by setting the idle screws leaner than lean best idle has very little effect at the 2500-3000 RPM cruise range. Based on the vacuum signal from the advance port I know that the throttle is open enough to expose the vac advance port so it is running on the idle nozzle and two or three of the transition ports. The max vacuum signal at the advance port should be when the throttle plate has fully exposed the three lowest transition ports and the lean hole is after the last transition port is open and before the main circuit starts. The cruise mixture only varies about .4-.5 between first transition hole exposed and the lean drop off as opening the throttle reduces the vacuum available at the transition ports.

The 28mm Venturis are a little better than the 32's at getting the mains to start at lower throttle openings but 28's are way too small for a 1967cc engine on the top end.

I want to keep the port matched Weber IDF/IDA manifolds so my choices for throttle bodies are limited to IDF replacements. Redline and CB both sell units that include a TPS and injector ports that will use the throttle linkage and air filter setup that fits and works well in the Ghia.

Choices and wants list:
Crank Angle wheel to bolt on to existing pulley or use the distributor for signal and the ECU for timing control.
Closed loop operation at idle to cruise loads below about 3500 RPM
Cold start enrichment and fast idle.
Hot idle trim would be nice but not required.
Self learning and mixture clamping at idle would also be nice but not required.

So a Built Megasquirt, CB IDF injector throttle bodies (includes TPS), IAT, CHT, IAC valve, Fuel Pump/Regulator/Filter/Hoses, Map Sensor, Relay board, Injectors, and a harness?

[Piledriver]

CB Throttle bodies are very expensive for what they are, and the quality...
Jenveys are hideously expensive but still usually cost less.

I have looked at them... You'd be far better off pulling the venturis and using the Webers for ITBs.
Lots cheaper,too, as you have them.
Injectors can go in the manifolds (ideal) or in the air cleaners shooting down (hidden if you like)

The Honda (Keihin or Mikuni, very high quality OEM bits) VFR ITBS ~bolt onto Weber IDF manifolds, using the right rubber flanged TB mounts.
There's at least one thread here showing how easy it fits, but the photos may have gotten "mislaid" during the server upgrade.
It is trivial to put a cable pull linkage on them as that's what Honda used.

The only "upside" of the $2700 CB setup is that its a complete, allegedly turn key kit.
You pay through the nose for that though, and the only support you can get is from CB.

I strongly suspect Mario could set you up with something as complete and far more capable for a whole lot less...
...And with a (decade+) experienced huge user base, and numerous vendors to go to for help if needed.

Two of my MS v1.01 mainboards are 15 years old. ...Still (effectively) supported.
I stuck an MS3+MS3X on one... Worked fine.
(Currently has a MS2 and an MS3X on it via a user-designed adapter)
It's fully electrically compatible, and was trivial to make mechanically compatible.
OTOH I'm set up to do electronic rework etc, including SMD...

... a microsquirt is pre-assembled, all automotive-grade bits inside as well as the harness/connector, and ~the size of a credit card. It uses an external MAP sensor like a GM unit.
For most folks its the way to go, it can be fully sealed and go in the engine compartment.
(It ships not sealed so it can have jumpers configured for various setups and VR amp adjustments)

[Bruce.m]

VW speed shop throttle bodies are nice vfm and the price has fallen for you folks today.

I'll be using VFR though, using o-ring seals into an aluminium plate, sitting on IDA manifolds.

[Bruce.m]

Dp