Can we talk Webers here, even if not on Alfa?

[JRatto]

I have a pair of 48IDA's I'm trying to sort out....figured there'd be some excellent advice from some Weber gurus here...but before I get too involved here and upset anybody, I thought I'd ask first...

Thanks,

Jim

[john.harrill]

Remove them from their current mounting and place them on top of the hood of an Alfa.

That'll be close enough.

[tubut]

Quote:

Originally Posted by JRatto I have a pair of 48IDA's I'm trying to sort out....figured there'd be some excellent advice from some Weber gurus here...but before I get too involved here and upset anybody, I thought I'd ask first... Thanks, Jim

[JRatto]

Well....alright...here it goes...
The engine they are on is an air cooled VW, albeit highly modified. It's approx 2200cc (94mm bore x 78mm stroke), 9.2:1 compression ratio, heads flow about 185-190 cfm @ 28", cam is 263' @ .050", 1.75" 4-into-1 merge header into 2-1/2" Magnaflow muffler. MSD 6AL ignition, NGK D7EA's gapped @ .036", I drive it semi daily on the street on 91 octane.
The carbs are set up as such:
40mm venturi
170 main
175 air corrector
F2 emuls. tube
65 idle jet in 120 holders (air bleed)
2.00 needle
4.5 aux venturi
floats set as per Weber
3.5psi @ idle fed by Holley red pump, AN6 lines

I'm having a couple of issues. First I am running into hard starting (engine will crank but not fire) after engine has come to temp and then I shut it off, and then try to restart 20 min later. Once it starts, it idles poorly and there is a "hole" in progression...between idle and mains, only after hot start. Anybody know what could cause it?
Second, I'm having what I think are lean issues once into mains and air corrector segment of powerband....3700-4000 and up.....especially steady state on highway. After a few plug checks, it seems plugs aren't getting much color to them....pretty white after hard run and clean cut. Looking thru magnifying glass....I do see some grey specks...peppering....to me meaning lean and molten piston on my plugs. But with a big 170 main?
Some sources say with F2's that air correctors need to be smaller than mains....anybody agree with this?
And has anybody set up a homemade AFR meter using 3 wire Bosch 02 sensor and digital voltmeter? I think I might try this and see what millivolts I come up with on freeway.
Thanks for any comments......sorry it isn't Alfa related.

[oz3litre]

Quote:

Originally Posted by JRatto Well....alright...here it goes... The engine they are on is an air cooled VW, albeit highly modified. It's approx 2200cc (94mm bore x 78mm stroke), 9.2:1 compression ratio, heads flow about 185-190 cfm @ 28", cam is 263' @ .050", 1.75" 4-into-1 merge header into 2-1/2" Magnaflow muffler. MSD 6AL ignition, NGK D7EA's gapped @ .036", I drive it semi daily on the street on 91 octane. The carbs are set up as such: 40mm venturi 170 main 175 air corrector F2 emuls. tube 65 idle jet in 120 holders (air bleed) 2.00 needle 4.5 aux venturi floats set as per Weber 3.5psi @ idle fed by Holley red pump, AN6 lines I'm having a couple of issues. First I am running into hard starting (engine will crank but not fire) after engine has come to temp and then I shut it off, and then try to restart 20 min later. Once it starts, it idles poorly and there is a "hole" in progression...between idle and mains, only after hot start. Anybody know what could cause it? Second, I'm having what I think are lean issues once into mains and air corrector segment of powerband....3700-4000 and up.....especially steady state on highway. After a few plug checks, it seems plugs aren't getting much color to them....pretty white after hard run and clean cut. Looking thru magnifying glass....I do see some grey specks...peppering....to me meaning lean and molten piston on my plugs. But with a big 170 main? Some sources say with F2's that air correctors need to be smaller than mains....anybody agree with this? And has anybody set up a homemade AFR meter using 3 wire Bosch 02 sensor and digital voltmeter? I think I might try this and see what millivolts I come up with on freeway. Thanks for any comments......sorry it isn't Alfa related.

[tubut]

I think fuel temperature is indeed worth looking at. Fuel injected Triumph TR6s were notorious for not starting when hot because there were gas bubbles in the fuel lines from the fuel pump running hot (cooling fins on the fuel pump solved that problem). Have a close look at anything that can create heat transfer to carbs, fuel lines and fuel pump.

I guess warm or even hot fuel would change the AFR towards lean (fuel would have more volume for same energy). If possible, see if you can temporarily supply fuel from an alternate source (e.g. a canister).

When you put in an AFR meter, I'd suggest to make this a fixed installation with a 5-wire sensor (because the reading is suposedly more accurate than with 3-wire sensors). This comes in handy for proper tuning at all speeds and for all temperatures (and who knows, maybe you go megasquirt some day).

[101 Alfa Mike]

Quote:

Originally Posted by JRatto Once it starts, it idles poorly and there is a "hole" in progression...between idle and mains, only after hot start. Anybody know what could cause it?

[JRatto]

Quote:

Originally Posted by 101 Alfa Mike Are we talking about an off-idle stumble between idle and the progression circuit? Or a flat spot between the progression and main circuits?

[tubut]

Maybe a couple of silly question:
Is the car a beetle or another car with a Volkswagen engine or chassis?
If it's a beetle, do you have the engine hood closed (or half open or removed)?

[1978alfa]

I had a different but perhaps related issue with my 1600 Duetto. It had a mechanical fuel pump and the carbs were jetted correctly, but I was getting symptoms of lean conditions at certain times because the mech. Fuel pump wasn't keeping the bowls full enough. $30 Electric fuel pump = end of problem. 2.5 - 3 lbs. of fuel pressure. The stumble? Accelerator jets and circuit good and clean? Good luck -Clark

[Slash]

Along with Reudi's question, if the engine is in a full-bodied VW, you might consider these ideas if fuel temperature is a problem:

Is all of the engine sheet metal in place?

Do you have an external oil cooler? It has been a while since I was into hot-rod VWs, but it used to be popular to mount an external oil cooler across the air intake on the front of the fan shroud. I always thought that this was a mistake because of the heat that would be added to the intake air and also kept in the engine compartment. I mounted mine on top of the transaxle.

Is the fuel delivery system (lines and pump) picking up heat from the case or elsewhere?

[JRatto]

Quote:

Originally Posted by Slash Along with Reudi's question, if the engine is in a full-bodied VW, you might consider these ideas if fuel temperature is a problem: Is all of the engine sheet metal in place? Do you have an external oil cooler? It has been a while since I was into hot-rod VWs, but it used to be popular to mount an external oil cooler across the air intake on the front of the fan shroud. I always thought that this was a mistake because of the heat that would be added to the intake air and also kept in the engine compartment. I mounted mine on top of the transaxle. Is the fuel delivery system (lines and pump) picking up heat from the case or elsewhere?

[tubut]

Quote:

Originally Posted by JRatto If I really belt it hard and run it up to 6500 or so, it seems it is running out of fuel.....the bowls. What's the trick needle valve these days? Grose ball valves? Stock Weber? The glass ball needle valves? Thanks again,

[oz3litre]

The original fuel tap/outlet on your tank might be on the small side. If I remember correctly we put one from a type 3 on mine because it had a larger diameter outlet pipe. Have you taken the outlet unit off and checked that it is clean and unobstructed? As I said my car ran easily to 8,000 RPM once we fitted dual valve springs. I too had an electric pump up front and the needle and seats etc were stock 44IDF. Before that it was only pulling 6,000 due to valve bounce. The springs that were in it at that time were single, supposedly high performance ones. The dual springs made an incredible difference.