A few things: Distributor Curve / Jetting / Gas Smell

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A few things: Distributor Curve / Jetting / Gas Smell

Postby Armodilo » Tue Sep 12, 2017 2:59 am

Hi guys,

Things have been going fairly well since we got our #171 Beck on the road and as you all know, the project list gets longer and longer each day.

My first task was working on the carbs/ignition to get her to run better. The carbs were way out of whack, the floats were completely wrong, the fuel pressure was at 6+ psi and the ignition was an old Accuvance from CB (it has a CB 2276 engine). We've done the following and I have a couple of questions, hoping someone has some thoughts:

1. I completely rebuilt both carbs, set the floats to 11 & 25mm
2. Current Jetting:
Idle Jet 5.0
Emul Tube F11
Air Corr 175
Main 135
3. Replaced the Accuvance distributor with a CB MagnaSpark II (http://www.cbperformance.com/product-p/2010.htm)
4. Added a fuel pressure regulator and fuel pressure gauge (now set at 3.0 psi)
5. Set all my valve as per CB tech tuning guide of zero lash (http://www.cbperformance.com/Engine-Tuning-s/149.htm). I closed the set screws until the push rods wouldn't turn, then backed it of a touch until they turned but had the slightest bit of resistance.

Notes / Questions:
1. To replace the distributor, I pulled the old one out and put the new one in -- didn't do anything with shims/washers, etc. I set my timing to ~8 TDC at idle, when I open the throttle, I can see the timing decrease at first from 1,000 to 1,300 - 1,400 rpm and then increase into it's advanced curve (about 28 deg TDC at 2500 to 3000 RPM), I doubt that's normal but wanted to know if anyone had any insight. It drops almost 2 - 4 deg or so before going back up to it's 8 deg and then onto the normal curve.

2. I have trouble getting the engine to start (before and after adjustments) -- not a lot of trouble but it takes one or two good depressions on the accelerator pedal followed by a couple of turns of the starter and then repeated soft feathering of the gas to get it going and keep it going for a minute or two until warm -- during that time, I get a bit of popping and hick-ups through the carbs until it warms up, then it idles quite well at 1050 to 1100 rpm with no issues, no popping, no backfiring at all.

3. I have a very strong smell of gas after a good drive (again before and after adjustments) -- strong enough that the garage doors need to be opened every few hours to dissipate the smell. I know there will be some -- it's a carb after all, but this is more than that. The engine is running a rich -- plugs are a good color but black on the metal parts (new plugs about a week ago). Could be gas boiling off in the carbs after a long drive -- I did pull her right into the garage and shut her off without shutting off the fuel pump before stopping engine (electric shut-off on pump).

4. I do get a very very slight amount of quite popping when decelerating with the engine at about 2,500 to 1,500 (estimated rpm range) -- very very slight pops.

I've had suggestions from Redline Weber to increase jetting of the idles to 55 or 60 and the main/air to 145/185 but I wanted to get some feedback from this community. The smell of gas could be as simple as the gas boiling off or there could be a leak somewhere (and there's nothing external that I can see). Everything was replaced during the carb rebuild. The carbs look like original Webers and have the Made in Spain cast into the body.

Thoughts?
Beck Spyder #171 (2276cc)
1963 Porsche 356B T6 S90
1969 VW Beetle
2007 Porsche Boxster S
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Re: A few things: Distributor Curve / Jetting / Gas Smell

Postby RS-60 mark » Tue Sep 12, 2017 9:39 am

#2 sounds normal on a cold engine (at least it is normal for me). I pump several times (3-4), hold at half throttle, push the starter switch, then modulate the throttle as it fires up, nursing the engine up to 2000-2500, then hold it at 2000-1500 while it starts to warm up, smoothing out the coughing and "chuffing". It doesn't take long (30 seconds). Sometimes when it is really cold it doesn't fire up on the first try. Basically, working the throttle is compensating for not having a choke. Even when the engine is starting from warm I still pump the throttle at least once.

#3 is not normal and the cause needs to be found. Look for leaks in all the obvious places (at every connection). You may not find actual dripping, but feel for wetness. I know you are confident in your float heights, but a sticking float, or a sticking (or missing!) float valve will allow the carb float bowl to overflow. This condition might also make the engine hard to start because it will be "flooded" to start with.

#4 is also normal for me. Although there are a number of things that guys will point to as the cause for excessively popping exhaust on deceleration (usually leaks between the exhaust header and its port), I have never been able to completely eliminate popping on hard deceleration. My personal theory is that the mixture goes lean when the throttles are closed and air is being sucked in at higher than idle volume during deceleration. Actually, it is not really a theory but an excuse to convince myself it is normal an not to worry about it. #-o
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Re: A few things: Distributor Curve / Jetting / Gas Smell

Postby Armodilo » Tue Sep 12, 2017 9:44 am

Thanks Mark, at least a couple of things are normal on my car :)
Beck Spyder #171 (2276cc)
1963 Porsche 356B T6 S90
1969 VW Beetle
2007 Porsche Boxster S
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Re: A few things: Distributor Curve / Jetting / Gas Smell

Postby Armodilo » Tue Sep 12, 2017 1:27 pm

I've talked to CB about the distributor 'sloop' and they suggest it's in the distributor drive pinion and very normal, so that takes care of #1!
Beck Spyder #171 (2276cc)
1963 Porsche 356B T6 S90
1969 VW Beetle
2007 Porsche Boxster S
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Re: A few things: Distributor Curve / Jetting / Gas Smell

Postby RBP » Tue Sep 12, 2017 1:47 pm

You state you set the floats to 11 open & 25 for full stroke, the 25 doesn't really matter as much as the 14. Did you verify tight shut off? In Canada we don't have the ethanol levels as they do state side, here you should set the floats at 14mm.

Do not change the jets especially if your plugs look black! Pull all 4 of the main stacks and go for a ride on the idle circuit. Don't try and accelerate fast just drive nice and easy. If you can drive around without the engine falling flat then you don't need larger idle jets but might need smaller ones. You want to try this till the engine doesn't run then go up one size till it runs. At this point you will be in the zone as for as the idle circuit is concerned.

Once you have this sorted take note of when the idles fall out, likely 2500 - 3000 rpm. Then you can play with the AC's to bring the mains in at the right RPM range, the larger the AC the sooner the mains will start feeding fuel through the carbs. You might need some larger mains. I would guess that engine would need 155 mains and 200 AC's or there about.

To really know you need a wide band O2 meter so you can see whats happening.

On the popping at off throttle. You need to check your high RPM sync. Get the engine warm and bring the RPM to say 2000 or enough so that the throttle plates are in play. Then use the snail and set the drop links so that both sides flow equal. I would try this first before starting to look for leaks and pulling the engine apart.
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Re: A few things: Distributor Curve / Jetting / Gas Smell

Postby Armodilo » Tue Sep 12, 2017 2:55 pm

Thanks RBP, I will look into everything suggested -- interesting about the 14mm setting as opposed to the 11. I will revise and check for tight shut off.
Beck Spyder #171 (2276cc)
1963 Porsche 356B T6 S90
1969 VW Beetle
2007 Porsche Boxster S
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Re: A few things: Distributor Curve / Jetting / Gas Smell

Postby egrant5329 » Tue Sep 12, 2017 4:29 pm

RBP's advice is right on based on my experience.

Those idles/mains/air correction, etc are what dual 44 IDFs come with. I would also guess that with the 135 main you will need 200 AC. That will probably take most of the gas smell away, but it doesn't mean the jets are correct. If the engine is from CB call them and talk to Pat Downs he should be able to tell you what the jetting should be.

Do you have a CHT to watch head temperatures? I highly recommend one if you don't. As you get the jets leaned out where they need to be, it is a good idea to see what the head temps are doing. I echo the suggestion of a wideband. As you approach an AFR of 14.7 your heads will heat up really quick under a load or WOT which is why aircooled engines are set to run richer.

As far as the distributor goes, I highly recommend the crank trigger setup over it, but it will work fine. On a type-1 I'd set the initial advance to 7.5 and go with the lightest springs blue-blue so you are all in at about 2500 with ~28 degrees. If you get any pinging at 2500 rpm when you stomp on the gas, go to the light silver and blue so it comes in ~2800.

I think carbs are the toughest thing to learn on these cars. It has taken a long time and the addition of a wideband for me to understand them and I still have a lot to learn. John Connolly at aircooled.net has postings about wideband tuning on thesamba. He is the one who helped me the most. I have posted this link in the past, but it is helpful http://tampavw.forumotion.com/t1215-tun ... e-1-engine
Good luck!
Ed
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Re: A few things: Distributor Curve / Jetting / Gas Smell

Postby Armodilo » Tue Sep 12, 2017 4:59 pm

Great thanks Ed!

I ended up calling CB to find out a bit more about the engine in the car -- it was advertised as a 2276 when purchased and turns out to be a 1915 based on their records but that's all they have. It explains the low power I've been wondering about and will obviously have me reviewing my jetting again.

I'm looking at getting a wideband installed next month to help with tuning and probably not do too much until then -- then we have the winter months; so no driving or tuning until next spring but I have lots of other projects for the car already.

For the CHT and Wideband, do you use temporary gauges or permanently mounted in car for constant on the fly updates?

Overall the car is great, but I hate no knowing exactly what's what with the engine -- I may end up looking at a whole new one down the road for some peace of mind, at least in terms of knowing what I'm working with. (The current one is 13 years old, with no history and no clue how long it sat at any given point -- whoever installed it never put an external oil filter on and who knows what else.)

Is it a giant pain to put a new engine in -- what am I looking at ?
Beck Spyder #171 (2276cc)
1963 Porsche 356B T6 S90
1969 VW Beetle
2007 Porsche Boxster S
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Re: A few things: Distributor Curve / Jetting / Gas Smell

Postby EEricson » Tue Sep 12, 2017 5:53 pm

Wow, if it's really a 1915 instead of a 2276 that's a big deal for your carb jetting and power. Maybe a PO had a bigger crank installed? The CB 1915s were (and still are) rated at about 120 hp and are well-cammed. I am told that a little head work (or a set of Panchitos) will boost power considerably and add at least 1000 rpm to the top end, but don't know. Pat would know.
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Re: A few things: Distributor Curve / Jetting / Gas Smell

Postby egrant5329 » Wed Sep 13, 2017 2:07 am

The 1915 will power the car very nicely and is a good solid engine. Did he give you jetting for it? I would bet that a 50 idle, 1.15 main and 170 AC will be close. That's what I run in my 2L (90.5x78) and WOT I am slightly leaner than I would like at ~13.7. General cruising down the highway my CHT reads 250 and pulling hard up a long hill climb at 75 or 80 I'll hit 300 on the CHT.

My CHT is mounted in the dash along with a clock and oil pressure, but my wideband sits in the floor on my left with a cable to my computer in the passenger seat. You really need RPM and AFR to do much, TPS or MAP is even better.

Putting in an engine isn't the easiest, but it is doable.
Ed
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Re: A few things: Distributor Curve / Jetting / Gas Smell

Postby RBP » Wed Sep 13, 2017 3:48 am

Another item to consider is that you bought a used car. As you pointed out, you don't know what's what with the engine and jetting. the PO may have been advised he needed larger jets, just as you were advised. At this point, instead of purchasing new jets, he may have reamed out those .50 idles in you carbs to who knows what size. You need to make sure you know what those jets are! Get a jet feeler gauge and find out what you have. You may find someone has been in there and messed things up.

As Ed pointed out, timing, AFR and CHT are all interrelated. But once you have the timing set (idle and full advance) and then the jetting right the CHT will be in check. Also Ed has a more sophisticated distributor that can be programmed for a changing advance based on RPM. I run a Mallory Unilite with mechanical advance so I have to run a little richer all around.

Your goal for AFR with the basic distributor would be 14.7 at idle and high 13's for all other driving, if you can get low 14 for cruising that would be good but its hard to get everything without being able to change the advance while underway.

BTY the engines are costly. A really nice place to be is the 180 HP & torque range. From a reputable builder these will cost in the area of 20 K give or take some $ depending on the builder. If you do go for the new engine its worth spending the extra money and getting the power! I've had a 550 with a 2165 T1 with about 140 HP & torque it was ok but not really exhilarating, my present engine is a 2316 T4 with about 200 HP & torque and is where I would want it, perfect balance.
Last edited by RBP on Wed Sep 13, 2017 4:38 am, edited 2 times in total.
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Re: A few things: Distributor Curve / Jetting / Gas Smell

Postby Armodilo » Wed Sep 13, 2017 4:02 am

Thanks again.

I have a set of gauges for the jets, I will check them this weekend and see what's going on there. I also have a set of main/air jets and idle jets on order from Redline so I can start to narrow down the jetting. At this point I think I'll concentrate my energy on getting this one running to the best of my ability and use it as a learning experience. Like Ed said, this should be a good solid motor, and even without an external oil filter, with regular maintenance should last a while. There's no use spending extra money replacing it quite yet.

There's so many other things to do on this car that I'll be busy enough this winter. I have a rubber gas line off the fuel tank, running to the fuel pump (which is close to the master brake cylinder -- impossible to get at) and then more rubber line running half way into the passenger compartment then to a steel line -- that has to all change.
Beck Spyder #171 (2276cc)
1963 Porsche 356B T6 S90
1969 VW Beetle
2007 Porsche Boxster S
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Re: A few things: Distributor Curve / Jetting / Gas Smell

Postby Armodilo » Wed Sep 13, 2017 4:56 pm

Quick update:

I measured the jets and it looks like they were all drilled / reamed to:
Idle: 60 [says 50]
Main: 150 - 155 (a bit loose at 150) [says 135]
Air: 200 - 205 (a bit loose at 200) [says 175]

Thoughts on this on a 1915cc with dual 44 IDFs?

Cheers,
Beck Spyder #171 (2276cc)
1963 Porsche 356B T6 S90
1969 VW Beetle
2007 Porsche Boxster S
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Re: A few things: Distributor Curve / Jetting / Gas Smell

Postby RBP » Thu Sep 14, 2017 4:12 am

In my opinion, your jetting is too rich for that engine and that's why your plugs are black. With a 1915cc engine I would expect you to end up with idle jetting of somewhere between .40 & .50, mains of 125 to 145 and AC's at 175 to 210. I have a high output 2316 and I run .50 idles, 155 mains and 200 ACs. All engines seem to be somewhat different so there is no exact chart, trial and error is the only way unless you have a wide band O2 sensor installed.
Order and install some idle jets .40, .45 & .50. Install the .45 idles, pull the main stacks out of the carbs and drive around as outlined in my previous post. Reduce the jet size till the engine falls down and won't drive, then go up one size so that it does.
After that you can reinstall the mains and start looking at that.
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Re: A few things: Distributor Curve / Jetting / Gas Smell

Postby egrant5329 » Thu Sep 14, 2017 5:02 am

I'd look at the numbers on the carbs and see if they are 40s or 44s. You should also see what size the vents are since you can't take anything for granted on cars that others have messed with. You will probably want some extra spark plugs in case yours are fouled and it's not a bad idea to carry extra's anyway. I'll admit I have spent a small fortune on jets during my ongoing carb education. I have reamers, but have never used them. I think it would be too easy for them to not be the same.
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