Hello,

I have a performance/race engine I am trying to get running. About 10 years ago I had it sort of running. I could take it for a mile run here and there, but it was very rough. It sat for the last 10 years but I am now back to working on it. This was a blue printed engine but I never received the blue print. Here are the basics as I know them:

B20B
2135cc
11.5/1 compression ratio
308 duration custom cam from Sweden with 106 lobe center
All new components
Port and polished
Valve job with Isky dual valve springs
Custom exhaust header
DCOE 45's
Must run on premium with octane booster or race fuel.

I just purchased an electric fuel pump. I also just purchased the 123 programmable distributor and a Bosch red coil.

Within the next couple days I will install the fuel pump, distributor and coil.

Since this is not an ordinary engine, I hope I will be able to get assistance from those that have had experience with a motor similar to this.

Octane boosters do very little to nothing, only a lead additive would actually work in such a small bottle, but such an additive would be illegal and dangerous.

Need to know what duration the cam is because "308 duration" means pretty much nothing. The Sweedes had a head porting competition a few years ago, they were using 11.7:1 with Enem's biggest 'street/race' cam which was 272°@.050", 0.315" lobe lift and the fuel used was Shell's Vortec Premium pump gas, 100 octane (R+M)/2 method.

You really need to find out what the cam is, then make sure it's degreed in correctly and has all 8 lobes.

What size are the valves? 106° LCA (aka LSA) Is a bit odd. 46/38mm valves need wider LCA than 44/35, I think Enem do 109° assuming the head is ported correctlty with 46/38 valves. With my 44/35 I go 102° aiming for maximum torque in the 3000-6500rpm range and with my 269°@.050" cam I used my 11.5ish:1 used lead premium on the street with timing locked at 27°, when taken to the track I added toluene and set the timing to 34° locked, but that was the 90's, now leaded fuel & toluene are illegal.

2x45DCOE use 38mm chokes, 4.5 or 5.0 aux venturis and F16 emulsion tubes. If you have a good motor, the mains and air correctors will end up about the same size, If it's a great motor, the air correctors will end up bigger.

I am now ready to start programming the 123 ignition. The notes from the builder show initial timing at 0-5 BTDC and 29-34 at 3000 or above. The 123 wants a full curve. Does anyone know how to go about getting the full curve?

In a pinch, you can go to the Volvo factory service manual which specifies the advance for the OEM distributors. Depending on the version of the engine, the RPM based advance starts around 10 deg BTDC at about 900 RPM and increases linearly (i.e. straight line) till it tops out at about 34 deg BTDC around 3000 - 3200 RPM. Above 3000 - 3200 RPM there is no further change in speed based advance. If you want to include MAP based advance the service manual specifies the change in timing with change in MAP. The MAP based change in timing in the manual may not be optimal in terms of horsepower because on 1971 and later engines Volvo diddled the MAP based advance to squeak under some changing emission standards.

No quantum physics involved in this process!

As you have the programmable 123 you should be able to tweak the timing somewhat. The 123 paperwork may say to select a setting to start with. I don't know the kit but the standard one comes with a collection of settings to match the range of Volvo engines. If the adjustable one also has this in addition to a custom option you'll probably have to select one of the highest tune standard ones and go from there. The B20b setting should get it running. As said, tuning on the dyno best but expensive. On the road with a passenger making changes on a laptop more usual but it really needs someone who's done it before.
I think I would email 123 quoting your spec and see if they can give you a baseline to start with and at least get you on the road. I'd have to read back to see but have you had the engine running yet?

Full curve, as in degrees of advance versus RPM or is your 123 also set up to measure manifold pressure is which case you need the 2 axis table showing advance versus MAP and RPM?

If you need the full 2 axis table you could Google "MS2 Extra spark map for Volvo B20" and you could likely find example spark maps that would get you started. If you only need the advance versus RPM input, just take the line corresponding to 100 kPa on the spark maps. There is a bit of a tutorial in the Megasquirt on-line manual about how to fill in an initial spark table.

Since required spark advance is affected by the combustion chamber shape and the turbulence and the presence or absence of effective quench zones, the specific curve for your engine will have to be fine tuned on a dyno while listening for detonation.

Do you know whether the block was decked and the piston crowns machined / matched to establish a consistent piston height above the deck at the correct height to establish the proper quench zone depth? Overbore B20 engines without establishing the correct quench zone can be relentless pingers requiring retarded ignition or ridiculously high octane. A B20E with a 10.5:1 with correct quench zones will run just fine on 89 octane. It would seem strange that the engine would require something beyond 104 (are you talking RON or R+M/2?).

If you are just trying to get it running, I wouldn't sweat the octane for now. Its not particularly important in terms of getting the engine to at least idle so that you can start the tuning process. By the way, getting a 308 deg duration cam to idle is going to be a challenge. Octane will become an issue when you start to establish the tune for maximum power.

I don't do Webers; but, my recollection is that too much fuel pressure is as much of an issue as not enough. What kind of electric fuel pump are you installing? You may need to install a fuel pressure regulator to control pressure to the carbs and install a return line if you went mungo on the pump.

Unless you have prior experience with Weber carbs and have a good guess at where the tuning starting point is going to be, you are going to be going through a lot of spark plugs as you do your mixture checks. I suggest you get a wideband O2 sensor so you get a sense of where your AFRs are. You can buy data loggers that will record engine speed and the AFR reported by the O2 sensor and that will allow you to make an educated assessment of what mixture adjustments you need to make on your Webers or how big the mixture adjustments need to be.

Can I ask what the intended use for this engine is? Its been sitting a long time so what are your plans now. Built for the track I guess and if the spec combines together and works well should be a lot of fun as long as the chassis compliments it. As an engine in a road car, it could well prove both annoying and frustrating at anything under half throttle.

The intent is a street car--that is what I asked for when I had the engine built. A street car that had extra hp. I didn't get what I asked for but I am where I am. I know it may never be a street car, but I have read it is possible so I am not ready to give up.

Agree on the fuel pump--I am told it is proven on DCOE45's. It puts out 60-70 gph at 4psi--so high volume/low pressure.

Weber's are very sensitive of fuel pressure, should be 3 lbs, racing fuel is a must, additive doesn't work you will detonate your motor. 36 degrees for timing, you will have to figure your Weber jetting, every motor is different

The mechanic that rebuilt the engine said "must run pump premium plus booster or 104 racing fuel". Is he wrong about the premium plus booster?