Firstly let me commend the regular contributors and everyone else on some fantastic threads lately, very informative to someone in the process of building a big bore B20
In the meantime I recently bought a very nice 66 121 that has been fitted with a new D cam and followers and twin SU HS6, when I got it, it had a huge flat spot at lower revs, I replaced the RL needles with some SM's I had, put a 2 inch exhaust on , 1 muffler, and advanced the timing a bit, that made a big improvement, the engine has lots of power ( well enough for how I use this car ) at higher revs but still not much midrange power, the carbs have been rebuilt and are sound, the engine is low mileage and feels very sound.
Are there some more suitable needles? any other possibilities?
Or do i just put in a B20?
Thanks
Hans

Hans,

On you last question, "Or do i just put in a B20?".

If I remember correctly, Phil has stated that, in a 122, a B18 will outperform a B20, in some respects. Can't remember exactly how it was stated, but I'm curious about that, too, if Phil could elaborate.

gary
'67 122s - Strong B18B w/ S.U.s
'72 1800 ES - Strong B20F w/ D-jet.
'70 1800 E donor w/ 36K mile B20E w/ D-jet.
which I'm keeping for backup, or for one of two other ES's soon to be delivered.

I know my B18B 1800S would outrun a B20F 1800E with both in completely stock form. That's a dual SU, high CR B18 compared to an injected, low CR B20. The B20 clearly has more torque, but the B18 has a slight advantage if you're willing to rev for the power.

A low CR B18 will not be as quick, of course. My impression is that condition, tuning, and the driver have a lot more impact on performance than the B20's extra 208cc. For the motor in question here, there's definitely a tuning problem, so my approach would be to fix that instead of replacing it with a different motor that may very well still have a tuning problem.

First, a lack of low end power is what would be predicted from using a D cam in a carbed B18. Essentially too much duration and overlap for a carbed street engine
where low end and midrange are priorities. It being a B18 rather than a B20 makes it worse. ( If you ask which cam would be best I would tell you one of ours, since we developed them to solve these problems and still give good top end power. )

Second, for further tuning you need to determine whether the engine is now running rich or lean, and at which ends of the RPM range and throttle openings. There are probably 100 or more needle options. See the charts at http://www.rrocncr.org/technical/SUChart/SUChart.html
A quick way to tell which direction to go on the needles is to raise and lower them
in the seat. Measure the exact amount and raise in something like .050 or .100 increments. If the car runs better with the needles raised, then go to a richer needle on the chart. If it runs better with the needles lowered, then go to a leaner needle, or at least one leaner in the range you are trying to tune. If you find a good combination with the needle you have raised or lowered, you can match
the stations of the raised or lowered needles with one off the chart and make further adjustments to the low or high rpm range in he selection. You can also play with spring pressures to make the mixture leaner or richer.
The easiest way to do all of this is on a chassis dyno with a widebanc 02 sensor
for air/fuel ratio readings. On the dyno, with the air cleaners off, someone can also see what the amount of needle lift there is at the point where tuning is needed. This helps in choosing an alternative needle.

Joe Curto at http://www.geocities.com/jcurtoinc/ probably has the best selection of needles in the US. Tell him I referred you.

Very nice looking car!

John Parker
V-Performance.com

I'd say that it's pretty difficult to tell a car with a B18 from one with a B20 just by driving it.

I'd go with Phil's suggestion and try KD's

Regards

Pete

and if you get offered a good B20 at a bargain price, take it!
Nice looking car! but the steering wheel is on the right, er wrong side....
If you are in UK, I guess you know that the SU company now goes under the name
of Burlen.
--
George Downs, Bartlesville, Oklahoma, Central US

Hans,

The stock needles for a B18B with C cam are KD. With a D cam, I would try those first, and if they are still lean in the midrange, try DX needles.

The D cam was originally a mild racing cam for the B18 before it became the standard D-jet cam. Your B18 should go very well with this.

--Phil

Hans,

One small clarification. Phil's statement is correct "The stock needles for a B18B with C cam are KD".

Only thing is, unless Phil knows something I don't about your car, you more likely to have a B18A or B18D, if it's a stock, original '66 122.

Plus, I'm curious.
Does the VID Plate Type # begin with "132" or "133"?
And do you know, for sure, if the engine is original to the car?

If the Type # begins "133.., you have a B18B, high compression, standard on the 1800 of that year.

If the Type # begins "132... you have a B18A or B18D, low compression, standard on the 122 of that year.

I have a '67 122 w/ a rebuilt B18B in it, but I swapped it from a rust bucket '67 122.
That donor car, however, was a Type "133", w/ the B18B original from the factory.
I've now seen 2 or 3 other 122's that were "133 ..." types, w/ B18B's, but it's not too common.

All that said, I'm using KD needles in this B18B, and I'm very pleased with the performance. I don't know what cam is in there, or even if the displacement was increased when the rebuild took place, because, from the moment I bought the rust bucket for $150, the engine has been rock solid and VERY strong, so I haven't messed with it other than adjustments and tuning.

The KD's seem to be more responsive, across the range of RPMs, than the previous setup, which had one ZH and one SM. Whether that was a mismatched set of needles, or front and rear carbs, I don't know. I've heard of mismatched needles being used, front and rear, on purpose, but don't know if this was the case.

gary

Hi Gary, the VIN plate shows 12136 HL, I imagine the engine was a B18A however the head was changed in England before it came to NZ so that could be anything, don't know the compression, although it ran a lot better with some leftover 100 octane that I use in my race car.
I tried some ZH needles and they were worse than the SMs the RL needles had been put in by a tuning shop with a dyno but that setup was hopless too.
I am building a 2150cc B20 motor for another car at the momment and I'm quite tempted to put that in the amazon with an A cam and a single SU.
Hans

Hans,

I'm curious, why would you go to a single S.U. carb on a big bore B20?

gary

hehe, it probably probably does sound a bit strange, especially to the petrol heads on this board.
Its partly how I want to use the car, partly the bits I have lying around, I have 3 sets of ACL 92.5mm pistons, I have single carb setups, the car is intended for everyday around town and touring use, if it never goes over 4000 revs thats fine. It still has to go up steep hills though. A single carb sound be a lot easier to tune and keep tuned on a minimal maintenance regime, there may also be some emission considerations. Some years ago I had a B18A (85hp) amazon wagon, as I remember it that sort of power plus 25hp would be ideal for this car. Our speed limits are policed so tightly now that more than 100kph is either difficult or very costly. Also since I've been circuit racing I have lost a lot of desire to go quickly on the road ( well most of the time anyway )the B18 could be ported and fitted with twin 40mm sidedraft Delorttos
( currently attached on an Alfa racer I am keeping as a spare ) and then mounted in my PV, more suitable for spirited driving anyway. In the meantime I have some KD needles on order and will see if that does the job.
Hans