B21 and B23 Cams

Note: I copied this material from the Geocities page: “B21/B23 Cams” in early 2009 after Yahoo announced that it would be shutting down Geocities permanently. The site was originally written by someone else, and is presented here in its unabridged form.

B21/B23 Cams

This is a working version – let me know if you strongly think I need to tweak or proof read some figures. Thanks to Bishop, 245GTi , and a few other turbobricks.com members so far.

My apologies for having specs here taken at more than one checking clearance. I was aware this was a problem, but thought I had it under control…

Thanks to Scott of Delta cam Tacoma Washington USA for supplying measured specs on some stock cams.

Enem cam specifications are compiled from public web records: http://www.enem.se/katalog/kamaxlar/4.asp

They are also sold and known as Unitek cams, and a few further custom designs have been manufactured by Enem for Unitek resale…

One of the more common reasons for dispute between my figures and others’ is that people have used the “setting spec for intake opening point” from the Volvo factory manuals (and supplied in Haynes manuals). This is not the intake opening point that a cam manufacturer would supply or a machinist uses to check cam timing when assembling a bare block, and to further complicate things it is supplied by Volvo at varying clearance points from one cam to another.

Note, that as there is no rocker ratio in the bucket-type direct acting cams Volvo use, the durations cannot directly be compared to the older OHV Volvo engines, nor to cams ground for OHV domestics by suppliers such as Crane, Crower, Isky and CompCams. They also cannot be numerically compared “at face value” to engines using a rocker arm in combination with an overhead cam (Toyota 22r, Mercedes) or a translating-follower type geometry ( Ford 2.0 & 2.3l 4cyl, Nissan 240-280z inline six)

Certain grinds of used cams in good condition might be reground. Please e-mail me if you want to discuss doing this, as I have done my homework and can send you to the right places. I have had made up for resale several VX cam made from other cores, as well as a pure V on a slightly tighter lobe separation (107), an X on a wide lobe separation (111), and a tight lobe separation (105) short duration cam made from two M-exh lobes. It is possible to make some very interesting cams using just stock lobes (eg K lobe on 106 lobe separation for hard-core street naturally aspirated, or a very detailed incremental progression of turbo cams from other short duration factory cams). Though you might think that aftermarket cams are superior, the ability to customize cams, or make up a couple of reground cams to compare to each other for just the price of one Enem/Unitek cam offers greater possibility for homing in on the ideal spec for your build.

Some advice on knowing what the info in the charts means:

* the longer the duration the greater ultimate horsepower potential

* the duration at .020 rise is called advertised duration and is usually used to ‘name’ cams.

* the longer the duration the higher rpm the engine will have to spin before it becomes efficient

* a duration change of six to eight degrees is noticeable in the way a car runs. If the overlap has been changed by 6 to 8 degrees that counts as well, even if it is caused by any combination of a couple degrees of lobe center change, a couple degrees duration change, or a couple degrees of advance or retard (the latter will change the timing of the overlap relative to the crankshaft).

* the narrower (smaller numerically, also called ‘tighter’) the lobe separation (the average of the two lobe center figures) the more powerful the cam will be in its power range, but the lower the mileage, and the higher the emissions. It also will likely have a slightly rougher idle, and slightly weaker throttle response at really low RPM, even if it’s not a long duration cam. In a Turbo application, a narrower lobe separation is not desireable beacuse of differences in the dynamics of cylinder filling and emptying. Generally a turbo should use 110-116 lobe separation.

* conversely, the wider the lobe separation, the power curve will be wider, but not as high peaking. However it will have other advantages. Most all original equipment cams use a wider lobe separation, and as stated, Turbo’s are ‘forced to’.

In Non turbo applications, the difference in torque curve will “generally” follow the pattern shown here

Click on any of the following to be taken down to the body of the page where each is detailed.

Hit “Back” on your browser to return to the top of the page
Volvo ‘M’ , Volvo ‘L’ , Volvo ‘T’ , Volvo ‘A’ , Volvo ‘B’ , Volvo ‘VX’ , Volvo ‘K’ , Enem V15 (256)

intake
Duration
exhaust
Duration
Overlap lift
intake
lift
exhaust
lobe centers
intk / exh
degrees
ret/adv
valve events
intake / exhaust
btdc abdc bbdc atdc
205@.050″ 222@.050″ -10 .374 / 9.5 mm .411 / 10.4 mm 108 117 4.3 adv -5     30.4       47.2    -5

OE M grind- supplied in naturally aspirated U.S Spec 23f and b230f for 83 and onward, therefore quite common- Its purpose was to produce low emissions and acceptable low to mid range power. Volvo list two part numbers – 1336779 and 1317745- presumably for the difference between having the cam drive slot and the earlier casting without. It is a dual pattern cam favouring the exhaust. These revised spec shown are from running a used cam in a “Cam Doctor” fixture/PC spreadsheet analysis combo Feb 2004. There is a spec produced of lobe area. It is 27.1 inch*degree for intake and 31.97″*deg exhaust, if that’s useful to anyone. My apologies for the partially incorrect figures previously posted here.

intake
Duration
exhaust
Duration
Overlap lift
intake
lift
exhaust
lobe centers
intk / exh
degrees
ret/adv
valve events
intake / exhaust
btdc abdc bbdc atdc
215@.050″ 215@.050″ -6.5 .385 / 9.8 mm .385 / 9.8 mm 111 111 zero -3     39       39    -3

OE L grind- The first generation of U.S. only “smog grinds”. Specified for California for 80-82 and federal 81-82. Superceded by the ‘m’ after 82. It has less lift than almost any other. This is a cam to change out for performance useage. Volvo p/n is 1306887. Checked by fixture Feb 2004, specs changed to @.050″ checking-clearance for duration figures. Lobe area 29.25inch*degree.

intake
Duration
exhaust
Duration
Overlap lift
intake
lift
exhaust
lobe centers
intk / exh
degrees
ret/adv
valve events
intake / exhaust
btdc abdc bbdc atdc
212@.050 212@.050 -6.6 .388 / 9.86mm .388 / 9.86mm 109.3 zero -3.3     35       35    -3.3

OE “T” grind – The U.S. spec turbo cam. In use, it has been clearly proven that this cam causes the torque curve to to fall-off rapidly at mid to high rpm. We can only guess Volvo used a short duration as a compromise to hide the early turbo’s lack of off boost power and possibly to suit the U.S. market, and those generally, who bought eighties and nineties turbos as “luxury” cars. (Some ‘international spec turbo’s used the ‘A’ cam and more compression). The American market in general sought low end power and quick throttle response, which despite the disadvantages, this cam produces.

This cam has been tried by several TurboBrick.com members with some small success in non-turbo applications where the priority is torque at low RPM.

I have mixed feeling about revising the specs based on the CamDoctor fixture measurement. It previously was listed as having a smaller exhaust lobe than intake. The measurement apparently doesn’t show that. It’s also apparently not as ‘small’ in comparative duration as had previously been thought. I’m going to measure a loose T cam I have to see if I can verify a single or dual pattern, and report back. The CamDoctor reported a lobe area of 29.3inch*degrees.

intake
Duration
exhaust
Duration
Overlap lift
intake
lift
exhaust
lobe centers
intk / exh
degrees
ret/adv
valve events
intake / exhaust
btdc abdc bbdc atdc
226@.050 226@.050 9.4 .412 / 10.45 mm .412 / 10.45 mm 108 / 108 zero 4.7     41       42    4.7


OE A grind-Note that I have come to believe the specification was ‘wrong’ up here for the past year or so, insofar as the 241 degree duration spec seen elsewhere is at a lesser checking clearance, and thus can’t be compared directly to other specs shown. Also I’ve seen a 107 lobe separation noted in several places, but the CamDoctor test came up with 108.4, and a lobe area of 32.6inch*degrees.

Used in naturally aspirated B21, B23 and b230 with several styles of carburation and injection. Not offered in the U.S. , but offered in Canada 80-84. A nice upgrade on stock b21f and b23f, giving a boost in torque from about 2300rpm up, compared to ‘l’ and ‘m’ cams. My mother who is in her 50′s, & not an aggressive driver, had occasion to ‘blind’ test an A vs an M, and could tell a power increase in regular driving.

On turbos, it should be considered nearly the largest practical cam with an early 240 turbo with stock or larger turbo and stock compression. On the other hand, it’s been found to be very good with raised compression and/or a smaller turbo, as used in the 700/900, or if you have changed your engine specification during rebuild. However, if intending to use an A in a 700/900, the Canadian spec cams found on Ebay, etc do not come grooved to drive the distributor. In theory, through Volvo parts channels this cam is available in both core styles- 1219706 & the rarer & more desirable grooved 1376767. The other place a grooved A can be sourced is from Penta Aq131 model b230-based marine engines (there seems to have been a b21/23 based AQ131, and these will not have grooves- it has to have an OE black cam cover.).


intake
Duration
exhaust
Duration
Overlap lift
intake
lift
exhaust
lobe centers
intk / exh
degrees
ret
valve events
intake / exhaust
btdc abdc bbdc atdc
229@.050 229@.050 14 .417 / 10.6 mm .417 / 10.6 mm 108.5 / 107 0.75 ° ret 7     42       42    7

OE ‘B’ grind - I had previous info here that was taken at a different checking clearance than I am now using, so though the VX has changed relative to other cams, the relationship between the remaining cams is actually unchanged, just different measurement giving different numeric descriptions. However in this case, the lobe separation figures were proved wrong by CamDoctor analysis, which is an important change. With the new information, the B seems more appealing.

intake
Duration
exhaust
Duration
Overlap lift
intake
lift
exhaust
lobe centers
intk / exh
degrees
ret/adv
valve events
intake / exhaust
btdc abdc bbdc atdc
238 236 14.6 .442 / 11.23 mm .440 / 11.2 mm 111 / 110.5 zero 7.3     50.9       47.6    7.3

OE VX grind . A lot of confusion exists regarding the origin and availability of this cam. It seems it was originally supplied in some b230 engines late in production and only in Europe. It was made up from the lobes of the ‘v’ intake and the ‘x’ exhaust. It has only been available as an aftermarket installation in North America, but has proven popular as an enthusiast upgrade. It has been proven in practice to be an effective turbo cam, but is slightly too large a jump for many, especially 700 cars with a non-removable rev limit. It’s been found this can be compensated for by advancing the cam 3 to 4 degrees, changing the centerlines to 107-108 / 114. Apparently some were actually ground this way, but all currently available ones require some sort of gear which repositions them at that degree-point. As an alternative to expensive adjustable gears, two Canadian Turbobricks.com members developed a jig that allows them to redrill the factory gear at alternative positions for far less expense.

For an alternative that is at approximately the 3/4 point between T and VX I suggest trying an ‘A’ grind, available used from Canada. Email me- I usually have several caustic clean used A-cams for US$30 plus US$20 mail.

intake
Duration
exhaust
Duration
Overlap lift
intake
lift
exhaust
lobe centers
intk / exh
degrees
ret/adv
valve events
intake / exhaust
btdc abdc bbdc atdc
253 250 31.5 .471 / 11.95 mm .471/ 11.95 mm 111/111 zero

Volvo OE K grind- Used in high output, high compression b23e engines in Europe and Canada 81-83. Peak torque point was pushed to 4500 rpm. I sometimes have these for sale- US$59 plus US$20 mailing.


intake
Duration
exhaust
Duration
Overlap lift
intake
lift
exhaust
lobe centers
intk / exh
degrees
ret/adv
valve events
intake / exhaust
btdc abdc bbdc atdc
256 256 38 .469 /11.9mm .469 /11.9mm see text zero 19     57       57    19

Enem v15 (256)-
Grown popular enough for me to pull this from the aftermarket section below, this grind has been known as the Unitek Phase One, or Enem V15, and is basically what IPD sells as a Turbo/Sport. Also available from OJ Rallye.

Enem in Sweden, who manufacture these, make this grind available with wider lobe centers for turbo use, or narrower for non-turbo use. See discussion near the top of the page on the compromise involved. The IPD grind that is extremely similar to this has a lobe separation halfway between the non-turbo and turbo Enem specification.

For aftermarket performance purposes, it is more useful to know what lobe masters are available than to read exact valve events, as you have the freedom to specify your chosen lobe separation and advance.

I am now listing the larger cams strictly as lobe masters, as well as all factory lobes for comparison or for custom street applications which may not deviate far from stock.
Special thanks to Janne Carneborn of Enem for his patience and willingness to share technical details. As is mentioned elsewhere on this page, the success of both Unitek’s product range (entirely) and IPd’s recent Turbo/Sport cam (one step removed) can be credited to Enem supply and/or engineering.

LOBE
NAME
Duration @
0.050″ / 1.27mm
Duration @
0.022″ / 0.55mm
Duration @
0.020″ / 0.51mm
Duration @
0.015″ / 0.38mm
lift
inch
lift
MM
comments
Volvo ‘M’ int 205 ? ? ? .370″ 9.4 mm
Volvo ‘T’ 212 ? ? ? .388″ 9.86 mm
Volvo ‘L’ 215 ? ? ? .384″ 9.8 mm
Volvo ‘M’ exh 223 ? 258 ? .410″ 10.4 mm
Volvo ‘A’ 226 ? ? ? .412″ 10.45 mm
Enem V15 ? 256 ? ? .469″ 11.9 mm
Volvo ‘B’ 229 ? ? ? .417″ 10.6 mm
Volvo ‘Y’ 232 ? ? ? .407″ 10.35 mm
Volvo ‘X’ 236 ? 274 ? .440″ 11.2 mm
Volvo V 238 ? 279 ? .448″ 11.37 mm
Volvo ‘D’ 253 ? ? ? .441″ 11.2 mm
Enem V16 ? 268 ? ? .480″ 12.2 mm
Volvo ‘K’ exh 250 ? ? ? .470″ 11.92 mm
Volvo ‘Kint/Hexh 253 ? ? ? .471″ 11.94 mm
Enem K13 ? 280 ? ? .492″ 12.5 mm
K G 001 ? ? ? 290 .449″ 11.4 mm
Volvo ‘H’ int 258 ? ? ? .472″ 12 mm
K G 002 ? ? ? 300 .468″ 11.9 mm
Enem K15 ? 292 ? ? .492″ 12.5 mm
Enem M1 ? 296 ? ? .457″ 11.6 mm
K G 003 ? ? ? 304 .433″ 11.0 mm
Enem C2 (263)? 292 ? ? .547″ 13.9 mm
Enem K14 ? 304 ? ? .492″ 12.5 mm
Volvo GT6 ? ? 312/306 ? .492″ 12.5 mm
Enem K20 ? 300 ? ? .512″ 13.0 mm
Enem K21 ? 308 ? ? .531″ 13.5 mm
Enem K25 ? 308 ? ? .571″ 14.5 mm for 38.5mm bucket
Enem Z6 ? 312 ? ? .551″ 14.0 mm
Enem K24 ? 316 ? ? .571″ 14.5 mm for 38.5mm bucket
Enem K27 ? 316 ? ? .610″ 15.5 mm for 38.5mm bucket
Enem K22 ? 320 ? ? .551″ 14.0 mm
Enem K26 ? 324 ? ? .571″ 14.5 mm for 38.5mm bucket
Enem K28 ? 324 ? ? .610″ 15.5 mm for 38.5mm bucket
LOBE
NAME
Duration @
0.050″ / 1.27mm
Duration @
0.022″ / 0.55mm
Duration @
0.020″ / 0.51mm
Duration @
0.015″ / 0.38mm
lift
inch
lift
MM
comments