Volvo B27A User manual

•^
ServiceManual
Repairs
andmaintenance
Section2 (21)
Reconditioning
engine
B 27, B 28
2601975-1983
*#

books4cars.com
485037thAvenueSouth
Seattle, WA98118 U.SA
B27A-B27E-B27F-B28A-B28E-B28F
1
Whatdothesedesignationsmean?
B28E
A= carburettedengine
E= fuelinjectedengine
F= fuelinjectedengine"USAmodels"
1
The B 28isinprinciplea B 27witha largerbore.
28(27)= ce
•
B= petrol (g«
Enginetype
B27A
B28A
B27E
B28E
B27F
B28F
pacity
jsoline)
Modelyear
1976-1979
1980-1982
1975-1980
1981-1983
1976-1979
1980-1982
Volvosaresoldinversionsadaptedfordifferentmarkets.
Theseadaptionsdependonmanyfactorsincludinglegal,
taxationandmarketrequirements.
Thismanualmaythereforeshowillustrationsandtext
whichdonotapplytocarsinyourcountry.

Group 21 Reconditioning engine
r
Contents
Contents
Important information
Specifications
Specialtools
Page
...2
...2
..11
Threadrepairs Operation
A 1-1414
Reconditioningengine
DisassemblyB 1-19
CleaningandinspectionC 1-41
AssemblyD 1-35
Cylinderhead,reconditioningE 1-26
Assembly(cont.)F 1-33
20
26
38
46
52
Indexpage62
r
r
Thismanualdealsexclusivelywiththeoverhaulofthe
engine.
Forworkcarriedoutontheenginewhenfittedinthecar,
andforengineremovalandinstallation,pleaserefertothe
separatemanuals.
Ordernumber:TP30447/1
Wereservetherighttomakealterations.

Group 21 Reconditioning engine
Important information
Importantinformation
Tighteningtorques
Nearlyallofthe B 27/28engineismadeofaluminium
alloy. The threads are tappeddirectlyintothealloy.For
thisreasonitisextremelyimportantthatallofthebolts
aretightenedtospecifiedtorque.
Twotypesoftighteningtorquesareusedinthismanu-
al:
I. Tighteningtorque40 Nm (30 ftlbs) = a torque
wrenchmustbeused.
II. Tighteningtorque 40 Nm (30 ft.lbs)= correctvalue,
howeveritisnotnecessarytousea torque
wrench.
Specifications
Group20General
Engineserialnumberandpartnumber
Locatedona plateinfrontoftheoilfilter.
On B 28E/F 1981- models:locatedontherearofthe
right-handcylinder head, showsthelastthreedigitsof
thepartnumber.

Group 21 Reconditioning engine
f^
Specifications
Group21Engineblock
CYLINDERHEAD
Height New-
111.07 mm(4.373in)
Max.warpis0.05mmover100mm.
NOTE! Donotlevela warpedcylinderhead,replaceit.
Cylinderheadgasketthickness 1.14-1.50 mm (0.045-0.059 in)
CYLINDERBLOCK
Cylinderliners
Pistonsandlinersarematchedsets.
Cylinderlinersaremarkedby1,2 or3 cutsintheupperedgeof
theliner. B27B 27
Bore, linersmarked1 (A-markedpiston)88.00-88.01mm91.00-91.01mm
(3.4646-3.4650 in) (3.5826-3.5830 in)
2(B-markedpiston)88.01-88.02mm 91.01-91.02 mm
(3.4650-3.4654in)(3.5830-3.5835in)
3(C-markedpiston)88.02-88.03mm 91.02-91.03mm
(3.4654-3.4657in)(3.5835-3.5838in)
Linerheightaboveblockface 0.16-0.23 mm(0.0063-0.009in)
Shimsforadjustmentoflinerheight:
thickness,bluepaintmarking0.070-0.105mm(0.0027-0.0041in)
whitepaintmarking 0.085-0.120 mm (0.0033-0.0047 in)
redpaintmarking0.105-0.140mm(0.0041-0.0055in)
yellowpaintmarking0.130-0.165mm(0.0051-0.0064in)
PISTONS
PistonsforB27
Pistonsandlinersarematchedsets.
Twodifferentmanufacturerssupplypistons,seenextpage
forspecifications.
f \
Demolin
Mahle

Group 21 Reconditioning engine
Specifications
DEMOLIN PISTONS(B27)B27A 1976-1979
B27E1975-1978
B27F 19791976-1978
Height,overall74mm(2.9134in)63.4mm(2.9960in)
fromgudgeonpincentretopistoncrown40mm(1.5748in)39.4mm(1.5512in)
Weight445±3gram
Maxweightdifferencebetweenpistonsinsameengine6 gram
Pistonfloat 0.090-0.110 mm(0.0035-0.0043in)
Pistondiameter,A-markedpistons 87.900-87.910 mm (3.4606-3.4610 in)
B-markedpistons 87.910-87.920 mm (3.4610-3.4614 in)
C-markedpistons 87.920-87.930 mm (3.4614-3.4618 in)
Pistondiameterismeasuredatrightanglestogudgeonpin
boreand:
11mm(0.43in)fromloweredgeofpistonfor B27F
1976-1978
8.5mm(0.33in)fromloweredgeofoilscraperringforother
engines.
Diameter,gudgeonpinbore:
MarkingpistonMarkinggudgeonpin
1Blue23.514-23.517mm(0.9257-0.9259in)
2White23.511-23.514mm(0.9256-0.9257in)
3Red 23.508-23.511 mm(0.9255-0.9256in)
MAHLEPISTONS(B27) B 27 A 1976-1979
B27E 1975-1978 1979-1980
B27F 1979 1976-1978
Height,overall63,4mm62.2mm65.3mm
(2.4960in)(2.4488in)(2.5709in)
fromgudgeonpincentretopistoncrown39.4mm38.2mm41.3mm
(1.5521in)(1.5039in)(1.6260in)
Weight445±3gram
Maxweightdifferencebetweenpistonsinsameengine6 gram
Pistonfloat0.020-0.040mm(0.0008-0.0016in)
Pistondiameter,A-markedpistons87.970-87.980mm(3.4634-3.4638in)
B-markedpistons87.980-87.990mm(3.4638-3.4642in)
C-markedpistons87.990-88.000mm(3.4642-3.4646in)
D
-ts.
Pistondiameterismeasuredatright-anglestogudgeonpin
bore, 8 mm(0.31in)frombottomedge.
Diameter,gudgeonpinbore:
Marking, pistonMarking,gudgeonpin
BlueBlue23.510 mm-23.513 mm (0.9255-0.9257 in)
WhiteWhite23.507-23.510mm (0.9254-0.9255 in)
RedRed23.504-23.507mm(0.9253-0.9254in)
4

Group 21 Reconditioning engine
Specifications
PistonsforB28
Pistonsandlinersarematchedsets.
Only Mahle pistonsareinuse.
Weight455±3grams
Maxweightdifferencebetweenpistonsinsameengine6 grams
Height,overallA-andF-engines62.8mm(2.4724in)
E-engine65.3mm(2.5709in)
fromgudgeonpincentretopistoncrown
A-andF-engines38.8mm(1.5276in)
E-engine41.3mm(1.6260in)
Pistonfloat 0.020-0.040 mm (0.0007-0.0015 in)
Pistondiameter,A-markedpistons90.970-90.980mm (3.5814-3.5818 in)
B-markedpistons90.980-90.990mm(3.5818-3.5822in)
C-markedpistons90.990-91.000mm(3.5822-3.5826in)
Pistondiameterismeasuredatright-anglestogudgeonpin
bore, 8 mm(0.31in)frombottomedge.
Diameter,gudgeonpinbore:
Marking, pistonMarking,gudgeonpin
BlueBlue 23.510-23.513 mm(0.9255-0.9257in)
WhiteWhite23.507-23.510mm (0.9254-0.9255 in)
RedRed23.504-23.507mm(0.9253-0.9254in)
Pistonrings
15mm Ringgapmeasured15mm(0.6in)from
loweredgeofcylinder
Height. mm
in
mm
in
3)
mm
in
Upper
compression
ring
1.478-1.490
9.0582-0.0587
0.045-0.074
0.0017-0.0029
0.40-0.60
0.0157-0.0236
Lower
compression
ring
1.978-1.990
0.0779-0.0783
0.025-0.054
0.0009-0.0212
0.40-0.60
0.0157-0.0236
Oilring
2.629-2.731
0.1035-0.1075
0.009-0.233
0.0003-0.0091
0.38-1.45
0.0150-0.0570
Sideclearance(measuredwithringonpiston)mm
Ringgapwhencheckedin91mm(3.5826in)cylinder(B28),
88mm(3.4646in)(B27),seefigmm
Gudgeon(piston)pins
Diameter
Marking, Marking,piston
gudgeonpin
BlueBlue(1) 23.500-23.497 mm(0.9251-0.9250in)
WhiteWhite(2)23.497-23.494mm(0.9250-0.9249in)
RedRed(3)23.494-23.491mm(0.9249-0.9248in)
Clearanceinconnectingrod0.020-0.041mm (0.0007-0.0016 in)
piston, Mahle0.010-0.016mm(0.0003-0.0006in)
Demolin 0.014-0.020mm(0.0006-0.0008in)

Group 21 Reconditioning engine
Specifications
VALVESYSTEM
Valve Clearances (varieswithenginetype)
Valveclearancemm(in)
Intakevalves,coldengine
warmengine
Exhaustvalve,coldengine
warmengine
Enginetype- modelyear
B27A 1976-1979
B 28A 1980
1981-1982
B27 E 1975-1978
1979-1980 Sweden+ Australia
1979-1980 Othermarkets
B28E1981-1983
B27 F1976-1979
B28 F1980
1981-1982
Type1
0.10-0.15 (0.004-0.006)
0.15-0.20(0.006-0.008)
0.25-0.30 (0.010-0.012)
0.30-0.35 (0.012-0.014)
X
X
X
X
X
X
X
Type 2
0.20-0.25 (0.008-0.010)
0.25-0.30 (0.010-0.012)
0.30-0.35 (0.012-0.014)
0.35-0.40(0.014-0.016)
X
X
X
Valvesmm(in)
29,5°
£
44(1.7322)
7.965-7.980
(0.3135-0.3141)
^
26.5
(1.0433)
Tapered
Intakevalves
7.975-7.990
(0.3139-0.3145)
44.5'
59"
37
iT (1.4566)
32(1.2598)'
Exhaustvalves
7.965-7.980
(0.3135-0.3141)
Valveseatsmm(in)
1.7-2.1 mm(0.0669-0.0826)
1.3-1.7 mm (0.0511-0.0669)
Intakevalveseat
Earlytypes Intakevalveseat
Latetypes(venturi seat):15° and60°are
correctanglestoreduceseatwidth.
2.0-2.4 mm(0.0787-0.0944)
Exhaustvalveseat

Group 21 Reconditioning engine
Specifications
Note! Whenreplacingvalveseats:theinterferencebetween
thevalveseatanditsboreinthecylinderheadmustbe
0.070-0.134 mm,(0.0027-0.0052in),i.e.thevalveseatdiame-
termustbe0.070-0.134mmgreaterthanthediameterofthe
boreinthecylinderhead.
Valveseatsareavailableinthreeoversizes.
Valveguides mm (in)
Length50.1-51.3(1.2725-1.3030)
Inner diameter 8.000-8.022 (0.3149-0.3158)
Press-inmeasurementtocylinderheadcontactsurfaceagainst
block:
intake39.5-40.5(1.5551-1.5944)
exhaust36.9-37.9(1.4527-1.4921)
Valveguidesareavailableinthreeoversizes,andaremarked
withgrooves.
Standard
Oversize1
2
3
Marking
Nogroove
1groove
2grooves
3grooves
Reamerforseat
5166
5167
5168
/"*
Valve springs
Twotypesofvalvespringsareinuse.Thespringsarecolourcoded
asfollows:
Greysprings:
B27A 1976-1979
B27E 1975-1978
1979-1980 Sweden+ Australia
B27F 1976-1979
Greensprings:
B28A 1980-1982
B27E 1979-1980 (excludingSweden,Australia)
B28E
B28F
1981-1982
1980-1982
Greysprings:
Length
mm
47.2
40.0
32.2
in
1.86
1.57
1.27
Load
N(kp)
0
233-268
(23.3-26.8)
521-585
(52.1-58.5)
lbs.
0
52-60
116-131
Greensprings:
Length
mm
47.1
40.0
30.0
in
1.85
1.57
1.18
Load
N(kp)
0
23.0-26.6
613-689
(61.3-68.9)
lbs.
0
51-59
137-154

Group 21 Reconditioning engine
Specifications
Rockerarmmechanism
Therockerarmcontactsurfaceagainstthecamshaftissurface-hardenedandmustnotbeground.
Diameter,rockerarmshaft19.959-19.980mm (0.7857-0.7866 in)
Holediameter,rockerarm19.992-20.013mm (0.7870-0.7879 in)
Clearance,shaft-rockerarm0.012-0.054mm(0.0005-0.0021in)
TIMINGGEARS
Camshaft
Threetypesofcamshaftswithdifferentliftheights are inuse.
Thepartnumberismarkedonthefrontend.
Camshaft
Marking(partnumber),left
right.
Max.liftheight,leftmm
rightmm
Checkofcamshaftsetting(coldengine):
Adjustvalveclearanceon1stand6thintakevalvesto0.7
mm(0,027in),theintakevalvesshouldthenopenat,
1stBTDC
6thBTDC
Type1
7910 245522
(-143or-144)
7910 245412
5.144
(0.202in)
5.059
(0.199in)
9°±3°
7°±3°
Type 2
74 01269138
74 01269 139
6.004
(0.236in)
6.004
(0.236in)
9°±3°
9°±3°
Type3
74 01 269615
74 01 269616
5.96
(0.234 in)
5.96
(0.234in)
8°±3°
8°±3°
Enginetype
B27 A 1976-1979
B28 A 1980
1981-1982
B27E1975-1978
1979-1980Sweden4-Australia.
1979-1980 Othermarkets
X
X
B28E1981-1983.
B27F 1976-1979.
B28F1980
1981-1982.
Journaldiameter,countingfromfront(alltypes):mm(in)
1st40.440-40.465(1.5921-1.5931)
2nd41.040-41.065 (1.6157-1.6167)
3rd 41.640-41.665(1.6393-1.6403)
4th42.240-42.265(1.6629-1.6639)
Radialplay0.035-0.085(0.0013-0.0033)
Endfloat,new0.070-0.144(0.0027-0.0056)
max0.5(0.0196)

Group 21 Reconditioning engine
Specifications
CRANKMECHANISM
Crankshaft
Maxrun-out(measuredontwocentremainbearingjournals).0.02mm
Crankshaft,endfloat 0.070-0.270 mm
clearance(mainbearings)0.038-0.088mm
Crankjournals,sideclearance0.20-0.38mm
clearance0.030-0.080mm
Rearsealingringdiameter,standard79.926-80.000mm
undersized 79.726-79.800 mm
(0.0007in)
(0.0027-0.0106in)
(0.0014-0.0034 in)
(0.0078-0.0149in)
(0.0011-0.0031in)
(3.1466-3.1496in)
(3.1388-3.1417in)
r
Mainbearingjournals
Outofroundness,max0.007mm
Taper,max0.01mm
Diameter,standard70.043-70.062mm
undersized 69.743-69.762 mm
Mainbearingshells,thickness,standard 1.961-1.967 mm
oversized2.111-2.117mm
Widthofcrankshaftjournalforthrustbearing(rearmainbearing
journal):
standard 29.20-29.25 mm
oversized1 29.40-29.45mm
229.50-29.55mm
329.60-29.65mm
Thrustbearingwasher,thickness,standard 2.30-2.35 mm
oversized1 2.40-2.45 mm
2 2.45-2.50 mm
3 2.50-2.55 mm
(0.0002 in)
(0.0003 in)
(2.7575-2.7583 in)
(2.7457-2.7465 in)
(0.0772-0.0774 in)
(0.0831-0.0833 in)
(1.1496-1.
(1.1574-1.
(1.1614-1.
(1.1653-1.
(0.0905-0.
(0.0944-0.
(0.0964-0.
(0.0984-0,
1515 in)
1594 in)
1633 in)
1673 in)
0925 in)
0964 in)
0984 in)
1003 in)
Connectingrodbearingjournals
Outofroundness,max0.007mm
Taper,max0.01mm
Diameter,standard52.267-52.286mm
undersized 51.967-51.986 mm
Connectingrodbearingshells,thickness,standard 1.842-1.848 mm
undersized 1.992-1.998 mm
Bearingjournalwidth39.99-40.09mm
rr
TaperOutofroundness
(0.0002in)
(0.0003in)
(2.0577-2.0585in)
(2.0456-2.0466 in)
(0.0725-0.0727in)
(0.0784-0.0788 in)
(1.5744-1.5783in)
Connectingrods
Endfloatoncrankshaft(bothconrodsfitted)0.20-0.38mm
Lengthbetweencentres146.15mm
Maxweightdifferencebetweenconrodsinsameengine±2.5grams
(0.0078-0.0149in)
(5.7539in)
Flywheel
Axialthrow,max0.05mm
Radialthrow,max(measuredatdiameter282.4mm) 0.15 mm (0.0019in)
(0.0059in)

Group 21 Reconditioning engine
Specifications
TIGHTENINGTORQUES
Thetighteningtorquesshownbelowapplytooilednutsand
bolts.
Degreased(washed)partsmustbeoiledpriortoassembly.
Tightenallboltsinstagesaccordingtobelow:
1= 10 Nm (1 kpm= 7 ft.lbs)
2= 30 Nm (3kpm = 22ft.lbs)
3= 60Nm (6 kpm- 44ft.lbs)
4= Wait 10-15 minutes
5= Slackenbolts
6= 15-20 Nm (1.5-2.0 kpm= 11-15 ft.lbs)
7= Angle-tightento 113-117°
8= Warm-upenginetooperatingtemperature
9= Coolblock30minutes
10= Slacken and thenretighten boltsoneata time in specified
tighteningorder.
Retightenaccordingtostages6 and7.
Tighteningsequenceforcylinderheadbolts
# ®
o a
!
©
©
ii
®
»
Tighteningsequenceformainbearings(vialowercrankcase)
Mainbearings
Tightenallnutsinstages:
1= 30Nm(22ft.lbs)
=Slackennut1
=Tightennut1 to 30-35 Nm(22-26ft.lbs.)
=Angle-tightennut1 73°-77°
= Slackenandretightentheothernutsintheorder
specifiedinstages2-4.
Nm
Cylinderhead(seebelow)
Connectingrodbearings45-50
Crankshaftfrontend, 1975-1977160-180
1978- 240-280
ft. lbs.
33-37
118-133
177-207
40mm= 1.575in
45mm = 1.772in
1975-1977 1978-
Nm
Camshaftsprocket70-90
Flywheel(alwaysusenewbolts)45-50
Sparkplugs(donotoil) 12±2
Valvecover 15
ft. lbs.
52-66
33-37
9±1.5
11
10

Group 21 Reconditioning engine
Specifications
Group22Lubricatingsystem
OILPUMP
Endfloat0.025-0.084mm(0.0009-0.0033in)
Radialplaybetweencogtipandpumphousing
wall (excl. bearingplay) 0.110-0.185 mm(0.0043-0.0072in)
Backlash(excl.bearingplay)0.17-0.27mm (0.0066-0.0106 in)
Bearingplay,driveshaft 0.015-0.053 mm (0.0006-0.0021 in)
idlershaft 0.015-0.051 mm (0.0059-0.0020 in)
Reliefvalvespring,lengthatvariousloads:
unloaded89.5mm(3.52in)
loadedto88.3N (8.83kp= 20lbs)56.5-60.5mm(2.22-2.33in)
Specialtools
999 Description- use
1426-9
1801-3
2484-7
2520-8
4090-0
5029-7
Drift:fittingpilotbearingincrankshaft(latetype)
Standardhandle:usedwith5101and5953
Centeringdrift:clutch,M45/46gearboxes(earlytype)
Stand: usedwithfixture5099
Extractor:pilotbearing
Drift:fittingintakevalveseat
Continuedonpage12.
4090 11

Group 21 Reconditioning engine
Special tools
999 Description- use
5092-5
5093-3
5096-6
5098-2
5099-0
5101-4
5103-0
5108-9
5109-7
5111-3
5112-1
5113-9
5128-7
5129-5
5165-9
5166-7
5167-5
5168-3
5192-3
5218-6
5220-2
5224-4
5953-8
Combinedtools:(6parts) removing-fitting gudgeon(piston)pins 5128 and 5129 alsorequired
for Mahle pistons.
Retainer:(4x)forcylinderliners
Spacersleeve:mainbearings
Protractor:forangle-tighteningcylinderheadboltsandmainbearingnuts
Fixture:forengine.Usedwith2520
Drift:fittingpilotbearingincrankshaft(earlytype).Usedwith1801
Drift:fittingcrankshaftfrontoilseal
Drift:fittingvalveguide- intake
Drift:fittingvalveguide- exhaust
Centeringdrift:clutch,M45/46gearboxes(latetype)
Lockingsector:lockingflywheel
Centeringdrift:clutch,M50/51gearboxes
Pistonsupport:removinggudgeonpinfromMahlepiston.Usedwith5092
Pistonsupport:fittinggudgeonpininMahlepiston.Usedwith5092
Reamerkit:valveguides:contains5164(earlytype),5224(latetype),5166,5167and5168
Reamer:valveguideseatoversize1
Reamer:valveguideseatoversize2
Reamer:valveguideseatoversize3
Support:fordialindicator.Measuringcylinderlinerheightandpistonheight.Also5094canbe
used
Drift:removingvalveguides.Fittingoilsealonvalveguide
Drift:fittingvalveseat- exhaust
Reamer:cleaningvalveguides.Also5164canbeused
Drift:fittingcrankshaftrearoil seal. Usedwith1801
(y)(§)
5128 5129
5092-15092-25092-35092-45092-55092-6
IIG3U
5092 5093
5099
T MEA !•
Wz
^Mm
A i
1
^~-a
L„iffli 1801+5101
M| 1426
^tor^^^f -•*
z^^^j
5101

Group 21 Reconditioning engine
Special tools
5103
5108, 5109
5111
r
5112 5113
n
ggg* #iU
(y) (g)
5128 5129
5092-1 5092-25092-35092-45092-55092-6
110214
5128, 5129
5165 (5166. 5167, 5168) 5192 5218
5220
*i
5224 5953
13

Group 21 Reconditioning engine
Thread repairs
A.Threadrepairs
A1
General
Adamagedthreadcanusuallyberepairedwith a thread
insert. Threadinsertsandinstallationtoolsareavailable
fromVolvoParts.
Note! Somethreadscan/maynotberepairedwith
threadinserts,seenextpage.
A2
Installationtools
Toolstoinstallthreadrepairinsertsaresuppliedinkits.
Somethreadinsertsarealsoincludedinthekits.See
thetablebelow.
Note! Eachtoolcanbeorderedseparately.
Thread
M6x1
M7x1
M 8x1.25
M10x1.5
M 12x1.5
M 14x1.25
M 14x1.25
M 14x1.5
M 16x1.5
M 18x1.5
5/8"-
18UNF
Complete
kit
9985840-9
9985841-7
9985842-5
9985843-3
9985844-1
9985845-81
9985846-6
9985847-4
9985848-2
9985849-0
9985850-8
Contentsofcompletekit
TapA
9985802-9
9985806-0
9985810-2
9985814-4
9985818-5
9985823-5
9985826-8
998 5827-6
9985831-8
9985833-4
9985860-7
Tang B
9985803-7
9985807-8
998 5811-0
998 5815-1
9985819-3
2)
2)
2)
2)
2)
2)
MandrelC
9985804-5
9985808-6
9985812-8
9985816-9
9985820-1
9985824-3
9985824-3
9985828-4
3)
3)
3)
CrankD
998 5805-2
998 5809-4
9985813-6
9985817-7
9985821-9
9985825-0
9985825-0
9985829-2
3)
3)
3)
ToolE
4)
4)
4)
4)
4)
4)
4)
4)
9985832-6
9985834-2
9985861-5
Threadinserts
(10x)F
956014-5+
956015-2
948015-3+
941843-5
956018-6+
956019-4
956022-8+
956023-6
948094-8+
948095-5
948756-2
948756-2
948758-8
947847-0
947843-9
948755-4
Notes:
11
Designedespeciallyforsparkplugthreads(donotdrill).
21
Useflatnosedpliersorsimilar tool.
3)
Suppliedwithset.
4>
Tool998 5830-0 isnotsuppliedwithcompletekit,butmay
beorderedseparately.
14

Group 21 Reconditioning engine
/^-
Thread repairs
A3
Donotrepairthesethreads
(Threadsshownbelowcannotormustnotbere-
paired)
foroilfilter
Connectingrodbearingsbolts
Cylinderblock
Timinggearcase
Adjustmentscrews
Idle adjustmentscrew
Lowersectionofair-fuelcontrolunit
B27E 1979-, B 28E, B 27/28F
Idleadjustmentscrew
IntakemanifoldB27/B28 Allconicalthreadssuchasplugsandnipplesinintakemani-
fold(alsoB 28/B28A)
75

Group 21 Reconditioning engine
Thread repairs
A4
Threadrepairinsert,
drilldiameter
0
ThreadLengthmm
M 6x1 9.0
12.0
M7x1 10.5
14.0
M8x1.258.0
11.4
16.0
M 10x1.510.0
15.0
20.0
25.0
M 12x1.512.0
24.0
30.0
M14x1.2514.5
M14x1.5 10.0
M 16x1.512.0
Mx18x1.513.5
5/88"x18UNF 8.0
P/N
956014-5
956015-2
948015-3
941843-5
956017-8
956018-6
956019-4
956021-0
956022-8
956023-6
956024-4
948094-8
948095-5
956028-5
948756-2
948758-8
947847-0
947843-9
948755-4
Drilldiamm
6.3
6.3
7.3
7.3
8.4
8.4
8.4
10.5
10.5
10.5
10.5
12.5
12.5
12.5
14.3
14.5
16.5
18.5
16.4
16
Combinationtap
Tapsection
Reamersection
Guide
A5
Repairingsparkplugthreads
Cylinderheadmustberemovedfirst.Tapholefromin-
sidetoavoiddamagingseatforspark plug.
Donotdrillthehole.Usetap9985823-5.
Re-cutoldthreadsonly.Donotcutfurtherinto
cylinderhead.Sparkplugboremustnotbethreaded
alongentirelength.
Screwinthreadinsert(P/N948756-2).

Group 21 Reconditioning engine
Thread repairs
Installingthreadinserts
Thread
Threaddepth
Drillingdepth
A6
Drillingdepth
Selectdrillsize,tapandinsert
Measurelengthandthreadofoldhole.
A7
Taphole
NOTE! Specialinstructionsforsparkplugholes,see
page16.
Measuredepthofhole.Drilloutholetothisdepth.
Cutthescrewthreadtosucha depththatthethread
insertmakescontactwithfullycutscrewthreadalong
itsentirelength.
Cleanthehole.
A8
Assembleinstallationtool
M6-M14threads:fitcorrectmandrelandcrankinin-
stallationtool9985830-0.
M16andcoarserthreads:usetheprescribedcomplete
installation tool.
17

Group 27Reconditioning engine
Thread repairs
Tang
Mandrel
Crank
A9
Fitthreadinsertininstallationtool
Fitthethreadinsertinthetoolwiththetangfacing
downwards.
Turnthecrankclockwiseuntilthetangofthethread
insertengagestheslotinthecrank.
Withoutpressing,screwthethreadinsertintothe
mandreluntilthefirstthreadoftheinsertisflushwith
theopeningofthemandrel.
AW
Installthreadinsert
Holdthetoolverticallyabovethecentreofthehole.
Withoutpressing,screwinthethreadinsertuntilthe
topthreadoftheinsertisatleast1/2 a threadbelowthe
workingsurface(0.5x pitch).Theinsertmustnotbe
screwedintothebottomotherwiseitwillnotbepos-
sibletobreakoffthetang.
AH
Breakofftang
M16-M12 threads: usethetangbreakerintheinstalla-
tionkit.
M14and coarser threads: useapairof flatnosedpliers
tobreakoffthetangdownwards.
Removethetangfromthehole.
18