Ser­vice Bay

The life and times of the en­gine which was de­vel­oped for the avant garde Rover p6.

Classics Monthly - - Contents - WORDS AN­DREW EVERETT

In­side the four-cylin­der en­gine which pro­vided the power for the in­no­va­tive and still pop­u­lar Rover P6.

I t’sa mys­tery why the Rover P6 has taken so long to climb in value when it was so highly re­garded for so long. Per­haps it’s the high sur­vival rate com­pared to oth­ers, but ei­ther way, the 2000 has been around for­ever as a de­cent use­able clas­sic car.

The Rover 2000 en­gine was a pretty so­phis­ti­cated bit of kit for 1963, and whilst it lacked the smooth­ness of the six-cylin­der Tri­umph 2000 en­gine, power out­puts of 90 bhp at 5000 rpm for the 2000 and 114 bhp at 5500 rpm for the twin car­bu­ret­tor TC were very good for the era - torque was 126 lbf.ft at 3500 rpm. Launched in late 1963 and win­ning the first ever Car of the Year tro­phy in 1964, the 2000 was in­tended to be a stand­alone model but Rover were al­ways go­ing to de­velop a higher per­for­mance twin car­bu­ret­tor ver­sion – this was launched in 1966 for ex­port mar­kets only but by late that year, Rover re­lented and launched the 114 bhp TC model in the UK.

Ba­sis of the 2000 en­gine is a cast iron block with 85.7 mm bores and sup­ports for a five bear­ing crank. The crank was a forged steel item (no cast iron here) with a stroke of 85.7 mm also, mak­ing this en­gine com­pletely ‘square’ with a ca­pac­ity of 1978cc. Up top was a cast al­loy cross­flow cylin­der head with a sin­gle over­head camshaft that runs in five bear­ings and which is driven by a Reynolds two stage du­plex tim­ing chain. The SC (sin­gle carb) ver­sion had part of the in­let man­i­fold cast into the head - in essence, there is still a re­mov­able man­i­fold but the cam sits so far to the left that there are very long in­let ports, all of which help the 2000 en­gine de­velop ex­cel­lent torque.

To aid qual­ity con­trol (this is be­fore BL don’t for­get), the iron block had de­tach­able steel side cov­ers so that the qual­ity of the block cast­ings around the wa­ter­ways could be mon­i­tored. The tim­ing chain is ten­sioned by hy­draulic ten­sion­ers and the TC ver­sions have dou­ble valve springs and all 2000 en­gines had a flat cylin­der head and pis­tons with both deep dishes and gen­er­ous valve cut outs. Pis­tons var­ied from the SC to the TC with com­pres­sion ra­tios of 9:1 for the SC and 10:1 for the TC that fa­mously re­quired the use of five star fuel.

Sturdy con­nect­ing rods are used, made from EN16 steel and which have hor­i­zon­tally cut big end caps that are se­cured by high ten­sile studs with nuts - an­other mark of a qual­ity en­gine when most mass pro­duced stuff used bolts with steel lock tabs.

The fin­ish­ing touch was a smooth cast al­loy cam cover se­cured by three nuts that act on

three studs in­te­gral with bear­ing caps 1, 3 and 5. Like­wise, the sump is cast al­loy as well whilst the dis­trib­u­tor runs off the aux­il­iary shaft. Fu­elling was taken care of by an SU HD8 car­bu­ret­tor on stan­dard cars, and twin SU HS8 carbs on the TC ver­sion.

De­signed from scratch with no parts taken from the P4 or P5, the new P6 en­gine was a su­perb thing built to high stan­dards and ca­pa­ble of a long life.

For 1973, the 2000 was re­placed by a new 2200 model, both as an SC and a TC. The ex­tra ca­pac­ity of 2205 cc was achieved by en­larg­ing the bore to 90.5 mm whilst the crank­shaft stroke re­mained as be­fore. Power was about the same as be­fore and the 2200 ma­jored on torque rather than a power in­crease - the SC de­vel­oped 93 bhp at 5000 rpm on a 9:1 com­pres­sion ra­tio,and 126 ft.lb at 2500 rpm whilst the twin car­bu­ret­tor 2200 TC de­vel­oped 115 bhp at 5000 rpm, and gave 135 ft.lb of torque at 3000 rpm on a com­pres­sion ra­tio of 9:1 also - by the this time the car­bu­ret­tors be­ing used were of the new HIF (hor­i­zon­tal in­te­gral float) type, the SU HIF6.

In pro­duc­tion un­til March 1977 when P6 pro­duc­tion fi­nally ended, the P6 en­gine was built for 14 years yet didn’t see ser­vice in other Rover prod­ucts.

The 2000 and 2200 were ef­fec­tively re­placed by the SD1 2300 and 2600 cars that ap­peared six months af­ter P6 pro­duc­tion ended, but they were blighted with re­li­a­bil­ity prob­lems and never gained the rep­u­ta­tion built up by the four cylin­der P6.

FIVE CYLIN­DERS, A DECADE BE­FORE AUDI

In 1964, a year af­ter the 2000 launch, Spen King along with Gor­don Ash­ford, Jack Swaine and Bryan Sil­vester as well as Mike Lewis and Erin Bran­son looked into a six cylin­der ver­sion of the 2000’s en­gine to be made on the same tool­ing as the four. How­ever, the 2000 en­gine was al­ready fairly heavy for a four and a straight six ver­sion was just too long and too heavy. So five cylin­ders be­came a com­pro­mise idea and the first blocks were made sim­ply by cut­ting up two 2000 blocks: one had only cylin­der cut off the front and the other was cut in half with the two sec­tions be­ing sent to Bari­mar to be spe­cially cast iron welded to­gether be­fore be­ing ma­chined. At four inches longer than the four cylin­der and 100 lb heav­ier, the new 2500 en­gine was a pro­duc­tion re­al­ity and it could be fit­ted into a stan­dard 2000 body with­out mod­i­fi­ca­tion. Whilst two com­plete en­gines were built and tested, Rover was still some way away from get­ting the en­gine to run smoothly enough. With four-cylin­der en­gines, a power

stroke oc­curs every 720 de­grees, or every two turns of the crank and there its no over­lap be­tween power strokes. Straight six en­gines are in vir­tu­ally per­fect bal­ance and pis­tons move in pairs with cylin­der 1 mir­ror­ing num­ber 6, 2 mir­ror­ing 5 and 3 mir­ror­ing 4. On a straight five though one pis­ton in ef­fect is the odd man out and there are al­ways large over­laps in power cy­cles and that’s what gives a straight five its dis­tinc­tive ‘thrum’.

Rover en­gi­neers got over a lot of this by ex­per­i­ment­ing with en­gine mount­ing po­si­tions and also at­tach­ing the en­gine mounts at the en­gine’s cen­tre of grav­ity - Rover took out a patent in 1972 (1293135) but this was long af­ter the whole idea of a five-pot en­gine had been dropped. There’s no doubt the 2500 five cylin­der en­gine would have been a suc­cess be­cause it was de­vel­oped by very clever en­gi­neers and built by Rover when things were made prop­erly.

How­ever, the fly in the oint­ment was the pur­chase by Rover of the rights to build the all al­loy V8 and sud­denly there was just no need for the 2500 en­gine. Of the two that were built, one is known to ex­ist still, an in­ter­est­ing look into what might have been.

STRENGTHS AND WEAK­NESSES

The Rover 2000/2200 en­gine is one of those units that has an in­def­i­nite life­span - if it’s ser­viced on the dot with good oil, it will just plod on un­til it wears out and there are very few, if any, real weakspots. One prob­lem is that the pressed steel side cov­ers on the block can rust through and weep coolant, and if that is left unchecked over­heat­ing can re­sult. Fail­ure to use the cor­rect 50/50 wa­ter and anti-freeze mix can cause cor­ro­sion of the al­loy head and that will re­quire weld­ing so a good used head is a bet­ter idea if you can find a good one. Tim­ing chains can rat­tle a lit­tle on start up as well as a weird ‘ring­ing’ noise at just over 1000 rpm. That’s not a prob­lem as such but re­plac­ing both the up­per and lower tim­ing chains is quite a big job al­though the top one isn’t too bad. Worn out SU carbs on the TC mod­els are com­mon now and worn spin­dles re­sult in air leaks that can cause idle prob­lems. The 2000 TC cars with the 10:1 com­pres­sion need Su­per Un­leaded with a lead re­place­ment ad­di­tive. A strange tin­kling noise heard from within the in­let man­i­fold on TC cars will pos­si­bly be an er­rant car­bu­ret­tor to in­let man­i­fold adap­tor, and you need to re­move the man­i­fold and fish this out be­fore if gets where it shouldn’t.

But that’s pretty much it – such was the de­sign of the unit and the qual­ity build that there re­ally are very few prob­lems.

Orig­i­nal press photo show­ing the 2000 en­gine in­stal­la­tion.

Ca­pa­cious en­gine bay was de­signed for gas tur­bine power, as in this pro­to­type.

The 2000 ver­sion was good for 90 bhp in sin­gle- carb trim...

Later four- cylin­der cars gained the bulged bon­net fit­ted to ac­com­mo­date the V8.

... while the twin- carb 2200 pro­duced 115 bhp.

Long in­let man­i­folds en­sured re­spectable torque fig­ures.

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