Replace camshaft without removing head

[peejay4A]

...no I haven't had to tip an engine up. I did say it might be worth a try. By all means correct that assumption from your experience but you might choose your words to be a bit less disparaging to others who are trying to help. That is all.

[Andy Moltu]

May I suggest it's probably not worth swapping from a CR to a CP cam. The difference is not the 25 BHP that the crude figures imply the 150 is an SAE measurement and the 124 a DIN measurement - so a lot cless than 25 , 12 is what many would suggest.

 

If you really want to change the came perhaps go for something a tad wilder to justify the effort.

Cam changing is a pain in the behind so I'd advocate taking the head off. This will let you examine the cam followers to check they are really new as well as check tdc accurately too so you can time the cam properly.

[RobinTR6]

Andy, good thinking only reason really is its a CP head so have been advised to ensure its a CP 150 cam. Your point is well made tho. I'll see what the timing and duration of the cam thanks in there reveals then seek further guidance.

 

The real issue is I dont what the cam is (its has 3 rings on the end journal so should b a 125 but ......, given the engine is a CF and been rebuilt and the head is a CP UK and been rebuilt been suggested I check hence)

 

This forum is still the best Ive used and people are always willing to help. Occasionally there is a misunderstanding....dont let this stop the contributions as there are many of us out here needing help keeping our babies on the road in an affordable way.

Edited November 14, 2013 by RobinTR6

[Rob Salisbury]

Hi Robin,

CP cam ......... 2 rings....number 307689 stamped on the shaft around the mechanical fuel pump cam lobe ........ timing 35/65/65/35

 

CR cam .........3 rings number 311399 ..... timing 18/58/58/18 (unless someone's gone to the bother of having it reground to CP spec.!!)

(also late Mk 11 Pi saloon cam)

 

Cheers rob

[RobinTR6]

Many thanks. Now don't berate me but whilst waiting for a dial gauge (ordered off flebay) thought I'd be inventive. Daughters compass which has a gauge markings on the outside and an inner wheel that turns with a pointer that reads degrees moved....stuck compass to cam end sticking out of engine ( no timing chain or wheel ) rotate cam and watch feel start and end of movement on the push rod , about 136 degrees duration, both inlet and exhaust . Lift 5 /6 mm , defo need DTI here. . Too difficult even with digital vernier.

 

From my recent education on the subject that's not far off ( doubled because measured at cam) the 280 of a CP cam........push rods 8.1 ins long, again think that'd right for a CP head. Yeah, yeah needs doing properly but I'm optimistic , ok hopeing, its a CP . Mind you its got 3 rings ion front and what looks like a wear mark on the petrol pump cam lobe.

[flatlandsman]

As I said nearly at the beginning of this long, drawn out saga:

 

" Do it properly first time, cheating and trying to be clever usually comes back and bites you in the bum"

 

More that a few people on this thread do have experience of doing a few of these motors in their time; it's not called experience lightly!!!

 

Sometimes the long way round is the right way.

[RobinTR6]

As noted earlier, engine rebuilt at Minisport, and head by ANO professional mechanic. My query was what's the Cam. If with the DTI its turns out to be a CP cam surely I should leave well alone ? And time it accordingly ?

[Alec Pringle]

Hi Robin,

 

this here engine was rebuilt 'some time ago' and you're unable to get detail from previous owners, other than supposedly one outfit built the short engine, and another built the head, and you don't know what the cam is . . . . . ??? So no documentary evidence of what is even supposed to be there ?

 

I wouldn't bother rattling around trying to determine just what the cam is.

 

I'd strip the engine down and inspect it properly, lubricate it afresh and bolt it all back together. At least you'll then know just what you have got, and that it's all sensible once you've sorted whatever needs sorting.

 

The idea of firing up an unknown quantity consisting of unknown parts and put together by a variety of folks somewhen back in whenever . . . . . you cannot be serious ?

 

Sounds to me like a recipe for a potentially expensive exercise in creating scrap metal unnecessarily.

 

Cheers

 

Alec

[RobinTR6]

Alec, agreed. As per guidance here had the sump off and removed bearings, posted some pics. Crank unmarked and bearings also, liners clean and think the term is honed. Oil pump removed and clean and to brown bible tolerances. Had a mechanic with me and he thought it had been done well. Cam also clean and unmarked, and covered in lube. Head , new gasket, all studs replaced all torque up, tappets etc all set correctly. Flywheel looks new and clutch replaced and cover, pics posted here. Spoke to PO who ran a garage and had three engines all rebuilt at same time to same spec. So think I have been cautious. As I said I'm no pro so having checked the above hopeing once cam identified can make progress to fitting gearbox etc.

[Tom Fremont]

Hi Robin,

 

The CR cam will lift the #1 inlet valve at 18 degrees BTDC which you can use the original pulley to determine ( CP with its 35 degrees will be off the scale, but with a little arithmetic and suitably marked piece of tape you can find this too ). In 5 minutes you can know if you have the former fitted .

 

SPMPW,

 

I believe the dropped tappet issue doesn't apply to the 2.5L 6-pot engine but will confirm it does for the 4-pot TR engine ( found that out the hard way in my teens! ). Pulled up as high as they go with the head on I think they're still in the bores in the former.

[Stanpartmanpartwolf]

And finally...inlet opening i/d method only works if the cam is correctly timed in the first place.

With the cam in v-blocks:

2-ring 0.250" lift, 105deg lobe centre angle

3-ring 0.240" lift, 110deg LCA

Your timing disc & DTI will help you find the LCA.

 

JFYI there were some very sick repro big-end bolts around not many years ago; if you have ANY doubts about yours, replace with ARP & follow their instructions to the letter.

Edited November 16, 2013 by Stanpartmanpartwolf

[RobinTR6]

Guys are you saying you can't determine the cam in situ in the block with.timing chain removed using the movement on the push rods to determine duration and lift as the cam is rotated ?

[Stanpartmanpartwolf]

No

[oldtuckunder]

Guys are you saying you can't determine the cam in situ in the block with.timing chain removed using the movement on the push rods to determine duration and lift as the cam is rotated ?

No, but you can't find out Who's cam, and if its a reground or what from? or what type of followers have been fitted, and if new ones did they clean them up properly before fitting?.

 

Someone will probably shout at me and say well he doesn't want to do it! but

 

It sound like you have the basics of a good engine, so when you've rebuilt the car and are setting it all up, do you want to wonder at every problem if its something to do with the cam as its the only thing you haven't looked at or know what it is?

 

You have the engine out, rocker gear off, you are 15 nuts/bolts away from taking the head off, lifting the followers out and pulling the cam shaft and finding out what you really have, at the same time you should also be able to see if you have new pistons, and if so what over bore if any you have, and you'll also see the state of the combustion chambers and valves.

 

The only extra expense could be you need another head gasket, but probably not if its a good one, I've pulled a head off several times when on a newish gasket and refitted without a problem. But to be extra safe you are probably talking £30 to really know a lot of usefull information.

 

And being a bit provocative - Timewise you would have had the head off, cam pulled, and head back on, in the time taken posting to this topic.

 

I know what I would do

 

Alan

[RobinTR6]

Ok,ok, despite my reticence and fears, not been here before ...... its off with her head. I know you guys are probably right and most importantly given I've given the diff, gearbox and O/D to Pete Cox on the same basis, ie all should be good but check it out before putting car together may as well do the same here. Ok ' off with her head and get her cam (isoles) off. I'll report back,new thread and

Thanks.

[Guest ntc]

You may end up finding more problems if you do.

[RobinTR6]

Cripes, no hope for me then. Neil you saying stick to measuring lift and duration with cam in with DTI and disc ?

[Chris59]

Tell me if I'm wrong, but the camshaft' reference could be seen from under the engine, if the sump is off, correct ?

 

About the followers, I would use magnets (been there, done that...)

[RobinTR6]

Chris, I started with another post, Off With Her Head. It's a CR camshaft. Now I need to sort a CP like one if affordable. Just painting bay , tomorrow, so on the hunt to sort engine.

[Chris59]

Hoops, sorry chap