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MG MGB Technical - MGB camshafts 1976

Hi

I know I've got the poor camshaft fitted to the 18v engines, but I believe the only difference from the previous cam is that it is retarded 4 degrees. the profiles overlap etc being identical.

Can anyone confirm this?

and if so, will advancing it using a vernier pulley bring the engine up to pre 18v specs. (Unfortunately I've the small inlet head as well)

Simon
S S Tew

Simon- It is really not so tough replacing the cam, engine in sitio. I'll bet you're flat now, and a new billet ground Piper 270 with Rockwell hard new lifters, sorry, followers, and push rods will be a very noticeable difference regardless of your "small" inlets. Mr. Peter Burgess is your man over there, over there.
I apologize advance for the inappropriate response to your question, bro. I wanted to get some thread chatter up on those stinking fed issue cams sabotaging the car both sides of the pond since the rubber bumper era.
Cherrios Vic
vem myers

Hi

Sorry should have said, I'm in the process of building the car to do hillclimbs and sprints .... then possibly the race series... but I intend to do it as ' unmodified ' road class so I have to use a stock cam... reading the regulations vernier cam pulleys are allowed and as the cam looks perfect if there is no difference between the cams except for the timing I can spend the money on something else

Simon
S S Tew

Simon

You probably still want to talk to Peter Burgess, or possibly Ray Downes at Mansfield Road Service Station in Skegby, Notts.

Ray was/is involved in the MGOC race series and has built some very quick engines using 'standard' cams. Apparently there are some strange anomolies regarding the valve clearance for checking cam timing/duration which allow for some very useful cam profiles within standard regs.

Dave
Dave O'Neill 2

From info provided by Clifton Gordon, the late cam has only 230 intake duration, as opposed to 252 for the early one. That's in addition to the 4 deg timing screw up. Haven't measured it myself.

FRM
FR Millmore

Fletcher, I haven't measured the later cams, I used the opening and closing degrees from the Haynes MGB repair manual and added 180 degrees to determine the intake duration for later engines. I should have added that the 230* duration applies to engine Nos 18V883AE(S,CC), 18V884AE(CC,0),18V890AE(CC,5), 18V891AE(CC,0), 18V892AE(S) and 18V893AE(0). This information is on page 24 in my Haynes manual.

The exception is the 18V847F(0), it has the same inlet valve duration as the earlier engines. It also has 9.0:1 compression.

In the Notes (CC)designates Catalytic Converter engines

Clifton
Clifton Gordon

Clifton
Yer OK in your procedure; I don't have a Haynes to check. Now I think about it, I realize I have a customer's late Bentley - guess what? It shows the late cars as having the same cam and timing as the early ones!

Don't trust anything you don't do yourself, and doublecheck that guy too!

The 847 engine sounds like a UK thing, so Simon may be alright on that.

FRM
FR Millmore

Simon,

i ordered a 285/2 from Piper directly in 2005, as it was hard to locate it somwhere else (grid from a blank!).
It works very well with the 1868 engine (compared to the stock cam and differnt Kent grids i tried), ralley head, country flat top pistons and HIF 6 carbs, throttle response and preformance are fine, although DCOE style carbs would even work better, if there is room enough to install one, i think. I could not try it for there is insufficient room on LHD cars with the late US style braking system.

After a few events, other drivers from the local MG club also opted for this cam too.

When fitting an other cam to your engine, be sure that it is propperly set with a deree wheel.

Ralph
Ralph

Simon,
The regs are on the speed championship website (www.mgcars.org.uk/mgccsc) - I think that you can fit any cam as long as it was 'standard' at some point. To be honest, in standard class it's not going to make much difference to your times anyway and you always run the risk of running against someone with a 'standard' engine that has cost several times more than a 'road going hard' engine. I don't know about the cam specifications, but if you're on a budget and want to advance the cam, use an offset key - a couple of pounds versus the best part of a ton for the vernier. And the vernier doesn't save much time anyway unless you are going to 'optimise' the timing on a rolling road in which case you'll be back into spending big bucks.
Neil
Neil Lock

Hi

Thanks for all the info guys!

Neil I inherited the vernier and a box of parts from a friend so hasn't cost me anything yet.

And my local college has a rolling road! So I'm going to join some of their night classes ;-)

simon
S S Tew

Hi

Just checked ... the engine is an 18v847F so I guess I'm lucky (for a change lol )

simon
S S Tew

This thread was discussed between 19/05/2007 and 21/05/2007

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