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MG MGB Technical - Hot Street Cam

Any recommendations on what type of cam I should run for some improved performance?

I already have a ported aluminum head (not crossflow), roller rockers and late style 18V rods which I plan to put into a 66 5 main and bore it out 30 over. Of course everything will be balanced.

Thanks
Mike MaGee

Piper 270 or 285 will give you what you are looking for - the 285 is a bit lumpy for low speed driving in town but perfect for fast country road driving with revs between 2,000 and 6,000
Chris at Octarine Services

Give the friendly folks at D. Elgin Cams in
Redwood City, California a call: 650-364-2187

Be aware that they are a small shop and can
sometimes have inconsistent hours of operation.

They're probably the most knowledgeable MGB
engine cam grinders on this side of the pond.

Most manufacturers typically offer 3, 4, or maybe
up to 6 different cam grinds for the MGB.

Demi Elgin offers 13 grinds for the MGB from
which to choose. They also carry offset cam keys.

Before sending you a cam, they prefer that you
send them your (new) lifters so that they can
test them for hardness and consistency.

They can also heat-treat the cam for more
durability.

I appreciate that kind of selection, thoroughness,
options offered, and attention to detail that only a
personable small shop can do.

No, I don't work for them...just an unsolicited
endorsement.
Daniel Wong

I can confirm Elgin Cams Keen intrest in MG cams, & personal interest his products concerning all MG engines. Len with a Chet Herbert Roller cammed TD.
Len Fanelli

APT was also mentioning them in their website. I'll have to Google them.

Too many choices though :)
Mike MaGee

I have the Crane cam and its pretty strong, but next time I'll try something else. The split pattern works well with the aluminum head. Whatever you do, base your cam decision on the flow numbers from your cylinder head. You did have it Flowbenched, right?
Jeff.

Jeff Schlemmer

Stay away from the Crane cam. I run it in my GT.

Pete
Pete

Pete, I agree, but what's your reasoning? The whole lifter failure rate thing? I run "strong stock" springs, just a little higher pressure than stock, and they seem to be holding up well with standard lifters. I'm not that happy with the power output though. It'll spin the tires and all, but its not what I expected.
Jeff
Jeff Schlemmer

Crane is not really interested in this item: they do not do a "kit". They offer no lifters or advice on such. They do not sell the offset key needed to degree the cam. The cam to lifter relationship has been suspect for some time. Springs I bough t did not work. Other than that, it works fine in the car. Bottom end sucks but that may be my set-up with the Weber.

My advice would to buy a cam from someone who speaks MG.

Pete
Pete

So glad to have this thread to respond as I was just thinking about the P285 yesterday on my way home. Coming up from Reno Nv., about 2700 foot climb over 21 miles back home, in the 77 B roadster chrome bumper conversion. Built with Burgess 9.75:1 CR "Fast Road, Big Valve", 60 over with D. Jackson rollers, Aldon Stage II, pertronix, Peco, OD. I wrung my hands for months over the P285 or P270, and went with the P285, bracing for the "lumpy idle". Well, there is none, even with the lightened fly!. It idles steady as a rock at 850, with 15* advance vac hooked up. Pulls a smidge sluggish-clutch off the line, but at 2500 you feel the come on, and it just springs to 5k without breaking a sweat. Playing around on straightaways, it was fun to shift out of OD , pedal down to a freight train pull in 4th to redline or more, then flick in the OD, dropping right into the torque band and just barrel on till I get scared. The P285 pulls up to 6k without a snivel or flat spot, and I've yet had the courage to find it's top end. I measured my 0-60 time at a scosh over 10 seconds yesterday. Doug Jackson built my 60 over cross flow with the Elgin #6625075-15(it has no overlap) MGB Cam and a Sierra 5 speed in 1999 just before he retired. The idle is 750-800 steady, and the car has exceeded 6300 RPM still pulling with this cam. With Burgess' crossflow grind head, rollers, 1 3/4 HS SU, Aldon, I don't know how much to give to the cam, but it clearly meshed well with the "hot" build. This car showed 9.5 sec 0-60 times last year ( the S.C. car, RB at around 2250 #, still beat em both with 8-8.5 sec et's, 0-60). Mike, with your better breathing, I'd think the P285 will give you sincere pleasure. Hard test the new lifters as I'm always amazed at how many "new" lifters turn out soft. Try Doug Jackson's great Tech Talk at WWWMGBMGA.com for an in depth evaluation of MGB cam Choices. Vic
vem myers

Whatever cam you choose, make sure you match the compression ratio to suit it. Elgin is very aware of this need as should be APT.

The Crane cam will only help you above 4000 or so and even then it's not much (probably less than 10HP over stock).

Sean
Sean Brown

In my modified engine with P&P head, +.060 pistons etc etc, I installed the Crane 342-0010. Couldn't be happier. It has a little lumpiness at 850 idle and pulls strongly across the power band. I would place it between the Piper 270 and 285.

As I simply wanted a very streetable auto with more sparkle and acceleration and grunt, this combo works for me. In my experience it pulls strongly from 2000 and continues to beyond 5000. With my setup, I'm certain it would continue to do so beyond 6000, but I simply don't find it necessary to push it that hard.

Whatever cam you choose, I recommend the Crane lightweight alloy pushrods and HD valve springs and Kent or ARP matched lifters.

If I should ever redo this engine, I'll go no larger than 1868cc, probably swich to roller rockers, but very likely keep the Crane cam unless I go with an Elgin.

I dismissed Elgin fore the present rebuild because it's my understanding that all of his cams are regrinds and I wanted a new billet cam. Why? Just because.
Gary Kinslow '69B roadster Pale Primrose

I have an Oselli 270 , great cam , the car flies when you get the revs up but is stil Ok at low RPM. There is atame version, the 500 which does not give the high RPM hit but idles better, depends how and how much you are going to use the car.
S Best

Does anyone here know the differences between Piper's different 285 cams? I see they list a street and an ultimate street cam on their website. Who sells them in the States?
Jeff
Jeff Schlemmer

Mike,

I've got a long period cam in my V8 and it's a bore to drive under 2000rpm. I'd think about some thing in the 260 intake / 270 exhaust range. I'd agree with the comments on long cams not having rough idles, as the V8 idles at 600rpm, and I had a 1275 Sprite that had a 270 (before I changed it for standard) that idled fine, the loss is the low end torque.

Regards,James
James

Jeff,

Forgot to mention; If you increase the cam duration, the engine will 'want' more idle advance, approximatelt the same full speed advance and a slower advance rate to therefore transfer from one to the other.

I mention, as a little of the low speed torque loss can be recovede by introducing a bit more slow speed advance.

Regards
James
James

I called BritTek yesterday and had a long conversation with Bob about rebuilding my motor and I think I will buy an 'engine package' from them including a Piper cam, hardened lifters and a new dizzy. I've heard good things about BritTek from friends and they will work w/my engine shop re: bearings and such.

BritTek sells Pipers.
Mike MaGee

I went with BritTek several years ago... I'm very pleased. They worked with me from begining to the end including the choice of Piper cams, hardened lifters, new push rods etc. I bought the complete engine rebuild kit and then added the hardened valve seals for my 68 head.

I gave the machine shop their phone number and after the finished with the crank and the cylinders, they called BritTek and ordered the correctly sized rings, pistons and bearings.

The best part of working with BritTek was while I was assemblying the engine, I was albe to call them to clarify any problems I was having. They are very willing to support you during your project.

I'm not affiliated with them yada, yada, yada just a very happy customer.

Cris
Cris DeYoung

Daniel

Do Elgin Cams have an e-mail address? Being in Australia (Down Under) phone calls may get a bit costly.

A local MG shop here in Aust. has recommeded a BLMC grind - 714 for general improvement in road use. Does anyone have a comparison between this and say the Piper 270/285 ??

Regards
Dennis K
Dennis Killeen

Mike, I got all my engine goodies from Brit-Tek. Bob is very comprehensive about getting you everything you need. I can't say enough about how easy it was to get the project rolling!

Are you going with the 285? Ultimate 285?
Jeff
Jeff Schlemmer

Ditto on all the Brit Tek comments.

Pete
Pete

A key issue is compression ratio.

A long duration cam reduces compression pressure and effectively lowers the compression ratio. A 285 type cam must have at least 10:1 nominal compression to perform well. Look at the various websites on cam design and choices. "effective" compression ratio is lower on hi overlap cams, and actual compression ratio is a necessity.

If you are running 9:1 or less stay with a 270 degree cam or less.

The stock iron head will begin to develop hot spots and start detonating after a few minutes of hi power motoring such as up a fast grade at hi rpm. If you go to hi compression and a hot hi output cam you will find the rapid heat dissapation of the alloy head will allow you to run a higher compression ratio under continuous load and produce more horsepower.

The argument is made that you are losing horsepower by the heat conduction of the alloy head. That is true only if you are running the same compression ratio on both types of heads. The higher compression ratio possible with the alloy head allows more efficiency at light loads and more power at continuous heavy loads.

The stock 1 1/2" carbs are adequate to 6000 rpm. The head, cam, and compression ratio are the key factors in producing more horsepower for the B engine.

Typically a little more cam makes a big difference. A lot more cam, can result in a less responsive engine with little or no power increase over the "3/4" grind cam. Changing the cam should only be part of a package of modifications. More cam is not necessarily better.

The pros say the area "under the curve" is what matters. The graphed horsepower curve is what they are refering to. A curve that jumps up early and provides a powerful midrange, is far more drivable and sporty than a really hot cam which shows a flatter line but with a higher peak horsepower at hi rpm, feels like it looks. -Not that much until you get into the 4000 plus rpm band- It's peak horsepower will be more, but it will be a pain to drive compared to the cam with the more conservative grind.

Barry
Barry Parkinson

I haven't decided on which cam to get yet as I don't know enough. I want a streetable cam with better mid power and a higher top but I don't want to get too radical. Since I'm using a new aluminum head and HC pistons I am clueless about the CR. I have a set of NOS 18V rods which I plan on using to reduce weight.

But first I need to drag an old 66 motor out of the garage and free it up as it's frozen. I plan to keep my original (?) motor together and use the spare I have to build on. Why rip apart a good motor?

I sold a lot of car parts on eBay and made far more more than I anticipated so I can afford to build the motor :)

After my talk w/Bob I realised I should have been using them before this time to purchase my resto bits.
Mike MaGee

I think a lot also depends on your driving style: do you regularly rev the car over, let's say, 4500 rpm?
If so, you might enjoy a 'wilder' cam (the higher CR can still be attained), if not, you might want something more like the Piper 270.
A friend of mine has a Piper 270 cam in an engine that is not that different from your 'new' one, and it's quite responsive and lovely to drive. I've also driven cars with cams like the Piper 285 and they don't feel extremely powerful in the range of 1500-3000 revs, but after 3500 rpm these engines just keep going!

fwiw,

Alex
Alexander M

Mike; This article by David Vizard may help, it you haven't read it.
http://www.babcox.com/editorial/ar/eb90252.htm

Clifton
Clifton Gordon

As Alex and others say, the real hot cams only help at upper rpms. In day to day driving it is really nice to have that power surge come in around 2500 rpm. (The 270 type cam) The engine still pulls better than stock on up towards 6k rpm. An engine that doesn't begin to come on until 3000 rpm plus (the 285 cam) requires you to adapt a driving style where you regularly run the engine in the lower gears to get ordinary performance. The 300 cam is a pain in the but to drive around town, or even cruise at medium rpm on the highway.

The 5 port alloy head has the large combustion chambers of the early head design. The early model shallow dish pistons barely produce 9:1 compression ratio. The alloy head runs cooler than the iron head and can run the same octane fuel at around 10:1. If you go above 270 degree cam you should have flat top pistons with the alloy head to get you CR up hi enough to make up for the compression loss with a hi overlap cam.

Barry
Barry Parkinson

This thread was discussed between 23/09/2005 and 29/09/2005

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