wolseley1800
Member
Posts: 127
Attribute: The Voice of Doom!
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Post by wolseley1800 on Feb 8, 2017 14:11:31 GMT
Do you mean the idle ignition advance is 25 degrees? What is the maximum advance (static plus mechanical)? David Fitted the 270 piper to my S. Did a rolling road to see improvement, got 63 bhp at rear wheels. Did some research and tuners recommend the MGB cam as best option. My ignition is set about 25 degrees to allow for the required advance for the cam. That's static because with a 270 cam the S engines are basically stage 2 tuned. The full advance at about 3000 revs is around 30 degrees is I remember right - Snoopy has the tuning bible. I have an early 123 ignition with 16 preset curves. The setting I have is for lower end torque. Later 123 ignitions are fully programmable so may be more suited to your needs. Snoopy also has a 270 but his was set up by a tuning specialist. Think I need to have a good look at the settings when we get the engine out.  |
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Post by andrewa on Feb 9, 2017 7:17:57 GMT
Morning
Old one was a Piper 285 - brand new at the time - my conclusions the same as yours David.
Am now beginning investigations of the other non engine ticks and squeaks that weren't there last week!
Engine quiet now so can hear everything - am sure they were there in reality before....or were they??
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Post by dave1800 on Feb 9, 2017 8:55:09 GMT
The thirty degrees full advance is around what John Twist and Peter Burgess recommend, but the 25 degrees static (idle?) seems a little high. Is it difficult to start with kick back? MGB owners with 270 cams seem to max out around 20 degrees advance at idle. I have some limited 123 data that shows the option for a stage 2 (MGB) engine but it only shows the max advance and the unit's static setting - which is not the idle advance. David Do you mean the idle ignition advance is 25 degrees? What is the maximum advance (static plus mechanical)? David That's static because with a 270 cam the S engines are basically stage 2 tuned. The full advance at about 3000 revs is around 30 degrees is I remember right - Snoopy has the tuning bible. I have an early 123 ignition with 16 preset curves. The setting I have is for lower end torque. Later 123 ignitions are fully programmable so may be more suited to your needs. Snoopy also has a 270 but his was set up by a tuning specialist. Think I need to have a good look at the settings when we get the engine out. |
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Post by dave1800 on Feb 9, 2017 9:02:35 GMT
Maybe time to invest in a louder entertainment system? David Morning Old one was a Piper 285 - brand new at the time - my conclusions the same as yours David. Am now beginning investigations of the other non engine ticks and squeaks that weren't there last week! Engine quiet now so can hear everything - am sure they were there in reality before....or were they?? |
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Post by andrewa on Feb 9, 2017 9:44:10 GMT
Agreed - turn the radio up!
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Post by Penguin45 on Feb 9, 2017 19:13:05 GMT
Just flicked back through the thread, Andrew. That cam was new in 2014, so that's not really any sort of service life at all. How many miles did it do?
Chris.
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Post by snoopy11 on Feb 9, 2017 19:37:58 GMT
I have one of those squeak and whine reduction systems on mine. I find it works quite well on the wife too.... |
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Post by andrewa on Feb 9, 2017 20:11:25 GMT
Here's hoping!
And on the other point - 10,000 miles - mostly foot to the floor but as above, don't believe it was bedded in properly at birth - if it's not, it's just a matter of time.
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Post by dave1800 on Feb 10, 2017 0:46:03 GMT
It appears that the first 20 minutes or less of running is what is critical in determining the lifespan of the camshaft even more than running it constantly at high rpm with a wild cam. The correct procedure must be followed when replacing the camshaft or any of the tappets. As mentioned earlier this is because modern oils have had the ZDDT additive removed (or greatly reduced). New cams generally come with their own break in oil/lube. There is plenty on the web, typical examples here and here. David Just flicked back through the thread, Andrew. That cam was new in 2014, so that's not really any sort of service life at all. How many miles did it do? Chris. |
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Post by andrewa on Feb 13, 2017 18:16:01 GMT
On the timing thing I was led to believe that about 10 to 14 degrees static is generally the norm and then you get another 20 degrees from the mechanical bit inside the distributor...but I guess the amount of mechanical advance depends on what springs are in there and so on.
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Post by dave1800 on Feb 14, 2017 0:31:24 GMT
It varies from engine to engine but as a general rule of thumb for a tuned B series engine with a 270/285 cam then the maximum advance ie static plus mechanical should be around 30-32 degrees which is achieved by around 3000 rpm to be safe. However, the initial static advance will need to be more than the standard engine to achieve a smooth tick over (maybe as high as 20+ degrees) This can be achieved by modifying the distributor springs or a programmable ignition such as 123 Tune.
The standard Mk11 crab engine with the 25D4 41234 distributor provides advance right up to 6000 rpm maxing out around 30 degrees plus the static timing. This clearly illustrates the need to be very careful to select the right timing curve as this would be way too high for a hotter cam over 3000 rpm (even the one used in the standard MGB / 1800S) and could likely to lead to severe engine damage.
David
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Post by andrewa on Feb 14, 2017 11:55:06 GMT
Ah ha!
Another argument in favour of keeping things std!
Next time round I'm going to buy one of Ray House's ex-forces brand new engines with a low compression ratio designed to run on any quality of fuel and quiet so not to disturb the top brass sitting in the rear!
Once you start modifying it does at times feel you're on a continual spiral which is not always upward!!
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Post by snoopy11 on Feb 14, 2017 19:06:23 GMT
You forgot to mention gutless and powerless.
Or or is that the brass in the back.
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Post by dave1800 on Feb 15, 2017 0:42:28 GMT
I purchased an ex RN car from the military auction back in 1979 with a view to immediately swapping the engine for one of my spares. However, most of my driving was on the motorways at that time and I found that the low compression engine performed much better than I had anticipated and kept it going for about three years - about 60k miles. No real problems with lack of performance, even hill climbing, and it would cruise all day at 80mph but it wouldn't have been any good as a track day car! It rarely if ever went off tune and never got overheated which was a bonus. Fuel consumption was not really any different from the HC cars despite all the theory that suggested otherwise. No idea about who used to sit in the back! David You forgot to mention gutless and powerless. Or or is that the brass in the back. |
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Post by andrewa on Feb 15, 2017 14:29:04 GMT
Wow - I was almost 15 then - Ian Dury was Number One with Hit Me With Your Rhythm Stick and the Sony Walkman was about to be launched!
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