choosing a cam

[julie4morris]

Right I have a picture of the flywheel for you Phil. I have also located a head that i think has big valves in it and I hope to look at that today if not tomorrow[frame][/frame]

[philthehill]

Albert
Many thanks for the picture.
The flywheel looks to be a re-drilled 1098cc flywheel with special adapter to assist with flywheel location.
Look forward to hearing more regarding the head.
Phil

[julie4morris]

Sorry I could not provide a picture of the other side of the flywheel as I was having trouble uploading the picture. Thank you much for the identification, I think the previous owner got the flywheel form from ESM. he did all the conversion but never actually install the engine.

I also picked up a 'big valve' head with has 35.6mm inlets and 29mm outlets from a montego, looks a bit rough but just need a good clean up (I would put a photo up but I'm having problems uploading photos for some reason). The guides also seem quite sloppy and they have a 2 rings on them at the top so i'm not to sure what ones are needed to replace them? I was also wondering if it was relatively easy job to replace the guides my self, as I have a hydraulic press to hand but understandably to be pushed into a certain depth?

I also took delivery of a Kent cam today and the kit has double valve springs, so I'm assuming I will need spring retainer to match them?

[philthehill]

Albert
Glad to hear about the 940 head.
The valve guides are easy to fit especially as you have a press.
The valve guides should be pressed in until the top of the guide is 13.72mm above the machined valve spring seat.
This is a tool I made up for doing the job.
Dimensions for the tool can be found in BMC Minor wksp manual Section AA19.
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Below is the tool in action with a spacer I made to ensure that all the valve guides are at the right height.
After fitting the new valve guides you may find that you have to cut the valve seats to suit the new valve guides.

You may find that the 940 head already has double springs which will give you the correct top and bottom spring seats.
The top cap has two spring seats and the bottom seat fits over the valve guide and keeps the inner valve spring central.
Here is a link to the MG Midget 940 head which has the same double valve spring arrangement:
http://www.moss-europe.co.uk/shop-by-mo ... 275cc.html
If you do not have the parts they are:
Item No: 100 - lower spring seat - Pt No: AEA403
Item No: 104 - Cap upper vsalve spring - Pt No: 88G617.
Phil[frame][/frame]

[bmcecosse]

Just change one guide at a time - and use a straight edge to set the height - comparing it to the others. You really don't want double valve springs unless you intend to use lots of high revs? They are just causing extra wear and tear on the timing chain/sprockets/cam followers - and camshaft - which you really don't need 99% of the time. So I guess what you have is a 'high revs' cam - I thought you wanted a 'torquey' cam - which is why I suggested talking to A C Dodd..... A very worthwhile job on that 940 head is to open the corner in the exhaust throat - stick a finger down and feel how tight that bend is - it can easily be opened up using a mounted point grind stone - especially when the guide is out - and this allows much better exhaust gas flow away from the combustion chamber.

[julie4morris]

Perfect Phil i shall make one of them up as I have access to a center lathe and i have a BMC workshop manual.
[frame][/frame]
what guides would you suggest? (Pt No:12G1963) (Pt No:C-AJJ4037)
I take it they do not need to be the same ones as the ones already in that are double groove? it also has triple groove valves and I think these retains will take double valves from what I can see, so i would just need inner valve spring lower collars? [frame][/frame]
Well that's kind of what i thought and I was expecting it just to come with single valve springs in the kit. but the chart it comes with suggests 'VS2' which is Kent's double valve spring setup. I don't know if you can quite make out from the photo but i went for the MD266 which pulls from 1000-6000 RPM. Would you perhaps just suggest I use just the single spring set up then?
[frame][/frame]

Thanks BMC, It looks like i have a man on the job as my dad text me saying a mate at work who's going to skim it for me will also port it.

[bmcecosse]

Standard single springs should be fine for 6000 rpm - especially as the cam will no doubt lift the valve higher - so compressing the spring more than normal. The extra inner spring is sometimes considered to be there to prevent 'harmonic' bounce as well as extending the revs before bounce. it's up to you if you use them . Pretty sure I have a set of the inner double spring collars if you want them. And only fit top hat seals on the inlet guides - single groove is fine. Don't go mad on the 'porting' - the exhaust part I mention is well worth doing, but any other porting on a 940 needs to be done frankly by someone who knows what they are doing - all too easy to break through into the water jacket.... And again - 'porting' really only helps when maximum air flow is required - ie at high revs on full throttle with good big carburation! Roy

[julie4morris]

Okay then i shall stick with the single spring, but thanks for the offer of the inner double spring collars. yes when I took it apart it only had them on the inlets. Well the guy used to work for Damico and did quite a bit of work tuning A-Series engines so i have been told so i'm pretty happy to let him work on it in return on beer. So bigger than a HIF 44?
Albert

[bmcecosse]

No that's plenty. You can have the inner collars - they will only end up in the bin here. I'll look for them tomorrow.

[philthehill]

Albert
Regarding the valve springs.
I personally would fit the double springs as recommended/supplied by Kent Cams.
Just because the springs are double does not mean that the double springs are any stronger.
You do need to know what the spring loading (for both single and double) is at a specified height and spring rate before making a final decision.
You could end up with a weaker spring than what was fitted originally fitted / required.
See information below.

The standard single valve spring (BLMC Pt No: 12G1015 / Terry's Pt No: 451-662) loading for a 1275cc engine is 124 lb at 1.065". The spring rate for this spring is 140lb

Standard Cooper 'S' (Pair) (BLMC Pt No: AEA767 - Outer) 47lb at 1.297" and (BLMC Pt No: AEA768 - Inner) 17.5lb at 1.165".
The spring rate for the outer spring is 105lb and the inner 37lb giving a total spring rate of 142lb.

The above information illustrates that fitting just a single spring from a double pair you can end up with a much weaker spring.

You have access to a press so the spring information can be determined so as to avoid a costly mistake.

Therefore you should aim to use valve springs that give no less than a 140lb spring rate.

Can you please post on this thread the quoted spring rate for the ones supplied by Kent Cams?

I would suggest that fitting the double springs supplied by Kent Cams will have little if any effect on the valve train.

Phil

[bmcecosse]

I stick by my words that the springs should only be strong enough for the revs you actually intend to use. Competition engine - yes of course - double springs. Road engine - not necessary. On an unbalanced 1275 I suggest 6000 revs should be the limit. So single springs are plenty, especially on a high lift cam. Extra spring loading definitely DOES increase the wear and tear on the valve train.

[philthehill]

bmc
I totally agree with your statement that you should only use springs of a strength relative to the revs used.
I was and still am concerned that Albert would/will ditch the inner spring as recommended and end up with a spring with a rate less than 140lb.
Until we know what the spring rate of the springs supplied by Kent Cams are I will stick with my recommendation of using the springs supplied by Kent Cams or at least using an original specification BLMC single valve spring with a spring rate of 140lb minimum.

Phil

[julie4morris]

Well you both put forward very compelling arguments as to whether I should install the springs as a double setup or not.
So I phoned up Kent cams and the guy quoted 74-200lb for the spring load. He went on to say that I would not reach that 200lb of pressure on the springs with the lift that given by an MD266 cam. The guy could not give me a rate for the inner and outer spring but said that under no circumstances would he fit just the single outer spring from the kit. He also mentioned that that they have been providing spring/cam setups for 30 years and that they've never had never any issues with this setup. The other point he raised was about missing a gear and that the spring setup would keep any bounce in a situation like that in check. I cannot quote exactly what he said there was along those lines.

I cant find a thread quoting the rate of springs supplied by Kent Cams but I scanned the chart that came with the can so you cant have a look


Maybe I can

http://www.kentcams.com/documents/downl ... 016(7).pdf

[philthehill]

Albert
Many thanks for the information above.
You are right in that we cant have a look as the information displayed on the chart (& even the link) is too small to discern.
As regards the spring rate as you have access to a press you can easily determine the rate of the springs supplied by Kent Cams. Take the data in my post above as a datum and see what readings you get.
The cams I have fitted to the various engines I have built over the years have all been supplied by either BMC Special Tuning or Kent Cams and were/are billet and not re-ground. Currently I have a couple of new billet Kent Cams on the shelf awaiting fitting.
I have always had good service from Kent Cams and personally would not look elsewhere.
I am most surprised that the person you spoke to at Kent Cams was unable to give you a spring rate for the springs supplied.
I will agree with his sentiments - but as it is your engine you have to make up your own mind as to what you want. I am happy to keep feeding information to assist you one way or the other.
I looked on their web site but could not find any data regarding spring rates.
Did a new set of cam followers come with the kit?
Used cam followers should not be used with a new camshaft.
Phil

[julie4morris]

You should be able to make out the information on the PDF if you zoom in with your PDF viewer the info is on page 21, but it is just the same as the chart provided to me with no information on the springs themselves apart from the part number.
okay then I shall have a play with my granddads hydraulic press, see what I come up with and report back to you.
when I'm very grateful to the information and i really do appreciate it as I'm learning lots, so many thanks again

yes I bought the cam kit, so it came with followers, springs and cam lube.

[philthehill]

Albert
Thanks for the pointer re pdf. Now able to read the data displayed on page 21 chart.
Comparing the MD 266 cam data with the standard Minor 1098cc cam there is a little bit added all round but nothing serious as regards valve lift, valve opening and duration etc.
No negatives regarding the MD266 from Vizard.
Phil

[julie4morris]

Well I made up a tool and pushed out the guides this afternoon. I also made up the 13.72mm piece of tube which I very much like the idea of for setting the depth of the guides.
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I completely forgot about taking the springs with me as I leave in a bit of a hurry. But I noticed whilst using the press to push out the guides, the needle has fallen off of the pressure gauge. This I think will render it slightly useless in trying to get an accurate reading to calculate the spring rate of the Kent valve springs haha.

Yes after reading what Vizard had to say the 266 was my preferred choice out of the Kent cams, so i'm looking forward to seeing how it performs.

As regards to assembly, I was wondering if you could give me any advice for a novice? When I took the engine apart it was fairly evident that the previous assembler had used silicon here and there when fitting gadgets and I'm wondering if I should follow suit?
My other main question was regarding cam lube. Is it acceptable to fit the cam using lots of lube and then leave the engine a few weeks before i fit it and run the cam in? I'm just fearful that if I leave it too long the lube will simply drip off the cam and followers, so when I start it there is not much left on the cam. Am I better off assembling it a few days before and then fit the engine and run the cam in?

[philthehill]

Albert
Well done with the guides.
Pity about the press but not to worry I am sure that those double springs will be just right.
There is absolutely no need to use any silicon or other sealer on any of the gaskets or joints.
What I do is give the engine gaskets a light smear of grease before fitting. It helps them bed in and keeps them supple so keeping their efficiency so much longer.
Reference engine assembly lubricant - A most essential product - I would not assemble an engine without it - It will not run off even with an engine standing for several weeks - just plaster it every where including on the shells/crank and anywhere there is a metal to metal interface including inside the oil pump
Just before the initial starting you need to remove the oil filter and then prime the oil pump through the oil way feed from the pump to the filter - remove the plugs and turn the engine over until the oil pressure light goes out plus 30 seconds. This gives time for the oil to find its way around the engine without any loading especially on the crankshaft bearings.
Refit the plugs and start the engine.
It is unfortunate that you cannot pre-prime the oil filter on the Marina engine as it is facing the wrong way i.e. upside down.
Phil

[bmcecosse]

Good idea though to add the last pint of oil just before starting - this ensures the rockers are well lubed - and it will run down into the cam follower chest and drip through on the cam.

[julie4morris]

Been a while but i have made some progress. Got the head skimmed and unfortunately the guy did not gas flow it like i was told he was going to (he was joking apparently), but he took 1mm off the head and asked if i got it out of a pond haha. But i got die grinder and some tungsten carbide bits so i will have a crack at what you said Roy
[frame][/frame]
i have just about all the parts for the build now so its just a case of 'following the instructions' and taking the time to check everything. The valves came up nice on the wire bush wheel but the seats look pretty poor and a guy down the road has lent me a valve seat cutting set but i'm not sure on the size i need? I did look in to it reading some old threads saying they need to be cut at 45° but i'm not sure on the dimension of the cutter. The one i had a little go with is 1 1/2" and that seamed to work ok on the exhaust side.[frame][/frame]
Thanks for the advice on the rebuild, i shall use lots of the Kent lube on the cam, pump, crank, est... yes shame about that dam oil filter but i shall remove it last min and prime the pump. I also have an oil pressure gauge already in my moggy so i shall hook that up and wait for good pressure before starting.

Many thanks

Albert