Spridget Tech Talk (MG Midget & Austin-Healey Sprite)
Does anybody have any experience with the aluminum cylinder head sold by British victoria for the 1275? I ordered the head and called them afterwards to find out the valve sizes I needed but they can't tell me. any help would be appreciated, thanks!
Sorry to deliver this news but you'll always get zero to no technical help from Victoria British. Could always send it back for a full refund and get one from Moss and you'll get all the help you want.
Rumor has it that there are several pros and cons...pros being self evedient
The cons are ... Easier to crack, the head needs shimmed if you use after market rockers, the torque specs are differant, and the head needs seasoned before assembled...i guess wiped with oil and baked...Nd the treads are easy to strip out
But i think this is all minor compared to the lite weight and the ability to cool better then iron
All in all its a good head i understand...you just have to be more vigalent with its use.
I think its the same valve train as the 12G1316 and the 12G940... But im not 100% on that ither
Good luck, let us know what happens
Call Pierce direct. Here's a link . . .
http://www.piercemanifolds.com/category_s/53.htm
These guys ported the co-owner of Moss Midget head...they should have all the answers you need plus some....
http://www.flowspeed.com/
Sean did the MGB head, not the 1275 head.
The static CR will need to be raised to compensate for the rapid loss of heat (heat INSIDE the cylinder is GOOOOOD, heat x-ferring to parts like pistons, rings, cylinder walls, head, spark plugs, valves, etc... is not. That's why we tinker to optimise the trade-off).
Good luck, let us know how you like it. :)
Thanks for the info I am planning to increase the CR to 9.75:1 and see how that works out.
I certianly wouldnt go anu higher, unless you have a souce for good NON ethionial fuel
Prop
Yeah your right about that, I first asked a local lbc mechanic if that would be a problem and he said the same thing "no problem but I wouldn't go any higher"
Trevor is actually correct, the youngsters are doing crazy stuff with E85. Aluminum head by nature can stand more CR than the cast iron head, and 9.7 will do fine on cast iron head 1275, I build plenty of street 1275 engines to 10.0 to 1, and truth be known you could go a little beyond that for the aluminum head. Now here's the punch line, out of the box, the aluminum head flows worse than the stock cast iron head, i5t not the best casting, lots of lumps and bumps in then ports, way owrse than a stock head, so if you want to see a gain, you need to port it. Aluminum heads don't crack too often when overheating, cast heads are more proned to this, but aluminum heads will warped badly if overheated.
Bob, yep good luck getting any tech advice from VB, I gave on them years ago, have not bought anything from them in almost 10 years. Stock 1275 use 1.31" intake and 1.15" and change exhaust valve, you can go up to the 1.4" intake valve, but I would leave the exhaust valve size alone, the the valve ratio percentages already favor the exhaust valve as being too big, so a bigger intake valve, but stock exhaust valve betters the valve size ratio. Vizard talks about valve size ratio in his A series book.
That's crazy! I've never heard of an engine that used bigger exhaust valves. Why did they do that? (other than the fact it's English)
Hmmm,
Im thinking hap may have started the weekend off a bit early....alcohal, texting and the antcipation of 2 days off tends to make one type a little off.....hahaha
Perhapes Hap meant to say the exhaust valve is 1.15 and not 1.5.....
hey havent we all been there....i know i have
Prop
1.5 exhaust
Haha... NOW that would be a breather 1275
Prop
Read it again guys, I said valve size ratio, meaning, these heads the size ratio wise the exahsut valve is already bigger than it needs to be for the given intake valve size it has, so going to larger intake valve, but not enlarging the exhasuit valve size betters the valve size ratio. Pull out Vizard and read up on it, it will all make sense then.
Ah.... Sorry about that
I mis understood, i thought you where refering to valve size
To get the more approprate 1.5 intake to exhaust ratio would it be better to up grade the intake to 1.44 inch...or is it more a case of reliability to stay at 1.4
I wonder why you cant go a smaller exhaust... say a .96 instead of a 1.15 seems easy enough if your doing hardened seats and just turn the exhaust valve face down, that would allow you to go to a 1.44 intake and have very close to a 1.5 ratio
Certianly an interesting thought...is it doable ??? Im sorta at that point at the moment building my new head...perhaps i should explore that a little further
Prop
Im liking this thread...this is a question ive got and from what ive heard a properly ported cast head can make more power than a bolted on aluminum head. But thats not so cost effective cause it can be upwards of 2g's to do a cast head right. Ive heard about the aluminum head having valves being too big. So making it work right then putting a bigger intake valve in a smoothing the ports, would that make it comparable to the properly done cast head? When i get around to building my 1380 this is the biggest decision i need to make.
Mark
There ya go prop, you're catching on :), an exahsut exahsut valve in a perfect world should be a certain percentage szie of the exahsut valve , bigger is not better, in our heads the exahsut valve szie percnetage is too big, for "ultimate" perofrmance a bigger exahsut valve imprfoves this situcation. Going smaller on a exahsut valve does not work that well because you got a give bowl size in the ehads, just putting a smller ID guide in there creates a ledge, no too god for flow, leaving the size you have there and be able to blend the bolw is more importating than making it smaller in valve ssize tne then upping the intake valve size. Lot of people get it all wrong on larger intake valve sizse, you need fit the bigger valve, ahve the seat ground. I use a head and guide machine for this, set up for thao valve size and grind the ree angles at oine time with carbide cutter, then you have to go back and blen the bowl back to the 60 degree cut, menaing a bit of parting, or you not accomplished that much.
AS for well done ported heads, Martk, they are not cheap, but i can do them for well under $2K, more like $1200-1300, and it's alot of labor, but it way better than bolt aluminum, which is really not even as good as stock cast iron, so a fully ported head IMHO is better bargain than the aluminum head, which is like a $1000 bolt on, and the casting inthise head's ports is terrible. far worse than stock.
Hey hap
I am grinding out that metal blob that surrounds the valve guild and using a brass shorter bullet guild
So would a smaller exhaust valve aka... A turned down .96 exhaust be a good modification when combined with a 1.44 intake....i personally found removing those huge blobs makes a huge differance
Sorry for the repetive question, i read your last response several times, but i was not able to comperhind its content
Prop
Never mind...i just had a good converstion with peter burguss in the UK
And he was saying the exhaust seat wouldnt fit as well and Cause flow problems to blend the seat into the throat, because the seat would be to thick
That makes an interesting thought.
Lrast now i know... And thats not bad... The 1.15 ex with 1.4 in and the ground out metal blobs around the valve guilds and short bullet brass valve guilds really make for a nice flowing head...among other tricks and tips
Prop
by this you mean it increased the mass throughput, thereby increasing the power?
I cant agree more...another area to avoid like plague is those vertical spliters at the bowels that seperates the fuel charge
Personally... I think everyone that likes to play with these engine should attempt a post at some point....what you learn is vs what you screw up is im measurable
As you say... Read read reed...there is alot of good info, if you search for it
Funny... Porting has become one of my favorite topics of converstion along side engine vacume...thats another topic thats mostly art over science....
damn i HAVE to get a girl friend...hahaha
Prop
Prop, here's a tip for you, lamp dimmer switch, you can get one at your local home improvment store.
Yes, and it would have ran even better if they had not did that :D
Not may folks have gotten serious about the S/C on the A series engine, like they have on the MGB, would be interesting to see what a serious blown 1380 can do.
Yepp ... I got a dimmer switch made up for my die grinder. And other tools for contring the speed....i have it set up thur a plug so i can just plug in the tool and dimm the speed
A couple of other things i found that work great
A large screen door spring for holding the grinder above your work attached to the cieling....that way you gently pull the grinder down to the work instead of holding up the grinder all the time
And O rings with play doh on the valve seats to keep.from bumping into them with the grinder
Also tap the old V. Guilds and put a screw into them....that way the little grinding ball wont catch the hole of the guild and kick the die grinder out of your hands
Use heavy packing scotch tape from the post office on the face of the head... 2 layers and razor around the chamber holes
A vacume cleaner and several magnet on a sticks wrapped in tee shirt material to swave out the metal dust
Ear plugs... Mainly to keep the metal dust out and axle grease around your eyes under your safty glasses aguan metal dust
And a flat file works great to clean off the metal build up on the grinding stones... As well as to reshape the stones to a shape you need for some strange angle
Just a few things ive found along the way
Prop
Thats a big AMEN on the time consumption, ill spend a good 15 hours on mine and its just a very basic port job, nothing fancy
for me its not about saving money, truth be told, i loose money porting my own heads, $30 an hour X 15 hours plus yhe head and parts, an materials and machine shop work....yeah thats a couple of grand $$$$, cha CHING!!!
But i sure love the scence of accomplushment i get from doing the work, esp considering how few people will ever attempt to try....it seems to feed the ego and i have the sence it somehow sets me apart from the rest of the crowd, an inside advantage...setting at the grown up table...a secreat insight .... Member of a secreat socity of head porters... Well okay more like i get to clean he tolit of the secreat socity of head porters...but at least im in the room ..hahaha
This will be my 6 th head to port and the 4th for the midget
Yet each time, i always come up with something new to try, or wished i tried something a differant way
If i do many more... Im starting to seriouslu think about building a flow bench...im starting to see where something like that can really take what im doing to the next level
Since im new to the A-series, a stupid question....what is the head/intake locating ring? is that the steel ring in the intake port on the head? right at the opening?
Mark
Ok, more questions then...my uncle has had a local guy do his head work....hes put together a number of 1380's, all making over 100hp, the one in his Westfield 11 is estimated to be around 110+ hp. Some of the things planned are a maniflo intake with a dcoe weber....the motors he putting together have tons of usable power, run on pump gas, and are steetable motors that hes had many hours with on tracks. Anyway...vizard is a book he told me to get, but also one of the heads he had done for over 2g's had those rings removed.....i know you said thats not recommended...but at what point do you wanna go that far? we are also talking i think round 10:1 compression....at this point, with the extra dispalcement and the hot cam for a 1275, which now is making much more low/mid end torque with more displacement...id think you want bigger ports...thoughts? And yeah, im planning on a 1380, my mind is kinda made up on that already
Most likly the reason for not having the centering rings could be because he is using HS4 Carbs and not HS2
From own personal perspective and not sure how the others frame of thought....im not a big fan of bigger is better
So when you mention bigger ports and bigger carbs, i think of a slower moving fuel charge and weaker atomisaztion
In other words 1 gallon of water flowing thur a 1 inch diameter pipe will move fast and with more force then the same gallon of water moving thur a 9 inch diameter pipe
Remember... HP is not everything, but where that HP is located in the rpm range
id rather have a 70 total hp engine with 55 hp peaking out at 3000 rpm then to have a 100 total hp peaking 85 hp at 6000 rpm
In other words...110 hp at the top end is awsome on the boonville salt flats, but probably suck for street driving where 85% of your driving is under 4000 rpm....i want all my power at the bottom end to mid range of the rpm scale...the the rpm area i normally drive ...the only time im driving 7000 rpms plus is when im passing a 18 wheeler on the interstate
I've tried a variety of inductions. Big Bore HIF6 with special intake,HS4s on a Maniflow intake and
I'm currently using HS2s with the aforementioned ported intake. Hap's carbs.
They all have their place I guess.
Even with the warmed state of my 1380 the HS4s were too much for the street. Ran like a demon at WOT.
LOVED that! Loaded up on the street if I didn't constantly open 'er up. Hated that.
HIF6 was very smooth and performed flawless. Bottom end stunk. Hated that. Not as much go on top
as the HS4s but a nice setup.
The HS2s are VERY responsive around town. Leaves a little off on the top end compared
to the HIF6 and the HS4s but overall they are the best setup for my ride. Great low/middle power.
Results may vary and it hasn't been dyno'ed with any of them.
Just my "seat of the pants" observations.
While that power band may be true for a 1275 with a real hot cam, add 100cc's or bore and that real hot cam in your 1275 isnt so hot. The motors my uncle is putting together are making tons of usable street power under 4k, lots of low end torque you wouldnt think could be there from a motor thats making power at 6k....100cc's in a motor so small as this is a huge difference....when i built my last volvo motor i stroked it, a whole 200cc's from 2.3 to 2.5....the torque difference was just stupid, i know bigger more doesnt equal more torque persay, but we are talking pure displacement...when you get to the bigger displacement, i would think removing the rings, then the nice porting is the way togo. as far as the carbs...hes got better throttle response with the weber than a pair of HS's
Mark
In the head kit i just got in the mail were 4 umbrella seals (intake) but there were also 8 O ring seals included, what are they for?
Hap, with this new aluminum head I received a Warning that reads as follows " WARNING the new style Payan Head Gaskets have a rubber O-ring for the block to head oil feed these gaskets will not work with the Aluminum A-series Heads" I also got a note that the plugs have been changed to 12MM and that the valve cover may have to be ground out above # 1&8 valve spring for proper clearance. Have you ever heard anything like this before?
My mind is a bit fuzzy on this, but I think you can flip the composite gasket and it will work. It should be obvious when you look at the oil feed path. 12 MM plugs is correct. I'd think that the stock rockers would be fine inside the aluminum valve cover if they were working fine on the iron head.