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MG MGA - crossflow head MGA geometrical problems

Hi all

I wanted to install a crossflow aluminium head 451-690 on my MGA

but as I wanted to install the SU carbs and induction system it was impossible to have enough clearance between starter switch and rear carb bottom . It is also impossible to reuse the original airfilter housings as there is no place for them . another issue is that the Damper cap of the front carb has only a few clearance between the cap and the bonnet and I think that if the engine is rot running regularly the damper cap can hit the bonnet and mark it for life.

What is wrong ? I fear that if I install new engine mountings the damper cap will be directly in contact with the bonnet

Have I to modify the starter switch position?

Has any body ever installed this head with SU carbs ?

Many thank for your reply

Pierre from France

Please appologise for my poor english Tongue Tied
P Windenberger

Hi Pierre,

I bet a picture would be relevant to show out context, yes I know, not that easy.
Starter relay may be displaced with no problem in order to fix first issue. Did you attemp the K&N filter use instead of standard filters? Which kind of inlet manifold did you match to that head?
Any way you may ask to your moss supplier how to solve these issues with it.
best regards.
Guy RENOU

Hi Pierre,

I have trumpets on my twin SUs and a foam 'sock' air cleaners on these. There is no clearance problem, other than the air cleaners and I am using HS6 on a standard HRG manifold.

Regards,
Mark
M Wellard

Assuming you have an early car would your clearance problems be eased if you had the later type bonnet top with the higher profile? ............ Mike
m.j. moore

Hi Pierre,

I have B with MSX head and on my forst setup I have same problems with starter solenoid and airfilter, so I relocate position of solenoid and insted K&N filters I ahve to useRamflo fiters. Later i bouhgt manifodl made for HRG head (by Derrington). Beside it better internal design it is also shortes so I gain some aditional space. So my question would be, what kind of manifold are you using?

toni


Toni Kavcic

and with ramflo filters

Toni Kavcic

and this is Darrington manifold (or copy of it). Unfortunately I do not have pic from car.

Toni Kavcic

That is one huge manifold.I'm sure that must cause all kinds of fitting issues. Here's mine,it's steel and has HS6's and came with my 1961 head.


gary starr

Hi all,

Thank you for your answers and replies
My manifold was the same than Toni (The first picture)
I say "was " because I solved my problem on an other way : brutal !

I shortened the thing for about one inch and soldered it again !

Now all is OK
no need of transfering the starter switch, and the original air filters can remain in place ...What is the problem? :o)

There is really a problem whith this manifold , not for fitting under an MGB bonnet but for the MGA it is "impossible" but impossible is not french !!!

See you latter for another questions

Pierre

P Windenberger

Hi Pierre,

"impossible" but impossible is not french"

yes, yes ... a bit drastic solution but efficient.
Guy RENOU

Thats a brilliant welding job Pierre, also a very brave thing to do.
Welding aluminium is really difficult and you must either be an expert welder to make such a neat job, or, like I would do, have found an expert to do it for you.
( I only attempted to weld alloy the once and I soon came to realise when most of the alloy I was welding ended up a melted pile of slag on the workshop floor, that maybe I didnt have the skills required! )

I would also recommend the use of carburetter trumpets (ram pipes) and the foam air filter socks. They work just fine, look right and will help solve the clearance problem.
Colyn
Colyn Firth

Just for info
The provided heater valve has reversed function vs original heater valve
P Windenberger

Hi all Hi Colyn
I did't do the welding , it has been done by an expert :o)
I only cut and prepared the manifold

It is running !!!
very impressive , lot of power and much more drivable than the genuine head ( don't know why ? ) I didn't change anything at the settings (needles, dampers, ignition, air filter)

But and there is a BIG but!
Since I changed the head engine is SMOKING blue !!! and a lot !!!! I worked very carefully and clean , bores where clean and not weared (engine was rebored for 6 years and I didn't drive more than 10000 km since rebuild and I never see the smoke with the old head )

Has anybody seen the same with these heads?

PierreW
P Windenberger

Pierre
If the blue smoke mostly happens when you first start up and also when you accellerate after the "over run" ( when you change down a gear and take your foot of the throttle to slow down ), this means that the vacuum in the induction tract is probably drawing oil from the valve gear down through the valve stems into the cylinders.
A new set of valve stem seals may cure it or less likely (but possible),a new set of valve guides AND valve seals.

If the engine smokes all the time especially under accelleration, it probably means that there is wear in the cylinder bores or at the very, least the oil control piston rings.

It could also be a head gasket problem or the seals around the oilways that feed oil to the rockers, leaking oil into the cylinders.

Plenty to think about Pierre!

Hope this helps

Colyn
Colyn Firth

Pierre,

What is the hole in the left end of the balance tube?


Mick

M F Anderson

@ Mike
I think the hole is for the vacuum pipe for a brake servo kit (or the recycling of the breather pipe "production" )

@ Colyn
I know all you what say and have no doubt about the condition of my engine that,s why I wonder. I drived a little today and noticed that the smoke becomes more intensive when engine is warm...

And last but not least : the crossflow cylinder head , valve guides, valves are brand NEW ...( bad clearences?)

I will drive more and see how high is the oil consuption
but I think that I have to open the engine to find the issue.

Pierre
P Windenberger

Pierre,

But what are using the hole for?
Have you just plugged it?
If you have connected a rocker cover breather pipe to it that would explain the oil smoke.
The breather pipe must not go to the high vacuum side, between the caburetters and the cylinder head.


Mick
M F Anderson

Hi Mick

I just plugged the hole
No breathing pipes are connected to the inlet manifold or the carbs
I runned my engine yesterday without rocker cover to see if to much oil is comming in the top of the engine but it is normal
Today I will check the compressions to see if some piston rings are broken ...issue hunting begins!
Pierre

P Windenberger

Pierre,

Does you rocker cover have a hole for a breather?
It should have either a fitting for a tube which goes to the air cleaner or a cap that has a large opening for air entry, with some type of air filtration in the cap.
Does it have the draught tube at the side of the engine, fitted to a tappet cover?
If you do not have a proper waste gas extraction system you will build up pressure in the crankcase and burn oil.
The side draught tube creates a reduced pressure and air must enter the rocker cover to complete the system.
Before you start pulling the engine apart do some checks.
Check that the side draught tube is not blocked (including the area inside the tappet cover).
Check for air entry into the rocker cover.
Do an engine cylinder compression check.
See if the valve stems have oil seals.

Mick
M F Anderson

Dear Mick I answer below in your text :o)

Does you rocker cover have a hole for a breather?
NO
It should have either a fitting for a tube which goes to the air cleaner or a cap that has a large opening for air entry, with some type of air filtration in the cap.
HE HAS THE VENTED CAP
Does it have the draught tube at the side of the engine, fitted to a tappet cover?
YES
Check that the side draught tube is not blocked (including the area inside the tappet cover).
IT IS NOT BLOCKED AN IF I BREATH IN THE TUBE IT GOES VERY EASILY
Check for air entry into the rocker cover.
IT IS OK
Do an engine cylinder compression check.
DONE THIS EVENING : ALL CYLINDERS HAVE EQUAL PRESSURE 9.5BAR
See if the valve stems have oil seals
THERE ARE NO OIL SEALS BUT THE OLD HEAD DIDN,T HAVE ANY TOO...

THANK YOU FOR YOUR TIME

Pierre
P Windenberger

I think you will have to look at fitting valve stem oil seals Pierre, Im not certain how much work is involved but my guess is that fitting them will help solve the problem.
Colyn
Colyn Firth

Hey Toni,

I'm very interested to see a better photo of how you connected the heater control. Or, perhaps an detailed explaination. Today, I have four neighbors coming to the house to help me set the coupe body over onto the frame. Big day! I'll be hooking up the heater in a few days so any details you can provide would be helpful as I too am running the Derrington H.R.G. head. Thanks!
Robert Maupin

Hi Robert,

First I use TR 6 heater valve and adaptor (pos. 15 and 16 at http://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=32975#15) but that valve sucks, I never manage to set cable so to be completely closed what was in summer very annoying so I change to different valve (I am shore you can find similar).

For both valves I used same hose that is in fact same as is used to couple matrix to copper pipe that comes from front of engine, I have just cut in the middle (pos. 13 at http://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=29084#13). As you can see I added also small valve to let air go out this is valve that I found at shop with house heating material. Second solution also enables you to take off rocker cover and adjust vale clearance what was with TR 6 valve not possible (if you use alloy rocker cover, with standard is that not an issue).


Toni Kavcic

air release valve

Toni Kavcic

different type of valve

Toni Kavcic

just valve

Toni Kavcic

You r colleague will be most probably interested in two additional changes specially if is he using DellOrto/Weber carbs. One is electronic ignition I am planning to go for 123 Ignition (or something similar that does not address replacing contacts and condensers) and to move oil filter.
I made my own remote filter adapter and hide it under front RH bumper (maybe not suitable for MGA). I use parts from Mocal you need one sandwich plate (type K), one BSP male- BSP male adapters, one BSP plug, two BSP male - NPT male adapters, remote filter head (I used RFH 3 right entry) and of course new hose.
I shortened original bolt for 10 cm and made at end 2 cm long tread. You will have to drill a hole in cap of sandwich plate so you can push newly made bolt and take ALU washer for sealing. At the end you have to drill two holes in body (not for purist) and I used original grommets to prevent hoses being damaged.


Toni Kavcic

bolt

Toni Kavcic

plate + bolt

Toni Kavcic

filter plate

Toni Kavcic

Thanks Toni! I think I'll go out the back of the head, where a water port plug is already rather than drilling an additional hole. Neat job though. Cheers!
Robert Maupin

Robert, I used same take off from the back of the head for both valves.
Toni Kavcic

FWIW, here are some manifold variants on the HRGs

http://www.rhodo.citymax.com/hrgmanifolds.html

General info here http://www.rhodo.citymax.com/HRG.html
Bill Spohn

This thread was discussed between 11/04/2010 and 03/05/2010

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