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MG MGA - Incremental Performance Mods

Budget constraints prevent me from doing a wholesale rebuild a'la Barney's web page.

I'm wondering what incremental steps I could do to get jump in performance. incremental meaning $500 a step

Redo the head with polishing and valves?

A $350 header?

Suggestions appreciated.

When I mean performance. Specifically I'm looking for better acceleration from a standing or slow start, particularly when two people are in the car.

I'm perfectly happy with my current top end speed of 65 or 70.
T McCarthy

1 - do the head. It is a bottleneck and will prevent anything else you do from having effect.

2 - think about whether you want to go to an improved engine. You can do this by building up a spare engine and replacing what you have. A 3 main MGB engine is a really nice way to go, but you can improve what you have.

Cam, compression and carbs are the way to more power once the head is done, but none are particularly cheap. A header is worthwhile, but again, not inexpensive if you get a decent one. The best way to improve an MGA is probably to install a stock 3 main MGB engine (there, I've said it - and shall now duck!)
Bill Spohn

Switching from the original Volks air filter cans and elements to K&N air filters with mini stub stacks is good for 2-3 hp, according to the experts. That's about $100.

Regards,
M.D.
'57 Coupe
M. D.

Flowing the head should help but you really need to decide what you are looking for. Camshaft changes tend to improve performance in an RPM range. If your are looking for more torque at lower RPM that will be a completely different cam grind then someone trying to increase the horse power. Most of the camshafts on the market are ground towards better midrange and higher RPM. Larger carbs with short intake manifolds increase power at the top end, longer intake manifolds will increase low end torque. While a header will help increase power at higher RPM's it will have little effect if you spend most of your time @3000 RPM or below.
Pick the RPM range that you want the greatest amount of power available and focus your search towards items that will improve the desired range.
J Heisenfeldt

Number one answer on the family fortunes board is:

Save your $500 a few times and fit a supercharger

Otherwise,

0) Lose weight (ducks and qualifies the tongue-in-cheek suggestion for both passengers - not being personal as I have never seen a picture of you)

1) get a head worked over to Stage 2

2) Fit a fast road cam

3) Fit a lightened flywheel or one from a B ( and do the B clutch mod at the same time)

4) if you want acceleration, fit a diff from a TF

Forget the cheap headers (fragile and make very litle difference
dominic clancy

Dominic, I've longed for your supercharger for a couple of years now, but I really don't have $3,500 and I don't think the supercharger fairy is stopping by soon. Though I did register for the Moss sc giveaway, sadly they forgot to send me a notice of my winnings.

As for band width of performance. First off let me say that I tend to shift in the 3,500 to 4,000 rpm range.

I will have to look at my driving habits but I'm going to guess I'm talking about the 1,500 to 3,500 rpm range for increased performance.

As for weight I'm down 25 to a svelte 170. Mrs. McCarthy would want me mentioning her weight but lets say she retains a nice feminine curvature. I could however dump the ducks.
T McCarthy

One thought I had was going to twin sidedraft Weber DCOE's
T McCarthy

Not sure you mean you want twin dcoes, one would be more than adequate. The weber would not be a good idea, it would add slightly to the power at high revs which you don't use and would only give you a very slight advantage on low down throttle response. Most performance mods need the engine to rev higher than 3.5K to take affect so your spec is rather demanding. The only real advantage to increasing torque at low revs (below 3.5K) is to increase capacity and thus the change to an 1800 engine from an MGB would be your ideal answer. IMO
Bob (robert) Midget Turbo

For 1500 to 3500 RPM range you are likely the best off with a stock or nearly stock cam. The lightened flywheel will allow it to rev quicker giving you a little more zip. The SU's work very well on a stock or mild performance motor.The side draft Webers are a waste of money until you get up to a stage 3 or better motor and like to run up the revs.
J Heisenfeldt

Install MGB valves with hardened valve seats. Rebore the engine and fit 1622 pistons + 30 thou. and MGB con rods. It will have the same performance as the MkII for not much money.

Andy 60 Coupe
Andy Preston

Interesting thread. Ignoring the cost for a moment, which option would result in more increased low-end torque and performance...supercharging a decent 1600, or switching to a 3 main 1800? Which option gives the most bang for the buck, and which would score highest on the grin factor scale?
Andy Bounsall

I would expect that a supercharger on the 1600 would run away from the stock 1800 and provide a wider grin.
J Heisenfeldt

Port and polish the head, especially the exhaust ports. Having just attended the University Motors MGA engine rebuild seminar, I learned that this is worth 5-7 HP for about $125 additional cost over a standard head reconditioning (valve seats, guides, etc).
G Goeppner

The SC 1622 eats standard Bs for breakfast. I suspect a 1600 would too.

It all really depends how many $500s you want to pay.
dominic clancy

What engine do you have?
Will MGB rods fit a 1500 or 1600?!
Cleaning up the cylinder head is the first step, hardened valve seats, a good 3 angle grind, porting the exhaust port and de-burring all ports per stage 1 and carefully removing any sharp edges in the combustion chamber can make a noticeable difference right off. My experience is that in order to fit MGB valves in the MGA head, the block must be notched for the valves to clear the edge of the block. I had to notch the block to clear a high lift cam (in my crazier days) which made it easier to fit bigger valves later. If you can find an early MGB exhaust manifold, it can be machined to clear the steering column to fit. Use the stock downpipes, angle the end to fit the exhaust pipe. It is rugged, sounds great, and at least gives the impression of increased performance.
'58 MGA 1500
Russ Carnes

Russ, you don't need to notch the block to fit MGB valves - the 1622 came with that size valves.

Mr. McCarthy - " twin sidedraft Weber DCOE's"??

Where would you put the other carb, in the boot as a spare?
Bill Spohn

You should only have to notch the block if you're using the larger valves used in the '72-'74 heads (stamped 18L), otherwise the standard B valves should fit. If you do the polishing and grinding, disassembly and reassembly, magnafluxing and machine work at a shop should cost your around $600.

Mark J Michalak

You don't need to notch the block at all for any size valves. You would need to add eyebrows in the block for a high lift cam or a severely shaved head. Also for the "L" head which has shallower combustion chamber (introduced on the 18V engine in 1972 in North America).
Barney Gaylord

Barney, if you put the larger valves in a standard head you don't need to eyebrow notch the block? You're saying it's just the shallower combustion chamber on the "L" head which necessitates this? Interesting. I had always read differently.
Mark J Michalak

Correct on both counts. With the standard head and cam all of the valve motion is well above the top of the block all within the height of the chamber of the head, so big valves are fine.

However, all B-series engines have the exhaust valve overlapping the side of the cylinder bore. If you shave the head to have shallower combustion chamber (like the "L" head), or increase valve lift, then you need to cut eyebrows in the block to clear the exhaust valves at full lift.

Additionally, the 1500 engine at standard bore size would have the intake valve overlapping the cylinder wall if you install one size larger valves like the "16" or "18' heads. With that setup and high lift (or shallow combustion chamber) you also need small eyebrows in the block for the intake side. See here: http://mgaguru.com/mgtech/power/cm202a.htm
Barney Gaylord

I know that rods from the 3 main 1800 and 1622 blocks are interchangable as I have done this. Not so sure about using the same rods in a 1500 or 1600. I believe these are different castings and not compatable. Of course I could be wrong. Electronic ignition is a nice way to avoid any performance decreases due to a wobly dizzy shaft.
J Bries

I supercharged my 1500 and it makes a huge difference in both performance and driveability even with a 3.9 rear end fitted. Of course, this doesn't fit in with the $500. increments. I put the blower on a bone stock 1500. I didn't even pull the head to check it out. The only other change to the engine is a header,free flow exhaust and new dizzy with pertronix. It runs great but I am putting together a properly built 3-main 1600 for the day that it goes Kablooie!

Rich
Rich McKIe

Rich whose s/charger did you fit? and what type.
My std. 1500 has simular set up to yours and pulls the 3.9 diff ok. With the std gearbox more torque would be nice. I don't antisapate any problems with the engine as it is tight eg., 1.5 thou clearence in all the bearings and 60lbs pressure at 2500rpm.
Do you have a picture ? Thanks Sean
S Sherry

Sean,
I used the Moss MGA blower kit but it's not in an MGA, it's in my Magnette which carries a few hundred more pounds than an MGA, so your performance should be even better. The kit installed well, very complete and straightforward. The unit has been quite reliable with the only failure to date being the idler pulley mount plate. This was repaired by welding the assembly together rather than bolting and by using larger, higher grade fasteners.

Rich


Rich McKIe

Looks very nice Rich.

I recall reading some where about a Judson equipped MGA on which the supercharger made so much noise that you could hear it coming down the street. Does the Moss blower make a noticable amount of noise?
Andy Bounsall

The Moss blower is quite quiet until you put your foot down then you get the characteristic supercharger howl. It is considerably quieter than a Judson as the Eaton blower used by Moss uses rotors which don't actually make contact with each other while Judsons use phenolic vanes which seal against the blower housing with centrifugal force and make quite a racket. (I think they sound pretty cool though!)

Rich
Rich McKIe

The Judson doesn't make that much noise if the oiler is set correctly. If not it makes a terrible clatter.

You can hear it coming very clearly when you put your fott down, but it's so much quicker than a standard A that the audible pleasure of the exhaust vanishes into the distance fairly quickly.
dominic clancy

This thread was discussed between 15/05/2008 and 21/05/2008

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