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MG Midget and Sprite Technical - rebuilding a 1500 engine

Having considered a K series transplant and dismissed it on cost grounds, I'm now leaning towards keeping the 1500 engine (albeit with a 5 speed - type 9 conversion).

Almost everyone I speak to has a different opinion about what to do, when and where to do it.

I think I'm likely to buy a second engine, just so that the time the car is off the road is less. Apart from that as a starting point, I think a new manifold would make sense - I'm keeping the exhaust, it's an almost new lovely stainless system. I can't afford a weber conversion, so will probably keep the carb as is (just re-jetted) with a couple of lovely air-horns.

I understand that oil is an issue, so mods to the bottom end oil paths are frequently suggested. As is an oil cooler. I will want to do an unleaded head, and everything else is up for grabs.

I don't believe there's much room for overboring, and will old fashioned head work reward the money spent? It'll need a new camshaft I'll bet.

Will also be putting in an electric fan.

Rather not go to the expense of new ignition/dizzy.

I'd love to hear from anyone who has built a good useable road engine. I won't be doing track days and racing this car.

Thanks for any help.

Tim
t halket

What is wrong with the current lump?

If it is not doing annything wrong i would start with the basics

carbs and exhaust manifold
then do the head
go for a set of roler rockers

see what that does first and mostly how you like it
then decide how to go futher
Onno Könemann

Where in Suffolk are you?

Some of your ideas are good - others are a little conservative - and some aren't actually correct in what you can and can't do ... ;)

Yes, an extra engine does help - if you can get a decent one!
rachmacb

Hi Tim

Lots of people will be along with their opinions, first you need to think what you want from the engine and what you want to spend. Sometimes these are far apart but usually a happy medium is found!

The 1500 has a known weakness of poor oil supply to the head so if you don't have it already the aftermarket rocker oil feed kit, get it, it is essential, as is a 13 row oil cooler. I had a 100bhp heavily modified engine and had no oil pressure/supply issues with this setup.

Cams are a good way to get a noticable power gain however remember you lose lowdown torque as you increase power as a rule, so in a road car I would suggest no more agressive than a Fast Road 83 cam or equivilent which doesn't give you any meaningful torque until 2500rpm.

Unless you want to get serious with the engine, I would not worry about the larger pistons & increased bores. I'd suggest that any headwork is limited to cleaning up the ports, unleaded valve seats and new/bronze valve guides. Anything more than this and you really need to fit larger valves, stronger valve springs and tubular pushrods.

Electric fan is good for peace of mind in traffic, dizzy should be fine though an electronic ignition fitted to the dizzy is a great fit and forget part. If you search the archives there was a thread which gave a link to a landrover (use the same dizzy 45D4) specialist who was doing the electronic pointsless system for less than £30!

All the above is my opinion only, I will also pop a little plug in here, for a pair of webers with everything you would need to fit them to a 1500 midget at a very reasonable price. ad in the classifieds here on this site or at the address below.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&rd=1&item=150548247894&ssPageName=STRK:MESE:IT

Have fun whatever you decide, I did!

Dave
D Prince

the electronic module ==>http://www.mm-4x4.com/britpart-electronic-conversion-kit-2721-p.asp as mentioned above, its for the 45d4 dizzy. i fitted one of these and it has been really good. only one issue is that you need to create a new 12V feed to the module. if your battery is not in great condition and your supply voltage drops far below 12V whilst cranking, it can effect the spark! but if you have a good battery, then you shouldnt notice it

another possibility is to go for a 1275 engine, or go down the kit car option, look for an old ford sierra or grenada engine (can use the gear box - 5 speed)

if your sticking with the HS4 carbs, buy the Vizard's A series tuning book. covers loads of carb mods to maximise air velocity and so on. although the 1500 isnt an A series, you would be surprised what you will learn
Rich K

oh could always consider tis http://www.amazon.co.uk/Midget-Austin-Healey-Performance-Speedpro/dp/1845841425/ref=pd_sim_b_3
Rich K

The Moss Midget & Sprite catalogue has an excellent article on tuning the Triumph 1500 as fitted in the Midget. Well worth a read.

Dave
D MATTHEWS

Wait for Deborah Evans, she knows what is to know about the 1500 (and A-series).

On my 1500 i had changed to a maniflow exhaustmanifold + Hs4 SU's + K&N airfilters + ford 5 speed + oil cooler.
Great roadperformance!
Never got to fidling with the internals(camshaft & so on)or had oilproblems.

Tim, dont forget to pay attention to the handling of the car in terms of frontsuspension, thicker antirolbar.


Im suprised Rachel hasnt suggested yet to remove the rubber bumpers.
LOL!!!! (I know im evil) ;)
Arie de Best

Lol Arie - I just know a few very useful places down there, and, as for bumpers, well, my car has won with them, so ...!

Hate to rub it in how it is better on cornering than yours ;)! I notice that you are using any excuse not to compete against me ... So, let the best car compete :)
rachmacb

Hi, and thanks for the great respone!

I should have mentioned that so far the car has been stripped of a load of weight. The bumpers are off, as is the windscreen. The doors are just the shells, there's no roof, wipers, heater, or carpets. I run it with a couple of brooklands aeroscreens and a gaffer tape interior. Nicely ratty.

All this has meant that it sits about an inch higher than it should. So I have under my desk and soon to be fitted a lowering kit from Peter May and shorter front springs. I'll also be getting a stiffer anti-roll bar fitted.

My thinking so far is: Get a second engine. Have it rebuilt with improved oil ways (need to figure out the details of that), high pressure oil pump, oil cooler. Have the head unleaded, tidied and skimmed. Rebuilt the HS4 SUs to get max airflow. Fit a new extractor exhaust manifold. Inside the engine just get a fast road camshaft and tidy up. The land rover electronics sounds like a sensible idea. New electric fan.

And an Archers Garage Sebring GRP bonnet.

Someone asked where I live; I'm on the southern border between Sudbury and Haverhill.

t halket

Thought you might like to see a picture (assuming I can handle the technology!)

It's the black car!

Tim


t halket

Get your antiroll bar from Magic Midget - it's almost too pretty to put on the car (but then, it's not in pink, so, not perfect ;)!)

It was me who asked where you are - there is a very, very good machine shop in Ely, where a couple of us are already planning on taking engines this year, so I didn't know if there was a chance of blagging a "bulk discount" ...?! You can go a little bit bigger without having to do too much to counter it.

If you have a spare £300, there's a pair of twin webbers set up for a 1500 (the ones on the ebay link) on the classified section of MASC, should you decide that that might be a possible way - and I'm sure you'd get at least half that back with your carbs!

Be careful what cams you go for - not all of them are good on the 1500 - and, don't go with quite alot of what's in the Moss catalogue - someone told me that, and, I respect her opinion way more than most of the people on this board .... ;) Don't forget to look at the Triumph parts as well as the MG ones, many of them are superior for the engine anyway.

Despite what people think, there's LOADS you can do to the 1500, it's just that, fewer people actually play with them, so, it's perhaps not as well known - hence the snobbish tendencies of the 1275 brigade (not that many of them actually have a 1275 ...:P) You can overbore, as I've mentioned above, and, one of the first things you should do is a duplex timing chain - assuming you've not already.

Let me know if you want the details of the machine shop
rachmacb

hey rach, does the roll bar (one from Magic Midget) make quite a difference (to a road car)? mine needs replaced, was going to get a standard one, but i am now interested.

I dont know if you should overbore the 1500 engine. I read the haynes restoration manual, and it said that the 1500 started life out as an 850 (ish) and was continually bored up to a 1500. According to the author, the space between the cylinders is very small, and the engine is at more risk of failing?

You can also look out for dellorto carbs, they are webber copies essentially, find them a lot on kit cars!
Rich K

Rich - any ARB will improve for road work, but, I don't just drive mine on the road ;) It does make quite a difference for other things. If you are just wanting one for road use, then, you might want to look at the 3/4" one, which is recommended for the 1500 general use. As I mentioned in another thread, you might also want to look at poly bushes on your car, and what tyres you are using - yes, it is more important to do these things on a Midget than on a mini! HTH

You can rebore out the 1500 engine, but, if you go too far, then you have to put new liners and do other work to it. All engines are at more risk of failing the more work you do to them ... but, it depends what you are going to do with it.

Dellorto ones seem to currently be about the same price at the moment - from what I've seen on ebay over the past few months ;)!
rachmacb

cheers rach, will have a look into the ARB. That magic midget site looks really good, can see me spending a fair amount there :D

I have heard mixed reviews about polybushes but mainly from the mini scene (but i think its due to the fact that the rubber doughnut style suspension isnt that good). will also have a look into it though thanks :)

It used to be that dellorto carbs were a lot cheaper than the webbers. I rebuilt my friends dells using a webber manual, pretty much the same :)
Rich K

You're welcome - he's a great guy and very helpful and informative - also sells polybushes ... ;)

I think that, if you're lucky, you can still get them cheaply enough, but, everyone seems to have worked out they are good ...:(
rachmacb

front suspension rebuid is on the list (mr MoT man warned me that all the bushes need replaced) :(

will put away the pennies
Rich K

As for converting to a heavier ARB, the usual caveat applies:

http://www.flickr.com/photos/safety_fast/sets/72157623942645649/

Cheers,

-:G:-
Gryf Ketcherside


Hi
It's true, the 1500 isn't as bad as it's reputation suggests. I had one in a spitfire that I rebuilt and added a free flow exhaust, twin webbers and a modified head, and Wilshires in cambridge got 85 up at the wheels. Drove it loads with no issues!
Another source of good info are triumph spitfire sites on the web. Also jigsaw racing, they even used to sell a guide to race prep (I have a copy and it seems to have some reasonable info). The rocker oil feed is quite contreversial a recent article in the TSSc club magazine concluded that it was more gimmick the anything and that it could negatively effect lubrucation of the main bearings. A cooler us a v good idea however.
Cheers
Tim
T Dafforn

I had forgotten to mention that a duplex chain would be a good idea and probably fitted.

I'm interested in the "controversy" over the rocker oil feed. That has been recommended to me and I was considering it. What's the story?

Tim
t halket

"I'm interested in the "controversy" over the rocker oil feed. That has been recommended to me and I was considering it. What's the story?"

From my larger article on the Triumph 1500:

EVERY kit I have seen uses a –3 hose with a banjo fitting to go into the oil gallery plug at the back of the head and a 1/8 NPTF fitting to screw into the main oil gallery beneath the distributor. A moment’s thought, given what I have said about oil feed to the centre main bearing, will show up just why this is a bad idea. By connecting the rocker feed in this way you will inevitably rob oil from the centre main, hence you will actually make your motor more likely to go pop!

Additionally, with no restrictor, you will over-feed oil to the rockers causing problems with inlet valve stem oiling at low rpm (meaning your motor will both burn oil and be closer to causing detonation from the reduction in octane of the fuel/air charge!).

Finally, merely fitting an external oil feed while the internal oilway to the cylinder head is active will cause cavitation in the oil galleries and ALL SORTS of flow problems. By far the best way to fit an external rocker feed is to firstly block off the vertical oilways in the block and head (use a tap and an 8mm grub screw in both block and head) and to take the feed from the main gallery at the rear of the block (opposite number 3 main) via the 5/16” UNF oilway plug tapping. To do this you will need a –2 to –3 male-male adapter to screw into the side of the block.
Deborah Evans

Rach,
Is the machine shop in Ely, or Littleport ?
Graham

Couldn't have put it better myself..
Just need to add, wouldn't you rather wear in an easy to change component set like the rocker gear, rather than new mains and crank regrind..
Hope this helps make your decisions.
Tim
PS interested in the decision to use a Sebring GRP bonnet. I'm thinking of similar for a road car. What do you guys think?
T Dafforn

Of course Tim,

You could come and see me and we could discuss EXACTLY what you want out of a 1500, and what you want to do with it.

Then I could build you one (30 years experience with the Triumph 4-pot).
Deborah Evans

Sorry Graham - busy weekend! Between Ely and Soham

Debs is, of course, the best person in the country to rebuild a 1500, and I would advise that as an option - she's got a head there that is positive drool making ...!
rachmacb

This thread was discussed between 13/01/2011 and 18/01/2011

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.