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MG Midget and Sprite Technical - PECO Tubular Exhaust

I have just received my latest eBay bargain, a PECO manifold 4:2:1. Prior to fitting it I would like opinions on lagging it to prevent heat escaping into the engine bay. I have heard horror stories saying that without the heat escaping from the pipe it transfers to the head. Opinions welcome

Nick Sayle

See my thread titled 'Weber 45DCOE heat shield' down the page.
Jordan Gibson

oh its a Peco, lag it all you the new ones actually fit?
Brad (Sprite IV 1380)

fits like a glove, all for 60 quid!
Nick Sayle

thanks Jordon, won't be lagging it. off to the garage with my spanners
Nick Sayle

and do they flow beter that the stock setup..
i have thrown several (not mine) in the trash
and by the look of it :(
just look how 1 and 4 join not realy a preformance item
Onno Könemann

As my original manifold has cracked and needs replacing,I'm thinking about a tubular. What's the view on these? Any good? Or any other recommendation?
Jonathan 1972 1275 RWA

My turn to say don't be cheap - I vote Maniflow!
Jordan Gibson

Maniflows also crack at the y-piece

Mine received major surgery and i reckon the manifold studs will now give way before the pipe or joins crack anywhere

i have just come in from the garage having fitted the new manifold. I welded in a small triangular plate on the "Y" section both side to give some extra strength. I have a tiny blow where it joins the rest of the pipe but I will sort that tomorrow. It sounds amazing and I have lost a load of unwanted weight yet again
Nick Sayle

from what Ive read.... your ahead, re-sell it on ebay or store away for use as scrape metal

nothing good will come of this


dont forget Im not fitted it to one of those silly 3 port exhaust engines. I will keep it on the car until it fails then do something else
Nick Sayle

Will the 4-2-1 fit into a midget? I've seen them on spitfires, but I do not think I've seen one on a midget.
Trevor Jessie

yes, this one is designed for the Midget

Nick Sayle

The PECO manifold is certainly better than the stock piece of rubbish that BL fitted to the Midget 1500 (basically a Herald/Toledo/Dolomite item that is nowhere near as good as the manifold used on the 1500 Spitfire) and works quite well on a std engine. However, it really is rather restrictive once you start tuning the motor owing to it's quite narrow Primary and Secondary pipes.

The manifolds made by both Falcon and Phoenix are better optimised for motors in higher states of tune. Qv later.


I'm not a fan of lagging manifolds. Firstly you change the exhaust gas velocity (and therefore the standing wave length of the exhaust gas pulse) which buggers up the pulse tuning. Secondly you get heat soak into the cylinder head which is never a good thing (albeit less bad on an iron head). Thirdly lagging hides any indication of damage to the manifold (and in many cases seems to exacerbate it).


"Will the 4-2-1 fit into a Midget? I've seen them on Spitfires, but I do not think I've seen one on a Midget"

Aside from PECO the only people who do a manifold 'off the shelf' specifically for the Midget 1500 are Falcon (marketed by Moss).

There ARE differences between a Falcon Spitfire 4:2:1 manifold and a Midget 1500 4:2:1 manifold, the major one being price - Midget manifolds being generally 20% more expensive! Having said that the Midget manifold has longer Primaries and shorter Secondaries than does the Spitfire one and is, therefore, less well suited to the cam profiles known to work well in the Triumph 4-pot.

The other difference between them is that the Midget manifold comes off the head at a different angle before the down turn allowing the Secondaries to run outside the chassis leg. There is then a bend after the Collector to swing the Tertiary to the left side of the car so as to match up with where the pipe would normally run.

On the Spitfire manifold the Primaries run slightly closer to the block allowing the Secondaries to fit inside the Spitfire chassis rail (which is significantly wider than the 'leg' on the Midget). The collector is such that the tertiary then runs along the car between the 2 rails of the Spitfire's X shaped chassis.

There is a slight problem with the Falcon manifolds in the location of the Primaries for numbers 2 and 3. The manifold flange is poorly designed here and (in stock form) does not cater well for accurate port matching. If using Falcon manifolds I modify them by adding blobs of weld to the areas of the flange (where it buts up against the manifold to head studs) and then machine these such that I get an accurate port match.

Given the price difference (and the fact that customers like to spend as little as possible!), as well as the fact that the Midget manifold does not perform anything like as well, I will generally fit the Spitfire set up to the Midget 1500. This merely requires some 'gentle persuasion' to the horizontal 'lip' of the Midget chassis leg to get the manifold in and and an 'S' bend in the Tertiary downstream of the collector to swing it to the left side of the car. On the 1500s I have done for people this set up works perfectly well.

I understand that Maniflow do a Triumph 4-pot manifold for a similar price to the Falcon one but I have not seen it and, therefore, can not comment.

The ultimate 'off the shelf' manifold for these motors is that made by Phoenix. This replicates the 'Works' race manifolds in that there is a one piece flange holding all 4 Primaries thus ensuring perfect port matching. However, while rather 'Gucci', this manifold is some 50GBP more than the Falcon one (and that's BEFORE you add the dreaded VAT [sales tax])!
Deborah Evans

i must admit
i am an A and B series guy
i just expected that peco was peco and rubbish anny way
good to hear it is an improvement over std on a 1500
Onno Könemann

I love the B engine. I have an Oselli 1860 in my B though I am finding more low rev torque from the 1500 Triumph. The new manifold and exhaust has made a fantastic difference. Sounds fab!!
Nick Sayle

I had a peco on my 1500 for years with K&Nfilters and 2 Hs4 carbs.
It ran well but sadly I had lowered my car to much and we have to much speedbumps in Holland...
After rewelding it for 7 times it was beyond repair.

Ordered a new one and guess what?
The bend from enginebay to rear was about 7cm lower!!!

I then ordered one from Peter May, that was excelend.
Its still on Rolfs midget and together with a custom made rfs exhaust its an excelent kit and sound!
I dont know if that was a Phoenix like Deb mentioned.

no more peco for me anymore

Anybody wants a 1500 Peco which needs some work on the bend? :)
Arie de Best

I too have the peco 4-2-1 on my 1500 but when removing my engine for a rebuild I had to cut the exhaust at the 2 section as we could not split the joints!! I now have to weld it back together and split the joint, any tips on ways to split the joint?

Thanks in advance
S J Dodd

Hey Arie,

Nice to hear it's a Peter May manifold, didn't know that. Indeed, the set-up is magnificient in build- and soundquality.
In the picture you see Arie and me talking about our excellent cars.:)


Nice brown socks with your shorts there arie!

Tarqs,atleast I have an excuse to look like that, whats your reason? LOL!!!

I came to the event in jeans, swapped to shorts when the sun got hotter and hotter but forgot my flip-flops so voila ;)
Arie de Best

I bought a good secondhand PECO 4-2-1 exhaust manifold for my 1500 and fitted it. The fit was so bad I took it straight off and sold it on e-bay.

Bought a Falcon one, bigger bore, better fit
l snowdon

I have a Janspeed 4-2-1 header that I purchased from the Motherland on Ebay. No problems with that on my 1500 Midget, although I agree that the runners could be larger... it still is better I think than the Monza/Pacesetter 4-1 header I used to have. "Street 4-1 manifolds"... lol 4-2-1 are actually better for street/road as they provide mid-range than the 4-1's high-end power gain which is better suited to race. (Who races 1500's anyways!)
Ron Koenig

This thread was discussed between 01/06/2010 and 18/06/2010

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