Carburetors

[Gene Gillam]

Excuse me if this is a dumb question, but will the 1 1/2" carburetors from an MGA or MGB bolt up to the manifold for the XPAG? If not, does anyone know if there's much adaptation to get them to fit? I see these advertised in Ebay all the time - and it seems like a set could be gotten at a reasonable price - if they were would fit. Thanks, Gene Gillam Saucier, MS

[C. Knight]

Gene Gillam wrote:

> > Excuse me if this is a dumb question, but will the 1 1/2" carburetors from an >MGA or MGB bolt up to the manifold for the XPAG? If not, does anyone know if >there's much adaptation to get them to fit?

The TF 1 1/2" ones will - others will confirm MGA/MGB. I would advise against though. The venturi is too large and you will find, as on the TFs that you need ridiculously light suction chamber springs and possibly a lightened pistons to get enough movement on the fuel metering needles. The breathing on the XPAG won't give enough suck to move the piston on the bigger carbs more than 1/2". MG only fitted the big carbs on the 1250 TF for marketing reasons - as confirmed by the Late Don Jackson who tested the 1250 and 1500 TF carbs for MG at S.U. Cliff

[Skip Kelsey]

Gene: The 1 1/2 inch MGA carbs are a direct bolt on. You have to hog out the manifold a little to take advantage of the 1 1/2 size. The linkage for the choke is different, and you can use what is on the original carbs. The MGB carbs are different, and will not fit the XPAG manifold. Skip Kelsey................................................... At 10:50 AM 7/25/02 -0400, Gene Gillam wrote:

>Excuse me if this is a dumb question, but will the 1 1/2" carburetors from >an MGA or MGB bolt up to the manifold for the XPAG? If not, does anyone >know if there's much adaptation to get them to fit? > >I see these advertised in Ebay all the time - and it seems like a set >could be gotten at a reasonable price - if they were would fit. > >Thanks, >Gene Gillam >Saucier, MS > > > > >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

[Skip Kelsey]

Cliff: I have to disagree with some of what you state. I have been running the 1 /2 inch carbs for over 30 years. I had to install the heavier "red" springs to further damp the pistons. The heavier to springs, the richer the acceleration. I do agree that the bigger carbs are a waste with a stock engine. My engine runs 9 1/2 to one compression, and is ported , polished, and bored out to 1350 CC.I also run a derrington extractor manifold. Plus I have to run EL needles to get it rich enough to not burn valves.It does go like stink though. Skip Kelsey................................................................................... At 04:17 PM 7/25/02 +0100, C. Knight wrote:

>Gene Gillam wrote: > > > > Excuse me if this is a dumb question, but will the 1 1/2" carburetors > from an >MGA or MGB bolt up to the manifold for the XPAG? If not, does > anyone know if >there's much adaptation to get them to fit? > >The TF 1 1/2" ones will - others will confirm MGA/MGB. I would advise >against though. The venturi is too large and you will find, as on the >TFs that you need ridiculously light suction chamber springs and >possibly a lightened pistons to get enough movement on the fuel metering >needles. The breathing on the XPAG won't give enough suck to move the >piston on the bigger carbs more than 1/2". MG only fitted the big carbs >on the 1250 TF for marketing reasons - as confirmed by the Late Don >Jackson who tested the 1250 and 1500 TF carbs for MG at S.U. >Cliff > > > >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

[Chip Old]

On Thu, 25 Jul 2002, Gene Gillam wrote to mg-tabc@yahoogroups.com:

> Excuse me if this is a dumb question, but will the 1 1/2" carburetors > from an MGA or MGB bolt up to the manifold for the XPAG? If not, does > anyone know if there's much adaptation to get them to fit?

The 1 1/2 inch carbs from a TF or MGA will bolt right up, but if I remember correctly the MGB carbs have a different bolt pattern. You'll need to either enlarge the manifiold bores to match the larger throat size, or else switch to a TF manifold. The linkage is different, so if you want the throttle, choke and slow running controls to work as they do on a TC, you'll have to substitute levers etc from your TC carbs. The standard TC air cleaner setup won't work, so you'll need TF filters or aftermarket pancake filters. However on an otherwise stock XPAG larger carbs are a waste of time and may actually make "around town" performance worse. To take advantage of the larger carbs you need larger TF-size valves and higher compression ratio at the very least, and preferably also larger displacement, a modified camshaft, and an extractor exhaust. By the way, if you come across a set of 1 1/2 inch carbs from a TD Mk II, leave them to the folks with Mk II's. They are 1 1/2 inch SUs, but of a different design. The TD Mk II is the only MG model to use them originally, as far as I know. -- Chip Old 1948 M.G. TC TC6710 XPAG7430 NEMGTR #2271 Cub Hill, Maryland 1962 Triumph TR4 CT3154LO CT3479E fold@bcpl.net

[tonygoodall]

Gene I have just removed TF carbs from my TC in favour of the original size and I am very happy with the result. My TC has a raised compression ratio,( 8.5 - 1) lightened flywheel and TF valves but I just felt the TF carbs were unnecessary. The new set up is much sweeter. I guess you have to go a bit further down the tuning line to get the benefit from the bigger carbs, as evidenced by Skip's E-mail. I seem to remember that the standard carbs are recommended in Blower for stage 1 and 1a. Tony TC 9825

> From: Gene Gillam anngene@bellsouth.net> > Date: Thu, 25 Jul 2002 10:50:05 -0400 > To: mg-tabc@yahoogroups.com > Subject: [mg-tabc] Carburetors > > Excuse me if this is a dumb question, but will the 1 1/2" carburetors from an > MGA or MGB bolt up to the manifold for the XPAG? If not, does anyone know if > there's much adaptation to get them to fit? > > I see these advertised in Ebay all the time - and it seems like a set could be > gotten at a reasonable price - if they were would fit. > > Thanks, > Gene Gillam > Saucier, MS > > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > >

[Clifford Lockrow]

My TC has a 1500 xpeg block(got it that way) bored to 40 thou, has a milled head, its been ported and polished. I run the 1 1/4" carbs and there is plenty of punch. My dad used to have a TC with a standard TF engine with the big carbs and I could run away from him.(this was before I had to bore 40 thou) tonygoodall wrote:

> Gene > > I have just removed TF carbs from my TC in favour of the original size and I > am very happy with the result. My TC has a raised compression ratio,( 8.5 - > 1) lightened flywheel and TF valves but I just felt the TF carbs were > unnecessary. The new set up is much sweeter. I guess you have to go a bit > further down the tuning line to get the benefit from the bigger carbs, as > evidenced by Skip's E-mail. I seem to remember that the standard carbs are > recommended in Blower for stage 1 and 1a. > > Tony TC 9825 > > > From: Gene Gillam anngene@bellsouth.net> > > Date: Thu, 25 Jul 2002 10:50:05 -0400 > > To: mg-tabc@yahoogroups.com > > Subject: [mg-tabc] Carburetors > > > > Excuse me if this is a dumb question, but will the 1 1/2" carburetors from an > > MGA or MGB bolt up to the manifold for the XPAG? If not, does anyone know if > > there's much adaptation to get them to fit? > > > > I see these advertised in Ebay all the time - and it seems like a set could be > > gotten at a reasonable price - if they were would fit. > > > > Thanks, > > Gene Gillam > > Saucier, MS > > > > > > > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > > > > > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

[murray arundell]

Gene, Skip is right, but you really should invest in some work on the head and a camshaft upgrade to get the full benefit from the bigger carbs. Murray (in Oz)

----- Original Message ----- From: "Skip Kelsey" kelsey@shadetreemotors.com> To: "Gene Gillam" anngene@bellsouth.net>; mg-tabc@yahoogroups.com> Sent: Friday, July 26, 2002 2:10 AM Subject: Re: [mg-tabc] Carburetors > Gene: > > The 1 1/2 inch MGA carbs are a direct bolt on. You have to hog out the > manifold a little to take advantage of the 1 1/2 size. The linkage for the > choke is different, and you can use what is on the original carbs. The MGB > carbs are different, and will not fit the XPAG manifold. > > Skip Kelsey................................................... > > > At 10:50 AM 7/25/02 -0400, Gene Gillam wrote: > >Excuse me if this is a dumb question, but will the 1 1/2" carburetors from > >an MGA or MGB bolt up to the manifold for the XPAG? If not, does anyone > >know if there's much adaptation to get them to fit? > > > >I see these advertised in Ebay all the time - and it seems like a set > >could be gotten at a reasonable price - if they were would fit. > > > >Thanks, > >Gene Gillam > >Saucier, MS > > > > > > > > > >Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > > > > > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > > >

[Chip Hellie]

Hey guys, If I'm not mistaken, the TD MK 11 or TF has a manifold to fit the 1 1/2 SU's. I know I have one someplace. I know were not suppose to talk about THOSE models here. Chip Hellie --- Murray Arundell arundell@ecn.net.au> wrote:

> Gene, > > Skip is right, but you really should invest in some > work on the > head and a camshaft upgrade to get the full benefit > from the > bigger carbs. > > Murray (in Oz) > > ----- Original Message ----- > From: "Skip Kelsey" kelsey@shadetreemotors.com> > To: "Gene Gillam" anngene@bellsouth.net>; > mg-tabc@yahoogroups.com> > Sent: Friday, July 26, 2002 2:10 AM > Subject: Re: [mg-tabc] Carburetors > > > > Gene: > > > > The 1 1/2 inch MGA carbs are a direct bolt on. You > have to hog out the > > manifold a little to take advantage of the 1 1/2 > size. The linkage for the > > choke is different, and you can use what is on the > original carbs. The MGB > > carbs are different, and will not fit the XPAG > manifold. > > > > Skip >

Kelsey...................................................

> > > > > > At 10:50 AM 7/25/02 -0400, Gene Gillam wrote: > > >Excuse me if this is a dumb question, but will > the 1 1/2" carburetors > from > > >an MGA or MGB bolt up to the manifold for the > XPAG? If not, does anyone > > >know if there's much adaptation to get them to > fit? > > > > > >I see these advertised in Ebay all the time - and > it seems like a set > > >could be gotten at a reasonable price - if they > were would fit. > > > > > >Thanks, > > >Gene Gillam > > >Saucier, MS > > > > > > > > > > > > > > >Your use of Yahoo! Groups is subject to > http://docs.yahoo.com/info/terms/ > > > > > > > > > > > > > > > > Your use of Yahoo! Groups is subject to > http://docs.yahoo.com/info/terms/ > > > > > > > > > > > Your use of Yahoo! Groups is subject to > http://docs.yahoo.com/info/terms/ > >

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[C. Knight]

Skip Kelsey wrote:

> > I have to disagree with some of what you state. I have been running the 1 > /2 inch carbs for over 30 years. I had to install the heavier "red" springs > to further damp the pistons. The heavier to springs, the richer the > acceleration.

To hopefully clarify: The problem with fitting larger carbs is getting enough piston lift at full load/full throttle to utilize the full calibrated lengths of the needles. 1 1/2" carbs work OK a 1500cc XPAG with big valves. They don't work well on a 1250cc engine with standard valves. In between you really need to check on a rolling road or you may get problems. Too little lift means the needle is only operating at the cruising metering part of the needle when it should be at the "rich" end of the calibration, resulting in weak mix at high road speeds and burned valves. Solution is to fit a needle that is richer in the middle to compensate such as EL or lower and accept over rich running at cruising speeds. The second problem is maintaining sufficient vacuum at the bridge to atomize the fuel in the jet. 12" to 13" is required but with 1 1/2" carbs you won't get this on a standard engine. MG's compromise on the 1250cc TF was to fit lighter "blue" piston springs and GJ or GL needles that ran richer at idling to aid atomization. Choice of needles that run that rich at idle are very limited and you will probably have to accept a poor needle match to your engine performance, as did MG on the TF 1250cc. I'll post this tomorrow as it is now such a lovely evening I think I'll take my MG out for a spin and see if I can still get full lift on my needles Best wishes Cliff