xpag-xpeg

[Walter Prechsl privat]

hello TABCers again, while watching some passed discussions about boring an XPAG to 1xxx cc s i thought also about modifications with XPEG blocks. i am not about to bastardize TC 7027, but i am keen to know: what is the difference between XPAG and XPEG ?? thanks in advance walter

[Charles Hill]

Walter, The big difference in the xpag and the xpeg is of course the cylinder bore. The water jackets on the xpeg are changed to accomodate the larger bores. I'm not sure, but I think they are so close together that they are siamesed. Regards, Charles Hill

[Chip Old]

On Tue, 4 Sep 2001, Walter Prechsl privat wrote:

> while watching some passed discussions about boring an XPAG to 1xxx > cc s i thought also about modifications with XPEG blocks. i am not > about to bastardize TC 7027, but i am keen to know: what is the > difference between XPAG and XPEG ??

The XPEG is the 1466 cc version of the XPAG used in the TF 1500. On the outside the block looks just like the XPAG/TD2 and XPAG/TF, but the cylinder bore castings are modified to suit the larger bore. Instead of having water jacket space between each cylinder as in the XPAG, in the XPEG cylinders 1 & 2 are siamesed and cylinders 3 & 4 are siamesed. The pistons are larger, of course, and the connecting rods have thicker beams. The rest of the XPEG internals are the same as in the late TD and TF XPAG. Installing an XPEG in a TC isn't difficult. At the front you'll need to install a TC bearer plate to accomodate the TC front motor mounts. At the rear the TC gearbox will bolt right on BUT the XPEG's 8 inch clutch won't fit inside the TC clutch housing. You can use a TC flywheel and a TC 7.25 inch clutch (the easy solution), or thin down the XPEG flywheel to move the 8 inch clutch forward (not always reliable), or get a special flywheel and clutch assembly from Brown & Gammons or some other source (preferred). If I remember correcty Bob Gruneau has an XPEG powered TC, so maybe he can fill in more details. It has been about 30 years since the last time I did something like that, and memory fades... -- Chip Old 1948 M.G. TC TC6710 XPAG7430 NEMGTR #2271 Cub Hill, Maryland 1962 Triumph TR4 CT3154LO CT3479E fold@bcpl.net

[Robert Grunau]

Everything Chip says about the XPEG is correct. However, the current racers often use XPAG connecting rods as the heavier XPEG rods have a tendency to be harder on connecting rod bearings due to the higher centrifugal force caused by the heavier rods. The 8" flywheel and clutch will also work in the TC if the flywheel has been lightened from the back side. My road TC has an 8" clutch/flywheel. Most racers today start with a light steel flywheel where some the steel has been cut away to form 6 "fingers" to hold the ring gear. This removes weight from the outside circumference so the flywheel revs easier. I use a 7 1/2" diaphram clutch as this has a greater holding power than an 8" spring clutch and stays together better at high revs. You can over bore the XPAG block to accept XPEG size sleeves. You probably hit water with the sleeve bore but this is usually not a big problem. Several different methods of installing sleeves are use, bore the block and leave a lip on the bottom and press the sleeve down to the lip was the "old" way. Some engine builders now make a top hat sleeve and counter bore the top deck surface to accept the lip on the sleeve. Either way seems to work. WKF Wood said use the banana block due to the extra reinforcing rib between cylinders 2 and 3. Current practise is to use round hole blocks which may have a thicker wall thickness in the bore area. Personally, I don't think it matters, certainly not for a 4000 rpm road engine. I think I have bored you enough about bores. Raced the TC at Lime Rock Conn this past weekend, had a great time, car ran like a watch and required no mechanical work. The only wrench I put on the car was to check brake adjustment when I installed new tires and wheels. Added a bit of oil, a cup of water and about 10 gallons of gas and that's it. Bob

> while watching some passed discussions about boring an XPAG to 1xxx > cc s i thought also about modifications with XPEG blocks. i am not > about to bastardize TC 7027, but i am keen to know: what is the > difference between XPAG and XPEG ??

The XPEG is the 1466 cc version of the XPAG used in the TF 1500. On the outside the block looks just like the XPAG/TD2 and XPAG/TF, but the cylinder bore castings are modified to suit the larger bore. Instead of having water jacket space between each cylinder as in the XPAG, in the XPEG cylinders 1 & 2 are siamesed and cylinders 3 & 4 are siamesed. The pistons are larger, of course, and the connecting rods have thicker beams. The rest of the XPEG internals are the same as in the late TD and TF XPAG. Installing an XPEG in a TC isn't difficult. At the front you'll need to install a TC bearer plate to accomodate the TC front motor mounts. At the rear the TC gearbox will bolt right on BUT the XPEG's 8 inch clutch won't fit inside the TC clutch housing. You can use a TC flywheel and a TC 7.25 inch clutch (the easy solution), or thin down the XPEG flywheel to move the 8 inch clutch forward (not always reliable), or get a special flywheel and clutch assembly from Brown & Gammons or some other source (preferred). If I remember correcty Bob Gruneau has an XPEG powered TC, so maybe he can fill in more details. It has been about 30 years since the last time I did something like that, and memory fades... -- Chip Old 1948 M.G. TC TC6710 XPAG7430 NEMGTR #2271

[Jeff & Merryl Redman]

G'Day Walter The answers re XPEG so far have been correct with the reference to the siamesed bores. Obviously this was necessary to obtain the overbore from the 1250's 66.5mm to 72.5 in the 1466 engine. The second part of your question is really a bit like a lottery. I have heard of a few people successfully boring an XPAG out to 1.5litre, but I have also seen bitter disapointment when the block fails. With the variations in casting thicknesses its Russian Roulette. What happens is the block's deck subsides in the centre because of insufficient 'meat' in the casting. This happened to a friend just recently. However even this can be remedied. Steam age machinery rescued by space-age technology - an epoxy was applied to the deck and when cured was surface-ground. The TC in question is now going like stink and seems fine.(Fingers crossed!!) Point of interest... back in the early 60's several TC racers here in Oz were running overbored to almost 2 litres! They were bored into the water, sleeved (coated with araldite or the like) and screwed together. They were good for about 30 laps... or a couple of hours! Mention was made of the TF having beefier rods. They're still a liability at the gudgeon end with that dreadful clamp bolt. It's well documented with sustained hard use this has been known to let go, the result is not pretty as it looks like a hand grenade has been let loose inside the block. But then again for wafting down the leafy lanes at 2000rpm I s'pose the originals will do. Interesting subject. Regards Jeff TA2828 TC3306 Message ----- From: "Walter Prechsl privat" walter@publi-consult.com> To: "tabc-list" mg-tabc@yahoogroups.com> Sent: Wednesday, September 05, 2001 4:17 AM Subject: [mg-tabc] xpag-xpeg

> hello TABCers again, > > while watching some passed discussions about boring an XPAG to 1xxx cc s i > thought also about modifications with XPEG blocks. > > i am not about to bastardize TC 7027, but i am keen to know: > what is the difference between XPAG and XPEG ?? > > thanks in advance > walter > > > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ > >

[Locktc7440@aol.com]

The xpeg block has bigger bores but the outward appearance of the block is the same as the xpag with the exception of the brass octagonal number plate wich is under the manifold on the xpeg and TD engines and on the left rear clutch housing on the xpag series TC. My TC has had a xpeg engine in it from the time I bought it and I never really realized it until I had to replace the crankshaft about six years ago. When the engine was torn down it turned out to be a xpeg block. I had always thought it was a TD engine. This also explains why I could usually outrun most other TCs andTDs. The engine has now ben bored .40 and one cylinder sleeved because of a casting imperfection. Runs beautifuly and plenty of go.. Jay Lockrow TC7440

[C Sherriff]

Message text written by INTERNET:cgrunau@pathcom.com

>Everything Chip says about the XPEG is correct.

However, the current racers often use XPAG connecting rods as the heavier XPEG rods have a tendency to be harder on connecting rod bearings due to the higher centrifugal force caused by the heavier rods. The 8" flywheel and clutch will also work in the TC if the flywheel has been lightened from the back side.

[Robert Grunau]

Hi Clive, George Edney says he uses standard XPAG rods in his race T types and Lester! Bob

>Everything Chip says about the XPEG is correct.

However, the current racers often use XPAG connecting rods as the heavier XPEG rods have a tendency to be harder on connecting rod bearings due to the higher centrifugal force caused by the heavier rods. The 8" flywheel and clutch will also work in the TC if the flywheel has been lightened from the back side.

[C Sherriff]

Message text written by INTERNET:cgrunau@pathcom.com

>Hi Clive,

George Edney says he uses standard XPAG rods in his race T types and Lester! Bob

[Walter Prechsl privat]

thanks, for all your extensive explantions about xpag-xpeg! but what i didn t got completly: - is there a diffrence, which can be seen outside the engine? - is xpeg really another casting than xpag? or did they use blocks with a accidential thicker cylinder wall as base for the 1500 bore? walter btw. thanks also for the words concerning "gymkhana"