Jump to content

Triumph straight six engine conversion spit mark 3


MikeK
 Share

Recommended Posts

Don't shoot me but I am going to drop a 2.0 straight six GT6 engine into my Mark 3 Spitfire. Tips on best way to do this with least disruption to rest of the car? I'd like to keep the original bonnet as is so outwardly normal looking Mk3. Radiator will have to move forward and slant for bonnet curvature ? Help !

Link to comment
Share on other sites

The engine will foul the bonnet, you won't get it in without a GT6 bonnet unless you pull the engine back into the cabin, but that means cutting the chassis. Richard at East Berks has done this on a 1500,  but major surgery.  You should use the GT6 radiator to cope with the engine. Brakes may also need upgrading.

Link to comment
Share on other sites

Yes, the only way to do it keeping the spit bonnet is t use a spitfire front engine plate on the 6 cylinder, there are quite a few about if you look carefully. Picton Sportscars have done a few.

It makes an excellent conversion. Very good handling and balance. However, not a cheap way to do the conversion and very involved meaning a lot of cutting and welding especially to the bodytub front bulkhead.

Yes, you will need a rather larger radiator, a diff/gearbox swap, and I would suggest a swap to swingspring rear suspension using late GT6 driveshafts.

And yes, definitely needs GT6 front brakes as well!

Link to comment
Share on other sites

Hi MikeK. Yes, David Picton did mine and it makes for a really neat & tidy package - but not cheap! You need to cut away the shelf behind the engine, so the engine can be moved back about 6" or 7". This means it misses the steering rack and can be about 1.5" lower - the same height as the 4-cylinder and easily clears the Spit bonnet. So as Clive says, you simply use the 4-cylinder front plate and it bolts straight onto the suspension uprights. It's best to change the whole front suspension for GT6 so you have the stronger vertical links and GT6 brakes to cope with the extra weight & power. Then you re-build the firewall and, as the gearbox is 6" further back, fabricate a new tunnel & shorten the propshaft. By the way, Triumph's PI fuel injection works best for this as the carbs stick out further and foul the master cylinders.

Are you getting an idea of how much is involved? But you do end up with a really terrific car - well worth the time & money! (Well, that's my view, but then I would say that ... !)

Cheers, Richard (East Berks)

Link to comment
Share on other sites

OK - Part 2 - I stripped the engine down yesterday, going to bore it out fit new oversize pistons, a reground camshaft + lifters,  new shells, plus get the head skimmed. Any tips on anything else I should consider to eak out the best performance and make it as like new as possible ? Also tips on the best place to buy the bits from a quality and price perspective ? Cheers - Mike

Link to comment
Share on other sites

Have a word with Newman cams... I would be tempted by a duplex timing chain too.

Worth getting the head skimmed to match the cam too. And then of course the distributor matched to the cam. Or megajolt/squirt....

As to the actual build, you can weigh the individual pistons and conrods, and try to get them all to match. Often lightest piston with heaviest rod, then work your way through them gets good results. JohnD will be able to offer advice re modifying the rods etc if you wish to go down that route.

One of the TR specialists have had vandervell crank bearings made, probably worth getting those as hopefully the best available.

I am uncertain what carbs you intend using, or what will fit in your application. Or even PI/EFI

Link to comment
Share on other sites

Rods are considered to be two thirds rotating mass, one third reciprocating, but either way, worthwhile equalising.   The difficult bit is weighing each end!    You need to suspend the unweighed end by a chain, and ensure that they are all horizontal.  I think I've posted about lightening rods (not lightning rods!) on Sideways: http://sideways-technologies.co.uk/forums/index.php?/topic/7553-pistons/&page=2  Pistons are easy to weigh, and to balance in weight.   I remove a fraction of skirt on the lathe, but others drill inside.

Overboring doesn't get much more performance, or capacity.    You're clearly ambitious, but for best effect the mods you intend have to be a package, togther with better breathing;  flowing the inlet and exhaust, and a tubular manifold, 6-3-1 for preference.    You can aim for 10.5:1 CR if you stick to ShellVR or equivalent for the highest octane available.     See: http://sideways-technologies.co.uk/forums/index.php?/topic/7551-how-to-raise-the-compression-ratio-safely-and-effectively/&tab=comments#comment-99739

And of course, raised performance must be a package with brake and suspension improvements, or at least optimisation.  Triumph brakes are fine on the road, but vented discs good for sport driving.      The halfshafts are the Achiiles Heel.  In swing axle or Rotaflex versions they have a design fault in a stress raising radius change  at the hub, but again, unless you get into motorsport, road use is unlikely to cause you a problem.

Good luck!

John

Link to comment
Share on other sites

  • 3 weeks later...

So all - 2 l straight six Engine stripped down - gunked and steam cleaned today, getting the head skimmed and rebored 40 thou ... so soon I am going to have to drop it in. Anyone out there got piccies of a Mk3 Gitfire and the mod needed on the Spitfire bulkhead to drop the engine back 6-7 inches ? What did you do with the tunnel and carpets with the stick further back? Also best engine mount method ? Thanks all ! Mike

Link to comment
Share on other sites

Simple answer for engine mounting is to use a spitfire frontplate, and use spit engine mounts. Not as strong as GT6, but should be fine and used by others. Have also seen DIY approach, using e-type mounts fitted to te tops of the front suspension towers. I have done something similar for my Zetec, a case of wedging the engine in place, fit whatever plates etc you have or make to the engine, fit the rubber mounts and then make the connecting pieces and tack weld up. Take off and fully weld up with any fillets required.

Gearbox tunnel, carpets etc are all DIY with a variety of approaches used. This type conversion requires a lot bespoke parts, and no 2 are ever the same.

 

As to pics etc, a message to Richard above is worthwhile. I would also suggest a trip to see such a car would be very worthwhile.Also a search on the web, but the photobucket problem seems to be a real hindrance.

 

Link to comment
Share on other sites

  • 1 month later...
1 hour ago, MikeK said:

Howdy all anyone got any contact info for Stephen Attenborough ? I'd like to get in touch if poss on this topic

He has left the Triumph scene, and seems very difficult to locate. I can't even find his blog now. He used various forum names, one was Blacktower....

You may be better off looking elsewhere.....

 

Link to comment
Share on other sites

Part 3 - putting a GT6 engine into a Mk3 Spitfire - anyone got tips on the tunnel housing inside ? I'm setting the engine back 7 inches. Also Carpets? I can buy a moulded set without the cutout for the gear stick (different position with my mod) but again need the tunnel shape to be much 7" longer

Link to comment
Share on other sites

14 minutes ago, Pete Lewis said:

i guess the steam blocks and moulds are not vaariabe but a call to newton commercials and chat about what you need , there may be others car tunnels that would adapt at the longer  requirement 

other  than  a diy  jobby   cut and stitch  to suit 

Pete 

Thanks Pete - Newton's seem to be the one ... they already told me they can make the carpets without the holes for stick and brake levers - I'll give them a call tomorrow - ATB Mike

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...