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GT6 Mk1 GT6 Engine Rebuild

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Hi there,

I just bought a 67 GT6, with gas (LPG) instalation. I am in europe, discovering this forum. The car will ne delivered in April. There is a problem to start the engine. I ve read after that the 67 engine are special...crankshaft bearing, conrod,....are not the same as mk2 engine. The parts seems difficult to find in europe.

Regards,
Geraldgt6
 
Welcome, Gerald!

The GT6 has always been a favorite design for me. I can't help you with your issues, but there are several members here who can, and I'm sure they'll be along here soon.

:cheers:
Mickey
 
geraldGT6 said:
Hi there,
The parts seems difficult to find in europe.
Regards,
Geraldgt6
Click to expand...

Welcome aboard and good luck with your car. I feel your pain concerning the parts issues.

I have not posted an update to this thread as I too have been dealing with the issue of finding parts. The parts may be more available over here but I was not interested in spending all the engine rebuild budget on shipping charges for heavy engine parts.

As it stands, my engine is still in pieces... most at the machine shop. I will be using a Mk1 TR-2000 block, the crank from a second donor engine, the head off my car's engine, and various smaller bits from other cars. Hopefully re-assembly can begin during the next 2 weeks.

Doug L.
 
3/25/12

I finally have the block back from the machine shop. I have enlarged the main journal oil feeds to 5/16" diameter. I have cleaned the oil galleries and re-fitted the gallery plugs. I have fitted the adapter plates to allow me to use this TR-2000 block with the GT6 engine mount brackets. Then I went to fit the core plugs.

These early engines used flat core plugs instead of the dished type that are available for the later cars. I did not realize that and I never saw a different listing for early engine core plugs. I took the ones I purchased and cut them down on my lathe until they were 3/16" high. That allowed me to drive them into the shallow spotfaces in the block. They are still a press fit and with sealant I am confident they will work. Obviously this is not practical for people without access to a lathe.

Over the next week I will check the ring gaps and assemble the new pistons to the rods. The rotating components are off being balanced so there is not much else to do until they are ready.
 
4/3/12 Update

After a really long time I have all my engine parts back from the machine shop.

In response to the advice I sought earlier I have enlarged the main journal oil feeds in the block to 5/16" diameter. I have followed some of the porting suggestions by Vizard, and I have sorted all my main journal and rod bolts to use the best factory parts I have.

My ring gaps have been set and all the piston/rod assemblies are balanced within a spread of about +/- 1 gram.

Before I start putting the pieces together are there suggestions for any last minute modifications or tasks to improve reliability?

As always, all suggestions are welcome.

Doug L.
 
Did you have the rods resized? I wouldnt re-use rod bolts, but that's just me.
 
I inquired about a the rod bolts on a couple of other forums. Most people commented that if I were not opting for ARP hardware that the old factory bolts would be better (assuming no apparent thread damage) than the new "standard grade" hardware. I had three engines worth of rod bolts to go through and selected the best of the bunch. I did likewise for the main bearing cap bolts.

The rods are one of the few things retained from the engine I pulled from the car. This was a race prepped engine (30 years ago) and the rods had been beautifully sculpted and were very uniform in finish and weight. The shop checked the rods for big end size and straightness. They commented that the rods were in good shape and did not need any reconditioning apart from the obvious new bearing shells.

Doug L.
 
Sounds like you're in good shape with the rods.

Call me paranoid (or perhaps a Disciple of Carroll Smith), but I don't trust reusing old factory rod bolts - even if they look fine. Unless you know how many torque cycles they've been through, I wouldn't re-use them.

APR bolts are stronger than the rods. $90 for piece of mind is money well spent. Rimmer used to sell Ford Sierra Cosworth con rod bolts for about half that price; they're claimed to work very well too.

Have you blueprinted the oil pump? It's claimed to add about 10psi of oil pressure.
 
True blueprinting wouldn't be possible without a whole bunch of oil pump parts to mix and match to minimize the clearances. However, I have lapped the pump parts for minimal endfloat and checked that all the radial clearances are within spec.

Thanks for the suggestions. Had I known about the rod bolts at Rimmer I would have included them in my last order with them.

Doug L.
 
4/28/12 Update

It is with great pleasure that I am able to finally say that the engine is back in our GT6. It's not hooked up... but it is sitting in there. I managed to put the lump back in place this morning and will spend the next day or so fitting all the ancillary parts.

In the end, this engine required a bit of this and a bit of that including...
A used block from an earlier TR-2000. That required engine mount adapter plates. Everything lined up perfectly!
The crank came from yet another GT6 as the one in my original engine was just slightly under stock grind and had welded up journals without fillets.
The head from our original engine was retained but with some additional porting.
The S2 Cam is new from TSI with new tappets and new springs.
The head studs were replaced but I re-used the rod and main bolts. I had a lot to choose from and selected the best based on thread and head condition.
I patched the header but have not touched the carbs or intake manifold.
I also beefed up the cardboard radiator cowl to prevent sagging and distortion.

Now I just need to put all those loose parts on and restart this thing. We have a show in 3 weeks and I am running out of time.
 
4/29/12 Update

I got the engine started about 3:30 p.m. today. I let it idle at 2000 RPM for 20 minutes to bed in the cam. It needed a little boost to turn over initially but it did run fairly well.

I am hoping to get some additional tuning done over the next few evenings. The back carb is leaking fuel and I am sure that the mixture and timing need a bit of tweaking to be right for this new build.

All in all I am hopeful and optimistic.
 
It must be very satisfying- congratulations!

Originally you asked for suggestions on cooling and lubrication, and although I am late joining the conversation there are a couple of items you may have already considered but which have not been mentioned; an oil cooler and spin-off adaptor kit and a recored radiator, possibly with electric fan.

Glad to hear of another Triumph back on the road.
 
I considered re-coring the radiator but the estimates I received were as much as the cost of a new brass radiator from the usual suppliers. However, I noticed during the past week than someone on eBay is now selling a made in the USA aluminum GT6 radiator for $300. I may consider that later if necessary.

I have a pusher electric fan installed in front of the radiator and am still using the crank operated fan behind. At the moment I have the electric fan set to come on rather low. I will change the thermostatic switch setting once I see how the engine heat behaves in the summer.

I have a spin-on kit and oil cooler ready to be installed. However, I am postponing installation of the kit until after the break-in period. I didn't want to introduce too many at this point.

I am dealing with some running issues at the moment that I need to iron out before taking the car on anything more than trips around the block. I have some rather poor vacuum readings and a very unstable idle. I have not found a vacuum leak yet but will be searching in earnest for one over the next week or so.
 
5/20/12 Update

I re-torqued the head a couple of weeks ago after the cam break-in. That of course required re-setting the valves followed by a round of minor carb adjustments. Apart from that I only worked on cleaning up small details in the engine bay.

Yesterday was the local car show held by the NC MG Car Club. The event is held about 25 miles from where we live. The GT6 made it there and back without any issues. The oil pressure was good, the temperature was good, and as my wife said... the sound was good. It did mark its territory a bit (perhaps 1/2 teaspoon of oil) both at the show and when we got home. Other than that I couldn't be happier. A check of the plugs revealed pretty good color, perhaps just a touch rich but I am OK with that compared to the oil soaked plugs and blow-by we were dealing with before.

One of the last additions to the car after the engine was installed was to fit a new gear reduction starter. I am very impressed with how well they work. I should have installed one a couple of years back when the brush springs broke in the old Lucas starter.

Thanks to those of you who posted advice both to this thread and by PM. I greatly appreciate all the help and advice.

Doug L.
 
Very cool! Sorry I wasn't around at the time that you were doing this, but i don't have much to add and it sounds like the guy who built the engine is a real pro. I took the opposite tack, thinking, these were low compression tractor engines that people used to work on under the shade tree - so while I measured everything to make sure it was within tolerances, I did a lot of "If it isn't broke, don't fix it".
I have other cars to scratch the go-fast itch, and with performance comes heat. We finally had to work done to fix the numbers matching block for ours, and when I finally get the chance to swap that over, I'll have the hardened valve seats put in the head and have that all gone through. I just used the off-the-rack valve lapping bit until I was satisfied it was nice and smooth. We're doing a little better than we were back when I did the original build or I might have had someone with more experience go through the thing, but as you recall, I have very bad luck with shops, so in my mind, a lot of attention to detail tends to yield me better results and a fatter wallet than hauling it to someone.

I'm glad to see you got it up and going though! I love seeing these things on the road, and so far I've only seen 2, counting mine.
 
Thanks. The engine has been doing well since the rebuild.

Those bearing caps I sent you came from a core engine I bought for the rebuild. I was hoping to use the block but found it was freeze damaged. I used the crank and a few bits off of it, scrapped the block, and sent the caps to you in the hope that someday you'll get your numbers matching engine back in your car.

I'm glad you have made so much recent progress with your car. Do keep us updated as you finish your work on it!4
 
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