The Triumph Dolomite Club - Discussion Forum

Hi all,

I'm slowly putting together the parts for a "very gentle" bolt-on engine upgrade for Molly the Tolly - NOT to go racing, just to give the old girl a little bit more vim. Call it the equivalent to HRT A skimmed, ported head** (with either single or twin valve springs, TBD), twin HS2s, the fabled TDC SS extractor manifold and downpipe are the key bits (plus some sort of fabricated exhaust system), but I'm also looking at putting in a warmer cam to go with it all.

All the smart money says use the Spitfire Mk III profile, which comes in large bearing form from Canley or Piper. And logically (since the Mk III used HS2s) this will suit the carbs rather than asking for more than they can give.

** memory also tells me the 1500 head has bigger valves than the 1300, though until I get the original head off and compare with the replacement (which started life on a 1500) I won't know for sure...

The basic engine seems very sound - consistent 150lb compression across all four, no discernible oil consumption, rattles clonks or other nasty symptoms.

Comments, suggestions or general mickey-taking, anyone? Does any of that make sense, or am I talking my usual combination of bollox and cow-poo? Ta...

Works for me, other than, possibly, the 1500 spit head.
You may need to skim it a lot to get a sensible compression ratio.

It's a similar mix to KAC, and works well

Hi, thanks for coming back - and so quickly.

Putting on a different head is (in part) so I can do an unleaded conversion without laying the car up while the original head is worked on - I hate it when a car ends up in pieces for too long! I can get this head ready to just bolt straight on when the other one comes off.

Different sources suggest different valve sizes - the Repair Operations manual says 1300 (1972 onwards) has 1.43 inlets, 1.17 exhausts, same as the 1500, whereas a previous TDC thread on tuning a 1300 Dolomite viewtopic.php?f=3&t=19060 suggested some (ahem) typically BL/Rover variations... including that the Toledo 1300 has 1.31 inlets - so I won't really know until I get the 1300 head off anyway!!

Also, the Repair Operations manual says to remove the head as part of a camshaft change (not sure why, unless the cam followers are inaccessible with the head in situ?) - so if the head has to come off I might as well.

Re skimming, yes, it'll need a lot of metal taken off to get a decent compression (ISTR way back in the early 1980s skimming a 1500 head 100 thou which gave something around 9.5:1 compression on a 1300 engine - that was to go in YRO318K along with various other odds and sods that I (ahem) acquired). But I always understood that most of the cost of skimming is in the setting up - once it's on the bench and running, it doesn't take 10x as long to take off 100 thou, as it does to take off 10.

True indeed, with regard to skimming, you may need to shim the rocker pedestals if taking 100 thou off, as you may be seeing some strange angles twixt the rockers, and pushrods.

Other than that, seems sound enough to me

Oh, and regarding valve sizes, I'm lucky enough to have a mk 3 Spitfire head for KAC's next incarnation, and am thinking of going for a Spitfire fast road cam.

May be the end of another gearbox, but hey, you've gotta have fun some way!

A good point re rockers, thank you.

I was hoping that as the power would be broadly comparable with a standard Mk III Spitfire, the three rail box would be able to handle it. Oh well... Reliability is an overrated attribute!

Your box will be fine, KAC is a FWD......

Duh - of course!

Good luck!

My repair operation manual gives the 1300 inlet valve size as 1.304" - 1.308" up to engine number DG25000 and 1.437" - 1.445" thereafter. This compared to the 1500 (export only) Toledo which stayed at 1.429" throughout. Exhaust valves for early and late 1300 and late 1500 are common at 1.168" but oddly the early 1500 has a larger exhaust valve at 1.232".

So basically you can't win! The late 1300 has the biggest inlet valve available (by a whole 0.008"), but the early 1500 has the biggest exhaust valve (by 0.062") I honestly don't know if the figures correspond to the 1500 Dolomite head that you have as I don't have a manual for that model!

Personally I don't think the engine build you are doing will grossly overstretch the 3 rail box, though I reckon a D type overdrive (again from a Spit III or early SpitIV) would boost performance and general driveability no end!

Steve

Re the overdrive, I won't disagree - the current 4.11 final drive makes anything above about 55mph a little frantic to say the least! Even compared with the silver nightmare machine which had a 4.5 diff (albeit with 15" wheels and an "overdrive" top gear ratio of about 0..

Re the head and the repair operations manual, I suspect we are looking at essentially the same publication. So I won't really know until the head comes off! The big advantage of that head is that it lets me do all the preparation work without taking the car off the road.

uphill racer wrote: ↑Wed Sep 06, 2017 8:54 am

Re the head and the repair operations manual, I suspect we are looking at essentially the same publication. So I won't really know until the head comes off!

Checking the engine number will give you a clue! Not conclusive obviously as heads can be changed, but on a mainly original car like yours it's probably a reliable pointer.

Steve

Yes, if the numbers/records are reliable then the head on there is the same sizes as the 1500 one.

However this is BL we're talking about...

Popped the valves out yesterday while waiting for my drill batteries to recharge (I was mainly getting the silver R25 ready for next weekend at Shelsley, and prepping the black ZR for a rally in East Anglia the following weekend). The head looks in good nick overall, though it'd benefit from a bit of cleaning up and smoothing in the ports. I want to have hardened seats put in as well as the skim, does that automatically mean new valves as well, or can I use the valves that have just come out? Obviously whatever valves I use, they will need lapping in, but the ones I already have are in good condition and are pretty tight in the guides.

I seem to recall Triumphtune in the past recommending turning down the valve stems and cutting away some of the back of the valve heads - is that worthwhile on an otherwise fairly mild state of tune?

O the other hand, I was less than delighted when I reached the garage yesterday morning to find that some nice person (check sarcasm filters) had knocked a tray of my HS2 bits all over the floor. Thankfully NOT the "1st XI" bits that will go together to make the other one of the pair going on the car, but even so - carburettor bits aren't normally improved by being thrown all over the garage floor. And whoever it was couldn't fail to notice. Thankfully the lads in the bay next door (most likely culprits) are moving out soon, good riddance.

The "best" combination of valve sizes for tuning is the Spit Mk 3 head. This is the same as the FWD 1300TC unit and both are rare now.

The later Spit Mk 4 1300 head is notably inferior (emissions control came into play) and the various 1500 heads are also not as good as the Spit 3. If you can find one the facelift 1500 FWD heads are supposed to be quite good but I have no direct experience.

With a 1300 engine results are better on twin HS2 SU'S than HS4's and again the Spit Mk 3 camshaft is a good starting point.

Bruce's comments are good solid advice. It is possible to get up to 125bhp out of a 1300 on SU's but it won't be very workable on the road, and will cost a lot of money to put the bottom end together.

Ideally you need to try and source a 1300 Mk 3 Spit engine as the starting point as these engines also have a much better crank, but folk know their value now (even needing a rebuild) and they are priced accordingly.

If you use your Toledo bottom end make sure you ascertain whether you have a recessed block or not - early Tolly engines didn't, later ones did. Your options are slightly more limited with the latter.

With some decent head work, a balanced bottom end and a Spit Mk 3 profile cam running twin HS2's you should be able to approach 80bhp, which will go nicely and be much stronger at revs than an equivalent 1500 lump. Fuel consumption will be virtually unchanged dependent how you drive it of course. I would strongly recommend you keep your current diff ratio and fit overdrive.

Doubtless folk like Jonners will be along urging you to just fit a slant four from an 1850 but my own experience of slants is all bad from a reliability perspective, and I like the idea of tuning the smaller lump - it's your car and your money so your choice....

I could have just dropped a 1275 or 1293 A series in my Austin A40 but chose to tune the 1098cc lump and now have a surprisingly agile little car that produces 79bhp on the dyno. Maybe I just like hard work.......

Keep us informed of what you do.

Found this. Not sure if it helps http://www.teglerizer.com/triumphstuff/ ... eblock.htm

Many thanks for the responses and the link.

Toledo work has taken a back seat in favour of finishing (ultimately disappointingly) my hillclimb season in the silver Rover, and an engine blow-up on the way to the start of a rally in the ZR. That engine is now back together and running albeit I think there's something nasty stuck in an oilway leading to one of the hydraulic tappets...

Re the Toledo block and recessed/not recessed. What recess(es), how do I tell? MOY is a 1973 car, so slap bang in the middle of the life of the Toledo!

Re slapping in a slant-4. Not going to happen. For one thing, done it before (I built JJB923K which Dan the Dolly-Nut now owns), but for another I had to promise hand on heart not to "molest" MOY when I bought the old girl. I don't think mild tuning of the 1300 is "molestation" but a slant-4 engine certainly would be!

This is just going to be used on the road, not for competition at all, and the main objective is the 2018 Club Triumph Round-Britain Run. An overdrive box would be a great upgrade, if I can find one. I don't remember for sure but THINK that none of the OHV small saloons had overdrive (possibly the Dolomite 1500HL??) but I assume the other work/changes would be:
Shorter propshaft
Different gearbox mounting (is the subframe itself the same?)
Wiring harness to the switch and solenoid
Speedometer drive/cable
POSSIBLY different gearbox cover
POSSIBLY different clutch slave cylinder (depends on gearbox - single rail or three rail?)
POSSIBLY different clutch plate/cover (depends on gearbox input shaft splines)

Mike Papworth should be able to supply you with an overdrive kit.

If you do a search on the site there are various posts on what John Kipping used, they seem be either single HIF44 or HS6 carbs.