The Triumph Dolomite Club - Discussion Forum

Hi folks, would like to get a few more horses from the 1300 Dolly. Thinking a mild cam upgrade, possibly some head work, and re jetting or changing to a HS6 carb. I want the engine to retain its standard look as the car has only done 16,000 from new (1979).
Would there be any advantage ( and is it possible) to fit, say a Spitfire head and cam and keep the standard inlet and exhaust manifold but with the single HS6 jetted to suit. I guess this would be something like what used to be called a stage 1 conversion.

Ralph

You make a lot of sense. I would suggest a mk3 spitfire cam profile and either get your head skimmed to get the compression up to 9.5 or so or a spitfire head. A single HS6 was found to be plenty for a 1500, so don't underestimate the potential of a single HS4 (on a 1500 there is very little bhp difference, 2 or 3, between a single and twin HS4s)
The biggest gains will then be to find a rolling road who can set it all up, honestly I have been so impressed by my tuning efforts, and then a session on the rollers makes teh car drive SO much better. And more economical. Witchcraft I reckon.

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Clive Senior
Brighton

The best head to use in terms of biggest valves is the earlier 1300 Toledo head and the best standard cam is that from the 1300 MkIII Spitfire.

However, the Spit cam is designed to run in bearings whereas the 1300 Dolly/Toledo cam runs directly in the block without bearings. There are advantages and disadvantages to both methods but they are obviously not compatible on a mix/match basis. For cheapness and ease of fitting, i'd look at a Dolomite spec fast road cam from Kent or similar to get the desired result. Whether to go to twin SUs or a single SU HIF carb is often discussed and has proponents of both flavours Or there's the eternal boy racers favourite of a single 45 DCOE/DHLA for which manifolds are still about. If you fit the twin SUs, you must use the 1500 exhaust manifold and the twin downpipe that goes with it.

The club is, I believe, still supplying a stainless steel 4 branch extractor manifold but its not especially cheap.

None of the above altogether is likely to give you as much as 100BHP, but it should make it a bit peppier to drive and maybe pull a taller final drive for more economical cruising.

My recommendation? Use the Toledo head, get it port matched to the manifolds, hardened exhaust seats fitted and 3 angle ground valve seats and a few thou shaved off to raise CR (20 thou should do)

Get all the rotating parts balanced/ blueprinted and add a fast road cam and a new oil pump.

Open up the original inlet manifold and adapt it to take a single HIF6 SU and keep the single exhaust manifold and pipes.

If you like it like this and want more, you can add a 4 branch at a later date. If it was mine, i'd also look at an Overdrive gearbox for max flexibility.

No doubt others will be along later with other ideas.

Steve

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'73 2 door Toledo with Vauxhall Carlton 2.0 8v engine (The Carledo)
'78 Sprint Auto with Vauxhall Omega 2.2 16v engine (The Dolomega)
'72 Triumph 1500FWD in Slate Grey, Now with RWD and Carledo powertrain!

Maverick Triumph, Servicing, Repairs, Electrical, Recomissioning, MOT prep, Trackerjack brake fitting service.
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Ok, I have found a Mk4 Spitfire cylinder head, with serial no 218142 which is the larger inlet valve head and 9:1 compression ratio (standard Dolly 1300 being 8.5:1). I have also found that Canley Classics do an exchange cam for the large bearing Dolly with the Mk3 spitfire profile. Interestingly the standard Spitfire4 cam is the same as the standard 1300 Dolomite, same part no.

On my travels around the Internet this morning I found the Teglerizer site which lists the combustion chamber capacities of the various Triumph heads, and lists the number of thousandths of an inch that need to be removed to gain each .5 increase in compression. In the case of the Spit4 with the 218142 head it is 0.033". I will have to check that has not already been skimmed, but should easily be able to get 9.5:1 compression.

Canleys blurb says the cam gives more power and torque, so the best of both for a road going motor and an improvement on even an otherwise standard engine. Coupled with an increase in compression and suitable re jetting of the carb I am hoping for a noticeable improvement, if not exactly a roadburner.

Ralph

Considering the mk3 spitfire was 75bhp, and you will have the same cam, better CR and the single carb won't make a noticeable dent in the figures, yes you will notice a difference from the 60?bhp you currently have. Remember the mk3 spit used the same exhaust manifold you are using.
The other cams you may wish to consider are Newman. They are probably making the best at the moment, and will make hybrid versions. You could look at the Chris Witor site for profile inspiration, he sells a cam with the mk3 spit profile (OK, early PI, but exact same profile on a six) but has fiddled with lift. Just a thought.
I should add that I own a vitesse 1600 which is an early one on solex carbs and the dreadful 10 50 cam. About 70bhp. Not much. But a swap to stromberg carbs used on teh later 1600 makes 84bhp from the factory. I also have an early PI cam (same as mk3 spit, GT6 mk2 etc) and intend to raise the compression from 8.5 to 9.5 I reckon that will see me into figures getting very similar to a 2 litre vitesse, but retaining the sweet 1600 engine.
And thank you for the nudge to look at teglerizer, that may help me work out how much to take off the head.

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Clive Senior
Brighton

Thanks for the confidence boost , the head I have has 1.43" inlet valves too compared to the 1.3 of the standard head, although that might only make a difference at higher revs. All info I can find list the late Dolly 1300 at 58bhp, I don`t expect to get the 75 of the mk3 spitfire, but 65 would be a respectable increase. Any improvement will not be measured, I will probably not get it on a rolling road, but hopefully will be able to feel an improvement through the seat of my pants.
For camshaft comparison purposes I noted below;
Standard 1300 Dolly (and Spitfire 4 after eng no 25000), 18/58-58/18 with .360 valve lift 256 degree duration
Newman PH1 20/60-60/20 .375 valve lift 260 degree duration
Mk3 Spitfire ( reground on large bearing Dolly cam) 25/65-65/25 .360 valve lift 270 degree duration

As can be seen above, the Newman cam was very close to standard timing, but had greater lift, and may have quicker opening and closing profiles, but there was no information on that.
The Mk3 Spit profile gives earlier opening and later closing, but with standard lift, but the bigger valve head and longer duration should compensate for that I hope.

The Newman cam was over £200 just for the cam, although it was brand new. The Canley Classics re grinds reckon to all be on original triumph chilled iron cams and there is a £39 surcharge for your old cam, and they say it does not affect the durability of the cam, so who am I to argue, and the cost is a reasonable £94 (+ refundable surcharge), so I have ordered one, and a set of new followers.

Can`t wait for some better weather now to get in the garage and start ripping the car to bits. I have a lot to do, gearbox is coming to bits for a new layshaft and bearings, new stainless exhaust to fit with new manifold studs and nuts, head was coming off anyway to fix the oil leak at back of head/block join, and now there is a new cam to fit. Oh also got perished tie bar rubbers to change front and back, so should keep me busy for a day or two.
Ralph

I hope you will use polybush in those locations.
I bought new rubbers for the axle on mine, from a reliable dolomite supplier. However, after a year or so the handling got really twitchy. The rubbers were falling apart. I fitted polybushes, and they have been fine.
I fitted poly on the fronts when I got my Toledo, and after 15 years, a few trackdays, several autosolos/autotests/PCTs and countless 12 car rallies, as well as being an everyday car for several years, not to mention a couple of RBRRs, I bought new polybushes. But the old ones were still pretty good. So they do last well.

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Clive Senior
Brighton

Slight curve-ball suggestion to improve drivability and gain some HP. Have you considered doing all your suggested mods on a 1500 engine, keeping the 1300 original engine standard and on one side to swap back if you ever want to part with the car?

The 1500 offers really nice torque in "Spitfire" set-up and it makes driving cars a much more relaxed experience even without higher horse power?
Some modest tuning and a single HS4 or HS6 on a well set-up 1500 would make a nice well behaved car.

The best reference I've found for head CR/valve data is here: http://auskellian.com/paul/links_files/ ... sion_Ratio

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Hi Steve, twin SUs will fit with the standard 1300 4 into 1 exhaust manifold.

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1972 Toledo 4 door "Betty"

Hi Steve, many thanks for your input. Could you clarify which Toledo head you are referring to? I looked on Teglerizer and it lists all 1300 heads as having 1.306 inlet and 1.170 exhaust valves, The only different ones are the Dolomite 1300 at 1.380 inlet (which must be what I have already), and 1.431 for the Spit4 1300.
Cheers, Ralph.

Hi Ralph, there are 3 different inlet sizes for 1300s (all exhausts being 1.17) Early cars, the so called "small crank" engines like the 1300TC FWD and 1300 Spit III have 1.31" inlets, the middle period cars that use the 218*** series head, like the Spit IV (218142) and Toledo (218141) have the most desirable 1.44" inlets and the later cars like your original Dolomite 1300 (TKC 1156 head) have 1.38" inlet valves.

The ONLY physical difference between 218141 and 218142 is in the comp ratio, 8.5 for the 141 and 9.0 for the 142, which equates to about 30 thou off the face. The OTHER difference, the one that sways ME, is a perception difference, which results in a price variation. People will often GIVE you a Toledo head as it's percieved as useless, but charge you good money for a Spit IV head which is seen as desirable, when, in fact, the only difference is a few thou of a skim!

A machine shop will charge you the same to chop 60 thou off a 141 head as to chop 30 thou off a 142 to obtain your desired 9.5 comp ratio. But this argument is academic as you already HAVE a 142 head.

Whilst i'm about it, there's one piece of advice I didn't give. And that concerns the advance curve, which is even more important if you take the comp ratio to 9.5. You gonna have to mess with the curve if you run 9.5 or more, especially on street fuel, even 99RON E5. Or the poor little thing will pink it's brains out and melt it's pistons! I'd recommend a 123 distributor, not cheap, but fully programmable (even Bluetooth from your phone if you option it) for near instant adjustment.

THIS is why I didn't recommend TOO radical a skim, 9.0 is, in my humble opinion, enough for street petrol wtihout too much faffing with the dizzy!

Hope this helps, Steve

_________________
'73 2 door Toledo with Vauxhall Carlton 2.0 8v engine (The Carledo)
'78 Sprint Auto with Vauxhall Omega 2.2 16v engine (The Dolomega)
'72 Triumph 1500FWD in Slate Grey, Now with RWD and Carledo powertrain!

Maverick Triumph, Servicing, Repairs, Electrical, Recomissioning, MOT prep, Trackerjack brake fitting service.
Apprentice served Triumph Specialist for 50 years. PM for more info or quotes.

Many thanks for the advice Steve. I was going to have the head skimmed to 9.5, but think I will leave it at 9.0 after reading your advice. While I am here, I was wondering what the differences were between Spit3 and early Spit4, both were 8.5 compression, both had same valve sizes, both used the 212164 camshaft, and both were on twin HS2 carbs, yet the Spit3 was 68HP and 73 ft/lbs torque, whereas the Mk4 came in at 63HP and 69ft/lbs, so managed to lose 5HP somewhere. Only thing I can think is emissions equipment like sealed crankcase breathing etc.
Ralph

The MKIII Spit actually has the smaller 1.31 inlets so SHOULD be worse! But the reason for the power drop on the MkIV is simple, it's that bigger crank with it's higher rotating weight that's almost wholly responsible for the missing horses! The sealed breather didn't make a lot (if any) difference.

If I was to build a Hi-po engine for a 1300, i'd want to start with a small crank block, crank, rods and pistons with a 218 series head. And go from there! The small crank engine is a lot quicker on pickup and revs freer and cleaner at the top end. So, in my opinion, it's the best place to start.

Steve

_________________
'73 2 door Toledo with Vauxhall Carlton 2.0 8v engine (The Carledo)
'78 Sprint Auto with Vauxhall Omega 2.2 16v engine (The Dolomega)
'72 Triumph 1500FWD in Slate Grey, Now with RWD and Carledo powertrain!

Maverick Triumph, Servicing, Repairs, Electrical, Recomissioning, MOT prep, Trackerjack brake fitting service.
Apprentice served Triumph Specialist for 50 years. PM for more info or quotes.

I have a feeling that the way power was measured changed. Not sure what date it changed, but the 150bhp v 125bhp TR6 is the obvious example. If both were measured using the same system, the difference is about halp the seemingly 25bhp.
In addition, the early MKIV spit had the same cam as a mk3, but was soon changed for a softer cam.

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Clive Senior
Brighton

The measuring system WAS changed, from gross to DIN, in the USA this happened circa 1971 and enabled the US car makers to "officially" downgrade their premium car's outputs for political reasons. In europe it happened somewhat later though i'm not sure when, possibly mid 70s so not sure if the Spit was included.

I've driven all sorts of TR6 both the 150BHP CP code engine and the later downgraded CR, which is 132bhp, not 125. The 125 horse unit was used in the last model 2.5PIs before it went back to carbs in the 2500TC and 2500S. Maybe, possibly, in the last handful of TR6s. But those 18 missing horses feel like 50 when you drive them! The only thing worse is a strangled, detoxed, carbed, federal spec TR6 which is barely over 100bhp.

I didn't know about the cam swap but it makes sense as all car makers were adapting their higher powered cars to cope with the impending loss of 101 octane 5* petrol which, if you are as old as me, you will recall disappeared almost overnight in 1971! BTW the downgrading of the PI engine was almost certainly down to this same loss of octane in fuel, CP powered PIs (including the hens teeth rare TR5 and mkI 2.5 PIs) were always factory advised to use 5* gas.

Oh, and both the Spits, III and IV had a 9/1 comp ratio not 8.5. But it's the same difference.

Steve

_________________
'73 2 door Toledo with Vauxhall Carlton 2.0 8v engine (The Carledo)
'78 Sprint Auto with Vauxhall Omega 2.2 16v engine (The Dolomega)
'72 Triumph 1500FWD in Slate Grey, Now with RWD and Carledo powertrain!

Maverick Triumph, Servicing, Repairs, Electrical, Recomissioning, MOT prep, Trackerjack brake fitting service.
Apprentice served Triumph Specialist for 50 years. PM for more info or quotes.