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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.
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