Firstly, I joined today after finding the Spritespot site late last night. What a great ‘spot-on’ forum this is for Sprite & Midget enthusiasts.
I am very much a ‘newbie’ having bought a good condition Mk IV Sprite in the summer. I was very pleased with the performance except for the oil pressure (when up to temperature was under 20psi at tick over and under 30psi on a run at around 65mph @ 3000rpm) I wanted to have full confidence in the engine for 2012 and so decided to do a rebuild over the winter months.
Stripped down everything & all was looking OK (crank at -20 – Bore at +30) for a straight rebuild with all new bearings, & balancing of crank, pistons and flywheel, new oil seals, timing chain, starter, clutch etc. etc… etc ….. BUT then discovered deep scores in cylinders 2 & 3. These have been diagnosed as being due to gudgeon pins not fitted correctly using heat treatment and subsequently moving.
So I now need a re-bore at +60 and so will need new pistons …… & so it begins ……
Am now thinking, (& encouraged by good friend (who has a 100/6 and frogeye) to do more than just a simple rebuild. So, was thinking about HiComp 21253 pistons, converting head to 11 stud, going to 2 x 1 ½ SU’s (or 1 x HF4), but keeping standard cam & valve gear etc. my exhaust manifold is apparently already a ‘good-un’.
BUT have now been reading about cams, high lift rockers, gas flowed heads, uprated valve gear etc…etc… and am thinking what is the best return for the modest outlay I am prepared to spend.
i.e. Would 21251 pistons and a kent 266 (or MG metro cam) with gas flowed head (still 9 stud) with the standard valves & rockers, be a better than 21253 pistons & no change of cam ? It appears that there are 3 cams that would suit what I would be happy with 1.) the MG metro cam, the Kent 266 & the Morespeed ph2
SORRY post is so long ………
O'h .... One last question ...... should I get the block & head 'crack tested' before I do anything ? Is this difficult or expensive ?