Jordon T Posted January 1, 2014 Share Posted January 1, 2014 Hi folks,I was wondering whether you guys could help identify a couple of cylinder heads I'm working on at the moment. Cylinder head (1) has the numbers; 307170, 514384, D75. Cylinder head (2) has the numbers; 304955, 509896, B113. General InformationCylinder head 1 is 60 thou shallower than cylinder head 2. Cylinder head 1 uses collets to retain the valve springs were cylinder head 2 uses disk shaped retainer. Valve sizes are all the same on both cylinder heads.Thanks Quote Link to comment Share on other sites More sharing options...
Jordon T Posted January 1, 2014 Author Share Posted January 1, 2014 ....also, did the later 48bhp 1200 engines with the larger diameter cam followers use camshaft bearings? I know the earlier 1200s didn't.Thanks Quote Link to comment Share on other sites More sharing options...
Mark Hammond Posted January 2, 2014 Share Posted January 2, 2014 Hello Jordan,The one with collets (1) is a skimmed by 60 thou Spitfire head, (2) with a keyhole valve retaining type of cap is a Herald head. AFAIK no Herald cam either large or small journal runs in cam bearings from the factory, but a GA/GB/GD block is identical to an FC block so you can fit a cam with bearings to a Herald block.I hope that this helps,Mark Quote Link to comment Share on other sites More sharing options...
Jordon T Posted January 2, 2014 Author Share Posted January 2, 2014 Cheers Mark. The Herald cylinder head (1) was taken off a early 1200 engine GA 63,***HE. An untouched unit, with 8:1 Comp. So the spitfire Head must have a compression ratio of 9:1 considering the 60 thou difference in height.Thanks Quote Link to comment Share on other sites More sharing options...
Mark Hammond Posted January 2, 2014 Share Posted January 2, 2014 It is probably 9.5:1 but don't get too hung up on CR. The important thing is that the cam is matched to the head. You may find that you will need to shim the pedestals of the rocker shaft to get adjustment correct for the tappets. Which inlet and exhaust manifold are you using?Mark Quote Link to comment Share on other sites More sharing options...
Jordon T Posted January 3, 2014 Author Share Posted January 3, 2014 Hi Mark,Well plans have changed for my engine rebuild. I have decided that I want to rebuild my original unit GA224,734. I plan to keep it standard but fit it with the spitfire 4 head and stromberg cd125 carburettor mated to a 12/50 inlet/exhaust manifold. This should produce roughly 55bhp. Still wondering what distributor to use?For now, I'm going to be fitting an early 1200 engine (39bhp) into the car so I can still use it while working on the original engine (only car).Just out of interest is there a huge difference between the early 39bhp and later 48/51bhp 1200s?Thanks Quote Link to comment Share on other sites More sharing options...
Mark Hammond Posted January 3, 2014 Share Posted January 3, 2014 The difference between the early and late engines are the camshaft and CR. Use the standard dizzy. If you used twin SUs and a Spit MKl exhaust manifold you'd get 63bhp. You don't need to remove the engine to do what you propose.If you are not using the SUs, are they for sale?Mark Quote Link to comment Share on other sites More sharing options...
Jordon T Posted January 3, 2014 Author Share Posted January 3, 2014 I meant is there huge difference in the driving characteristics between the earlier and later 1200 engines. I haven't fully crossed the Twin SU's off the list yet, but if I do you will be the fist person to know. Quote Link to comment Share on other sites More sharing options...
Mark Hammond Posted January 3, 2014 Share Posted January 3, 2014 In my experience the lower powered engines seemed smoother, quieter but noticeably slower, other than that, not a lot.Mark Quote Link to comment Share on other sites More sharing options...
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