Guys,

I have a '69 Capri 1600GT engine (the one with the small combustion chamber in head) that I am going to rebuild for my Anglia. I have a couple of questions I am hoping you guys can help me with...

Firstly I need to get it rebored (+40thou) as the bores are fairly worn therefore will need new pistons and rings. I have heard you can get 1300 pistons to fit that will increase comp ratio - so what will fit? Will 711M 1300 pistons work? If not are 1300 pistons made to suit the block/head I have?

Secondly I was planning on keeping the head pretty std (gt spec) apart from getting it refurbushed and new valves fitted. I wanted to keep the std twin choke weber and std extractors, which cam would be best? I am considering Kent cams in the following profiles BCF2, 224, 234 and 244 cams - What do you think would be best with the engine setup as mentioned.

Thanks for your help.

Steve.

'Sorry for previous misleading advice'

There was a good article on tuning early crossflows in 'Classic Ford' a while back called pushrod performance i'll see if i still have it.

711M pistons will work but you will need to have the valve cut outs machined into them as per originals otherwise your valves will hit the pistons. Apart from that, same size slug, everything else will go. 1300 have a slighter smaller bowl and thats where the increase in compression ratio happens. You could get the propoer 1300 pistons (you will have a 681 or 691 block) and save that grief.
Make sure you put stainless exhaust valves and hardened inserts in so you can use unleaded. You'll spend the $400 on additive anyway...

BCF2 would be a good cam, it will be quite lumpy at idle and will make it sound like a proper engine from the old days. You could go a 234, has slightly less duration so might pick up some low down driveability. Both are going to run out of urge at sensible revs.

If you can get a V6 Weber it will bive a bit more go; bigger chokes and both barrels open together.

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Originally posted by Smcka

711M pistons will work but you will need to have the valve cut outs machined into them as per originals otherwise your valves will hit the pistons.

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Thanks for the reply but...

Ok now I am confused! The pistons in it do not have valve cut-outs. I thought that they weren't required for the 681 block that I have?

I thought the 711 pistons were already machined with valve cut outs and this was because there was no combustion chamber in the head of 711 engines therefore the valves are closer to the piston...

Anyway bottom line is I can use 711 pistons, and I should also be able to get 681 1300 pistons so that is reassuring.

Am I correct in assuming that if I use the BCF2 cam then I shouldn't need to worry about the valves hitting the piston? Or is that the point you made above about having the pistons machined??

I wasn't planning on doing S/S valves or hardened seats cause I won't be using the car that much - maybe 2000k a year absolute max so I am not that worried about the valves wearing out.

whooops. Got my injuns mixed up. Trying to sneak Escort stuff into work time doesn't work. Maybe thats why mine doesn't make that much power [:-(]

681/691 have the solid top and chambered head, 711M have valve reliefs and flat top. So you could drop 711M 1300 slugs in no prob. Might also drop the ratio a tad which the books say comes in at 11.0:1 IIRC. I think there are some sets of pistons on ebay right now.

BCF2 have no clearance issues, 234 may as the have 1mm more lift. especially with the 681 slugs you might have touching issues.

if you have to bore it, why not go 83.5mm that will give you 1700cc with std head gasket. Use 1300 flywheel (std GT capri clutch will still fit)its about 20tonne lighter than 1.6 flywheel. spend a couple of bucks on steel rocker posts.

I can tell you from bad experience that it you are putting in a higher lift cam than standard you will need to have relief pockets machined into the standard pistone for this engine.

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Originally posted by Bloodyeck

I can tell you from bad experience that it you are putting in a higher lift cam than standard you will need to have relief pockets machined into the standard pistone for this engine.

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What cam did you fit to your engine? How much lift did it have?

Sorry for not responding sooner. It was an ordinary (early) 1600 cross-flow (small chamber in head)which I fitted with a GT camshaft. Even with that small amount of extra lift the pistons hit valves. The 711 pistons have larger combustion chambers than the 681 pistons. If you fit 711M pistons, which already have valve cut-outs, you may end up with too low a compression ratio. If you are wedded to the idea of using the 681 engineI would stick with the pistons for that engine (smaller combustion chamber in piston)and have valve cut-outs machined in. A better option would be to get hold of a 711M engine from an Escort. They're are stronger if your intention is to treat the car to a bit of motor sport.