77xcfalcon 177 Posted November 7, 2017 Hi all. I am rebuilding a xc falcon. The engine was rebuilt by the previous owner and has only done about 5000 kms since. After tearing it down I could still see hone marks in the cylinders and all seals bearings etc still looked barely worn in.it had a aftermarket standard cam standard crank and rods and aprox 28 cc dish pistons.I would like to use the original block but I just took some measurements and the cylinders measure around 94.4. Does this mean it has already been bored out 40 thousands of an inch? And would I be better of starting with an new block. It will not be a super high power engine, plans are midrange cam, standard crank and rods, c1 alloy head with standard valves and bigger springs,efi with aftermarket ecu(probably mega squirt if I dont pick up anything else in the mean time) 6 3 1 extractors and 2.5 inch exhaust, msd 6 al ignition. I have most of the combo already just got to get cam, new pistons and ecu. Thanks guys Sent from my iPad using Tapatalk Share this post Link to post Share on other sites
LJDB 103 Posted November 7, 2017 The part number on the pistons generally tell you if it’s oversize. Nothing wrong with over sizing as long as it’s not overboard 1 77xcfalcon reacted to this Share this post Link to post Share on other sites
351XD_Fairmont 604 Posted November 7, 2017 If it was freshly rebuilt then why tear it down, you could of just swapped out the cam and lifters or was there something wrong with it? Not having a go at you just checking what the reasoning behind it was 1 Valvebouncer reacted to this Share this post Link to post Share on other sites
77xcfalcon 177 Posted November 7, 2017 Just wasn’t 100% sure about the history of the car. Wanted to check it all out to be sure, plus it had been sitting for a while. And I want to bump up the compression a bit as well. I thought the best way would be to replace the massive dish pistons that were in it. It had a iron head that I’m replacing as with a alloy. And I’m painting the car so it was coming out anyway.Sent from my iPad using Tapatalk 1 351XD_Fairmont reacted to this Share this post Link to post Share on other sites
gerg 10,871 Posted November 7, 2017 Piston choice is pretty limited with these motors as there were no crossys in the USA market.Upping the comp is best done by decking the block, as this requires the least amount of material removed for a given increase in ratio.To zero-deck, you should get your pistons first, install without rings, bring each one to TDC and check your deck clearance. The biggest clearance is the amount to be shaved. All other pistons will need skimming down to that height if they differ by more than a couple of thou.Everything else should be fine if it was a good runner before but just check the bearing shells for even wear, etc. A very light hone will be needed to bed the new rings. Dunno how high you want to rev it but a balance makes a big difference on a long-stroke motor.Sent from my CPH1607 using Tapatalk 1 77xcfalcon reacted to this Share this post Link to post Share on other sites
ando76 4,354 Posted November 7, 2017 I'm with Greg. Zero deck with those pistons and a c2 head would yield very nice compression. I've taken big hp and torque blocks to .060 and I know others have taken them further so be guided by that. Balance is pretty much a must if you want reliable trouble free running on these old girls. Factory tolerance on these things was very wide. Id be using that engine as a base for sure, especially if it's fresh. They generally have anything from .045-.050 deck height so giving them a mow, even with the dish pistons, nets good comp. add in a c2 with .040 off it and your in good comp territory if it's .040 over 1 77xcfalcon reacted to this Share this post Link to post Share on other sites
Slow250XC 1,512 Posted November 7, 2017 Yup as above and give the ironhead to ando so he can flow test it for shits n giggles!!! Coz ironhead is missing from the flowbench section lol 2 77xcfalcon and ando76 reacted to this Share this post Link to post Share on other sites
77xcfalcon 177 Posted November 14, 2017 The part number on the pistons generally tell you if it’s oversize. Nothing wrong with over sizing as long as it’s not overboardTalked to a mate and he told me if I can’t find a oversized stamp on the piston then I measured it wrong. He was right both ways as I cleaned up the top of the pistons and found a 030 stamp on the top.Sent from my iPad using Tapatalk Share this post Link to post Share on other sites
77xcfalcon 177 Posted November 14, 2017 Yup as above and give the ironhead to ando so he can flow test it for shits n giggles!!! Coz ironhead is missing from the flowbench section lolYeah it’s funny that there is no info readily available for the iron head. I’ve been looking to find the chamber size with no luckSent from my iPad using Tapatalk 1 Slow250XC reacted to this Share this post Link to post Share on other sites
Slow250XC 1,512 Posted November 14, 2017 Your in luck, mine has had at least 1 skim in its life and i cc'd the chambers a few months ago. Will check my notes when i get home but was 47 or 48cc. 1 gerg reacted to this Share this post Link to post Share on other sites