Maximum displacement from 170?

Hi everyone. I was looking at ways to increase power and I was thinking. What are the ways to increase displacement. Well I know that that could be achieved with shorter con. Rods and a longer throw crankshaft as well as boring out the engine. So I was curious on some parts or combos I can use to + my displacement and hence + HP and torque. Also would this hurt the reliability of the engine and wouldn't o be able to rebuild it because I know you can only bore an engine so far and usually a rebuild requires boring the engine a tiny bit. Thanks

You would probably be ahead to just swap to a 200. A 250 can go in, but takes some trans tunnel mods, and is a tight fit. Getting a 289 or a 302 in there is a whole 'nother story.

You could use an early 200 crank (four main) if you could find one of them, this would drop right in your 170 and give you a 181 cu.in. engine ( 170's block at Std. 3.50 Bore) your rods would still be the same. The bore could go to at least .060 over and likely more (the early 144 and 170 blocks had thicker cylinder walls) then it all depends on finding Pistons or having a set custom made, the Australian's also built some Ford six's in the 188 cu. in. size this was a early four main crank 200 block (3.680 bore size) with a 170 crank dropped in. If you can talk to Xtancy our resident site expert on the Azzie built Fords he knows more about what was available over there in his area and the possible combos and pistion choices. I don't know how far over size they made the pistions for the 170 blocks but boring out the block will only give you a few cu. in. At max over bore maybe another 8 or 9' cu. in. Lastly you could weld & stroke the crankshaft but at that point and depending on the amount of stroke increase you could need custom sized Rods, plus Pistons and the cost would be somewhat higher. At that point it would likely be better to go with the later 200 block. Back in the day there were lots of Hot Rodded 170's roaming the streets, Good luck

Howdy F_M and All:

If you are rebuilding the 170 engine the practical (read cost effective) thing to do would be to plan for an overbore of .030" and Off-set grind the crank throughs to increase the stroke.

Overboring more than .030" will begin to reduce the cylinder wall integrity and may risk the possibility of a future rebuild. Stock type flat-top pistons are redily available.

Off-set grinding the crank throws will increase the stroke slightly at little or no risk and can be done by a competent machinist with very little added cost over a normal crank turning and new bearings expense.

Both overboring and offset grinding the crank will increase displacement by approximately 7 ci. I was checking the possibilities out to meet Bonneville rule of 3 liters or 180 ci classes.

I will be interested to hear what you decide.

Adios, David

OP, the best you can do is 188ci. that would mean an early 200 four main crank, and boring .060" over. you would also need to upgrade the cam to take advantage of those few extra cubes. in the end swapping in a 200 would be more economical.

F_M i agree with the first response a 200 is a direct swap and 7 mains are super nice if you want to make make more power later via boost what have you. I understand its easier to make what you have better than to do a completed change so to speak but when it comes to these little motors i like to keep all the stock parts together so to speak original crank and rods and flat top pistons you can zero deck the block and take about .060 off the head and you would majorly increase the compression of the motor then its just a matter of getting more air and fuel into and out of the motor and your set. seriously if you havent picked up the falcon handbook its got a bunch of knowledge and if you every get bored just start reading the tech archive and searching through the forum.