new member needs help with 170

[bkaiser]

hey,

new here and had some questions:

i have a 1967 bronco i bought years ago with a 170. ran casting numbers, found head is from a 70 falcon, block is from 68 falcon. not sure if the head is from a 170 or 200? i know the lifter or whatever are not adjustable and heres why:

had a head gasket fail on me due to running waay too lean. took head to machine shop and he took off either 12 or 20 thousands off it, this was a few years ago and i dont remember which. well i reinstalled the head and it has ran poorly since. not missing or bogging really, just no power. ran compression check cause i thought maybe head gasket crapped out again all cylinders read 140, my shop manual says 155 is minimum. head gasket was fine. i was wondering how much a difference the pushrod legnth made after getting my head milled down? i didnt change the pushrods cause i figured they had probably shortened a bit the last 30 years they were in there and this would be better cause the head was now shorter? but im wondering if they are still to long and the valves are staying open?

other than that im at a loss to know whats going on. the engine has never been rebuilt and im sure has a million miles on it. i really want to find another 170 or 200 to throw in there and eliminate the shorter head problem, but i cant seem to find many around. anyone know a god source other than ebay?>

thanks!

 

[mustang6]

Getting the head milled that little amount would not have messed up a hydraulic lifter engine, the lifters can absorb more than that.

Here's my guess- you do have a 170 and you originally had a 170 head with it's smaller combustion chambers. When you took your head in to be redone they exchanged it (on purpose or by accident) with a 200/250 head they had there. Not being super familiar with these engines, they either didn't notice the difference in the combustion chamber size or didn't care. You put the rebuilt head back on, and with it's larger combustion chambers your 170's compression was now something close to 7.5:1 and your engine runs like a dog. The only way to be sure is to take off the head and cc: the chambers. See the difference below:

1970 DODE 170 head

1978 200/250 head milled .075" but the chambers are still bigger than the 170 (shown during cc measurements)

 

[DupleDreux]

Hi bkaiser,

do you know if you have solid or hydraulic lifters?

I think unless its a late 170 you probably have to use solid lifters and if you have solid lifters you need the adjustable rockers.

As I understand it the early 170s can't be retrofited because they don't have the proper oiling circuts.

One way to tell is take the rocker shaft off and push down on a few of the pushrods. if nothing happens, you probably have solid lifters (or they're so badly varnished they might as well be), if they gradually bled down, or have a little spring to them you have hydraulic.

It still doesn't answer if your block can oil hydraulics though. If you post the block and head casting number maybe we can help there too.

If you need an adjustable rocker shaft and rockers, look up some specialty mustang junkyards - theres one in San Bernardino and another in the san fernando valley somewhere. I don't know but they would probably ship.

Hope this helps!

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