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valve guide questions

2K views 6 replies 2 participants last post by  BOBCRMAN@aol.com 
#1 ·
hey guys,

not your typical hotrodders engine here, but my daily driver blew a head gasket and i've put some work into it now to get going again.
i plan to turbo it later this year so i thought it'd be good to check out at least the top end before that. btw it's a 2.0l DOHC 4banger Ford, 1992 Ford Scorpio (similar to the merkur scorpio).

so while apart, i also spent all yesterday putting some effort into porting. then finding that #3 exhaust valve guide has shifted/dropped by about 3-4mm (about 0.150 inch)... see picture.
this IS a budget project and as such i'm wondering about the severity of this.. fix it or leave it, as long as i can get the valve seal on top of it? guide looks good inside and valve too.

from what i gather, some turbo engines have a groove in the top part of the valve guides securing them from dropping with some kind of lock ring. i say turbo engines because exhaust is much hotter and hence more risk of loosing the press fit of the guides.
so with the turbo in mind, maybe i should buy some lock rings and take a chance to make some grooves to secure the guides in place?

thanks for your advice,
greetz from austria

andi
 

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#2 ·
If a budget engine. Leave it. But, remember it moved once. There is a great chance that under high heat and rpm it may move again. I have pressed them out. Knurled the top portion, then re-installed the guide and had no problem. Chrysler tried the grooved/snap ring on their turbo 4 engines and it didn't really work. With high heat the guide would still fail as the snap ring would pop out of the groove and let the guide fall.

The only real cure is to use a guide with a collar on it.
 
#3 · (Edited)
thanks bob! do you think it would be possible to give this a DIY shot with an oven and a freezer? ;) also wondering if i'd have to redo the seat when just putting the guide back up to its original position..


haha right, i WAS talking about the 2.2/2.5 turbo engines ;) i'm into those k-cars...
here's a pic (though from an old style ford) to clarify about those clips/retainers securing valve guides.

haven't heard about much about the ones in the turbo-dodges fail though, but maybe i haven't looked close enough.
anyways, do you think it'd be worth a try to secure from further dropping?
 
#4 ·
on second (well or third or fourth) thought .... damn, i just remembered taking apart a scrap k-car engine and i found one of these clips lying around in the head.. couldn't make out where it was from at first but then found out the valve guides had these. so actually i already experienced one of those coming off!
 
#5 ·
Yes it was a very common problem along with seats falling out and bad head crack/warpage!!

I can't tell you how many of those heads I had to scrap back in the ninties. Cheaper to get a new casting, back then.
You can move the guide back in place, cold/room temp, with a press or very carefully with a hammer and a home made arbor. I turn them down from bar stock/bolts on a lathe. So they pilot in the valve guide and push on the guide body.
 
#6 ·
that chrysler head i took apart was actually scrap because the camshaft broke and wiped out a saddle being angled by the force of the belt.

i tried putting that guide back up a bit with a hammer and a nut that just fit the nose of the guide last time but didn't move a noticable amount and i was since too frustrated to go back to the garage ;) but might try again with a BFH then.. open for any suggestions and details into that direction. thanks again.

oh and what do you think about putting some kind of said locks onto the guides to secure them when turboing this thing?
 
#7 ·
Need to find some strong snap rings. Even tho the grooves are round. A square Tight snap ring should dig in and hold the guide. Maybe try a snap ring for a slightly smaller shaft. Good luck.

Did a big block chevy today that had loose guides. Old closed chamber rec port heads. Installing bronze liners and several guides moved. Haven't seen that before in old cast GM iron heads.. Usually if you need to move/remove them it tahes a BFH and muscle or a ten ton press..:thumbup:
 
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