Cant hold idle after Rocker lash adjustment

[jjg73]

for some reason, my car will not hold an idle after i adjusted the rockers. all of them were off by about a 16th or so ( yes i said 16th, some even worse!) for some stupid reason i did not check it after i rebuilt the thing, but right after i did that i cannot hold an idle to save my life. 340 bored over .030 runnin AV fuel with edelbrock 650. any ideas whats up???

 

[moper]

Is this a hydraulic cam?

 

[67Dart273]

I think you've made a drastic mistake. We need more info SURELY this must be a hydraulic cam

Just how did you adjust them? That is what did you use for a method? Details

WHAT is the cam?

WHERE did you position the crankshaft to adjust each valve?

WHAT method did you use to determine how much lash you have/ had/ changed it to?

My guess is you have a hydraulic cam, and now at least some of 'em are way way too tight.

 

[RustyRatRod]

You know, when I want a good answer, I give a good question.

 

[MRL Performance]

Sounds like the valves are being held open

 

[dodge freak]

Sounds like the valves are being held open

Thanks, was thinking the same.

You SURE you only turn them a 1/16 of an inch:-k

 

[RustyRatRod]

1/16"= .0625". That's a TON of solid lifter lash OR hydraulic lifter preload. Take your pick.

 

[dodge freak]

huh, I got mine lash set around 1/2 turn down from loose. Its a HYD cam. I know it might get more rpm with an 1/8 of a turn but the engine seems to be enough for this old guy

 

[crackedback]

1/16"= .0625". That's a TON of solid lifter lash OR hydraulic lifter preload. Take your pick.

Not to a place in Illinois on there recommendation for lifter preload on hyd rollers.... .080-.085.

Yes, that's what one member got from them and the results weren't pretty.

 

[toolmanmike]

Sure would be cool if JJG73 would answer back. It's ok to use adjustable rockers with hydraulic cams but don't use a yard stick to measure preload. LOL
Sorry just trying to be funny.

 

[67Dart273]

don't use a yard stick to measure preload. LOL

Yeah, even if you put in in "flatways"

 

[jjg73]

Sure would be cool if JJG73 would answer back. It's ok to use adjustable rockers with hydraulic cams but don't use a yard stick to measure preload. LOL
Sorry just trying to be funny.

sorry, i work midnights and i have been on 12s all week, haha. i do NOT have a Hydraulic cam. i meant that some of my rockers had 1/16th+ play in them, as in i could slap them up and down from the valve to the push rod, thats how loose they were. a guy i work with used to drag race a challenger and he told me to set lash to seated plus a quarter turn. i didnt do that, i just went to where it was seated for fear that the valves would stay open, like someone mentioned. i am not sure what cam is in it, when i had it apart i didnt measure anything, i just know the guy i bought it from said he didnt want me running it on the street cause he used it for the strip and it was too wild for the street. this is the best pic i could find when i had it apart...
http://i156.photobucket.com/albums/t8/gullo53/DSC00159.jpg

 

[RustyRatRod]

Not to a place in Illinois on there recommendation for lifter preload on hyd rollers.... .080-.085.

Yes, that's what one member got from them and the results weren't pretty.

Still though, .0625" is about 3/4 of that WHOLE travel. Get me? Depending on WHERE the plunger is.....it could be beyond bottomed out holding the valves open.

 

[RustyRatRod]

sorry, i work midnights and i have been on 12s all week, haha. i do NOT have a Hydraulic cam. i meant that some of my rockers had 1/16th+ play in them, as in i could slap them up and down from the valve to the push rod, thats how loose they were. a guy i work with used to drag race a challenger and he told me to set lash to seated plus a quarter turn. i didnt do that, i just went to where it was seated for fear that the valves would stay open, like someone mentioned. i am not sure what cam is in it, when i had it apart i didnt measure anything, i just know the guy i bought it from said he didnt want me running it on the street cause he used it for the strip and it was too wild for the street. this is the best pic i could find when i had it apart...
http://i156.photobucket.com/albums/t8/gullo53/DSC00159.jpg

If you have a mechanical camshaft, you cannot just turn the adjusters. You have to use a feeler gauge and MEASURE the clearance between the rockers and the valve tips. You need to find the valve adjustment specs for your cam and adjust it correctly.

 

[dodge freak]

There HAS to be some play in the rockers with a solid cam.

Stop listening to your work buddies who might not know what a solid cam is

 

[moper]

If it's a hydraulic, there's only a coule ways to do it, and it depends on the rockers, cam and lifters...

So what type of rockers?
What cam, or do you know at laest how old the cam is?

 

[67Dart273]

i do NOT have a Hydraulic cam............ i meant that some of my rockers had 1/16th+ play in them,........... i just went to where it was seated for fear that the valves would stay open, i am not sure what cam is in it, http://i156.photobucket.com/albums/t8/gullo53/DSC00159.jpg

If you don't know what cam you have, you just as well plan on getting something "you can use" and changing the thing.

For now, I'd set them all at .020". This is undoubtedly not correct, but will protect the valves from burning and won't hurt the valve gear.

BECAUSE THESE ARE SO FAR OFF, start by setting them "engine cold" then get the engine running well, set timing, idle, etc, and reset them HOT

Plan up so you can

warm the engine

remove one cover

adjust that side

replace the cover

re-warm the engine if necessary

remove the opposite cover

adjust that side.

Adjust the valves with the engine warm and shut down. You MUST get the cam on the "back side" of the lobes to get a correct adjustment. Do this by one of two methods

I use the EOIC method. This means:

When an EXHAUST valve starts to OPEN, adjust he intake valve on that cylinder.

When an INTAKE valve opens and is almost CLOSED, adjust the exhaust valve for that cylinder.

In other words, start on one bank, at the front. Bump / wrench the engine until the front (exhaust) valve just starts to move, and adjust the intake right next to it. Next, bump the engine until the intake you just adjusted opens, goes "over the top" and is almost closed. Adjust the exhaust on that same cylinder.

Move back one hole and do it again. Yup. Takes some practice.

An alternative method is to scribe marks on your balancer every 90* and use this chart:

And here is the same procedure as the above chart from Hughes engines. When they say "put a cylinder on TDC" it is the same as the chart:

http://www.hughesengines.com/Upload/productInstructions/Valveadjustmentprocedure.pdf

If I'm setting valves at, say, .020, use an .020 guage AND one a couple or three thousands larger. You should be able to "get the .020 in" with some resistance, but NOT get, say, an .023 gauge in.

If you have ANY idea who made the cam, you might contact them. It might just be that they didn't MAKE all that many mechanical grinds, and could help you ID it. Why you did not do this when you had it torn down is beyond me.

 

[moper]

Ok. I think i get it... The rocker is lose on the shaft, rather than the lash or preload is wrong... What kind of rackers are they? Aluminum or iron?

 

[67Dart273]

Ok. I think i get it... The rocker is lose on the shaft, rather than the lash or preload is wrong... What kind of rackers are they? Aluminum or iron?

Read his post again, sounds like lash to me

 

[turboJoe]

Regardless of it being a Hyrdaulic or mechanical cam, THEY ARE TIGHT! find out what you have and adjust accordingly...

Good luck and have a great day :happy7:

 

[oldkimmer]

...................U may have just flattened the cam....hope not...solids need clearance.......kim....

 

[daredevil]

Dont think it would flatten the cam but for sure hold the valves open. On a solid cam there is .020 to .035 of clearance between rocker tip and valve with lifter on the base circle of the cam lobe journal. This is with a warm engine. cold lash will be larger.

 

[daredevil]

sorry, i work midnights and i have been on 12s all week, haha. i do NOT have a Hydraulic cam. i meant that some of my rockers had 1/16th+ play in them, as in i could slap them up and down from the valve to the push rod, thats how loose they were. a guy i work with used to drag race a challenger and he told me to set lash to seated plus a quarter turn. i didnt do that, i just went to where it was seated for fear that the valves would stay open, like someone mentioned. i am not sure what cam is in it, when i had it apart i didnt measure anything, i just know the guy i bought it from said he didnt want me running it on the street cause he used it for the strip and it was too wild for the street. this is the best pic i could find when i had it apart...
http://i156.photobucket.com/albums/t8/gullo53/DSC00159.jpg

get some friends that know what they are talking about.please read this http://www.wallaceracing.com/valvelash.htm

 

[waggin]

set the lash on the intakes to .022 and the exhausts to .026 and she'll be fine it should sound like an old ibm typewriter hydraulic cams need preload whereas your solid lifter (mechanical cam) needs clearance (lash) hope this helps........Wagg's

 

[T56MaxTorq]

set the lash on the intakes to .022 and the exhausts to .026 and she'll be fine it should sound like an old ibm typewriter hydraulic cams need preload whereas your solid lifter (mechanical cam) needs clearance (lash) hope this helps........wagg's

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