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sstarace
Anonymous Poster
sstarace9605@yahoo.com
Dec 20, 2007, 9:06 PM
Post #1 of 13
(1543 views)
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can you give me a quick easy fix suggestion
i have a 1985 full size chevy blazer 4x4 350 5.7 liter
i have an intake lifter sticking causing a backfire and
making the truck run crappy i have tried marvel mystery oil nothing i tried a brake hone repeatedly nothing aside from machine work i dont know what else to try can anyone suggest anything please
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Dec 21, 2007, 2:46 AM
Post #2 of 13
(1540 views)
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Are you willing to go postal on this lifter? Try a new valve spring on just that one and douse down at the lifter with some PB. Get it to the low area of the cam and push it back down. Are you sure this is the lifter sticking from either varnish or mushrooming, or could the valve be sticking in the guide?
Either way if you have drivien this, this way too long it may have fried that intake valve,
T
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Guest
Anonymous Poster
Dec 21, 2007, 7:36 PM
Post #3 of 13
(1533 views)
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these are brand new trick flow heads and i tried three different sets of lifters i havent ran it much because of this problem a couple of lifters got thrown pretty far postal isnt even close
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Guest
Anonymous Poster
Dec 21, 2007, 8:00 PM
Post #4 of 13
(1527 views)
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its deffinately the lifter bore i took the valve spring off the valve moves freely this motor did this with the old heads
i was told to use heavier springs wont this be a problem for
other valvessstarace9605@yahoo.com
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Dec 21, 2007, 8:02 PM
Post #5 of 13
(1527 views)
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Oh! You are spending some bucks of this - sorry. What's the deal with those heads? There should be a pre-set for valve adjustment and they can be tweaked from there. Not sure just where you are at with this one.
Does this have good oil pressure? Will oil come up and out of the push rods?
T
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Guest
Anonymous Poster
Dec 21, 2007, 8:10 PM
Post #6 of 13
(1524 views)
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oil pressure is great at idle covers off oil goes over the fenders ive adjusted the valves a few times and had them
proffesionally adjusted definately a block issue
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Dec 21, 2007, 8:16 PM
Post #7 of 13
(1522 views)
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Hmmm? Camshaft issue/valve timing, timing?
T
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Guest
Anonymous Poster
Dec 21, 2007, 8:28 PM
Post #8 of 13
(1521 views)
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cam came with the heads went all out with msd distributer
6al box blaster 2 coil 8mm wires and had a mechanic freind do the timing so we can rule out my stupidity he has no ideas aside from machine work or another motor
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Dec 21, 2007, 8:42 PM
Post #9 of 13
(1515 views)
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Back to first post here: An intake is backfiring. Is it just one or multiple that pop back up thru intake? The rocker arms should set the initial valve adjustment. Been a while but I think those are 9/16 nuts that you bottom out at the rocker arm and back off six turns (don't quote that). Like I said "been a while" and it may be different on this one. None the less they are meant to self adjust within a certain range.
You said you had some help with this. The cam gear must be on the right tooth and the dist must point at the right cylinder and timing adjusted when these things are moved or replaced. There's lots of room to be off there and it can be fussy but the valve timing must be on target first.
Arggh, I'm getting tired and may not be back at this for few hours. Post any observations that might not have been proven out yet,
T
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Guest
Anonymous Poster
Dec 21, 2007, 8:52 PM
Post #10 of 13
(1514 views)
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5 /8 and there roller rockers the nuts have allen key set screws timing is right on and yes just one intake valve backfires what do you think about heavier sprjngs any problem with keeping other valves open thanks for your help and ideas ill check back tomorrow unless your still at it
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Dec 22, 2007, 3:51 AM
Post #11 of 13
(1510 views)
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Kitty woke me up and said I'm not done here yet You might guess I'm not always wrapped too tight?!?!?
I'm in favor of the stonger valve springs for this project. Think: The cam is new as are lifters and it could be hard on older stuff with a stronger return spring. You should have good oil pressure and may fiddle with which oil is best for this engine for best performance and life.
This intake valve just doesn't return fully to closed, either tight at valve guide or lifter too tight (adjustment), or doesn't slide in its bore well which you may simply feel as you have been at those a few times now. All things perfect they should fall back to cam under their own weight. Used ones get "shroomed" at the cam end and don't like to come Up and Out as you may know but that can be handy to stick them up to get cam out.
Also, valve should be free in the valve guide. I've had those in original engines with over 100k that were tight and valve would stick part open. No matter but that was a Buick 350 and merely turning that valve 90 degrees would correct that and was periodic for that engine about once a year (a vehicle of my own) and I never tore it down to correct as it was easy to do and dependably worked.
If you suspect that the clearance valve to guide is too tight then if all this is new the valves that can do that should be removed and either guide or valve would need adjustment by machining - that one I had would have responded to the valve compound on the valve shaft. This problem could show up with sludge, varnishing from overheats or lack of lubrication but that doesn't seem to be your situation.
Hey - we are off on a tear here so the other techs may not read this far and have some real good insight into this for you. The technical know-how is here. You may do best to summarize this whole thread and start a new thread and use a subject line like "84 Chev 350 Valve/lifter problem" and that may generate some other ideas for you.
You do know the Chev small block V8 is the most versitile engine to play around with and is used as a staple for power in all kinds of things and a mainstay for marine use too,
T
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Guest
Anonymous Poster
Dec 22, 2007, 9:27 AM
Post #12 of 13
(1508 views)
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thanks very much for the ideas ithink i am going to attempt the stiffer springs Im using it was suggested i use full synthetic so mobil 1 it is i will try the springs after the
holidays and repost my problem and my solution should i find one thanks again for the ideas happy holidays
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suko123
New User
Dec 22, 2007, 5:46 PM
Post #13 of 13
(1502 views)
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very good information
intex007.newautocars@blogger.com
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