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Discussion Starter #1
ok this is getting really tiresome. I expected to get my car ready today. But no I get a call from one of my friends at the shop telling me that the car didn't run. They are telling me that pushrods are too long. They are also telling me that some ported/polished LT1 aluminum heads that I bought off ebay are shaved too much at the head near the valves and that is messing up the geometry of the valvetrain. Because its sitting too close to everything and therefore the pushrods are too long cuz of the overshaved head?!?


I tried to get a lot of information I could but what in the world is going on? Could it really be my heads? I just told them to slap on my OLD heads because I just need a running car.

could some of you experts try to explain what is going on? They are telling me the heads I bought off ebay are useless but its not like I can get my money back. Any help would be appreciated thanks...

Ernesto
 

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It would be a hell of alot cheaper and easier to put in different push rods rather than swap the heads back. I have been following your threads and I'm afraid that this shop doesn't have a clue as to what it is doing
 

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Did they say the valves were slaping the top of the pistons. And who every sold the heads to you more and likey had the same problem. See if a smalller cam will work. sometimes a big cam can do that. Or use a thicker head gasket to raise the deck height on the heads. Just my two cent here.
 

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It would be a hell of alot cheaper and easier to put in different push rods rather than swap the heads back. I have been following your threads and I'm afraid that this shop doesn't have a clue as to what it is doing
i have the LT4 hot cam kit and the roller rockers. I appreciate your followup raid. They got the pushrods for me but told me like I said that the heads are useless because its shaved down too much. Making the pushrods too long and messing everything up with the roller rockers and cam. Could you please explain how I could use different pushrods to fix that problem? I just really want my car back.
 

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raid i called them up and asked them if I could use shorter pushrods and they mentioned they already got the smallest one.:crazy: and I asked them if I machine shop and make them shorter but they said that might affect how the intake manifold fits and it might leak. Thats what I was told. Just wanted your opinon. I made sure to let them know im not paying anything EXTRA and they agreed. They are going to lend me a car for the next couple of days while they wrap it up.
 

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when the piston goes up all the way the exhaust valves open and hits it and either you get different heads or shorter push rods... whichever is cheaper if im wrong correct me
 

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As long as your pistons are not hitting the valves then shorter pushrods will do the trick. BUT!!! You will more than likely have to take your intake manifold to a CNC shop and have it decked (shaved) a little bit. Because of the new heads sitting closer to your block you messed up the position of the intake openings on the head. Now they sit lower than stock. The intake is designed to sit on those heads at a factory height and angle to seal around the intake holes perfectly. Now you will have to modify your intake manifold to get it to seat properly with the now lower heads.
If you can make it work with shorter pushrods and a decked intake I would do it, this is going to bump up your compression a little bit because of the deck height.
More compression=more power as long as you don't ping on 91 octane!
 

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Sorry B-906s piston to valve clearance will be determined by the amount of camshaft lift with proper valve lash. I have had a lot of heads milled in my 30 plus years of drag racing and I have never had to replace a push rod on a small block chevrolet because of the length. The heads have studs that the rockers slide onto and they have always been long enough to allow me to achieve proper adjustment and if the heads have been milled more than .020 the machine shop will mill the intake side of the head to allow the intake manifold to fit. I don't know all the circumstances involved with these heads maybe they're different. Just thought I would put in my 2 cents worth good luck!:thumbsup:
 

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Discussion Starter #9
im trying to get as much information as I can but they want to use my old heads for the job. They told me the heads that I bought are useless? How can that be? Does that mean I can't sell them or anything. I just don't see how my heads that I bought ebay are useless. Well anyways they are going to use my old heads to get everything working. I spend 1200 for the ported heads and ported manifold.

im just a little frustrated because its one thing or another. But I just hope everything works out ok.
 

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I understand what the shop is telling you. Alot of things can change your valvetrane geometry like cam change, shaving the head, valve tip highth, valve spring seat, and different rocker arms. Any or all of these things effect where the rockers run on the tip of the valve. So if you change any of these, you must compensate for it by lengthening or shortening your pushrods. What you want is for the tip rocker arm to make the smallest pattern on the tip of the valve as possible. If you don't do this, the rocker will fall off the valve and hit the retainer, and it will bend your pushrods. What the shop is saying is that they ground those heads past their limits, and that they don't make a pushrod short enough to compensate for it. Which is very unfortunate but possible. That is the chance you take on ebay. You could have your factory heads ground to accept 2.02/1.60 valves if you want. I had mine done and put miloden stainless valves in them for alot less than a price of new heads. But you will still need new pushrods to match the new valves. Let me know if you need any more info., I've been through all this before.
 

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I understand what the shop is telling you. Alot of things can change your valvetrane geometry like cam change, shaving the head, valve tip highth, valve spring seat, and different rocker arms. Any or all of these things effect where the rockers run on the tip of the valve. So if you change any of these, you must compensate for it by lengthening or shortening your pushrods. What you want is for the tip rocker arm to make the smallest pattern on the tip of the valve as possible. If you don't do this, the rocker will fall off the valve and hit the retainer, and it will bend your pushrods. What the shop is saying is that they ground those heads past their limits, and that they don't make a pushrod short enough to compensate for it. Which is very unfortunate but possible. That is the chance you take on ebay. You could have your factory heads ground to accept 2.02/1.60 valves if you want. I had mine done and put miloden stainless valves in them for alot less than a price of new heads. But you will still need new pushrods to match the new valves. Let me know if you need any more info., I've been through all this before.
pm sent..
 

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Why don't you contact the person on ebay? If they are reputable, which is very possible, they may have just the solution for you if they sell many of these heads. You're not the first person that has run into this, I'll bet. They may take them back, also. They could say, "yes, you need part #12345678 pushrod for the milled heads to work with your setup". Of course, they could tell you, "sorry, bud". I thought these guys had this running once.
 

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Discussion Starter #13
ok here are the heads that I bought off ebay. I took these pictures BEFORE i took them to the shop. COuld you guys tell me if it looks like its really milled down and that why it won't sit right on my block right. I don't know if its possible to tell that from these pictures. Thanks again guys.:thumbsup:






DO THEY LOOK LIKE THEY WERE MILLED TOO MUCH NEAR THE VALVE COVERS?

if it is true then thats the last time I buy something like that from ebay. Should of gone to Llyod Elliot...right Joe B:lookinup: :thumbsup:

This is the explanation from the seller on the heads.

You are bidding on a set of LT1 aluminum heads and powder coated LT1 intake manifold that have been professionally ported and polished, the bowls have been unshrouded to improve flow and power. These heads have been totally reconditioned, the guides have all been checked and replaced if needed, they feature a competition three angle valve job, new valve seals, valves have been resurfaced, heads have been pressure checked and milled. Valve sizes are 1.94 intake and 1.5 Exhaust. The springs are Komotion springs good to .600 lift and the heads are fully assembled ready for you to bolt on and see incredible horsepower and torque gains!! The max flow out of these heads was 242 cfm on the intake and 183 on the exhaust at .550 lift at 28"H2o, if you see haeds that have been flowed at a higher pressure than 28" H2O thier flow numbers will be higher but the head is not actually flowing that amount, 28" is the standard pressure for flowbench work. With this head and intake package you can expect at least a 30-40 horsepower increase and more power is available with the right combination of parts. The performance shop that ported these heads recomended the GM Hot Cam and roller rockers to go with this setup. The intake manifold has been ported and polished, has been port matched to the LT1 heads and the throttle bore has been opened up to accept up to a dual 58mm throttle body."

Factory Casting Number 10128374...92-up...350....Gen.II LT1, 53cc, angle plug,aluminum, reverse flow cooling,175/68cc ports
 

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Normally when a head is milled during the reconditioning process, they are only trying to shave off the outside layer to clean the surface up. For a head to mess up your valve train geometry they have to be milled quite a bit, and then you would probably start to notice a different look to the chamber shape as well.

Take a look at this pic of a cleaned head the chambers look the same, which to me says your have not been milled significantly. But without actually taking some measurements none of us could be sure by just looking at a picture.



But as previously stated by others, a head with a slight milling should bolt on fine, and your stock pushrod would work. Now, even if for some crazy reason the stock pushrods didn't work, you can buy ALMOST ANY size pushrod in increments of .05" from summit and they make specific tool called a 'pushrod length checker' that would help them figure out the length they needed (if that was really the problem which I doubt).

IMO the stories you have been getting don't add up- first they fired it up and heard a noise, then its a cam bearing (which as everyone says seems unlikely), now its your pushrods being the wrong size because of your heads.....whats next?

The best advice I could give you is have your car towed to better shop or learn to work on it yourself as I wouldn't trust any work that this shop does on your car.
 

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First of all.....SIT BACK AND READ "EVERY" WORD HERE SO YOU "FULLY" UNDERSTAND:D .........your heads (from Proflow jake on Ebay) are NOT shaved very much at all(THIS IS A 100% FACT, NOT MY OPINION) and would NOT be a problem on "ANY" (stock bottom end) LT1 that you were to put them on......In the picture of your combustion chamber, "directly" above your exhaust valve(the smaller one:D ).....there's a little area that those familar (like myself) look for on a set of LT1/LT4 heads...and that area that Im refering to, is still 100% visable on your heads.....I can tell by the indent that im refering to in the pictures, that your heads have only been cleaned up(IE: VERY lightly shaved)....you can even shave them about 30-40 thousanths(which is a good chunk) thus "NEARLY" removing that little area that you can see that Im talking about "above" your exhaust valve in your pictures, and "STILL" there will be ZERO "hard to correct" issues with installing them........With the amount your heads have been decked, and the (THINNER THAN STOCK) 29 thousanths compressed thickness IMPALA head gaskets that their "supposed" to be using, everything would normally be fine, and the "only" thing ever needed is a bit shorter pushrod(WHICH YOU KNEW BEFORE THEY STARTED)....stock is 7.2 inches....and 99% of ALL people with LT1's end up needing a 7.150 - 7.200 length set of pushrods to get the "perfect" rocker geometry after these heads and cam installations........."but realize" your factory 7.2 length pushrods would get your car running for the time being "JUST FINE" , "supposing" they were too stupid to get the correct size pushrods...so I don't know what the hell their talking about, And, you can order nearly "ANY" size pushrod a person would ever need(FOR ANY ENGINE COMBO, PERIOD)..........NOW... where a possible issue "COULD" come in, is the new 60 over pistons they "supposedly" put in, "AND" how much they decked your block(if they even did at all)...this is partially why I've been asking you to find this HIGHLY VALUABLE Information out from them......This seems to have turned into a real nightmare for you....and I have to say , it dosn't really surprise me one bit.....from the begining, with them telling you some really crazy off the wall stuff that made ZERO sence, I diddn't trust their ability...and this is why I said "over and over" NOT to let them touch your (still in good condition) bottom end, and that it sounded like they would "MORE" than have their hands full with just the heads and cam installation........IMO, If this dosn't take a drastic turn for the better real soon...I would seriously tow the car out of there and look for someone else to put it back together(in TX their are several AWESOME shops so finding one shouldn't be an issue at all).....the rudementary (child like) issues that their having with your engine, shows that they don't have a clue about what their doing....and they especially don't have a single clue about LT1/LT4 engines.....they probably have NEVER even performed a cam or heads installation on one(im sure of it)...........PS: SERIOUSLY consider getting your car out of there right away...........Joe
 

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And also, MAKE sure they are checking the piston to valve clearance(with the clay method and a micrometer).....you don't wait to see if the valves are hitting the pistons to find out things are too close(damage is done if that happened, NO DOUBT).....Ya know, That's probably the "serious" noise they first heard when they started it up, and "NOT" a (unlikely) cam bearing comming loose, and now they are making up lies and excuses since your good "expensive" heads probably need to come off for having bent valves or worse(THAT THEY CAUSED), but who knows now, just my thoughts.............they should have checked this during the build (right "before" the heads were "permanently" put on) and they should be able to tell you an EXACT figure for what the clearance is for BOTH your intake valves, AND your exhaust valves.....as long as you have aprox 80-100 thousanths on the intake Valve side, and 100-125 thousanths on the (hotter) exhaust valve side....this range of valve to piston clearances is MORE than safe on an LT1.........also, only in situations where the LT1 block was decked, a thinner head gasket was used, "AND" the heads were cut a bunch does the LT1 intake manifold "NEED" to be cut......some shops like to go ahead and shave it the mathamatical equated amount for what was changed (IE: block, gasket, shaved heads, Ect...) and thats good too... but most people after performing these EXACT commonly done mods were talking about here, are able to "EASILY" get away with just "slightly" slotting the intake manifolds bolt holes(and many "Like Mine" don't even need that done for it to line up perfect)...and your head port to intake port alignment should be fine as well.......god... this is really basic stuff that they should know , especially if they have any business working on someones car...no less a corvette....and, shame on them for lying to you about ALL this, which they "certainly" are.......and as you know , I "MUCH" prefer Lloyd Elliotts or Advanced Inductions Cylinder Head port work over Proflow jakes stuff that you got from Ebay(no real comparison)......but as I told you, I have seen many of his (proflow jake) heads in person, and installed a few sets as well.....and they "all" went on just fine and performed pretty good as well.......and "Just" like your cylinder heads in your pictures, the other sets of his heads I've delt with were just lightly skimmed as well, "just enough" to give a nice clean even head gasket surface......always remember... when you see an LT1/LT4 head with that indent area still present "above" the exhaust valve(like in your pictures) you know the head was just skimm cut....that area dissapears after "aproximately" 30-40 thou of a cut(sometimes even less).........Joe
 

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After looking at the heads I agree with JOE B. The marks in the combustion chambers he is refering to is a line created when the head is originally milled, and makes a pretty good wear inducator. And it appears yours aren't close to those, so your heads should be fine.But it is really hard to tell by the pictures. If the guy you got the heads from was a place known to sell good heads in the past, and it sounds like JOE B knows who it is, I would tend to feel they are OK. On the other hand, it sounds like the shop that is doing your motor, might not be the greatest. I was thrown by the cam bearring deal because I've never heard of that happening in all my years of working on cars, but I wasn't gonna say it wasn't possible. But I did however say that I don't believe it wouldn't have torn up your cam if it did come out. So that is a little far fetched. If all that was milled was thousands of an inch, the most you should need is .050 shorter pushrod. And summit does sell those. Comp. Cams has a good selection of sizes. But if the valves were changed, that could be another issue, but normally when you do that, the pushrods would need to be longer due to the valve stems being taller. What I'm wondering is if they were freaking out if the rocker was no longer centered on the valve. When checking pushrod length, you are not trying to get the rocker centered on the valve which alot of people think. You are actually trying to get the rocker to make the smallest travel pattern on the tip of the valve as possible. Without falling off of course. That won't always neccessarily be directly in the middle of the valve tip.
 

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Joe's right on target. He's provided excellent advice, and you would be wise to listen to his wise counsel.

Steven
 

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BECAUSE JOE KNOWS!!!!!!!!!!!!!!!!!!!!!!!!!:rolling: :rolling: :rolling::rolling:
 

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After looking at the heads I agree with JOE B. The marks in the combustion chambers he is refering to is a line created when the head is originally milled, and makes a pretty good wear inducator. And it appears yours aren't close to those, so your heads should be fine.But it is really hard to tell by the pictures. If the guy you got the heads from was a place known to sell good heads in the past, and it sounds like JOE B knows who it is, I would tend to feel they are OK. On the other hand, it sounds like the shop that is doing your motor, might not be the greatest. I was thrown by the cam bearring deal because I've never heard of that happening in all my years of working on cars, but I wasn't gonna say it wasn't possible. But I did however say that I don't believe it wouldn't have torn up your cam if it did come out. So that is a little far fetched. If all that was milled was thousands of an inch, the most you should need is .050 shorter pushrod. And summit does sell those. Comp. Cams has a good selection of sizes. But if the valves were changed, that could be another issue, but normally when you do that, the pushrods would need to be longer due to the valve stems being taller. What I'm wondering is if they were freaking out if the rocker was no longer centered on the valve. When checking pushrod length, you are not trying to get the rocker centered on the valve which alot of people think. You are actually trying to get the rocker to make the smallest travel pattern on the tip of the valve as possible. Without falling off of course. That won't always neccessarily be directly in the middle of the valve tip.
ya know what, I honestly don't even think the shop checked anything they did, No-less trying to achieve the correct roller rocker geometry....and the reason I say this(KNOW THIS), is because they(the shop) assembled the entire engine and then "after" they were all finished, they started the car up, as you do at the end of a job to make sure everything is alright with no leaks.......and "then" they had major issues...some of which (if checked) would have NEVER dictated actually starting the engine as if everything was all ready to go.........."proof" that they never checked anything.........you don't assemble an engine, then start it up on a wing and a prayer only to have major issues.....and then "after" the fact of starting it and potentially causing major damage....go back and say, "this" was not right, and that was not right, and this wasn't right, Ect.........you check things along the way of putting it together, and correct any (and all) issues as nesessary....PERIOD.................Joe
 
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