Push rod help
09-20-2011, 11:39 PM
#21
Burning Brakes
I called Texas Speed and they would not confirm if the base circle was smaller or larger than stock. They told to me check my push rod length to make sure, "every combo is not the same" They said.
So I can't assume that the base is smaller. And the heads have been milled, by how much I'm not sure. I'm on the base. I checked 4 rods/valves and came out the same on each one. I assumed I was to short as well at first and installed 7.425 and the thing would idle but died as soon as I let out the clutch. I was hanging the valves open at the point.
So I can't assume that the base is smaller. And the heads have been milled, by how much I'm not sure. I'm on the base. I checked 4 rods/valves and came out the same on each one. I assumed I was to short as well at first and installed 7.425 and the thing would idle but died as soon as I let out the clutch. I was hanging the valves open at the point.
09-21-2011, 02:49 PM
#22
Melting Slicks
Member Since: Dec 2003
Location: Near Jacksonville Fl.
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I called Texas Speed and they would not confirm if the base circle was smaller or larger than stock. They told to me check my push rod length to make sure, "every combo is not the same" They said.
So I can't assume that the base is smaller. And the heads have been milled, by how much I'm not sure. I'm on the base. I checked 4 rods/valves and came out the same on each one. I assumed I was to short as well at first and installed 7.425 and the thing would idle but died as soon as I let out the clutch. I was hanging the valves open at the point.
So I can't assume that the base is smaller. And the heads have been milled, by how much I'm not sure. I'm on the base. I checked 4 rods/valves and came out the same on each one. I assumed I was to short as well at first and installed 7.425 and the thing would idle but died as soon as I let out the clutch. I was hanging the valves open at the point.
The stock cam for the LS1 is ground on the largest base circle that will pass the cam bearings, even the LS6 cam is on a smaller base circle.
The way to make sure your on the base of the cam is to make sure the the other valve in the same cylinder is fully open then you will be sure your on the base of the other lobe.
09-21-2011, 09:41 PM
#23
Pro
Thread Starter
Apparently whom ever your speaking to has little or no knowledge of the LS1 engine.
The stock cam for the LS1 is ground on the largest base circle that will pass the cam bearings, even the LS6 cam is on a smaller base circle.
The way to make sure your on the base of the cam is to make sure the the other valve in the same cylinder is fully open then you will be sure your on the base of the other lobe.
The stock cam for the LS1 is ground on the largest base circle that will pass the cam bearings, even the LS6 cam is on a smaller base circle.
The way to make sure your on the base of the cam is to make sure the the other valve in the same cylinder is fully open then you will be sure your on the base of the other lobe.
Don't know what's going on. Bottem line is the heads are coming off and the lifters are going to be replaced, heads checked to see how much came off of them and checking valve height as well.
I did this same mod on my 04 GTO and never had any of these problems, It was pretty much trun key and go.
Last edited by TheDEfan; 09-21-2011 at 09:52 PM.
09-21-2011, 09:46 PM
#24
Pro
Thread Starter
Humm, then why did run fine when I put the bone stock rods back in it? I could barely get it back up the drive way.
Last edited by TheDEfan; 09-21-2011 at 09:52 PM.
09-22-2011, 10:00 AM
#25
Team Owner
This thread has got me all intercoursed up. From the 1998 LS1 needing .118 preload, but a 99 LS1 needs .080, all the way to wondering whether .005 preload remains after engine warm up. I personally was thinking the preload would increase with temp. but after thinking about the aluminum block and head expansion rate, now I'm wondering too. Surely sombody here has adustable rockers that has (or will) set preload cold then checked it hot just to see where the valve train is at during operating conditions. My old SB 400 with pontiac heads decreased the lash by ~.015 from cold to hot settings. 
However, while I was playing around with lashing them, I found that I had to get them close with the engine cold, warm the engine, and re-set them. In my experience, with an aluminum head, iron block engine, the lash opened up a bit once the engine had reached operating temp...
09-25-2011, 09:48 AM
#26
Pro
Thread Starter
If you have valve train noise with 7.400 push rods how can it be expected to decrease with shorter push rods? And I need to ask another question, as I'm fixing to add the YT's myself. I have a adustable pushrod for lenth checking, why not just adjust the lash to zero, measure the lenth and add .040. I'm asking here, would that method be acceptable? After verifying wipe pattern of
course.
course.
Too much preload is also going to make alot of noise. If you have more pressure on the top of the lifter, more preload, which will also limit the amount of oil for cushion (travel). So you push all of your oil out on the up stroke and have none when you come back down, or not enough to cushion anything. This will give you too little preload on the way down (plunger depressed due to no oil) and CLACK!!!!! I know this to be true with my car because it is only loud below 3000 rpm. Above that and it is the sewing machine noise. This is all dependent on oil pressure. At Idle it is not enough to counter act the springs and ramp rate with to little oil below the plunger, and once its bled down it will stay like that until you get more oil pressure. By going to 7.35 rods they will allow .050 more oil under the plunger while keeping a .030 preload. It will still bleed down but will still have plenty of oil left for cushion, plenty of preload to keep it quiet, and less of a refill the next time around. this is why preload is so important. Why do comp Rs only have .004 preload? Cause they are used with aggressive cams that have serious ramp rates and tough springs that are going to push down the lifter plunger. The lifter is the same length as stock. It is also built stiffer than stock. just my .02 Oh and I got all this info from LG
