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I'm a high school senior and this is my first engine build and my first Corvette!
I have a 1976 L48 Corvette that I just finished the engine build on the 350, new Comp Cams Hydraulic Flat Tappet cam, an Edelbrock EPS intake, HEI distributor and wire, and a Holley carb, with new stock crank, lifters, pushrods, pistons, and seals. I reused the original oil pump and lapped the valves in the original 882 heads (I know are not the greatest, but new heads were not in the budget). I got everything together and dropped in the car and was able to get the engine to idle, tho being a very rough idle. That being said I found my #3 and #5 cylinder not firing and hoping that new sparkplugs will solve that issue.
The reason I'm here is I can't get any of my rockers to tighten up. I followed the advise in a previous thread on how to set pre-load to get the rockers tight just enough wherethe push rod is unable to turn, and was able to tighten them up then. Now after starting the car several times to set the timing and start tuning, I cant seem to get any of the rockers to tighten up. I can bottom out the nut and the rockers are still loose. I checked the original push rod length to the new push rods and they are exactly the same. I have mulled it over for a few days now and cant seem to find any reason why the rockers wont tighten.
Hello High School senior! Welcome to our forum! And a huge congratulations on your first engine build. Must make you feel really good.
Anyway, I was a High School senior back when your car was brand new. Funny that.
And I to once had to learn to lash lifters.
So.
Not sure what you read. But sounds like your going about it all wrong.
Your never going to get your pushrods totally tight, And you don't want to! Your over preloading your lifters. Probably why it's idling like ...... well, less than great.
Valve covers back off. All spark plugs out.
when you go to adjust the lifters/pushrods. Back off the nut untill you can feel a bit of up and down shake. Just a tad of shake. Of course it will spin. And very easily. Run nut down with one hand while continuously checking shake. When you hit zero lash. There will be no shake. And although it will still rotate, you will feel it's a bit stiffer. That's the zero point. Then. 1/2 turn down. NO MORE.
Follow these charts.
Now, when they say intake valve at full lift. That means that valve is all the way open. The intake valve will match up with the intake port on your intake manifold, the exhaust valve will line up with the exhaust manifold. Some cylinders are one way, some the other. So look and pay attention. If you follow these charts you will find they take you from one to the next with a minimum of turning the engine.
Remember, find zero lash. Than a half turn of the nut. NO MORE. Follow this procedure. And your done.
Hello High School senior! Welcome to our forum! And a huge congratulations on your first engine build. Must make you feel really good.
Anyway, I was a High School senior back when your car was brand new. Funny that.
And I to once had to learn to lash lifters.
So.
Not sure what you read. But sounds like your going about it all wrong.
Your never going to get your pushrods totally tight, And you don't want to! Your over preloading your lifters. Probably why it's idling like ...... well, less than great.
Valve covers back off. All spark plugs out.
when you go to adjust the lifters/pushrods. Back off the nut untill you can feel a bit of up and down shake. Just a tad of shake. Of course it will spin. And very easily. Run nut down with one hand while continuously checking shake. When you hit zero lash. There will be no shake. And although it will still rotate, you will feel it's a bit stiffer. That's the zero point. Then. 1/2 turn down. NO MORE.
Follow these charts.
Now, when they say intake valve at full lift. That means that valve is all the way open. The intake valve will match up with the intake port on your intake manifold, the exhaust valve will line up with the exhaust manifold. Some cylinders are one way, some the other. So look and pay attention. If you follow these charts you will find they take you from one to the next with a minimum of turning the engine.
Remember, find zero lash. Than a half turn of the nut. NO MORE. Follow this procedure. And your done.
Thanks for all the help and insight, was able to get all of the studs tightened down and set lash. I was only able to get one rocker on cylinder #5 to not tighten at all. Was able to find a friend of a friend that regularly build small blocks to come out and I unfortunately have a pulled stud. So I fortunately/unfortunately will be replacing the heads in the coming weeks.
Thanks for all the help and insight, was able to get all of the studs tightened down and set lash. I was only able to get one rocker on cylinder #5 to not tighten at all. Was able to find a friend of a friend that regularly build small blocks to come out and I unfortunately have a pulled stud. So I fortunately/unfortunately will be replacing the heads in the coming weeks.
that doesnt mean the head needs to be replaced really... unless you want to be
BTW these are a GREAT deal on clearence right now for $819 for the PAIR
I run the same castings on my 355... 200cc is kinda large for a 350 but they will still outperform what you have on the car now at all rpms. (these are the same castings that are commonly sold as 195s by places like AFR.)
You can also have a machine shop "pin" the studs with a dowel pin. Very inexpensive if you give the shop the heads. I did this on both of my L-79 small blocks. Also, how many miles on the oil pump? They are pretty inexpensive to purchase. Jerry
Yup ^ thats what I was going to suggest too but if your going to go through the effort to remove the heads your already half way there to get rid of those very restrictive limiting smog heads.
76' Engine Rebuild Help
