Setting the valves on exhaust and intake on a 1957 corvette fuelie

[John S.]

I have a 1957 Corvette with solid lifters and a duncof(?sp) cam. I need to know how many thousands to set the exhaust and intake valves. How many thousands do I set the exhaust and intake valves when the car is warm?

[Duke W.]

Re: Setting the valves on exhaust and intake on a 1957 corvette fuelie

Spend 10 seconds doing a Web search:

Hinckley Williams valve adjustment

Make sure you get the 9/08 revision. You do them cold using either of the indexing procedures and clearances for the Duntov cam assuming that's what you have.

Post any questions here.

Duke

[Tim S.]

Re: Setting the valves on exhaust and intake on a 1957 corvette fuelie

Here you go John..........

http://www.metroli.org/pdf/WHITE%20PAPER_Solid%20Lifter%20Cam%20Valve%20Adjustment.pdf

It works!
Tim

[William F.]

Re: Setting the valves on exhaust and intake on a 1957 corvette fuelie

So use the technique for 30-30 and LT1 cams with Duntov cams also?

[Joe R.]

Re: Setting the valves on exhaust and intake on a 1957 corvette fuelie

Do you have an 097 camshaft?

Find out and the specs will be furnished.

JR

[Duke W.]

Re: Setting the valves on exhaust and intake on a 1957 corvette fuelie

So use the technique for 30-30 and LT1 cams with Duntov cams also?

The indexing scheme described in the paper for the 30-30 and LT-1 cams to ensure that the lifter will be on the base circle for the valve being adjusted works for ANY mechanical lifter cam.

Duie

[John D.]

Re: Setting the valves on exhaust and intake on a 1957 corvette fuelie

John Smith. On a fuel car you might consider setting the valves cold. Unless you are a very fasts worker as you can't remove the drivers side valve cover. The air meter (throttle body today) is in the way. You don't want to do like one of four fuel injections that come in my shop.
Bubbas cut the bottom of the piezometer ring and sometimes the air meter. Causing major damage and big bucks to replace the parts.
Fuel injections run on the vacuum. Take the vacuum away and they run horrible and idle at high RPM.
Hopefully you have the correct '097 or a good replacement.
Now listen to what our cam guru, Duke has to say.
John

[William F.]

Re: Setting the valves on exhaust and intake on a 1957 corvette fuelie

But Duke, is there an easier way if you're sure you have a Duntov cam, like in my '62 340 hp?
Thanks

[Duke W.]

Re: Setting the valves on exhaust and intake on a 1957 corvette fuelie

The easiest way is the method described in the paper. Years ago someone timed me. Not including R & I of whatever was necessary to expose the rocker boxes, it took me about five minutes to check and reset all 16 valves. That included me rotating the crank with a 1/2" breaker 90 degrees after every two valves and running back and forth from one side to the other as necessary to adjust the correct valves at each 90 degree crank position.

I did have a helper with a chart of what valves to adjust at each crank position. After completing the two at a given position he called out what valves were next as I rotated the crank.

Like I said, the indexing procedure will work for ANY mechanical lifter cam, but you need to know the recommended clearances for the installed cam. Otherwise there's no point in trying to set clearances as you may do more harm than good.

I the paper I recommend clearances for all SB mechanical lifter cams, "adjusted" for rocker ratio behavior as I explain in the paper. (Have you read it?) I don't have a reliable data set to determine big block rocker ratio behavior, and if you have an unknown cam your best bet is to take several dial indicator readings of lift to try to determine the inflection point where the constant velocity clearance ramp transitions to the opening flank.

Duke

[Frank D.]

Re: Setting the valves on exhaust and intake on a 1957 corvette fuelie

But Duke, is there an easier way if you're sure you have a Duntov cam, like in my '62 340 hp?
Thanks

Here is the meothd I used for years for my 61 270 hp Duntov 097 cammed car; I could do the adjustment in about 45 minutes includiing double-checking each setting afte the initial adjustment.

[William F.]

Re: Setting the valves on exhaust and intake on a 1957 corvette fuelie

Duke,
Won't this work if you're sure you have an 097 cam? Seems a littler simpler than what you have to use with LT1 and 30-30 type cams.

[John D.]

Re: Setting the valves on exhaust and intake on a 1957 corvette fuelie

Heres a tip that may work in seeing if you have a 30-30 cam or a '097 cam in your car.
Take a vacuum reading at idle to see how many inches of vacuum have.
For the many phone calls I get with my NCRS job this helps me out a lot.

I use my 63 fuel car as an example.
At 900 RPM it has about 16" of vacuum
For a 30-30 car you tell me what vacuum you like to hear. I hear 10-11 plus.??
Recently a '65 FI owner called and said he had an original cam. I asked him what RPM his engine is running and he told me 750. I said REALLY.
I said sir I don't think you have an original cam. John

[Duke W.]

Re: Setting the valves on exhaust and intake on a 1957 corvette fuelie

Here is the meothd I used for years for my 61 270 hp Duntov 097 cammed car; I could do the adjustment in about 45 minutes includiing double-checking each setting afte the initial adjustment.

THAT METHOD IS ONLY VALID FOR HYDRAULIC LIFTER CAMSHAFTS!!!

You guys need to understand that mechanical lifter camshafts have VERY LONG constant velocity clearance ramps. For example, the 30-30 cam lobe from the beginning of the opening clearance ramp to the end of the closing clearance ramp is about 540 CRANK DEGREES. So that's 270 degrees on the cam lobe, which means that the base circle only occupies 90 degrees, or one quarter of the lobe's circumference.

The Duntov cam is 450 degrees as measured above and the LT-1 cam is something between 540 and 450.

I have most of the OE cam lobe engineering data and I've plotted several of them out. To develop my valve adjustment procedure with John Hinckley, I was looking for a simple crank indexing scheme that would absolutely, positively guarantee that the lifter is on the base circle for the particular valve being adjusted, and I know that if I could find one for the 30-30 cam it would work for any other OE mechanical lifter cam and probably for any aftermarket mechanical lifter cam since most of them have shorter clearance ramps even if actual valve open duration is longer than the 30-30.

It turns out from looking at the plots of the 30-30 lobe's 540 degrees total "duration" including the clearance ramps that every inlet lifter is solidly on the lobe's 90 degrees long base circle 90 degrees after that cylinder's TDC of the compression stroke, and for the exhaust the lifter is comfortably on the base circle at 90 degrees BTDC of the compression stroke for that cyliinder.

So if the engine is at TDC #1 of the compression stroke, #2 inlet lifter is on the base circle along with #8 exhaust lifter, and so on through the firing order. So every 90 degrees of crank revolution means that at TDC of that cylinder's compression stroke two lifters are on the base circle - the inlet lifter of the preceeding cylinder in the firing order and the exhaust lifter of the next cylinder in the firing order.

I tried as best as I could to explain this in the paper, the link to which is in post #3. I expect some have not read it or maybe it just hasn't sunk in. If you have never read it or maybe only read it long ago, please do so again. It's only two pages.

Duke

[Frank D.]

Re: Setting the valves on exhaust and intake on a 1957 corvette fuelie

Interesting since that method has worked for me forr10 years and if its wrong it certainly did no harm.
My 61 was a "screamer" and I redlined it at least weekly. Moreover a "running, hot" check verified the gap more than once.

Having said that I suggest folks read Duke's paper and go that route.

I don't want anyone claiming the motor got boogered up through this method, even tho I had zero issues with it.

[Duke W.]

Re: Setting the valves on exhaust and intake on a 1957 corvette fuelie

Look at the 1963 Corvette Shop Manual page 6-14, bottom of right hand column. The title of that section is:

Valve lash adjustment (Hydraulic Lifters)

At the end of that section, near the bottom, first column, next page:

Lash Adjustment (Solid Lifters)

Refer to tune-up section page 6-6.

That section clearly has something missing because under "On models equipped with solid lifters" it states what parts to remove in order to remove the valve covers, then goes on to "On models equipped with hydraulic lifters."

Back in the day I did them "hot and running", but what a PiA... oil flying everywhere... burnt fingers... there had to be a better way. But I wasn't able come up with a reliable way do the job with the engine cold and not running until I got the lobe data 15 years ago. Then I knew I could figure out a sure fire method to adjust the valves correctly by being assured that the lifter was on the lobe's base circle with the engine off and cold.

Duke