My90Iroc

iTrader: (26)

Working on pushrod math...

(SCBC) Stock cam base circle: 1.552 dia. (.776) rad.
(CCBC) Comp cam base circle: 1.455 dia. (.7275) rad. I'm using the futral base circle number assuming it's pretty close to the comp until I get my cam and cam card
(SPR) stock pushrod length (actual): 7.380
(APR) aftermarket pushrod length: 7.400 Variable
(SHG) Stock '00 head gasket: .056
(NHG) New head gasktet: .043
(M) Milling: .010

So hear's what I've come up with...
(SCBC-CCBC)-(SHG-NHG)-M-(APR-SPR) = plunger height difference from stock
(.776-.7275)-(.056-.043)-.010-(7.400-7.380) = .0055

Assuming my base circle number is right then using 7.400" pushrods would only make my lifter plunger .0055" higher than stock. Am I missing anything here?

redtail2426

iTrader: (10)

everything looks good except that stock pushrods are more like 7.395.'' I measured stock pushrods from two different f-body ls1's,with 3 different tools and came up with an average of 7.395.the shortest was 7.391 and the longest was 7.398.i dont know where the 7.380 originated from but its incorrect.

My90Iroc

iTrader: (26)

Ok, so then using 7.395 as stock that would put the plunger .0205 higher than stock.
(.776-.7275)-(.056-.043)-.010-(7.400-7.395) = .0205

That should work because I was told that the tolerance for the lifter plunger is about .020

Again, this is all assuming the base circle of a Comp Cam is 1.455" Can anyone verify this? The cam is 232/234 .595"/.598"

GuitsBoy

iTrader: (4)

He probably got the 7.380 number from me. Its the number ive seen tossed around the forum quite a bit. It may even be in one of the stickies. Not to mention that its the default number in the pushrod calculator sheet

Since the search is broken, i used google and viewed this cached page:
http://72.14.203.104/search?q=cache:...ient=firefox-a

Ill take a caliper to one of the stock PRs I took out of my car and decide for myself.

white2001s10

iTrader: (4)

The math is good, but there's only one real way to find out exactly what you need. Things like just a valvejob can change the numbers.
Are the heads untouched?
I ask because you list milling and new gaskets.

GuitsBoy

iTrader: (4)

Theyre absolute speed 5.3 heads with bigger valves, so theres a good chance the valves may not seat at the stock height.

white2001s10

iTrader: (4)

You should go across the fence and help him mock it up so it'll be right.
You could do math all day and still be off.

GuitsBoy

iTrader: (4)

Ill definately be lending a helping hand. Ive actually had these heads in hand briefly while I was helping him clean them up. I forgot to take some measurements vs. a stock ls1 head. Ill do so before we mill them, hopefully this weekend.

My90Iroc

iTrader: (26)

Update...

Today we mocked up the head, rocker, and push rod then took some measurements. It appears the valves in my AS 5.3's sit .050" higher (basically canceling out the difference in base circles) than the stock setup. We also measured a stock push rod and a comp 7.4" and found the stock to be 7.398 and comp 7.411. So here's my new formula..

(.776-.7275)-(.056-.043)-.010-(7.411-7.398)-.050 = .0375
(.776-.7275)-(.056-.043)-.010-(7.375-7.398)-.050 = .0005

So the comp or SLP 7.375" PR's look like the best fit. I know most people just throw in 7.4's or 7.35's and I'm not sure if that's due to cost, proven setup, or if my setup is that unique (which I really doubt). But with all the different setups out there I'm surprised the stock lifters have enough tolerance to accomodate all the different setups let alone the .050" difference in the popular PR's I just listed. Anyways I thougtht these results would be interesting to share. My wheels have been turning while I'm sitting here waiting for all my parts to arrive.