lsnoobster

im new with the ls engines. i know the bottom ends are stout and can make dummy power with boost. my question is how long of a push rod do i need for a 223/226 cam. i plan on running a pro charger with 6-8 psi of boost so any other cam options would be appreciated

G Atsma

Depends more on any head machine work or if the cam base circle is different than stock.
Normal length is 7.4"

lsnoobster

the hads are just going to be ported and 2.02/1.57 valves will be put in. with the cam being bigger than stock and with a 1.8 rocker arm wouldnt i want a shorter pushrod

G Atsma

The cam's base circle is the cam dimension that relates to pushrod length. Lift does not. If 2 cams have the same base circle, regardless of lift, pushrod length will be the same, all other factors being the same.

RB04Av

The way these motors are designed, and with the variability of the parts that you buy, NO ONE can reliably tell you what length push rods you will need. NO ONE.

First new tools you should buy to help cure your n00bness are an adjustable push rod and a dial indicator. Comp 7702 is the most common adj PR around here. You can buy PRs in .025" length increments so that's the level of precision you need to work towards.

You will need to get good at finding the "heel" of cam lobes. Easiest way for me to get it REALLY ACCURATE is to look at the same valve in the cyl 4 cyls away in the firing order. Turn the crank until that one is at peak lift, then work on the ONE valve that is now at "zero". For example, to set #1 int on the "base circle", turn the crank until #6 int is full open (check its motion w dial indicator), put the adj PR in the #1 int spot, install the rocker arm, adjust the adj out in ½ turn (.025") increments until all of the VERTICAL play in the rocker is taken up, remove rocker, count how many turns out the adj PR is from all the way in, add .050" per turn to its fully screwed-in length (6.80" in the case of the 7702, and .050" because it's a ¼"-20 thread, therefore 20 threads per inch, therefore .050" per thread), add your desired preload to that number, buy. You'll have to know what the preload specs are for whatever lifters you're using. For example, if you had the adj screwed out 10½ turns, then your "zero lash" length would be 10½ × .050" or .525", added to the 6.8" which gives 7.325", if your lifters need .050" of preload add that to the 7.325, buy 7.375". DO NOT try to use the "twist the push rod" method for finding zero lash!! Jiggle UP AND DOWN looking for VERTICAL play ONLY. DO NOT try to measure the adj PR with a micrometer: the way they are spec'ed in the aftermarket IS NOT like that. Just follow the instructions I just gave you. I'd suggest doing at least the int & exh at the 4 corner cyls to make sure the same length will work for the whole motor. (might not, you know... might have to buy partial sets... probably not but you won't know until you measure)

Most often, the length of the adj push rod is most likely to come out to around 7.30 - 7.35", which will mean your motor wants push rods around 7.35 - 7.425". Stock length in aftermarket specs is 7.40". Note that I said "most often" and "most likely". This DOES NOT mean that yours will necessarily be in that range!!! Only, that most of the time for yerbasic stock motor that has an aftermarket cam and not many other mods, that's the most likely range for it to end up, that most of us who have worked on them have come up with most of the time. Yours might be different. I'd be suspicious if you came up with something ALOT different but who knows, until you measure it's all just guessing.

You can buy the 7702 and whatever length push rods, in .025" increments, at Texas Speed. You can get a cheeeeeep but entirely adequate dial indicator from lots of places; Horror Fake, McMaster-Carr, Summit Jegs etc., and so on. They're usually around $35 - 40 for example https://www.mcmaster.com/20715A44.

lsnoobster

another question. will this intake system work with a 5.3. i know it wont work with a procharger
https://www.edelbrockspeedshop.com/E...FOR_p/2068.htm

G Atsma

You don't need that much cfm for a 5.3. A large single 4bbl will be plenty, on a dual plane if you insist on a carb.

lsnoobster

i planned on running spray with 10.5 11 to 1 comp pistons. is my cam that i chose to aggressive for street strip use

G Atsma

A 223/226 cam should work well. How much lift? LSA?

lsnoobster

these are my 2 cam options
1. Stage 4 5.3 Truck Cam 223/226 .600"/.600" Truck Camshaft, 111 LSA
2. Cleetus McFarland Dumpster Fire 224/228, .600"/.600", 114 LSA

which 1 would be better. i also plan on running 91 octane with a octane booster (97-100 octane) what would probaly be the max safe compression with spray

lsnoobster

anyone

Utinator

Out of those two cams, cam #2 would be better for boost. Cam #1 has some overlap, so it will take longer to spool up. I wouldn't recommend either of those cams for a Pro Charger. You would be better off with "boost" cam. There are lots out there, and almost any of them would be better then the two you listed.

lsnoobster

would these cams be good with spray and how hard can i hit a forged 5.3 turned 5.7

lsnoobster

anyone

lsnoobster

anyone

G Atsma

Patience, Grasshopper.....

lsnoobster

thank you sensei

Utinator

I would go with the first cam (1. Stage 4 5.3 Truck Cam 223/226 .600"/.600" Truck Camshaft, 111 LSA) if you are going to bottle feed it. It's a better N/A cam than the second one. The way I see it, a nitrous engine is just a N/A engine that gets a little extra jolt now and then. You aren't forcing air into the cylinders, so the valve events should be the same as a regular N/A engine. Changing the valve events with a turbo or supercharger becomes more important. You can dramatically change the street manners of a boosted engine by changing the valve events. I would get a good N/A cam for a nitrous engine, but that's just me. I'm not an expert, so you probably shouldn't take my advise.

With forged internals, it should be able to handle at least a 200 shot. I have seen stock bottom end LS1s handle a 150 shot reliably. A forged 5.3-5.7 could probably handle whatever you plan on throwing at it.

lsnoobster

this is a little off topic but how much boost can i throw at a completely stock 4.8/5.3 before
1. no more more power is made or
2 i start apollo 18 with the internals

i mean completely stock. nothing exept for tuning

lsnoobster

anyone