hey guys i need help on what size pushrods to use i know i can get a pushrod length tool to measure but i wanted to get them prior to the install so it can all just go in at in time the block is stock 350 bottom end it had LT4 hotcam, 1.6 NSA RR and all other bolt-ons for a smooth running car the heads are as follows:
LT1 castings, 180CC intakes, 58cc chambers. 2.02/1.6 Ferrea 5000 valves .100" longer than stock Crane "10308" springs 7/16" screw in ARP studs, Comp Cams Guide plates,
thanks alot i hope someone can help me.

 

maybe someone else will chime in...but i believe its 7.2 inches

 

Correctamundo

 

You may need 7.300 with the .100 longer valve.

 

if the valves are longer wouldnt he need shorter pushrods?

commas are your friend.

 

so i take it for a stock engine its 7.2 inches? Im asking cuz im about to do a hot cam kit and im gonna do pushrods and ls7 lifters while im there so ill need 7.2 inch pushrods?? help !!

 

so i need 7.200 or 7.300 does anyone know forsure

 

You really should measure. The reworked heads may have offset the longer valves but one can't tell over the internet. You may get by with stock 7.2s or you may end up with F@#ked up geometry and have to redo your new expensive valve train when you screw up the valve guides.


Your porter may be able to put you in the ballpark!
Mike

 

I bought the heads off of a user here he used stock 7.200 but says hes not sure for mine

 

You can use the stock length 7.200". If you're going to use guide plates, I would suggest hardened,and/or chromoly.

 

someone told me that the comp cam guide plates i have on the heads wont work on the 350 anyone have so truth to this

 

cam lift, cam base circle, valve job depth, valve length, head gasket thickness, block deck ht, head milling, lifter used and cup depth in the lifter, etc, etc will ALL effect the geometry and PR length needed. If you change any one of these things, you need to check PR length. Most people are changing most or all of these when doing a head/cam install so checking PR length is a MUST.

PR length is something that you need to check to get the EXACT length. Use an adjustable PR checker and start at 7.100" and adjust the length until you get the wear pattern most centered in the valve. Go .050" shorter and watch the wear pattern move. If it gets worse, go .050 longer. It could be anywhere from 7.00 to 7.250 depending on everything done but a 7.100" (Trik Flow 2417100) is what I suggest for people that do not know how (or do not wanna take the time) to do this.

You can see a detailed description with pics on how to do this here . . .

https://ls1tech.com/forums/generation-iii-internal-engine/327734-cam-guide.html

post # 5 shows it all. Ironically, this info is supposed to be about LS1 engines although the info is usless for LS1's since the valve stem tip and rocker pedestal are fixed and will not move so the PR length for an LS1 only controls the lifter preload. The PR length on an LT1 (or any SB Chevy or other engine with adjustable valve trane) will effect where the rocker tip sits on the valve and how centered the rocker is on the valve and how much side load the guide sees as a result of the wrong/correct length pushrod. You can adjust the lash with rocker adjustment.

The following is a method of verifying proper valve train geometry. After you have estimated the required pushrod length using a Pushrod Length Checker, use this method to verify that the valve train geometry is correct (using the rockers you are using in your engine):



1
The first step is to install a solid lifter and an adjustable pushrod. Mark the tip of the valve with a marker



2
Install your rocker arm and set it up with zero lash.



3
Rotate the crankshaft clockwise several times. Remove the rocker arm. The contact pattern of the rocker tip will be where the marker has been wiped away from the valve tip. The pattern should be centered on the valve tip, and as narrow as possible. If it is not, experiment with varying the pushrod length to yield the best pattern.



4
Pushrod Too Long: Notice how the pattern is wide, and shifted to the exhaust side of the valve tip.



5
Pushrod Too Short: Notice how the pattern is wide, and shifted to the intake side of the valve tip.



6
Pushrod Length Correct: Notice how the pattern is narrow and is centered on the valve tip.

Lloyd

 

ok all check them to get the exact size thanks alot guys

 

No I don't know anything

 

the Comp, Carne, etc guie plates are for standard SB Chevys and the LT1has a slightly different valve spacing that requires a special guide plate.

The Trick Flow 30400623-8 guide plates will work.

Lloyd