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Username Post: push rod length        (Topic#192686)
george88gta 
"10th Year" Silver Supporting Member
Posts: 1764
george88gta
Loc: new york
Reg: 04-23-03
06-24-08 11:13 AM - Post#1463062    

In the process of installing new aluminum heads on my 350. It originally had a flat tappet cam and the head builder sent me .100" longer push rods to compensate for the larger deck height. I am switching over to a roller cam. The stock roller lifter push rods are 7.122" long. I have only found ( so far) 7.200" and 7.250" push rods. Is it worth getting a solid roller and an adjustable push rod to verify correct length or just use one of the two available? Cam kit came with matching rocker arms and valve springs.

 
55chevy383 
Silver Supporting Member
Posts: 1306
55chevy383
Age: 46
Loc: Noble, Ok.
Reg: 12-08-05
06-24-08 12:37 PM - Post#1463124    
    In response to george88gta

Absolutely 100% check for correct length! Any good cam company cam make you a set of pushrods to the length you supply them. I wouldn't guess at the correct length or settle for what's available. Just my .02 worth.

Phil
11.66 @ 115 N/A.
Phil's '55


 
Tommy518 
Contributor
Posts: 371
Tommy518
Reg: 01-20-03
06-24-08 01:52 PM - Post#1463198    
    In response to george88gta

Would these be ProComp heads by chance? I just installed a set of ProComps and they suggested the same change in length of pushrod. I'm also running a roller cam with retro roller lifters and need to lengthen my pushrods. I'll be interested to know what size you settle on.

Good luck.
'69 Camaro 396 SS-RS, TCI 4-link, Tremec 5-sp, Ford 9", 10pt-cage, etc...


 
MikeB 
Senior Member
Posts: 9479
MikeB
Loc: Plano, TX
Reg: 08-28-03
06-24-08 01:58 PM - Post#1463208    
    In response to george88gta

Have you thought about using one of your hydraulic lifters and a checking spring? There's not enough force to make a witness mark on the valve stem tip, but you can eyeball the roller tip-to-stem contact (or use a magnifying glass) to adjust the pushrod to the correct length. The goods news is there also isn't enough pressure to compress the lifter plunger.

CompCams P/N 4758-2

Real Hot Rods have a Clutch!

1955 210 2dr: 327, Brodix IK180 heads, Jones cam, M20, Wilwood front brakes

1982 C-10 SWB pickup, 250 six, 3-speed

My car pictures



 
george88gta 
"10th Year" Silver Supporting Member
Posts: 1764
george88gta
Loc: new york
Reg: 04-23-03
06-24-08 03:37 PM - Post#1463297    
    In response to Tommy518

Yes, same heads. I have found several tools for checking the pushrod length. I plan to stop by my friends machine shop next week and see what method/tools he has and if he will let me borrow them. Looks like I will need an adjustable pushrod as a minimum. Dont have the cam installed yet and havent ordered the lifters, so I have time for research. I like that CompCam spring idea, no stress on the valve train.

 
mnblaster 
Member
Posts: 36

Reg: 04-26-04
06-24-08 03:55 PM - Post#1463315    
    In response to george88gta

I used this method with a Comp Cams adjustable mic-style pushrod, no need to buy springs and take lifters apart.

http://www.carcraft.com/techarticles/116_0401 _sett...

 
george88gta 
"10th Year" Silver Supporting Member
Posts: 1764
george88gta
Loc: new york
Reg: 04-23-03
06-25-08 04:22 AM - Post#1463625    
    In response to mnblaster

I bookmarked this article, very helpful. Thanks. Looks like I will have to see what my buddy has and if he cant help then I will start with an adjustable pushrod. Thanks for the help guys.

 
MikeB 
Senior Member
Posts: 9479
MikeB
Loc: Plano, TX
Reg: 08-28-03
06-25-08 02:02 PM - Post#1463979    
    In response to george88gta

  • george88gta Said:
I bookmarked this article, very helpful. Thanks. Looks like I will have to see what my buddy has and if he cant help then I will start with an adjustable pushrod. Thanks for the help guys.


George, how does that method keep a hydraulic lifter from compressing? Am I missing something?
Real Hot Rods have a Clutch!

1955 210 2dr: 327, Brodix IK180 heads, Jones cam, M20, Wilwood front brakes

1982 C-10 SWB pickup, 250 six, 3-speed

My car pictures



 
george88gta 
"10th Year" Silver Supporting Member
Posts: 1764
george88gta
Loc: new york
Reg: 04-23-03
06-25-08 02:23 PM - Post#1463992    
    In response to MikeB

Mike, I reread the article. As I read the process, you "place" the rocker arm back in to position and do not perform the adjustment ( tighten adjusting nut until drag on the pushrod) this process seems to not compress the roller piston to its mid-point. This begs the question, "does compressing the piston to its midpoint have no effect on valve train geometry?". I checked with Edelbrock today, their heads also have the +.100 pushrod requirement. They state that if you are using a "full roller rocker arm" just use the 7.200" pushrod. That confuses me, what difference does the type of rocker make? I plan to get an adjustable pushrod and do it the right way.

 
greg_moreira 
Very Senior Member
Posts: 3264

Reg: 10-06-03
06-25-08 03:09 PM - Post#1464017    
    In response to george88gta

you are correct that there is possibility of compressing the lifter with this method giving a false reading. The method itself is sound...but I dont like the possibility of compressing a lifter. So......

A few ways to combat this. One, use a solid lifter cause its definitley not going to compress. However....youve got to be sure to measure and make SURE there is no difference in lifter height as well as the depth of the pushrod cup/holder compared to the hydralic lifter you are going to use.

If there is a difference...you need to factor that difference in when doing your final calculation.

Another way....use an old hydraulic lifter, but take it apart and modify it so that it wont compress. Effectively, you are using the solid lifter method now...but it might be more convenient just in case you dont have a true solid lifter anywhere to try it out with.

Lastly.....using a very light checking valve spring. This will help keep from compressing the lifter any, giving an accurate reading. But, its also my least favorite method.

Id just prefer one of the previously mentioned methods with a solid type lifter of the same measurements using ALL of the exact same components that will be used when the motor is truly run to guarantee nothing happens with the lifter.

Edited by greg_moreira on 06-25-08 03:12 PM. Reason for edit: No reason given.

 
motorman 
Dedicated Enthusiast
Posts: 5176

Loc: south western pa.
Reg: 01-25-00
06-25-08 08:11 PM - Post#1464260    
    In response to george88gta

the best push rod length checking tool ever made for use with roller tipped rocker was made by "ferry's aluminum cylinder head & block repair" dallas texas. if anyone has a march 1995 hot rod magazine go to page 158 to see this tool.
retired race engine builder,former NASCAR tech inspector. new corvettes owned 1959,1962,1963,1964,1965, 1966,1997,1999,2002,2005, 2008 plus 30+ other chevy cars and trucks along the way. 2008 corvette sold and waiting on a C-7.


 
motorman 
Dedicated Enthusiast
Posts: 5176

Loc: south western pa.
Reg: 01-25-00
06-26-08 09:27 AM - Post#1464612    
    In response to motorman

i have my instruction sheet for this tool and if someone wants to post it here i can e mail it to them.
retired race engine builder,former NASCAR tech inspector. new corvettes owned 1959,1962,1963,1964,1965, 1966,1997,1999,2002,2005, 2008 plus 30+ other chevy cars and trucks along the way. 2008 corvette sold and waiting on a C-7.


 
fcsallan 
Newbie
Posts: 62

Age: 48
Loc: Port Saint Lucie FL
Reg: 10-13-07
06-26-08 12:05 PM - Post#1464748    
    In response to motorman

I can post it for you if you wish.
fcsallan@comcast.net

 
motorman 
Dedicated Enthusiast
Posts: 5176

Loc: south western pa.
Reg: 01-25-00
06-26-08 12:26 PM - Post#1464762    
    In response to fcsallan

i will send it off,thanks
retired race engine builder,former NASCAR tech inspector. new corvettes owned 1959,1962,1963,1964,1965, 1966,1997,1999,2002,2005, 2008 plus 30+ other chevy cars and trucks along the way. 2008 corvette sold and waiting on a C-7.


 
fcsallan 
Newbie
Posts: 62

Age: 48
Loc: Port Saint Lucie FL
Reg: 10-13-07
06-26-08 12:52 PM - Post#1464778    
    In response to motorman

Lets see if this works


Direct link to image

 
motorman 
Dedicated Enthusiast
Posts: 5176

Loc: south western pa.
Reg: 01-25-00
06-27-08 05:01 AM - Post#1465239    
    In response to fcsallan

thanks for posting and ZOOM to +200 to be able to read.
retired race engine builder,former NASCAR tech inspector. new corvettes owned 1959,1962,1963,1964,1965, 1966,1997,1999,2002,2005, 2008 plus 30+ other chevy cars and trucks along the way. 2008 corvette sold and waiting on a C-7.


 
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