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Push Rod Length
I am going to place my order tomorrow morning for my heads and pushrods. My question is, I am getting the Trick Flow Specialties 23 Degree heads with the 1.25" valves, can I use Comp Cams part no. 7812-16 pushrods with these heads? I already have these pushrods but didn`t think anything about pushrod length when I was buying these. I also have the Comp Cams 1.52 Roller Tip Rockers and an XE-262 Cam. Does this sound like everything will work. If any more info is needed I will gladly prvide. Thanks.
Generally speaking, pushrods are one of the last things you buy. After assembling the rotating assembly and heads, you put a few of your "old" pushrods in and use them as a guage for whether you need longer or shorter rods, or the standard length is still ok.
If you already have the pushrods, either send them back and wait until you've got the engine reassembled, or try them when you do. Longer/shorter pushrods aren't much longer or shorter (0.030 or 0.060 inches), so there's generally no way to tell if they'll fit until after you're reassembled.
Eddie can you clarify on the (1.25 valves) ? Is this a 350 motor or a 383 with small base circle cam?About the heads.Do they have the stock lenght valves?Did you have the block decked?
Eddie,
I went to the Trick Flow site.Quick math tells me you will need a + .150 long pushrod.You cannot in my opinion get any closer than this unless you cut your own to lenght.Still though proper checking is needed.Might wind up needing just a .100 long.Any way though the stock 7.800 pushrod will not work.
Something else caught my eye.When ordering specify you want the 1.260 valve springs.You need this for cam life.
I went to the Trick Flow site.Quick math tells me you will need a + .150 long pushrod.You cannot in my opinion get any closer than this unless you cut your own to lenght.Still though proper checking is needed.Might wind up needing just a .100 long.Any way though the stock 7.800 pushrod will not work.
Mountain...how did you calculate +.150? TFS recommends a -.050 (7.75) pushrod for that cam/rocker combo. I use stock 7.80 pushrods and my valvetrain geometry is perfect & my motor runs like a beast so with all due respect, IMHO the stock pushrods WILL work.
Mark,
My quick math was too quick.A stock lenght pushrod is 7.800.They are calling for a 7.850 with a STD hydraulic cam.That is a .050 longer pushrod right there.Then the fact that the XE cam lobe base circle is smaller than conventional say,Crane or Shneider for example adds even more needed lenght.To determine that the base circle would have to be measured.Still only getting close due to decking and milling variables.They need checked for sure.
Eddie,
Sorry about the quick math thing. A +.050 long pushrod will be what you need in my opinion.Still,check upon assembly.But if you are not going to use an adjustable pushrod on assembly,this will be very close to start and will probably work in the end as well.That is the key part of this post.
When ordering the heads though,ask if the std lenght valve is used.Many these days are setting up the higher end heads with +.100 long valves in anticipation of the use of a roller cam with a small base circle.
if you are using roller tip rockers ferrys head service sell a tool that uses a dial indcator to check for push rod length. 214-286-6199. cost less that $75.00. best tool i have ever used :chevy