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914World.com _ 914World Garage _ Stock Push Rod Length
Posted by: R Dub Mar 14 2019, 01:14 PM
Can anyone verify what the stock push rod length is for these cars?
From my research the stock length is 271mm and the stock part# 021-109-301-A. I ordered 2 of these to replace the 2 bent ones that I have. I have no history of what push rods were in my motor so I just assumed they were stock but it doesn't appear that way as my 2 new ones are about 1/4" longer than what was in there. Just want to verify before I go buy 6 more stock rods.
Posted by: Highland Mar 14 2019, 03:12 PM
I just measured two of mine and get 275.6 mm and 275.9 mm.
So just under a 1/4" longer than yours.
Do you have your actual pushrod lengths?
Posted by: R Dub Mar 14 2019, 03:30 PM
I just measured two of mine and get 275.6 mm and 275.9 mm.
So just under a 1/4" longer than yours.
Do you have your actual pushrod lengths?
The car is back at my parents but my dad measured one that came out of the motor and said it was 10.25 inches so about 260mm.
Posted by: Highland Mar 14 2019, 03:56 PM
Forgot to mention aircooled.net sells custom cut aluminum pushrods assembled.
Do you have the rebuild history on the motor? Someone may have installed custom length pushrods to achieve correct valve geometry.
Posted by: mgphoto Mar 14 2019, 06:57 PM
Post a couple of photos of both.
Posted by: rudedude Mar 14 2019, 07:49 PM
I'm sure there are many used stock pushrods around if you ask. i probably have 5 sets that i don't know why I'm saving.
Posted by: bdstone914 Mar 15 2019, 03:14 AM
Do you have a solid or hydraulic lifter engine?
You need to measure one of your non bent pushrods.
You may have custom lenght rods which is commom depending on how the engine was built.
Posted by: R Dub Mar 15 2019, 11:46 AM
Post a couple of photos of both.
Will do once I can get back there to snap a pick of the ones that were in it.
Do you have a solid or hydraulic lifter engine?
You need to measure one of your non bent pushrods.
You may have custom lenght rods which is commom depending on how the engine was built.
It had a hydraulic lifters in it. I am switching over to solid based on the advise of this forum.
Posted by: 914sgofast2 Mar 15 2019, 12:20 PM
You need to replace all your pushrods if you are converting from hydraulic to solid lifters. Solid lifters need the aluminum pushrods while the hydraulic lifters use steel pushrods.
Posted by: Mark Henry Mar 15 2019, 02:13 PM
Post a couple of photos of both.
Will do once I can get back there to snap a pick of the ones that were in it.
Do you have a solid or hydraulic lifter engine?
You need to measure one of your non bent pushrods.
You may have custom lenght rods which is commom depending on how the engine was built.
It had a hydraulic lifters in it. I am switching over to solid based on the advise of this forum.
You can't just switch out the lifters, you have to change the cam as well.
Hydraulic cam has a different profile than the stock FI cam, and there also was mild performance hydraulic carb cams.
Posted by: R Dub Mar 16 2019, 06:18 PM
You can't just switch out the lifters, you have to change the cam as well.
Hydraulic cam has a different profile than the stock FI cam, and there also was mild performance hydraulic carb cams.
Yeah I have a new Web cam grind #86 with new solid lifters and a new cam gear on the way. I'm hoping that the stock push rods will work with this cam and the heads. Will have to check once I get the cam in and the heads back from Adrian at Headflow Masters
Posted by: R Dub Mar 17 2019, 09:38 AM
Here's a picture of the different ones. Hopefully you can see how much bigger in diameter the new one is.
http://s582.photobucket.com/user/rwdirtbike/media/Porsche/0317191033.jpg.html
Posted by: Mark Henry Mar 18 2019, 05:57 AM
You can't just switch out the lifters, you have to change the cam as well.
Hydraulic cam has a different profile than the stock FI cam, and there also was mild performance hydraulic carb cams.
Yeah I have a new Web cam grind #86 with new solid lifters and a new cam gear on the way. I'm hoping that the stock push rods will work with this cam and the heads. Will have to check once I get the cam in and the heads back from Adrian at Headflow Masters
Web cam grind #86 is a mild carb cam, much like the Scat C25, but it still requires HD single springs, Manton Cr-Mo steel cut to length PR, 1.7 modified rockers and 911 adjusters. The HD springs can bend the aluimum PR.
Posted by: brant Mar 18 2019, 09:50 AM
if you are changing the cam and lifters...
a full rebuild then....
you really need to measure and cut the correct length of push rods to take full advantage of the valve train/cam geometry
this is a precise measurement
the length of the pushrod effects the ratio of the rocker and how much valve lift you will get from the cam. skipping this step means you likely have too much or more likely too little lift. You essentially do not get the performance out of your cam lobes and could of just left the hydraulic cam alone if you don't perform this necessary step.
you need to read the articles on measuring push rods.
you will need an adjustable push rod to take measurements and then
transfer that measurement to your new pushrods to cut them to the correct lengths
you need a dial indicator, a mounting base, a timing wheel, an a large set of calipers to go longer than a push rod
this is a 4-8 hour job that is completed during re-assembly
you should also have already purchased the correct 1.7 rockers with the correct swivel feet. Modify the rockers to accept the swivel feet
do it right
its time and money, but a motor rebuild is no place to cut corners.
someone here can likely loan you some tools, or walk you through the process.
there are good tech articles, including Jakes that can help
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