Pushrod help
Pushrod help So I am almost finished building my engine and have to order the last part, pushrods. I have a 1999/2000 5.3 with a comp cams Thumpr cam. I put in LS1 1.7 rockers, LS6 lifters and have had the heads milled 0.015". Comp recommends a 7.400" pushrod with unmilled heads. Subtracting the milled heads comes out to 7.385". I used a comp cams pushrod length checker and came out with 7.325", then i added 0.060" for lifter preload and matched the 7.385". So I am new at this and was wondering if I am right with the numbers. Also do I need specific pushrods besides 5/16 and both ends are balled? Do I have to have the exact 0.060 lifter preload or can i use 0.050" and go with 7.375 pushrods?
Will these work? http://www.summitracing.com/parts/su...s/media/images
Or http://www.jegs.com/i/Edelbrock/350/9646/10002/-1
Will these work? http://www.summitracing.com/parts/su...s/media/images
Or http://www.jegs.com/i/Edelbrock/350/9646/10002/-1
Last edited by RabidStreetRacer; Jan 4, 2013 at 08:35 AM.
So I am almost finished building my engine and have to order the last part, pushrods. I have a 1999/2000 5.3 with a comp cams Thumpr cam. I put in LS1 1.7 rockers, LS6 lifters and have had the heads milled 0.015". Comp recommends a 7.400" pushrod with unmilled heads. Subtracting the milled heads comes out to 7.385". I used a comp cams pushrod length checker and came out with 7.325", then i added 0.060" for lifter preload and matched the 7.385". So I am new at this and was wondering if I am right with the numbers. Also do I need specific pushrods besides 5/16 and both ends are balled? Do I have to have the exact 0.060 lifter preload or can i use 0.050" and go with 7.375 pushrods?
Will these work? http://www.summitracing.com/parts/su...s/media/images
Or http://www.jegs.com/i/Edelbrock/350/9646/10002/-1
Will these work? http://www.summitracing.com/parts/su...s/media/images
Or http://www.jegs.com/i/Edelbrock/350/9646/10002/-1
save yourself some grief and $$$
Order a push rod checker for $20 (ws6store) and get the exact measurement.
I was told that I could use the same length with no problems.....now I'm having to wait for my checker to come in. I just did some work on my heads and threw in LS7 lifters with 7.4" CM PR's now I have noise unlike before.
Order a push rod checker for $20 (ws6store) and get the exact measurement.
I was told that I could use the same length with no problems.....now I'm having to wait for my checker to come in. I just did some work on my heads and threw in LS7 lifters with 7.4" CM PR's now I have noise unlike before.
Ok. I probably would have told you to run a 7.375 length, knowing now you have .075 preload with 7.400s. I shoot for a .040-.060 range myself on builds, but it really depends on the lifter manufacture. You will be fine though.
save yourself some grief and $$$
Order a push rod checker for $20 (ws6store) and get the exact measurement.
I was told that I could use the same length with no problems.....now I'm having to wait for my checker to come in. I just did some work on my heads and threw in LS7 lifters with 7.4" CM PR's now I have noise unlike before.
Order a push rod checker for $20 (ws6store) and get the exact measurement.
I was told that I could use the same length with no problems.....now I'm having to wait for my checker to come in. I just did some work on my heads and threw in LS7 lifters with 7.4" CM PR's now I have noise unlike before.
I'm going to try out the 7.4"s and see if they work. Worse case is i'm out $50. If they don't work I will go with the 7.375's.
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7.385" is the stock length. Throw the originals back in there and see how it runs and how quiet it is. Go from there. Just don't go crazy with the motor while they are in there.
I would also recommend 11/32" OD pushrods rather than 5/16".
I would also recommend 11/32" OD pushrods rather than 5/16".
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I went with everyone telling me stock were 7.380-7.385 and that 7.400 were longer than stock. Wasn't true. They were .003 different. Ended up needing 7.425. Just be careful with everyones advice
I measured them tip to tip with a caliper. Granted, I know this is not gauge length, but the 7.400 measured exactly the same as my stock rods and everyone said the stocks are shorter than the 7.400. Not the case
That measurement is OAL and not valid due to differences in end chamfer, wall thickness, etc. of any two given pushrods. I have measured several stock pushrod sets using gauge length and they all came out at 7.385". Even the parts houses like TSP will tell you the same, the 7.400" myth started with that being the aftermarket cam replacement part used to make up for the smaller diameter base circle on the cam.
That measurement is OAL and not valid due to differences in end chamfer, wall thickness, etc. of any two given pushrods. I have measured several stock pushrod sets using gauge length and they all came out at 7.385". Even the parts houses like TSP will tell you the same, the 7.400" myth started with that being the aftermarket cam replacement part used to make up for the smaller diameter base circle on the cam.
That's the point. I can take two identical pushrods of the exact same guage length and then bore a larger hole in one and the overall length measurement will indicate it is much shorter even though the gauge length has not changed.
