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Adam, I feel your pain since I went through this issue about roller cams and the pushrods in 2014 when I completely rebuilt/upgraded my OEM L-82 engine into a 355 with AFR 180 Heads, Howards roller cam (.525 lift/duration 219/225/LSA 110) and 10.2:1 compression. I found most of the advice on the forum conflicting, contradictory, confusing, and bewildering. After much reading on my own, considering forum advice, speaking directly with Howards cam, and consulting with my expert engine builder who did the bottom end of the OEM block, I did the following which has been validated by 4 driving seasons and counting with zero issues:
First off, I did NOT deck my block mostly due to the low mileage, the straightness of the block when checked, and the desire to preserve the block numbers. I did use a .015 head gasket with the AFR heads which is quite a bit thinner than the OEM head gaskets (.040) used on these engines. I bought the comp cams pushrod checker which measures 6.8-7.8? lengths. I did not use checker springs for the measurement, just the AFR springs as installed in the AFR heads. I knew from howards and my builder that the needed pushrod in a gen 1 block with AFR's and roller cam would be somewhere between 7.1-7.3 inches. Howards told me that the lifter preload height would increase by .040-.060 inches when filled with oil and I used that number (I settled on .050 inches) to be added to the pushrod length that gave me what cooper9811 stated earlier:
IMO, the real take-aways should be this: •Get the smallest sweep pattern possible,
•Make sure it's not too close to the valve stem side. I try to keep it in the middle "half" of the stem tip. Scott's approach is a good place to start
I installed the roller lifters and began checking and rechecking with the comp cams roller tipped 1.5 rockers with the comp cams checker tool until when the engine was rotated, the roller ball had the smallest even sweep pattern and did not get too close to either side of the valve stem tip.
I consistently came up with 7.15 inches for the best sweep pattern, added the .050 inch figure from howards for the preload factor and finally ordered 7.2 inch pushrods (7.15+.050=7.2). This year after 4 driving seasons, I checked a few values by removing the roller tipped rockers to sample the wear pattern and miraculously, the roller ball pattern on every valve stem was perfect...tight sweep pattern evenly spaced from the tip of the valve stem. Go figure...............
I can write a whole other paragraph about the roller cam "walking" issue as well....again overcomplicated verbage but relatively easy to address.....
... Howards told me that the lifter preload height would increase by .040-.060 inches when filled with oil and I used that number (I settled on .050 inches) to be added to the pushrod length ... I consistently came up with 7.15 inches for the best sweep pattern, added the .050 inch figure from howards for the preload factor and finally ordered 7.2 inch pushrods (7.15+.050=7.2)...
Thanks for your good write-up jb. This part confused me though. Intuitively I would have subtracted .050" from the measured 7.15" (7.15-.050=7.1) to account for the lifter's expansion.
Thanks for your good write-up jb. This part confused me though. Intuitively I would have subtracted .050" from the measured 7.15" (7.15-.050=7.1) to account for the lifter's expansion.
You are correct...I went back and looked and I actually ordered 7.15 pushrods...The best sweep was with a 7.2 checker so the 7.15 pushrods + the lifter preload with oil actually adds another .050 inches (increases the total pushrod length by .050 inches or requires a pushrod .050 inches shorter than with the checker dry-no oil in lifters) for a total length of 7.2 inches which is what I was looking for....it has worked for me.
My memory transposed the length I was looking to achieve (7.2) and the pushrod that I actually ordered to achieve that (7.15+.050) total pushrod length when oil filled. I do remember talking with the Howards tech and him basically telling me that the lifter preload height oil filled was so very small not to be too concerned with that measurement but I did account for it when I ordered the 7.15 pushrod instead of 7.2 pushrod using the checker on the dry motor.
I went with the theory that my engine is a gen 1 SBC, not a hand built AMG Mercedes motor or even my hand built LS7 in the Z06, and I had a lot of latitude in a street driven sub 6K motor, spending most of its time in the 2,500-4,500 RPM range. I also figured if I was wrong I could eat the pushrods and sell them for a discount on ebay/craigs list....it all worked out perfectly.
Another way of avoiding checker springs is to get a solid version of the lifter you are using, or buy an extra hydraulic lifter and take it apart and put washers inside so it won't compress.
Then subtract the hydraulic lifter preload from the push rod length before ordering.
Another way of avoiding checker springs is to get a solid version of the lifter you are using, or buy an extra hydraulic lifter and take it apart and put washers inside so it won't compress.
Then subtract the hydraulic lifter preload from the push rod length before ordering.
I was really looking to avoid the checker spring procedure and on the advice of my builder, I pressed howards for the pre load lifter height of the lifters with oil. Again, my builder was spot on since he said the pushrod length with a retro roller for the SBC Gen 1 would be 7.1-7.3 inches depending on certain variables like decking, head gasket, head type etc and he also told me that typically the preload height would be .050 inches for the wet lifter. Howards gave me the range of .040-.060 and I went with .050 inches.
I do find it curious that cam manufacturers do not provide the preload lifter height readily to buyers to help avoid some of the checker springs, using solid lifter cams with shims, etc to help the 1 timers doing this procedure. I basically came up with the solution on my own...
I was really looking to avoid the checker spring procedure and on the advice of my builder, I pressed howards for the pre load lifter height of the lifters with oil.
Why would you avoid using checker springs? You can pull the valve spring in less than 10 seconds. If it's to avoid buying a valve spring compressor, than I guess I understand. But is there another reason? You really want to pull the valves anyway to inspect the valve job, check guide clearance and retainer-to-guide clearance. I also think it's the easiest way to check piston-to-valve clearance (valve drop method both before and after TDC).
if you have any kind of stiff valvespring that checker tool will snap if you try and turn the motor over. THey are a few dollars makes it so much easier
If length isnt right it can eat at pushrods but will really wear your guides out in a hurry
Why would you avoid using checker springs? You can pull the valve spring in less than 10 seconds. If it's to avoid buying a valve spring compressor, than I guess I understand. But is there another reason? You really want to pull the valves anyway to inspect the valve job, check guide clearance and retainer-to-guide clearance. I also think it's the easiest way to check piston-to-valve clearance (valve drop method both before and after TDC).
Mostly based on advice and comments on this forum, when I had the AFR's tapped for the OEM temp sending unit, I asked my builder to go thorough the heads to check them. I bought the heads in 2013 and at that time he commented to me that he has rarely found issues with AFR's but he would do as I requested. Know what he found wrong with them? Nothing as I suspected at that time. Now if I was using some lesser brand heads or even today with AFR's, I would have been much more interested in the head checking. Like I said, all has worked out perfectly so far....
BTW- I just checked my AFR install instructions from the heads from 2013 and AFR does NOT mention using checker springs for pushrod length determination, just a pushrod checker tool....with the installed AFR springs.....................which seems to make more sense intuitively since one would figure you would want to get measurements from the actual springs being used during the running of the engine, no?
Mostly based on advice and comments on this forum, when I had the AFR's tapped for the OEM temp sending unit, I asked my builder to go thorough the heads to check them. I bought the heads in 2013 and at that time he commented to me that he has rarely found issues with AFR's but he would do as I requested. Know what he found wrong with them? Nothing as I suspected at that time. Now if I was using some lesser brand heads or even today with AFR's, I would have been much more interested in the head checking. Like I said, all has worked out perfectly so far....
BTW- I just checked my AFR install instructions from the heads from 2013 and AFR does NOT mention using checker springs for pushrod length determination, just a pushrod checker tool....with the installed AFR springs.....................which seems to make more sense intuitively since one would figure you would want to get measurements from the actual springs being used during the running of the engine, no?
Using the actual spring just puts big loads on the pushrod length tool. The tool is just hollow aluminum threaded stock, so it might bend with some decent spring pressure on it. If you feel comfortable that the heads and guides were machined right then you might not have to pull the spring. However, with a new head and cam combo, I always check retainer to guide clearance and PTV clearance using the valve drop method. You must use checking springs for these clearance checks. You can clay the piston, but I feel the valve drop method is better for PTV clearance checks.
It is a better product than the JEGs brand ones you have listed.
Will
Update: I should've listened to rklessdriver and everyone else who said to go with the CompCams checker!
I bought the Jegs $11, but it doesn't work with 5/16" guideplates...!?!?
-The "standard" and by far more common outside diameter pushrod and guideplate size for street SBCs...
Now I have to go buy the CompCams tool anyway.
If anyone wants the Jegs pushrod checker, I'll probably let you have it for free. Just pay shipping.
@#$@#%@%##@!!
Adam
Last edited by NewbVetteGuy; 03-19-2018 at 04:44 PM.
Let me add my voice to the mostly excellent advice you are receiving. You must check pushrod length. You are putting together a unique combination of block, heads, cam, lifter, and head gasket. All of these will change the necessary push rod length. You also must use the checker springs for this as the length checker is not designed to stand up to full spring pressure. Use a dry erase marker to mark the tip of the valve. I tried a felt marker, gear marking compound, and a few other things. The dry erase marker was by far the best. Get a decent valve spring compressor and removing the valve springs is no big deal. As for putting them back in, just put them back with the same end up they came out with, and even that doesn't matter for all springs. I found that when the length was right, the sweep pattern on the tip of the valve was both centered and short. As I shortened or lengthened the pushrod, the pattern moved inboard or outboard and got wider. Here is the pattern I ended up with:
My pushrods worked out to 7.45" with .300" taller lifters and a reduced base circle cam.
Something I haven't seen mentioned here yet is the need to check piston to valve clearance, especially with your 1.6 rockers. Once you get your pushrods, trial assemble the engine (I used an old head gasket), and rotate it through 720 degrees with some modelling clay on the top of the piston. Pull everything apart again and measure the clay.
You also must use the checker springs for this as the length checker is not designed to stand up to full spring pressure.
From a forum member back in 2008:
"As near as I can tell it looks like the pushrod checker is made from a regular Comp Cams pushrod! :-) The feel and weight of it is the same and it even has the oil hole in it! Heavy springs...no problem! I used it with the Comp 921 springs without issue. My only caveat is that the tool should probably not be used when turning the engine over with the starter as it felt like the narrow area (where the two parts of the pushrod separate) catch on the head a bit while traveling up and down in the head."
Neither AFR (in my case) nor comp cams with either the steel checker tool or the checker tool made from an actual pushrod mentions using checker springs when measuring for the correct pushrod length.
From com comp cams website:
"Other companies offer their own versions of pushrod length checking devices, funny little plastic things with complicated instructions to calculate the length." A non comp cams pushrod checker will require checker springs...........
Ok folks, I'll try to repeat back what I THINK I understand.
I KNOW that I need to actually measure the push rod length; I'm going to do that with the Comp checker now that I know the cheapo Jegs won't work with my guides...
I KNOW that I need to measure the valve to piston clearance, especially with my aggressive cam and 1.6 rockers and a total intake valve lift of 0.600" with only 229 @ 0.050" duration (if not a worst-case, a pretty bad one, anyway).
It seems like there's controversy on whether you actually need to use checker springs or not, but no one thinks that using checker springs would be a PROBLEM, right?
(I've already got the stud-mounted valve spring compressor tool and already removed the springs that came with the heads and installed some PAC 1219x Beehives, so I'm comfortable with the process.)
"As near as I can tell it looks like the pushrod checker is made from a regular Comp Cams pushrod! :-) The feel and weight of it is the same and it even has the oil hole in it! Heavy springs...no problem! I used it with the Comp 921 springs without issue. My only caveat is that the tool should probably not be used when turning the engine over with the starter as it felt like the narrow area (where the two parts of the pushrod separate) catch on the head a bit while traveling up and down in the head."
Neither AFR (in my case) nor comp cams with either the steel checker tool or the checker tool made from an actual pushrod mentions using checker springs when measuring for the correct pushrod length.
From com comp cams website:
"Other companies offer their own versions of pushrod length checking devices, funny little plastic things with complicated instructions to calculate the length." A non comp cams pushrod checker will require checker springs...........
On normal street engine builds you really need a checker spring so you won't collapse the hyd lifter and give an inaccurate pushrod length measurement.
If you internally shim up a hyd lifter (so it acts as a solid), or find a solid lifter with the same pushrod seat height, you can use most adjustable pushrod tools with the regular valve springs.... now yes there are some solid roller springs that are too high of a rate and will break these tools but like I said for most street car stuff, it won't be a problem.
On normal street engine builds you really need a checker spring so you won't collapse the hyd lifter and give an inaccurate pushrod length measurement.
If you internally shim up a hyd lifter (so it acts as a solid), or find a solid lifter with the same pushrod seat height, you can use most adjustable pushrod tools with the regular valve springs.... now yes there are some solid roller springs that are too high of a rate and will break these tools but like I said for most street car stuff, it won't be a problem.
Will
I'm struggling with what to do about this particular issue...
I am NOT going to buy a single solid roller version of my hydraulic rollers to do this.
Maybe shimming the hydraulic roller with some washers is the way to go, But...
What if: I use my distributor hole-based oil pump tool and a drill with the trigger on via a zip tie to pump oil into the lifters and use a checker spring while I check for pushrod length? -Is this a good way to go? (Is battery-powered drill RPM going to be enough to pump the lifters with enough oil pressure that they don't bleed down?- I can do 440 RPM or 1,600 RPM with my drill- no idea how much torque it has @ 1,600 RPM....)
My lifters are short-travel and have a slow bleed-down rate, so I have that working in my favor, at least. (The Johnson (now Scorpion) short-travel lifters).
Spring Update: My spring pressures are 145# closed and 350# open.
Adam
Last edited by NewbVetteGuy; 03-20-2018 at 01:30 PM.
10-10-2017, 07:02 PM
