The rocker arms on my 455 Buick are on shafts and don’t adjust like this Chevy but I think the info you have provided will still hold true… I’m gonna see what I can figure out… thanks for the info.
But when you set your lifter preload this would change where the rocker arm lands would it not? So how do you achieve proper rocker arm geometry with a certain amount of preload. And how do you even find the correct lifter preload?
hi , i have a question , i have a 87/95 sbc tbi engine , with the tbi swirly heads , what would cause my valve spring retainer to be busted , i took the valve cover off and found that , i bought the engine from a guy used out of a chevy truck , i just want to go back stock , what all do i need to change , thanks
Maybe just get a piece of dowel wood and cut it exactly to lifter length with a divot in top to hold pushrod. Then it will be exactly to running lifter length
How about if one use lifters with different seat height? I was thinking of buying a crower lifter but it has a seat height of 1.7”. My original lifters have 2.02”. Would that mean I would need .302” longer pushrods?
Yes seat seat height of the lifter will change the push rod height. Once you have all your parts get your self a comp cams adjustable pushrod and see what your specific setup needs for length
I just watch to see what he was saying, vice grip us a cool guy! Good advice especially when you are going to be far off from stock length, most of the time its not needed to do the mid lift check like that. I will be touching base on more pushrod and valve train fun in a upcoming video series! Should be fun! Cheers!
I'm a little confused. If the hydraulic lifter compresses doesn't this throw everything off significantly? I would expect the rocker to be off center of the stem, shifted towards carb side, with the lifter fully compressed during opening and closing. How do you make your flat tappet hydraulic lifter "solid" in order to better facilitate measuring for the correct rod length?
Very good point, I talk about that around the 3 min mark in the video. You can take a spare or junk lifter (exactly the same size) remove the snap ring and fill it full of shims or washers to make it a solid lifter. (Or use a solid lifter that's exactly the same size) You can also put a very light valve spring in the head. But what I find with a lower lift cam, with weak valve springs.. you usually can just roll it over as it is. Or prime the engine before you spin the engine over to put some oil in the lifters. Another thing you can do is just color in the top of the valve at TDC set your lash and wiggle the rocker (dont roll it over) pull the rocker off see how centered the pattern is at the top of the valve. You can usually tell if your pushrods are close without even rolling the motor over
@@cuttersperformance Ahhh...right on man! Pump the lifter up by priming the engine prior to doing this measurement. Then I would be testing my exact configuration. Got it. Thank you so much for the quick reply and several good options.
Great video man. I did the same measurement for pushrod length, except I turned the nut 1/2 turn more for preload. The rocker is hitting the center of the valve tip. My pushrod length came to 7.700. Is this correct?
TDC is not accurate enough for any significantly over stock type of camshaft. The EOIC method is required to ensure that you are on the base circle for doing pushrod length checking. It is best to just use EOIC all the time. You do not get an accurate valve stem pattern by testing with the stock valve spring tension and collapsing the lifter.
I like using one peice comp cams push rods Stock length with a oe roller cam is 7.200 inches but you will have to check the length on your setup Cheers!
I prefer the comp cams 7808-16 push rods myself, especially for running a 1.6 rocker, stock length is 7.195 and the 7808's are 7.205 which gives you the little extra length for the 1.6 rockers!! Comp Cams 7808 are also a quality hardened steel
I don't mean to pop any bubbles or anything, but the comment about the pushrod having a little extra length for the 1.6 rockers, isn't necessarily needed just because it's a 1.6 rocker. While this may be true in this specific case, it may not be in another case. In other words just because it's a 1.6 rocker, doesn't mean the pushrod should be longer. There are so many individual things that affect push rod length. Engine block deck height, cylinder head deck height , cylinder head deck height to rocker arm mount height (all of this can be different depending on overall design from each manufacturer, whether milled, etc etc. The camshaft grind, the lift, duration, ramp rating, etc affects it's base circle, which in turn can affect needed pushrod length. The base circle can also affect the needed lifter length. Not to mention, that the lifters themselves can be different from manufacturer to manufacturer, & can be with the actual rocker arm, where the ratio may be the same but the actual pushrod "seat" on the different rocker arms, can be different, & so affect pushrod length. In other words, if everything else is exactly the same, except for changing only the rocker arms, & with using the same ratio, the pushrod length could be different. All of this is why checking pushrod length is so important, & should be done with any new build, or when changing anything that can affect the valve train.
like this method aren't you wiping the grease of the lobes because youre turning the engine over? I could be wrong about this. Can't you just put the cam and lifters in the block with engine oil and then messure the push rods(you can rotate the engine as many times as you want). if you have the wright pushrod lenghth than you can take the cam and lifters back out and remove the oil and then put the grease on the lobes and lifters and install everything back so you didn't have wiped the lube of the lobes. just thinking. thanks for youre good explention and vids
This was just a cam swap so I never had the heads off but my guess would be that the block deck height/ head deck height is the reason for needing longer push rods. But the cam, lifters, valve tips, rocker arms, head gaskets, block and heads are factors in changing the pushing rod length. Always check....never guess! Let me know of you have any more questions
No mostly just throws off all the geometry and the rocker rides off the tip of the valve. But I guess its possible if it was excessively long and the rocker arm pivot bottomed out
I don't get everyone talking about using a lifter that might not have anything to do with the height of the new lifter you are going to run. What I did was get the zero lash, then adjusted the the push rod to almost bottomed out lifter (new lifters never pumped up). Then measured the amount from the start to where it ended . My lifter collapses near .200 from zero lash , but then you have to factor lifter preload, which will be .030 for my lifter. So I get the right pattern and then subtract .170 (in my case) from the push rod tool that has the correct pattern. If you have a engine that was ran you would have to verify the lifter was bleed down for this to give accurate results. I have a dual pattern cam so checked both intake and exhaust one cylinder from both banks. If you want to be really anal check every one, because who knows if every valve is at the same correct height, or every lifter bottoms out exactly the same, or is exactly the same length. Uneven block deck height, or uneven heads, ect. In all reality close enough is probably good enough if the rockers have roller tips. There is some great info on youtube if you have a full roller rocker arm, but there is no way to find one of the two pivot points on many other examples like on a ball and falcrum rocker to the best of my knowledge. If you had springs light enough that the lifter would not collapse after zero lash, I don't know you would see the pattern show up on the valve tip with a roller tip. I would try it and report back, but I only will if the springs I use to check piston to valve clearance are good enough, which I doubt will be. That is just going to be enough to keep the valve closed and work against a dial indicator.
I just thought I would add my first approach to how far the lifter would collapse didn't meet what was observed when it was placed under 300 pounds of pressure vs my trying to push it in by hand and trying to record the measurement with a caliper. The push rod tool by nature Should deflect far more from zero lash than a real solid push rod would, at least in my case. Where was the error, I don't know, and I'm not sure the results are really going to make a difference anyway with anything other than solid lifters
The important thing is to make sure you have a lifter with the same cup height when using a solid lifter for checking patterns. I have a roller lifter that I shimmed to .050 under the clip that I use to check my oe roller cams. Works great! And I don't have to swap springs on the head to check the pattern There's many ways to check pushrod length and they are all right as long as you get the same answer haha
Thats with the lifter collapsed .050 and pumped with oil Ideally you want a very light valve spring so when you turn it over the lifter doesn't push the oil out at all But realistically the stock length would be fine for this mostly stock engine. That engine is actually coming apart now becuase he wants vortec heads and a lumpy cam! 😂 So we shall see what size push rods it will need now?
Right, but with that spring on there your just collapsing the lifter and getting a wrong reading, usually unless the heads have been milled or block have been decked with stock sized lifters the push rod will stay the same length, but it's actually better to slightly favor the lower section of the valve stem slightly due to the angle
Very good point, I talk about that around the 3 min mark in the video. You can take a spare lifter (exactly the same size) remove the snap ring and fill it full of shims or washers to make it a solid lifter. (Or use a solid lifter that's exactly the same size) You can also put a very light valve spring in the head. But what I find with a lower lift cam, with weak valve springs.. you usually can just roll it over as it is. Or prime the engine before you spin the engine over to put some oil in the lifters. Another thing you can do is just color in the top of the valve at TDC set your lash and wiggle the rocker (dont roll it over) pull the rocker off see how centered the pattern is at the top of the valve. You can usually tell if your pushrods are close without even rolling the motor over
Question. My roller cam sbc engine is assembled already. The rockers are very close to the intake side of the valve stem. No where near center. Seems the machine shop did a poor job at choosing pushrod length. Question is, what’s the best way to test for correct length on assembled heads? I have an adjustable pushrod. On the last engine I used the light valve spring, added length for .030 lifter preload, and .015 for head gasket. Had a good center patten on valve. Then when I assembled actual valve springs and head gasket the pushrods were way off. Not sure what happened there. Just looking for some advice. Thanks!
@@cuttersperformance You should have a solid lifter same length as a hydraulic lifter checking geometry, the hydraulic lifter collapes when running it through the cam lift checking the pattern? you dont get full rocker arm travel.
@@cuttersperformance ok, on small block chevys it is probably more commen to have to run .050 longer pushrods than shorter? Bigger cams and more lift the base circle is smaller and small base circle cams would need longer rods?
@Jesse Syfie yeah base circle often causes a longer push rod, but the most common for a larger push rod is aftermarket cylinder heads. Often requiring a +.100 longer
That's not a 100 % with a hydraulic lifter going down all the way on max lift u are not getting the full cam lift? Need a mechanical lifter to check it?
What pushrods lenght u use on a 98 vortec 880 block with the lt4 hot cam with the 15 thou shim gel pro gaskets heads been milled 10 Thou so right now I’m having issues trying to figure out my pushrod length
Btw I went 1.6 rollers and guide plates and 7/16th screw in studs with the hex shaft had to cut the stud bosses down what size pushrods do u use with that block and that cam cause I know ur running that lt4 hot cam
Авто/Мото
thanks, all the other examples are roller rockers, i needed this video :)
❤ that was so perfectly said and showed how too do it. Very nice my friend. Thank you.
Thanks for that video it helped me visualize what I was being told by other people
Excellent video ,thanks for sharing
Keep rolling out the vortec videos!
Great video! Thanks!
The rocker arms on my 455 Buick are on shafts and don’t adjust like this Chevy but I think the info you have provided will still hold true… I’m gonna see what I can figure out… thanks for the info.
Great video. 👍
Nice video, very informative
Nice angle view of illustration
Gracias amigo
Thanks for the video! Due, you got alot of crickets! LOL
But when you set your lifter preload this would change where the rocker arm lands would it not? So how do you achieve proper rocker arm geometry with a certain amount of preload. And how do you even find the correct lifter preload?
hi , i have a question , i have a 87/95 sbc tbi engine , with the tbi swirly heads , what would cause my valve spring retainer to be busted , i took the valve cover off and found that , i bought the engine from a guy used out of a chevy truck , i just want to go back stock , what all do i need to change , thanks
How wide should the contact patch be?
Maybe just get a piece of dowel wood and cut it exactly to lifter length with a divot in top to hold pushrod. Then it will be exactly to running lifter length
I told my wife that too short is better then too long and she laughed at me.....
How about if one use lifters with different seat height? I was thinking of buying a crower lifter but it has a seat height of 1.7”. My original lifters have 2.02”. Would that mean I would need .302” longer pushrods?
Yes seat seat height of the lifter will change the push rod height.
Once you have all your parts get your self a comp cams adjustable pushrod and see what your specific setup needs for length
Any input on visegrip garages current big block build and his advice on pushrod length?
I just watch to see what he was saying, vice grip us a cool guy!
Good advice especially when you are going to be far off from stock length, most of the time its not needed to do the mid lift check like that.
I will be touching base on more pushrod and valve train fun in a upcoming video series! Should be fun!
Cheers!
Man you are definitely dialed in. Thanks for the feed back. 👍🏻
I'm a little confused. If the hydraulic lifter compresses doesn't this throw everything off significantly? I would expect the rocker to be off center of the stem, shifted towards carb side, with the lifter fully compressed during opening and closing. How do you make your flat tappet hydraulic lifter "solid" in order to better facilitate measuring for the correct rod length?
Very good point, I talk about that around the 3 min mark in the video.
You can take a spare or junk lifter (exactly the same size) remove the snap ring and fill it full of shims or washers to make it a solid lifter. (Or use a solid lifter that's exactly the same size)
You can also put a very light valve spring in the head.
But what I find with a lower lift cam, with weak valve springs.. you usually can just roll it over as it is.
Or prime the engine before you spin the engine over to put some oil in the lifters.
Another thing you can do is just color in the top of the valve at TDC set your lash and wiggle the rocker (dont roll it over) pull the rocker off see how centered the pattern is at the top of the valve. You can usually tell if your pushrods are close without even rolling the motor over
@@cuttersperformance Ahhh...right on man! Pump the lifter up by priming the engine prior to doing this measurement. Then I would be testing my exact configuration. Got it. Thank you so much for the quick reply and several good options.
@@dennis6325 No problem!
Use a solid lifter to check length
So do you need to check each valve or will they all be the same after you measure one like you did here?
You can check everyone, but usually, I just check one in/ex on each bank. They should be the same
Great video man. I did the same measurement for pushrod length, except I turned the nut 1/2 turn more for preload. The rocker is hitting the center of the valve tip. My pushrod length came to 7.700. Is this correct?
TDC is not accurate enough for any significantly over stock type of camshaft. The EOIC method is required to ensure that you are on the base circle for doing pushrod length checking. It is best to just use EOIC all the time.
You do not get an accurate valve stem pattern by testing with the stock valve spring tension and collapsing the lifter.
Which pushrods would you recommend with a lt4 hotcam on a 1997 chevy 5.7 vortec and with 1.6 rocker arms
I like using one peice comp cams push rods
Stock length with a oe roller cam is 7.200 inches but you will have to check the length on your setup
Cheers!
I prefer the comp cams 7808-16 push rods myself, especially for running a 1.6 rocker, stock length is 7.195 and the 7808's are 7.205 which gives you the little extra length for the 1.6 rockers!! Comp Cams 7808 are also a quality hardened steel
I don't mean to pop any bubbles or anything, but the comment about the pushrod having a little extra length for the 1.6 rockers, isn't necessarily needed just because it's a 1.6 rocker. While this may be true in this specific case, it may not be in another case. In other words just because it's a 1.6 rocker, doesn't mean the pushrod should be longer. There are so many individual things that affect push rod length. Engine block deck height, cylinder head deck height , cylinder head deck height to rocker arm mount height (all of this can be different depending on overall design from each manufacturer, whether milled, etc etc. The camshaft grind, the lift, duration, ramp rating, etc affects it's base circle, which in turn can affect needed pushrod length. The base circle can also affect the needed lifter length. Not to mention, that the lifters themselves can be different from manufacturer to manufacturer, & can be with the actual rocker arm, where the ratio may be the same but the actual pushrod "seat" on the different rocker arms, can be different, & so affect pushrod length. In other words, if everything else is exactly the same, except for changing only the rocker arms, & with using the same ratio, the pushrod length could be different. All of this is why checking pushrod length is so important, & should be done with any new build, or when changing anything that can affect the valve train.
like this method aren't you wiping the grease of the lobes because youre turning the engine over?
I could be wrong about this.
Can't you just put the cam and lifters in the block with engine oil and then messure the push rods(you can rotate the engine as many times as you want).
if you have the wright pushrod lenghth than you can take the cam and lifters back out and remove the oil and then put the grease on the lobes and lifters and install everything back so you didn't have wiped the lube of the lobes. just thinking.
thanks for youre good explention and vids
I like your thinking but you'll do the same thing when setting the valve lash. The grease wont completely wipe off the lobe
What do you think caused this motor not to be able to use stock length push rods?
This was just a cam swap so I never had the heads off but my guess would be that the block deck height/ head deck height is the reason for needing longer push rods.
But the cam, lifters, valve tips, rocker arms, head gaskets, block and heads are factors in changing the pushing rod length.
Always check....never guess!
Let me know of you have any more questions
Most aftermarket cams require a slightly longer pushrod
If a push rod is to long will it bend when engine is turned over?
No mostly just throws off all the geometry and the rocker rides off the tip of the valve. But I guess its possible if it was excessively long and the rocker arm pivot bottomed out
One point - if you used a stock rod at 7.8 and the adjustable only
maxes out at 7.8?? Did you use another push rod checker?
You can get a little extra out of that one but they also sell longer ones
Which Comp Cam tool would you recommend for stock ish length push rods pt# 7702 ( 6.8 - 7.8 " ), or 7703 ( 7.8 - 8.8" )
I don't get everyone talking about using a lifter that might not have anything to do with the height of the new lifter you are going to run. What I did was get the zero lash, then adjusted the the push rod to almost bottomed out lifter (new lifters never pumped up). Then measured the amount from the start to where it ended . My lifter collapses near .200 from zero lash , but then you have to factor lifter preload, which will be .030 for my lifter. So I get the right pattern and then subtract .170 (in my case) from the push rod tool that has the correct pattern. If you have a engine that was ran you would have to verify the lifter was bleed down for this to give accurate results. I have a dual pattern cam so checked both intake and exhaust one cylinder from both banks. If you want to be really anal check every one, because who knows if every valve is at the same correct height, or every lifter bottoms out exactly the same, or is exactly the same length. Uneven block deck height, or uneven heads, ect. In all reality close enough is probably good enough if the rockers have roller tips. There is some great info on youtube if you have a full roller rocker arm, but there is no way to find one of the two pivot points on many other examples like on a ball and falcrum rocker to the best of my knowledge. If you had springs light enough that the lifter would not collapse after zero lash, I don't know you would see the pattern show up on the valve tip with a roller tip. I would try it and report back, but I only will if the springs I use to check piston to valve clearance are good enough, which I doubt will be. That is just going to be enough to keep the valve closed and work against a dial indicator.
I just thought I would add my first approach to how far the lifter would collapse didn't meet what was observed when it was placed under 300 pounds of pressure vs my trying to push it in by hand and trying to record the measurement with a caliper. The push rod tool by nature Should deflect far more from zero lash than a real solid push rod would, at least in my case. Where was the error, I don't know, and I'm not sure the results are really going to make a difference anyway with anything other than solid lifters
The important thing is to make sure you have a lifter with the same cup height when using a solid lifter for checking patterns.
I have a roller lifter that I shimmed to .050 under the clip that I use to check my oe roller cams. Works great! And I don't have to swap springs on the head to check the pattern
There's many ways to check pushrod length and they are all right as long as you get the same answer haha
Can you buy new pushrods in +.- lengths ?
Yeah in typically .050 increments
But if the lifter is collapsing the .50 allowance, then you should still be at stock length of the 7.8 push rod?
Thats with the lifter collapsed .050 and pumped with oil
Ideally you want a very light valve spring so when you turn it over the lifter doesn't push the oil out at all
But realistically the stock length would be fine for this mostly stock engine.
That engine is actually coming apart now becuase he wants vortec heads and a lumpy cam! 😂
So we shall see what size push rods it will need now?
Right, but with that spring on there your just collapsing the lifter and getting a wrong reading, usually unless the heads have been milled or block have been decked with stock sized lifters the push rod will stay the same length, but it's actually better to slightly favor the lower section of the valve stem slightly due to the angle
Very good point, I talk about that around the 3 min mark in the video.
You can take a spare lifter (exactly the same size) remove the snap ring and fill it full of shims or washers to make it a solid lifter. (Or use a solid lifter that's exactly the same size)
You can also put a very light valve spring in the head.
But what I find with a lower lift cam, with weak valve springs.. you usually can just roll it over as it is.
Or prime the engine before you spin the engine over to put some oil in the lifters.
Another thing you can do is just color in the top of the valve at TDC set your lash and wiggle the rocker (dont roll it over) pull the rocker off see how centered the pattern is at the top of the valve. You can usually tell if your pushrods are close without even rolling the motor over
Question. My roller cam sbc engine is assembled already. The rockers are very close to the intake side of the valve stem. No where near center. Seems the machine shop did a poor job at choosing pushrod length. Question is, what’s the best way to test for correct length on assembled heads? I have an adjustable pushrod. On the last engine I used the light valve spring, added length for .030 lifter preload, and .015 for head gasket. Had a good center patten on valve. Then when I assembled actual valve springs and head gasket the pushrods were way off. Not sure what happened there. Just looking for some advice. Thanks!
Its a 87+ roller block? What heads? And do you know what length is in it now?
@@cuttersperformance Yes. 89 block. The roller top rocker is almost on the edge of the valve tip towards intake side. Not sure the length now.
@@cuttersperformance heads are ATK aluminum, cast by Profiler.
@@cuttersperformance 7.200” length.
@@cuttersperformance If I just eyeball the rockers centered on valve stem, at zero lash, add .050 for lifter preload they are measuring 7.450”.
Did you get my last comment?
Not sure? What was it?
@@cuttersperformance You should have a solid lifter same length as a hydraulic lifter checking geometry, the hydraulic lifter collapes when running it through the cam lift checking the pattern? you dont get full rocker arm travel.
Yeah I think i talk about that in the video. My roller lifters I have ones i shim solid
@@cuttersperformance ok, on small block chevys it is probably more commen to have to run .050 longer pushrods than shorter? Bigger cams and more lift the base circle is smaller and small base circle cams would need longer rods?
@Jesse Syfie yeah base circle often causes a longer push rod, but the most common for a larger push rod is aftermarket cylinder heads. Often requiring a +.100 longer
That's not a 100 % with a hydraulic lifter going down all the way on max lift u are not getting the full cam lift? Need a mechanical lifter to check it?
What pushrods lenght u use on a 98 vortec 880 block with the lt4 hot cam with the 15 thou shim gel pro gaskets heads been milled 10 Thou so right now I’m having issues trying to figure out my pushrod length
Btw I went 1.6 rollers and guide plates and 7/16th screw in studs with the hex shaft had to cut the stud bosses down what size pushrods do u use with that block and that cam cause I know ur running that lt4 hot cam
As long as everything was done correctly with the rocker studs the push rod length should be right around the stock length of 7.200.