Question about checking pushrod length
Thread Starter
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
I'll defer to the experts on that question. I call the cam companies to get recommendations and then plug their suggestions into a desktop dyno program to see what the result looks like. Then, I call the same company again two or three times, on different days and different times of day to try to see how many answers I get and see how they compare, and try again using Comp Cam's free download software. I usually end up picking a little milder than average unless the DD simulations suggest there's a strong advantage and nothing significant lost by bumping up a bit.
With a flat tappet cam, I'd search all the car forums I could find for either a good used set of comp pro magnum full roller rocker arms, their roller tip rockers, or Crane gold roller rocker arms. Stay away from any other brand if you go roller tip, but many companies make good full roller rockers- find some you like and post up to see if anyone has had trouble with them. I'd avoid CAT and the Chinese ones on ePay.
If the timing set was a good name brand, it will be fine. Cloyes stock replacement timing chains will outlive most performance builds, to tell you the truth. Beehives are great so long as you get the right ones for your cam.
EDIT: The springs in that kit don't look like beehives, but that doesn't mean they won't be fine. It's not a radical cam.
With a flat tappet cam, I'd search all the car forums I could find for either a good used set of comp pro magnum full roller rocker arms, their roller tip rockers, or Crane gold roller rocker arms. Stay away from any other brand if you go roller tip, but many companies make good full roller rockers- find some you like and post up to see if anyone has had trouble with them. I'd avoid CAT and the Chinese ones on ePay.
If the timing set was a good name brand, it will be fine. Cloyes stock replacement timing chains will outlive most performance builds, to tell you the truth. Beehives are great so long as you get the right ones for your cam.
EDIT: The springs in that kit don't look like beehives, but that doesn't mean they won't be fine. It's not a radical cam.
I looked up the valvespring part number on Comp Cams website, and it's a beehive spring, the picture isn't of the literal k-kit in question, just a stock photo of one.
Scott
Thread Starter
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
The pushrods only come in 0.050" increments, and it's unlikely you'll be all that far off so long as you measure to confirm you'll be in the ballpark. You're running hydraulic lifters anyway, so there's some variation in effective length on each stroke of the lifter anyway. On a street engine, if you're off .050" it likely won't hurt much, but if you're off 1/4" your valve guides will take a beating. SBC guides aren't exactly known for longevity anyway. Measuring all of them isn't a bad idea, but you will end up buying pushrods of all the same length anyway.
Scott
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Only u can decide how much u can spend on rocker arms.
I am beginning to think that since my project is going to involve new cam, lifters, pushrods, valves, springs, retainers, locks, heads, timing chain and sprockets, pretty much every single piece of the valvetrain except the rocker arms, I might as well just get new rocker arms, too. What the hell, right? Any recommendations for new stamped steel rockers, good quality to price ratio?
Scott
Scott
Myself for a mild street engine i would go with a stamped roller tip like crane or some other name brand (Elgin?). I don't know who or ProForm parts are made but they sell inexpensive (cheap) roller tip rockers too.
But u didn't post your cam lift or rpm range so its good luck to u then.
Good night Scotty,
cardo0
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
I would not agree that being .050 isn't going to matter - if it was .050 longer, I'd agree - .050 shorter, no way. The issue isn't just the side load on the guides. It's better to be a fair bit longer than even the slightest bit shorter.
Measure one cylinder, easy to do on the car with the right tools, and order one set of custom. They come in increments, but custom pushrods are available...but generally not used. Often the stock ones work fine...but we still check.
I generally don't check valve-to-piston clearance until the lift gets up around .480 or so. You'll definitely need to check ALL the other clearances - rocker-to-stud, etc.
Finally, I'm not a big fan of full rollers on the street. They're not really a daily-driver item - they're a race-only item. People do run them, but it's a waste of money.
Measure one cylinder, easy to do on the car with the right tools, and order one set of custom. They come in increments, but custom pushrods are available...but generally not used. Often the stock ones work fine...but we still check.
I generally don't check valve-to-piston clearance until the lift gets up around .480 or so. You'll definitely need to check ALL the other clearances - rocker-to-stud, etc.
Finally, I'm not a big fan of full rollers on the street. They're not really a daily-driver item - they're a race-only item. People do run them, but it's a waste of money.
Pro
Joined: Jul 2005
Posts: 517
Likes: 7
From: Peoria IL
I would not agree that being .050 isn't going to matter - if it was .050 longer, I'd agree - .050 shorter, no way. The issue isn't just the side load on the guides. It's better to be a fair bit longer than even the slightest bit shorter.
Measure one cylinder, easy to do on the car with the right tools, and order one set of custom. They come in increments, but custom pushrods are available...but generally not used. Often the stock ones work fine...but we still check.
I generally don't check valve-to-piston clearance until the lift gets up around .480 or so. You'll definitely need to check ALL the other clearances - rocker-to-stud, etc.
Finally, I'm not a big fan of full rollers on the street. They're not really a daily-driver item - they're a race-only item. People do run them, but it's a waste of money.
Measure one cylinder, easy to do on the car with the right tools, and order one set of custom. They come in increments, but custom pushrods are available...but generally not used. Often the stock ones work fine...but we still check.
I generally don't check valve-to-piston clearance until the lift gets up around .480 or so. You'll definitely need to check ALL the other clearances - rocker-to-stud, etc.
Finally, I'm not a big fan of full rollers on the street. They're not really a daily-driver item - they're a race-only item. People do run them, but it's a waste of money.
I take your knowledge as gospel. What would you run on a street hydraulic roller in the 0.540-0.550" lift range? I'm squeamish about full rollers on the street but so many of the alternatives look like they are also fraught with risk.
I've stuck with old Pro-Magnum rollers because I had no confidence in stamped stock rockers when 300# over the nose/ 450 lbs through the pushrod forces were being applied even at 5500 RPM when they have been known to split open on some stock applications.
Your thoughts?
Burning Brakes
Joined: Jan 2007
Posts: 1,057
Likes: 4
From: Concord Calif
Ideally pushrod length should be such that the tip of the rocker passes across the center of the valve stem twice during its travel...when the valve is either fully open or fully closed the rocker tip should be toward the inside of the valve stem; when the valve is halfway open the rocker tip should be toward the outside of the valve stem. Set your checking pushrod to whatever length gives you this geometry, making sure that there is no retainer-to-rocker contact when closed. Obtain 16 pushrods of this exact length and you should be OK.
Pro
Joined: Jul 2005
Posts: 517
Likes: 7
From: Peoria IL
Not looking to create problems for all to understand, but the rocker needs to be in the middle of the valve stem at 50% lift! In this fashion the rocker starts out on one side and moves to the other side of the stem in equal amounts, think about it, don't agree watch your rocker movement while turnning the engine by hand and it will be clear why you put the contact point in the middle of the stem at 50% lift!
I position the valve at 1/2 lift. There are probably dozens of ways to do this, but I do it with a valvespring height mic set to installed height less 1/2 full lift travel. Either way, I put the valve in this position, install the rocker arm and hold the roller against the valve stem tip and hold it up against a poly lock installed on the stud. I then adjust the lock until the roller is centered on the valve stem tip. Lock the poly lock into place.
Next I remove the valve stem locks, retainer, reinstall the valve spring, retainer and lock. Make sure the lifter is on the cam's base circle by rotating the engine by hand. When I'm working on the intake valve, I rotate the engine until the exhaust lifter is just starting to open. If you're working on the exhaust valve, rotate until the intake lifter has fully opened and is almost closed.
With the valve spring installed the valve is sure to be fully closed, and the lifter is on the base circle, so I slip in the adjustable length pushrod and find the minimum overall length. I round up to the next readily available length increment and record the value. Next, I do the same thing on the adjacent valve (exhaust if I just did the intake, or the intake if I just did the exhaust).
In my case, the block has almost always been zero decked, so block height is very uniform. With new (aftermarket) heads, the valves are usually in almost exactly the same position, but it's smart to check at least the four corners of the engine (eight valves, I&E on cylinders 1, 2, 7, 8). There isn't usually much variation- within .020" or so, well within what a street hydraulic lifter can handle. I take an average of these and round up to the next readily commercially available .050" increment, then place my order.
This might not be the best or perfect method, but right or wrong that's how I do it until someone "sets me straight". Who knows, maybe it's all wrong- if so, please educate me!
