Pushrod length madness

[Irishman999]

Gen VI big block with the regular Gen V heads, its got a aftermarket cam with .510 lift. I have already converted it to adjustable rocker studs, for the rockers I went with summit brand (exact same as scorpion rockers) aluminum roller tip rockers that are 1.7 ratio. Lifters are comp cams 900 series hydraulic roller.

I got the comp cams master push rod length checker kit, the ones that have a line you watch as you lengthen the push rod. Each full rotation is aparantly .050 of an inch.

I had to make a dummy lifter out of a lifter and some epoxy. First attempt was a ******* disaster. I finally got a dummy lifter made but the epoxy set up before I could set a .050 preload on it. I figured I would just add one turn to whatever readings the pushrod tools tell me.

So my wife and I got after it, we did everything how you are supposed too according to the internet. We confirmed our readings were right over and over again to double check, I even twisted the pushrod checker tool out a few turns to confirm the test works and it did work.

I went to order some good 3/8's pushrods at my custom lengths and could not find anything in 3/8's. They offered 3/8's pushrods but the lengths were not close to what I need. I somehow ended up on the page with my cam and lifter specs, never noticed the link to their pushrods designed for the cam lifter kit.

The lengths were close enough to my recordings to make me second guess my measuring so I gambled 40 bucks and ordered them. My plan is to spin up the oiling system and rotate the engine a few times to make sure the lifters all get filled with oil. After that I was going to pull the plugs, install a couple of the push rods and crank the motor over a few times with the starter. With the magic marker on the valve top trick it should tell me if they will work, in theory.

I am open to any advice on this, tell me what you guys think. Biggest thing I am confused about is the fact comp cams sells pushrods specifically to go with their cam/lifter kit. They are close to my readings but still different.

 

[gpmorgan]

Not sure what your solution is going to be but with the valve lash set, I'm assuming it's zero lash being "hyd" roller lifters, I would make sure the valve geometry is correct since you are using roller tip rockers. Have you checked it with one of the hyd roller lifters installed?

 

[Irishman999]

Not sure what your solution is going to be but with the valve lash set, I'm assuming it's zero lash being "hyd" roller lifters, I would make sure the valve geometry is correct since you are using roller tip rockers. Have you checked it with one of the hyd roller lifters installed?

The boxes showed up and the pushrods are wrong, I never even tried. 3/8's is way fatter than my guide plates will allow, the lengths seem off comparing them to my checkers so I am going to try and mail them back and order custom ones.

I was told to check it with my dummy lifter I made, I was instructed to epoxy the plunger to the body with .050 preload. So far the only checking I have done is with the dummy lifter I made, I think I know what you are getting at. Next test is to actually pump everything up with oil and spin it over a few times to see what happens. I suspect that hydraulic lifters are a little more spongy than expected.

 

[SlickGTP]

I know for my Gen IV I had to rob my 427 that had aftermarket guide plates so I could fit the larger diameter pushrods on the 454. Game plan is to buy another set or modify my existing guide plates when and if I ever get around to putting the 427 back together.

 

[bucket]

The length is probably a little different than your readings because they accommodate different head types and I'm assuming yours have been milled too. And why not just get guide plates for 3/8 pushrods?

 

[Irishman999]

The length is probably a little different than your readings because they accommodate different head types and I'm assuming yours have been milled too. And why not just get guide plates for 3/8 pushrods?

Talking pushrod length, they are way off in length. You brought something up I forgot to consider, heads did get milled at at one point the block has been milled and that combined equals some turns on the pushrod checkers. Throw into that mix the fact I switched to stud type adjustable rocker studs and the aftermarket aluminum rockers and its no wonder everything is way off.

I figured out how to order the right length ones, 8 of them are in the mail and the other 8 are on back order. Only thing that can be wrong at this point is my measuring, which I checked multiple times.

 

[gpmorgan]

Did you end up checking the length with the lifters installed? I think the best way to get the length would be to install the new lifters on one cyl (int & ext). From here you would have to experiment with different settings of the push rod to give you the best valve geometry with the valve lash set. Of coarse the valve lash would have to be set after every change in the push rod. It might be a little time consuming but in the end I think you could expect good results. It's pretty important to have good valve geometry when using roller tip or full roller rockers. If this is done correctly you can expect to heve longevity also, and to me, that's the most important factor.

 

[Irishman999]

Did you end up checking the length with the lifters installed? I think the best way to get the length would be to install the new lifters on one cyl (int & ext). From here you would have to experiment with different settings of the push rod to give you the best valve geometry with the valve lash set. Of coarse the valve lash would have to be set after every change in the push rod. It might be a little time consuming but in the end I think you could expect good results. It's pretty important to have good valve geometry when using roller tip or full roller rockers. If this is done correctly you can expect to heve longevity also, and to me, that's the most important factor.

I checked the length on cylinder 1 intake and exhaust using the sold dummy lifter I made with epoxy. I added the .050 to what I measured for the lash in the lifter, they are actually a tiny bit longer. As soon as I have the new custom pushrods I am going to pump up the oil pressure and crank the motor a few times and pull the rockers to see if they are showing the right length. I am almost positive they will be correct.

 

[gpmorgan]

Sounds like a good plan. Let me know how it comes out. My next project will probably be a big block. I'd like try my luck at a 540. Got to gather up some cash, parts, and do some research. Hopefully in a year or so. I've got a pretty strong little 355 that I put together about 7 or 8 years ago. It's still running good for now.

 

[Irishman999]

Sounds like a good plan. Let me know how it comes out. My next project will probably be a big block. I'd like try my luck at a 540. Got to gather up some cash, parts, and do some research. Hopefully in a year or so. I've got a pretty strong little 355 that I put together about 7 or 8 years ago. It's still running good for now.

Keep your eyes peeled for a Gen VI block, that will put you way ahead of the game. Look for anything Dave Vizard published about the big block, the one you need is about making big horsepower with a big block. Thats the one I have.

If these pushrods do the trick my next update should be a video of it running. Oil pressure was excellent, that means tolerances are good to go. I triple checked the mains and rod caps so everything should stay together. With the spark plugs in and no push rods its almost impossible to turn the engine over so I know its got compression. I had Jims86 rebuild the throttle body and it looks like a very quality rebuild so I have no concerns about that.

Only hurdle left is the fuel lines, finding a hard line is going to be a pain in the ass so its gonna have to be AN fittings and braided stainless hose. Really, its the little things that kill you on stuff like this.

 

[bucket]

Keep your eyes peeled for a Gen VI block, that will put you way ahead of the game. Look for anything Dave Vizard published about the big block, the one you need is about making big horsepower with a big block. Thats the one I have.

If these pushrods do the trick my next update should be a video of it running. Oil pressure was excellent, that means tolerances are good to go. I triple checked the mains and rod caps so everything should stay together. With the spark plugs in and no push rods its almost impossible to turn the engine over so I know its got compression. I had Jims86 rebuild the throttle body and it looks like a very quality rebuild so I have no concerns about that.

Only hurdle left is the fuel lines, finding a hard line is going to be a pain in the ass so its gonna have to be AN fittings and braided stainless hose. Really, its the little things that kill you on stuff like this.

What hard lines are you looking for? The ones to the TB? I have a set I think, at least the engine half of them.

 

[Irishman999]

What hard lines are you looking for? The ones to the TB? I have a set I think, at least the engine half of them.

those are them, are they the same between big block and small block?

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