I'm an old school hot rodder who has never given much thought to pushrod length checking. I've always bought a cam with it's corresponding kit and never checked the lengths. I have noticed there are more & more people doing it now so I decided to check the pushrods in my '85. My engine is now a 383, I swapped late '86 aluminum heads on it and bought 1.6 roller rockers to enhance the VERY mild Comp Cam I installed. I was completely amazed to find that my puhrods which came with the cam & kit were .3 in. too long! That's 3/10ths of an inch and a very noticeable difference. I don't know what kind of difference the new pushrods will make, they will be here today. I will get them installed and let you all know what I find.
This is just a heads up to the importance of checking your pushrod length when modding your engine, it really is a very important step. You younger builders are going to say, "well no ****!" but this is aimed at old dogs like me and novice rodders who are just learning.

 

Good advise!

 

Even if you want to do it the cheap way. Color in a couple valve stems completely with a sharpie and run the motor over a few times. If the wear band is not in the middle then it may be time to look at a pushrod length checker to get custom pushrods.

 

I agree, mine are a 1/4" shorter than stock, on my 355. I was surprized how much shorter I needed. Decking, shaving heads and valve train parts, can up up to quite a difference.

 

UPDATE
Got the new, shorter pushrods installed today, all I can say is....
WOW!!! I have no idea how many ponies I found but the sotp dyno was VERY impressed. Well worth the little trouble it takes to be sure.

 

very nice ! this is often overlooked !
we have a problem because me and a friend thought we used the same pushrods
but we were wrong !

Here's the deal ...i have AFR #1040 Heads (65cc) and im using 7.200 pushrods
this is the way they look :




My friend,with a set of 75cc AFR Heads (1038) thinking fast , ordered
the same pushrods i did...to his surprise ...it ended up lookin like this :



Today i got confirmation that he needs 7.300 !
But my friend was too hurry and ordered the 7.200 , big mistake !

Picture proof !

 

I'm glad your car is running well, but I don't think there is any horsepower increase with proper length pushrods vs wrong length pushrods unless your length is so far off that the rockers are falling off the valvestems. The advantage with the correct length is you will be able to rev higher and your guides will last longer because of less sideloading. Nonetheless, enjoy the ride.

 

And if your valves were falling off the side...

Either way, good job.

Calderone, were the block decks the same? Same gasket, that all could skew things too.

 

You may very well be right, I sure don't have any solid proof that it made the engine stronger. All I can say is that something I did quieted down a valvtrain I have been trying to quiet down for a long time and my tired old *** dyno knew something had happened for the better.

 

Might have better lash this time. If they were too noise before they could have been too loose and basically taking duration off the cam. Slight but perhaps.

 

How do I determine correct pushrod length?

The cam, lifters, head gaskets and heads are all in place that you plan to use. Starting on the base circle of the cam you need to adjust your "Adjustable Checking Pushrod" out, including your lash settings (at the valve), or preload on the lifter (generally .030" - .060"). Make sure the rocker tip never rides off the tip of the valve, favoring the center of the valve through its travel. For longevity on your guides and seals you are looking for the shortest sweep across the valve tip. For increased performance, you want the pushrod side of the rocker tilted back with the roller tip of the rocker off center towards the intake side of the engine. Also you will want at least .040" clearance between the edge of the retainer and the under side of the rocker.

Pushrod Length

This has to be one of the most asked questions ever. If you are putting together a new motor or just changing a set of cam and lifters, guess what? If you changed everything else in the motor don't you think you might want to see if the pushrods you have will work with your combination? Heads/cam/rocker/lifters, etc! Any one of these pieces can and will change your rocker arm geometry which leaves you with pushrod length as your only adjustment. So after you have every other piece (except your pushrods) get a set of Adjustable Checking Pushrods. Or, make them! This is the only way you can acurately find the length that will work and make the best power for your combination!


http://cranecams.com/?show=faq&id=6

 

I tried everything from 1/2 to 3/4 turn after zero lash and the result was always the same. I'm new to checking pushrod length but have been adjusting rockers correctly for many years. I used to run nothing but solid lifter cams. You have a valid point though for novices to consider.

Right on and the rockers are in exactly the position you describe for best performance with clearance all around the rocker, retainer, stud base.