Sorry, I know that there are a ton of posts on general stuff. I have AFR 225's (old casting) ported by TEA to 237's. I have Yella Terra Ultralights. I've shimmed the rockers .047 to correct rocker wipe. My comp pushrod checker measures 7.462 at zero lash with #1 at TDC. My lifters are comp oe replacement hydrollic roller lifters.

Questions:

1) What is the recommended preload for these lifters? .075? .060? .040? ???
2) With .075 preload, my pushrod length would be 7.537. Isn't that way long? Where can I get a pushrod of this length?
3) The largest standard pushrod I've seen is 7.5. This would give me .038 preload. Isn't this too little?

Thanks - Daniel

 

i was told :
take one rocker that had the valve closed and the cam is not closing and not opening and tourq it down to 22 lbs/tq if you can tq it 1 ring and 1/2 then you are in good range if you only can go 1 1/4 then your pushrod is .025" too long to be in range, if you can take it 1 3/4 then you are .025" too short from good range.

but i don´t know if that is the sam whith the yellow´s

but the funny thing is i have 7.700 and harland sharp and thought i needed shorter rods because i milled the heads down .035" and swapped to ls7 lifters, but that only got me in perfect range....
but i had valve noise before and that stopped, so it tells me that i must have been running to short pushrods before...

good luck

 

They are not too long, however you may want to increase the diameter with this length. ETP heads required pushrods longer then that. You may want to run a set of 11/32" pushrods from Terry Manton who will make them to any custom length and the cost is about the same as standard Comp pushrods. Trend also stocks 5/16"-0.080 wall in 0.025" length increments (they make most aftermarket pushrods including Comp).

I am running 7.475 pushrods with AFR heads and Morel lifters which require less preload and are longer. If I were running LS7 lifters my length would be around 7.550".

Bottom line, trust your measurement not internet theory.

 

I still can't find any info on suggested preload for the comp oe lifters. Anyone?

 

Recommended preload for those is the same as stock LS1 .055"-.085". I would run a larger dia. 11/32" or 3/8" 7.525" or I can have the EXACT lenghth Manton pushrod made for you. If you want 7.517" I can get them. I wouldn't worry about being that picky but that is an option. Let me know if you need a set. I can normally have Mantons shipped out next day.

Thanks,
Shane

 

Shane,

If you could order me a set of larger diameter 7.525 I would really appreciate it! Feel free to contact me via PM and let me know how to take care of payment! Thanks again!

 

PM Sent

 

Will 3/8" straight pushrods go in those AFR's? I was told no and went with 3/8-5/16 double taper that did clear.

 

does anyone out there have a reason why to use bigger pushrods like 11/32 or 3/8...I see alot of recommendations just wondering what caused this change to the larger size...

if I can keep the size/weight down on my TFS I want to... thanks

 

PM Sent back Shane.

That is a good point about weight with the valvetrain. Minimal weight would be ideal I would think. Do you suppose RPM or cam lift is the biggest determining factor?

 

Weight on the lifter side doesn't matter nearly as much as the valve side. However, stiffness does matter (pushrods that is ) and you want to keep pushrod flex to a minimum. The way to increase stiffness is with outside diameter, thickness doesn't buy much here. My only question is the 3/8" as I was told they wouldn't fit in the AFR's without machining. Since my heads were on the car I went with a double tapered pushrod. You can read about them here: Link

 

My opinion on larger pushrods is this.Dont need them.We ran 5/16 by 9 inches long in a pontiac that rev to 8.000 rpm with no sign of flex.Solid roller 250lbs seat and 700 open!Trend has pushrods in any length,as said above.

 

So verdict is don't go with bigger pushrods?

 

I understand the weight issue and it is not as big a factor on the pushrod side...I also completely get flex is alot more controled with a larger o.d. vs thickness but what causes this new theory that these bigger pushrods were needed...is there a post or link with good technical data...

 

unless there is further data I am going to stick with the 5/16....

 

Bottom line, your car your choice. Do a search on spintron testing of the LS1. Pushrod flex will not show up on the dyno or how the car drives. Consult some engine builders and make your choice.

 

I'm thinking that given my setup is a fun weekend car that will never see the track, I'm not going to be as concerned with the slight added weight for the pushrods vs. the peace of mind.

 

did some searching couldn't find anything that showed the 5/16 .080 wall chromoly pushrods were getting flex...anyone have a good find on this...

 

The subject of pushrod flex is not something you're going to read about on the internet. This is something we've studied during spintron testing of cam lobes and valvesprings. Sometimes, in certain rare occasions, pushrod flex is actually desireable with a poor lobe design, this is by far the exception rather than the rule. That being said, real world spintron and dyno testing has shown a signifigant increase in power and valvetrain stability using better, stronger, stiffer pushrods. This also gives an added benefit of longer valvespring life. I will normally run the biggest diameter pushrod I can for any application. The weight of the pushrod is almost inconsequential compared to the weight of components on the valve side of the rocker. The added stiffness will more than make up for the small increase in mass on the lifter side of the rocker.

I guess this may be one other reason I see so many lifter and valvespring failure stories here but have rarely seen them in my experience building engines professionally for over 10 years and as a hobby for 15 before that. I've had the privelege of working with and listening to some of the greatest head porters, engine builders, and valvetrain specialists in world over the last few years. I will tell you, the information is out there for those willing to listen. You won't find many individuals willing to share this information. I'm not trying to sell anyone pushrods here. I'd be glad to give you the info to buy them directly from Manton. I am really just trying to spread some good information to help your engine make more power and stay together longer

Shane

 

thanks that is a great response...