Pushrod priority
In our July RET-Monitor, we looked at Terry Manton’s projected use of a copper-hybrid pushrod adjuster tip to aid NHRA Pro Stock runners in the Full Throttle Drag Racing Series. Manton Pushrods, of Lake Elsinore, California tested the initial product with Warren and Kurt Johnson, and then took the new pushrod unit to Joliet to see if anyone else was interested.
The upshot? Fourteen Pro Stock drivers – some fulltime, others who run the category on a part-time basis – are using the product to great affect. “Nobody has contacted us with any problems so far; not one of them has worn out the pushrod yet!
Normally, Pro Stock racers swap out their pushrods after 15 runs at the most, but there have been zero reports of wear to the pushrod or to the adjuster to date.
The problem with keeping oil flowing through the pushrod is due, in part, to the fact that Pro Stock engines normally use “0” weight oil. “Their oil is very thin and that has a lot to do with it. There is no cushion built in,” Manton told me.
The new pushrod adjuster insert material is a copper blend without beryllium using a high iron content and has to be cut with carbide, Manton said.
The bottom of the tip’s cavity has to be flat, as does the insert, in order to spread out properly on the tip. Tolerances are very, very tight, according to Manton, citing a normal tolerance of 0.0006.
Cost of the pushrod tube and its adjuster tip go up incrementally with this new product, thanks to a three-time increase in production effort to make the unit. While the tooling and machinery are the same, the new tip is more time consuming and more difficult to make, giving it a 35 percent price increase.
At this point, Manton is still experimenting with his new product “Since the original design, we have modified the adjuster tip twice and now have both radiused and V-cut tips available to our clients. As for who is using which ones, Manton is not about to divulge.
Larry Morgan, currently running a Mopar engine, figures he might be happy with the new adjuster on the new Ford Pro Stock mill he is about to start building up. “Our cams are so big we cut off the oil to the adjusters on the pushrod ends, so Terry’s copper insert is making a big difference,” Morgan said. “His insert has a bigger radius” to keep oil flowing through the pushrod.
While he believes the new pushrod insert could be a better product, Morgan is still using his older pushrods. “I fixed my problem without having to go to the newer pushrod end. We found with a stiff valvetrain, we can use a stiffer pushrod as a tuning tool. We control the life of the cam with the pushrod.”
Working with the older specification pushrod, Morgan has concentrated on his cam profile to get more power up high. “It has been a trial-and-error procedure because the camshaft profile has to be changed to get a more accommodating and stiffer valvetrain” that can last a significant period of time.
Manton expects his pushrod with the copper blend adjuster tip insert to increase both longevity and durability. No doubt, should it perform as expected – and once he settles on a distinct specification after experimentation – it will become the standard of the Pro Stock industry.
Written by Anne Proffit.