7/16 pushrods using new RB Trick Flow heads

[pwtjr]

Getting ready to mock things up and get some pushrods ordered and on their way. Anybody running a 7/16 pushrod using the Trick Flow heads? Sure looks like there is some extra room using my adjustable 3/8 pushrod.

I am running a 286HR from Comp and their hydraulic roller lifters. My bench racing buddy says the 7/16 would be overkill, but I figured if they will fit and I have to buy a set anyway, why not. I am assuming a 7/16 thin wall would be better than a 3/8 heavy wall?
He also said the pushrods don't need to 'oil thru' because my Hughes 1.6 rockers will provide sufficient lubrication to everything up top. Is there any additional benefit to buy oil thru pushrods on a big block hydraulic roller cam application?
The reason I ask is because the engine I am rebuilding had a solid flat tappet cam and Isky iron adjustable rockers. The old pushrods I took out had a hole at the lifter end, but the cup up top was solid???

 

[Jackpot50]

Make sure you mock up with heads and push rods in place. With the roller hyd lifters they put the push rods at a different angle and heads may have to be clearenced to clear. I used 3/8" rods and had to grind clearence in head on 440 source aluminum Stealth heads

 

[Budnicks]

IMO
7/16'' is overkill unless your running 700#'s of spring pressure
& a 0.750" or more aggressive solid roller, also the extra weight in the
valve-train doesn't help either...
I had 3/8" even on that set up too, proper thickness & materials
make a world of differences

Contact Smith Bros. Pushrods they won't steer you wrong...

 

[bobtile]

...

 

[pwtjr]

lol, okay sounds like the added expense of 7/16 would be a waste of money for a hydraulic roller camshaft.
Thanks for the input gentlemen.

 

[66Satellite47]

I ran 7/16 thick pushrods in my 452 low deck, 690 roller cam. I was running over 7000 RPM all the time. Strong pushrods be good. I'm sure good 3/8 are fine.

 

[IQ52]

IMO
7/16'' is overkill unless your running 700#'s of spring pressure
& a 0.750" or more aggressive solid roller, also the extra weight in the
valve-train doesn't help either...
I had 3/8" even on that set up too, proper thickness & materials
make a world of differences

Contact Smith Bros. Pushrods they won't steer you wrong...

Budnicks and I agree on almost everything but we diverge somewhat here. Some of my recent studies are sending me to the largest diameter heaviest wall pushrods I can reasonably afford for my engine builds. It seems that extra weight on that side of the rocker arm doesn't seem to matter and the stronger pushrods help in valve train stability.

I too have had excellent service and results from Smith Brothers.

 

[pwtjr]

Budnicks and I agree on almost everything but we diverge somewhat here. Some of my recent studies are sending me to the largest diameter heaviest wall pushrods I can reasonably afford for my engine builds. It seems that extra weight on that side of the rocker arm doesn't seem to matter and the stronger pushrods help in valve train stability.

I too have had excellent service and results from Smith Brothers.

Thanks IQ.
This is what I have read and been told lately. I know I am not going to be running crazy spring pressure with this hydraulic roller (PAC 420 per inch) and my shift points will likely be around 6500 give or take, but my thoughts are if the 7/16 diameter pushrods will fit, why not buy them now and run them? The weight on that side is not nearly as critical as the weight on the other side of the rocker.
I have a solid flat tappet, a solid roller, and a hydraulic roller lifter sitting in front of me right now. There is definitely some heft to these hyd roller lifters compared to the other two. I am thinking the hydraulic design will limit RPM potential ofcourse, but not entirely because of its extra weight... more so because of the limits of its internals. This does not concern me. I chose to go hydraulic roller because I never really planned on spinning this stock block 440 much over 6500 anyway. I also envision the hydraulic setup being easier on the valvetrain components compared to the solid setups with lash. Do you agree with this line of thinking?
One big advantage I think the solid roller has going for it is that a guy could physically keep a better eye on things during routine valve adjustments. If you were to detect some extra lash, it would encourage one to investigate why. This could possibly prevent a big problem with say a roller lifter getting loose. With the hydraulic rollers, you may not get a good warning until there is bigger problem, often times after some sort of damage is already being done, like a lifter getting sloppy down by the wheel and axles. Once again, do you agree with this line of thinking?
I have often wondered what are the pushrods on a typical mildly built V8 ACTUALLY DOING at a pretty high rpm? I would think they do some funky stuff personally. This is why I posed the question initially.
Thanks for your input IQ52. I have followed many threads on here, and I value your opinion greatly. I know the guy with the GTX you just built the Trick Flow headed 440 for is in for a big smile the first time he unleashes that street brawler you built for him.

 

[pwtjr]

Budnicks and I agree on almost everything but we diverge somewhat here. Some of my recent studies are sending me to the largest diameter heaviest wall pushrods I can reasonably afford for my engine builds. It seems that extra weight on that side of the rocker arm doesn't seem to matter and the stronger pushrods help in valve train stability.

I too have had excellent service and results from Smith Brothers.

So... should I ante up for the 7/16 if they fit? Also, this may be elementary but do I need to buy oil through pushrods or not? My guess is "not" but once again, I value your opinion greatly. No one else has commented on this part of my original question... maybe they think I'm dumb, lol.

I appreciate all the time you guys, and gals, take to help other people out. I often catch myself saying I wish I was born of a different era. I like old stuff, I like old people (easy, Im 40 myself), I think the world was a better place 50 years ago, but then I realize how technology enhances our lives in certain areas. This forum is a prime example of technology being a good thing.

Thank you FBBO

 

[IQ52]

Do you need 7/16 pushrods? Probably not. Will you have a more stable system if you use 7/16 pushrods? I believe so. You do not need oil through pushrods. On the Trick Flow heads everything is oiled from the #4 cam bearing, through the block and heads and then to the rocker shaft.

I will never run a hydraulic roller in one of my personal builds. If the customer wants it, okay, but they are going to pay the $800 for lifter bore corrections and bronze lifter bore bushings. Just the way I roll.

 

[64 Post]

It's not just spring pressure the pushrod sees. The pushrod also has to get the valve moving against the added combustion pressure. In a 14-15:1 high comp race engine I'd say go with 7/16 or bigger. In a 10:1 street engine with a mild hyd. roller, ⅜ with a thicker wall should be sufficient.

That's my 2 cents...

Did I miss the specs of your cam?

 

[69 GTX]

Jim would the extra weight of the pushrods cause earlier rpm float with hyd roller lifters? I'm asking because I have no idea.

 

[Budnicks]

Thanks Jim/IQ52

I mainly thought it was just overkill for a street engine...
Especially with a moderate hyd. roller application...

I'm always open to learning something new from someone
actually with the proper skills, knowledge & background telling me....

 

[IQ52]

Thanks Jim/IQ52

I mainly thought it was just overkill for a street engine...
Especially with a moderate hyd. roller application...

I'm always open to learning something new from someone
actually with the proper skills, knowledge & background telling me....

View attachment 351767

Overkill is probably true. I'm looking at it from the standpoint we are in the Racer's Hangout section.

 

[IQ52]

Jim would the extra weight of the pushrods cause earlier rpm float with hyd roller lifters? I'm asking because I have no idea.

I believe that some of the hydraulic lifter float (not float really, lifter pump up holding the valve open) is caused by pushrod lifter flex, loading and unloading the hydraulic lifter mechanism. Just as if the spring pressures were to light and the lifter was launching off the top of the lobe. The hydraulic lifter bleeds down so slowly, under valve spring pressure, the extra weight of the pushrod shouldn't effect the hydraulic lock in the lifter while it sets steady on the cam lobe. It's when the lifter is in the air and not on the lobe you have troubles.

 

[pwtjr]

It's not just spring pressure the pushrod sees. The pushrod also has to get the valve moving against the added combustion pressure. In a 14-15:1 high comp race engine I'd say go with 7/16 or bigger. In a 10:1 street engine with a mild hyd. roller, ⅜ with a thicker wall should be sufficient.

That's my 2 cents...

Did I miss the specs of your cam?

My cam specs are 236/242 @ .050 and with the 1.6 rockers the lift will be right at .580"
10.5:1 Ross Pistons, aluminum Trick Flows
Pretty mild setup for sure. Its going in a heavy car with 3:55 gears and I have been guilty of over camming engines before. It's going to be raced less than a handful of times a year, so maybe this isn't the proper place to post, but I generally like to pick the brains of racers, so I wanted feedback from you guys. I can't afford 2, so I have to wet both whistles with 1 machine.

Thanks for your time guys. I believe some heavy wall 3/8 will be my choice... If I get more serious about the racing, a solid roller would be part of the upgrade package.

 

[pwtjr]

Just to update this thread, I ended up using a 3/8 heavywall from Trend. I really liked the cool factor of their double taper 7/16, but it was throwing money away according to them and the feedback on this thread.
If anyone uses a 7/16 with a trick flow head I would be curious if they fit without doing any grinding.

 

[Hemirunner]

I will never run a hydraulic roller in one of my personal builds. If the customer wants it, okay, but they are going to pay the $800 for lifter bore corrections and bronze lifter bore bushings. Just the way I roll.

What valve spring pressures are you running with these combos to see this happening? I built that last one with some hefty pressure and no lifter bore work. 180seat and 460 over the nose.

 

[IQ52]

I didn't say I was having pushrod problems with hydraulic roller lifters. I just intend to run the largest diameter pushrod I can safely fit for reasons of valve train stability. I've run hydraulic rollers from 230 @ .050 to 255 @ .050, 130#/360# to 170#/455#. Any problem I felt like I had with them was instantly solved by dropping a set of solid rollers on the cam. I just don't like hydraulic rollers and I have no problem with those who love them. I think hydraulic rollers are wonderful on mass produced factory production cars. I personally see no reason for them on individual built aftermarket high horsepower engines.

 

[Hemirunner]

I think hydraulic rollers are wonderful on mass produced factory production cars. I personally see no reason for them on individual built aftermarket high horsepower engines.

I can respect that. I tend to look at what would be the best fit for the owner and how they'll use the engine/car. For me, I'm a solid roller on the street with an 8000rpm rev limiter kinda guy.