I run a tall deck 427 in my car. I ended up buying a set of 3/8" pushrods that were Std tall deck length +.100".
If I remember correctly they were a Lunati brand, roller cam rated, pushrod.
My cam is a .640" lift roller.

 

Running Comp pushrods. 3/8ths. Over 600 open pressure with 714 lift. But, if I had to do it all over again, I would consider 7/16ths. Less deflection, more ponies.

 

I run the manley 3/8 .080 wall pushrods in my motor and that's with 250 lbs seat pressure 750 lbs open pressure .748/.748 lift to 7500 rpm. I recommend not going to to a 7/16 pushrod because of the weight. That heavy pushrod is going to increase the chance of valve float at high rpm. A good .080 wall chromemoly 1 piece pushrod will be fine.

 

... I would consider 7/16ths. Less deflection, more ponies.

Exactly! :thumbsup:
It's always amazed me why guys fret for months over just the perfect cam for their motor only to go cheap on wimpy pushrods...easily giving away 050" lift because of deflection. :clonk:
Think I'm kidding...put a dial indicator on your rocker. And the additional weight is negligible.

 

is this a roller cam?

 

i run the 7/16 they look huge and close to the heads but no rubbing.

I went through all the trouble of measuring everything so close so i got the stronger ones just for peace of mind and cause it was'nt much diff in price.

 

I run the manley 3/8 .080 wall pushrods in my motor and that's with 250 lbs seat pressure 750 lbs open pressure .748/.748 lift to 7500 rpm. I recommend not going to to a 7/16 pushrod because of the weight. That heavy pushrod is going to increase the chance of valve float at high rpm. A good .080 wall chromemoly 1 piece pushrod will be fine.

=
This is not necessarily correct. All testing lately (actually for quite some time) has shown that what I have been preachin for the last few years is in fact correct.

It has been known in most of the higher end race shops like Cup & Busch etc for years, just not talked about much that the weight on the lifter side of the rocker is relatively unimportant compared to the valve side.
Stiffness & strength are way more important then weight. Even the cam companies are starting to actually tell you this now.
About damn time,,,,
Here is a pretty fair article for you guys to read about pushrods if you are interested
http://www.aa1car.com/library/2004/eb30431.htm

While a good 3/8" pushrod is normally all you need do not assume a 7/16", especially the taper or double taper is not worth some power just because of weight,,,

Here is something I posted a while back for you to ponder
==============
Now,,, as to the diameter of pushrods,,, I have posted most of this before but here it is again just for lack of anything better to do this evening ,,,
for most applications a 3/8" .080 wall is just fine but,, with any serious roller application with real springs you might be surprised at what works.
Consider the pushrod as a piece of spring steel complete with harmonics & resonant frequencies for a moment.
Now consider what happens when your spring goes through it's harmonics & dances clear off the head & retainer.
And at some point in your rpm range I can just about guarantee it does.

Also, a 600lb spring has over 1000lbs on that little piece of "spring steel" tubing.
All pushrods deflect & rats are one of the worst offenders with their goofy angles.
A pushrod cannot be to stiff to control valve movement.
If you consider it as a piece of spring steel you can see why the thick double taper ones are the pushrods of choice in most professional hi rpm applications.
Once you see a spintron test & what spring & pushrods do you may never want to build another engine
It gets ugly!!
I don't think you can get the valvetrain too stiff.

As an example, we went from a very good quality 3/8 .080 wall pushrod to 7/16 .120 double taper & picked up about 12HP with no other changes on an 18 deg small block deal & the torque curve got a bit smoother above about 8200 with a lot less of the cute little dips & spikes in the torque curve we were blaming on the springs.
And these were very short pushrods, approx 6.5" long
(Tall lifter, shaft rocker)

Within reason, I could basically care less about pushrod weight & have seen more power in the same engine with pushrods that were substantially heavier then ones that came out.
It has been proven that, within reason, weight on the cam side of the valvetrain is not real important especially at the expense of rigidity.

All that aside, we normally use 5/16" or 3/8" in SB & 3/8's in rats in almost all engines & don't seem to see any problems. (that we know of )

But,,, I am starting to look at this more after seeing what the big pushrods did in this little 332" engine considering they were only about 6.5" long
12 HP is a lot for such a simple part & yes we went back to the 3/8's just to verify it was the pushrod.
Of course, this deal runs well over 9000 rpm & does have a bit of spring pressure

 

Alot of good inf.

Yellow68SS are you running GM heads or aftermarket heads with the 7/16" pushrods ?

To install 7/16" pushrods I need just to change the guideplates or I need to grind with GM 990 heads ?

 

Yeah mike that was my experience too, I have used 3/8 pushrods in my motors for years and had no problems. And like you said, at the shop I worked at we ran 3/8 pushrods in every big block basically under 1000hp or with triple springs. As far as I know Reher-Morrison was doing their motors the same way also. I never had a motor that would go to 9000 so I don't know if that is a reason, but I guess it's like everything else sometimes you need a change. I always felt that if the lifter accelerates the pushrod the valvespring has to stop it, so why put extra strain on the springs. I guess if you can fit the pushrods then go with the heavier one. If there is no gain in hp and it doesn't change the valvetrain weight, it didn't hurt anything. Thanks for the info Mike.

 

So if you happen to be stuck with a 3/8" pushrod for a roller application in a BBC, what would be the best one to use??

 

I don't know if you have the same problem I do but with the dart Pro 1 heads, the 3/8 pushrods barely clear the heads. I would have to take the heads off and grind the holes bigger to clear a 7/16 pushrod. I actually did a motor with one of the iron eagle heads when they came out and the pushrods rubbed the heads.

 

HPseeker,
You are correct, on the stock heads the 7/16" should fit no problems with a plate change. GM used them many years ago in some applications.
Maybe they knew something we didn't????

So if you happen to be stuck with a 3/8" pushrod for a roller application in a BBC, what would be the best one to use??

=
Actually, you would be very surprised at how few companies make the high end pushrods,, bull-pucky advertising aside

And what bracketracer said is very true, the majority of aftermarket heads are going to need some work to make 7/16" fit.
Half the time the 3/8" don't fit without rubbing which actually doesn't hurt a damn thing if it is just touching, who knows, might even help dampen the suckers

Far as I know, Manton & Smith Brothers make their own & are excellent.
The ProMagnum Comps as well as all "their New" Double Taper ones that they claim to have perfected or whatever the ad says are also excellent as are CV Products among others that are all made by the same company. And no, it ain't Comp,,,,, ads can be very deceiving.
Still an excellent pushrod.

 

The CC rods I pulled out of the sbc sure looked a lot like the summit rods I put in. The text printed on the side looked the same.
Does CC actually make anything in house?

 

I used a set of summit pushrods in my 396 and yes they did look the same as any other that I've used Manley,comp etc. I guess somebody is making them for all of them. We know Summit isn't making them.

 

with any serious roller application with real springs

Mike,
What would you consider a serious roller and springs?

Would 7/16 pushrods be overkill for a street, lite strip BB?

 

I'm not sure who they are tied to or if they truly do their own stuff or not, but they were able to get me a set of 1-pc. custom length, double taper pushrods with 210 deg. ends sent out "next day air". Very good customer service and excellent quality.

http://www.trendperform.com/

I called around lunch time and was told initially they couldn't get them out for a couple of days. I told them I really needed them to hit a date with the dyno. They put me on hold for a minute and came back and said if I can live without having them coated they could machine and send them out that afternoon. I told them get after it! They arrived the next day :thumbsup:

I've had good luck with the Trick Flow pushrods through Summit as well if you are looking to save a few bucks. 1-pc 4130 .080 wall.

 

I'm not sure who they are tied to or if they truly do their own stuff or not, but they were able to get me a set of 1-pc. custom length, double taper pushrods with 210 deg. ends sent out "next day air". Very good customer service and excellent quality.

http://www.trendperform.com/

I called around lunch time and was told initially they couldn't get them out for a couple of days. I told them I really needed them to hit a date with the dyno. They put me on hold for a minute and came back and said if I can live without having them coated they could machine and send them out that afternoon. I told them get after it! They arrived the next day :thumbsup:

I've had good luck with the Trick Flow pushrods through Summit as well if you are looking to save a few bucks. 1-pc 4130 .080 wall.

=
Trend is a major manufacturer of the better pushrods for a lot of
folks
They are also the parent company of Diamond pistons.
I have been a dealer for them for a number of years now & they make some pretty fair stuff..

 

If you have questions about the size of pushrod needed, give Terry Manton a call (951-245-6565). They make pushrods from 140,000 - 275,000 psi tensile strength, 3/16' - 5/8" diameter and .036" - .188" wall. In laymen's terms, the larger diameter reduces deflection and the thicker wall reduces compression. Although stiffer pushrods will help almost any engine, they really come into play with high lift, high rpm and high spring pressure combos.

 

Alot of good inf.

Yellow68SS are you running GM heads or aftermarket heads with the 7/16" pushrods ?

I'm running AFR's

 

Manton 7/16" .120 wall on AFR's. If your running a high lift, fast ramp cam and/or high RPM, I'll take the extra weight pushrod for minimum deflection / compression any day.

John

 

Comp Cams Hi-Tech 3/8 cro-mo forged pushrods - reasonably soft lobe roller under 700 net lift under 7500 rpm - 250lbs on seat mid 700s over the nose.

MAT

 

Comp Cams Hi-Tech 3/8 cro-mo forged pushrods - reasonably soft lobe roller under 700 net lift under 7500 rpm - 250lbs on seat mid 700s over the nose.

MAT

How much were they? How much time do you have on them?

 

Pushrods are very critical, case in point. I had a customer doing a Super Dirt Late model engine, 417CID with a set of the 12X12 Brodix's. These heads require a very long pushrod for a SBC, around 9.5" if I remember correctly. Well on the dyno it had some wierd A/F numbers, very eractic, along with power seemed to jump around. With some discussion we thought it may be pushrod deflection. It was decided to run the engine in the morning 1 more time and then pull the intake. Well the one more time resulted in chucking 2 pushrods out. So single taper 7/16" pushrods replaced the 5/16 pushrods in the engine. Overall an average gain of 30HP was achieved over 5000 rpm over the old set up.

So yes pushrods are worth power. The added weight on the valvetrain is minimal to the gain in power by reducing deflection.

 

Jim:

Have 2 full summers of driving with the roller, had 6 summers of various flat tappets.

From memory they are .080 wall and stock length (heads are decked to the limit the intake valve job would allow with a 2.30 valve)

Make the power with the cylinder heads and not the cam - that way you pay only once - IMO

MAT

 

Re:NEW question ... What pushrods diameter are you running in your BBC ?

I called Jegs for a set of TALL DECK 7/16" pushrods .300 + longer ,but no company make this pushrods only custom made ,They do got the exhaust in 3/8" , 9.950" exhaust and I will stay with the 3/8" for now ..

They do not got the correct measure for the intake pushrods only got them

8.950 (.030 SHORTER ) than 8.980 and 9.000 (.020 longer )

Which is my best option ?