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charlie66 · 03-14-2015, 10:52 AM

I was told I should use a 1/2 push rod because of all the boost im running. Does anyone know what's involved to make this happen with studded stock locations?? Any advice would be really appreciated..

Thanks a head of time...

Mr. P-Body · 03-14-2015, 11:46 AM

Unless you're using nitro, 3/8 are fine. 7/16 with nitro. Whoever said 1/2"? Never ask them again...

Jim

charlie66 · 03-14-2015, 02:19 PM

Quote:

Originally Posted by Mr. P-Body

Unless you're using nitro, 3/8 are fine. 7/16 with nitro. Whoever said 1/2"? Never ask them again...

Jim

I'm using 30 pounds of boost...

If I can get away with 3/8 that would be great..

Any other opinions?

Thanks

mike leech · 05:10 PM

Quote:

Originally Posted by Mr. P-Body

Unless you're using nitro, 3/8 are fine. 7/16 with nitro. Whoever said 1/2"? Never ask them again...

Jim

Bad advice. No disrespect. You want as big as you can fit. 3/8 are spagetti noodles. Boost or 1000+

Im 7/16 full taper

I would be 1/2 if i could get it in there.

73 TRANSAM · 03-14-2015, 05:30 PM

Charlie,
I did fit a 1/2" on my Butler wideport heads. I had to drill the hole with a 5/8" bit on the milling machine then elongated from front to back. It works but I change my combo to an IA2 block and needed a different length from using Marty P's sealing rings. I am currently running a 7/16 straight with .135 wall on my setup. How long of a pushrod do you need?

Tom Vaught · 03-14-2015, 06:10 PM

Pontiacs use a fairly long pushrod and with high lift camshafts, 1.65 ratio plus rockers, and valve springs capable of controlling valve trains with high HP (boost or NA) try to fit the largest diameter ones in there that you can. Also thick wall stuff.

"3/8 are spagetti noodles" In some combinations that can be a very true statement.

Charlie runs a 4 cylinder engine but with over 30 PSI in the Intake Jim on E-85.

Tom V.

cfmcnc · 03-14-2015, 07:15 PM

Make every effort to fit the biggest diameter pushrod in the engine.Bill C.

charlie66 · 03-14-2015, 08:00 PM

Quote:

Originally Posted by 73 TRANSAM

Charlie,
I did fit a 1/2" on my Butler wideport heads. I had to drill the hole with a 5/8" bit on the milling machine then elongated from front to back. It works but I change my combo to an IA2 block and needed a different length from using Marty P's sealing rings. I am currently running a 7/16 straight with .135 wall on my setup. How long of a pushrod do you need?

There 9.500 but im going to double check because my machinist thinks they might be a bit too long. Do you know if a non wide port could be drilled with a 5/8 bit? Sounds scary.

By the sound of everyone's opinions I better get at least a 7/16 in there and a stud girdle ..

Are you set up for boost. What psi ?

charlie66 · 03-14-2015, 08:01 PM

Quote:

Originally Posted by cfmcnc

Make every effort to fit the biggest diameter pushrod in the engine.Bill C.

Thanks, I will...

73 TRANSAM · 03-14-2015, 08:45 PM

I will be running a single PT 91.5 turbo. I have a lot of work ahead of me but I'm hoping to at least have it done before the summer is over. It will be easy on a non wideport as there is no angle on the intake side. You still need to open up the pushrod hole to 5/8 with a 7/16 setup. PM me your email and I'll send you some pictures.

BruceWilkie · 03-14-2015, 10:48 PM

If your pushrod hole is already 1/2"(measure them) 5/8" shouldnt be an issue unless ported. Eigth inch over half inch is only one sixteenth (.0625") per side. As long as you dont get too thin on port sides your good. Breaking out on side away from port is no issue. Shouldnt be any issue on water jacket or valley side.

fwiw Stock 6x heads and 4x I have are 1/2" hole stock and mine could easily go more than 5/8 hole.

blaktopr · 03-14-2015, 11:57 PM

You will have to work at getting 3/8 in there. Since you need guide plates, you have to modify them or use a sbc type. Its not about the size of the hole to the size of the pushrod. Its about where the pushrod travels through the range of the lift based on the rocker. As the rocker goes from closed to open, the pushrod will travel back and forth. Depending on the ratio of the rocker, the pushrod can rest at different positions of the pushrod hole. The higher the ratio, the closer to the rocker. You have to mock up the setup on a block and start taking out material until it doesn't bind. You may even get thin on the pushrod wall/port side and adding a sleeve may mess with the area at that part of the port. You can't run a tapered pushrod with a guideplate. And others here are running shaft rockers so they don't need guideplates and can run any size they can make fit.

charlie66 · 03-15-2015, 10:42 AM

Quote:

Originally Posted by 73 TRANSAM

I will be running a single PT 91.5 turbo. I have a lot of work ahead of me but I'm hoping to at least have it done before the summer is over. It will be easy on a non wideport as there is no angle on the intake side. You still need to open up the pushrod hole to 5/8 with a 7/16 setup. PM me your email and I'll send you some pictures.

The site wont let me send you a pm. Maybe you can try shooting me one??

Thanks

charlie66 · 03-15-2015, 10:47 AM

Quote:

Originally Posted by BruceWilkie

If your pushrod hole is already 1/2"(measure them) 5/8" shouldnt be an issue unless ported. Eigth inch over half inch is only one sixteenth (.0625") per side. As long as you dont get too thin on port sides your good. Breaking out on side away from port is no issue. Shouldnt be any issue on water jacket or valley side.

fwiw Stock 6x heads and 4x I have are 1/2" hole stock and mine could easily go more than 5/8 hole.

The head was ported by SD .It flowed 225 cfm @ 600 lift . At this level I don't really know if much is taken off the pushrod area. I wish there was a way of measuring it...

charlie66 · 03-15-2015, 10:48 AM

Quote:

Originally Posted by blaktopr

You will have to work at getting 3/8 in there. Since you need guide plates, you have to modify them or use a sbc type. Its not about the size of the hole to the size of the pushrod. Its about where the pushrod travels through the range of the lift based on the rocker. As the rocker goes from closed to open, the pushrod will travel back and forth. Depending on the ratio of the rocker, the pushrod can rest at different positions of the pushrod hole. The higher the ratio, the closer to the rocker. You have to mock up the setup on a block and start taking out material until it doesn't bind. You may even get thin on the pushrod wall/port side and adding a sleeve may mess with the area at that part of the port. You can't run a tapered pushrod with a guideplate. And others here are running shaft rockers so they don't need guideplates and can run any size they can make fit.

I'm shooting for 7/16..

blaktopr · 03-15-2015, 11:27 AM

It's going to take work. Not easy especially with guide plates. How bad are your current pushrods flexing and touching the head? How many more pounds per square inch does 30 to 35 lbs of boost add to the valve? 70 something? Tom? So if the pushrod sees 300 lbs closed with boost and valve spring pressure why can't 3/8 120 wall work. Call butler and see what they say.

v869tr6 · 03-15-2015, 11:50 AM

Are you having issues now?
All the size advise and not one person asks what the cams specs are?????
My baby cammed engine started bending stock replacement pushrods at 20 psi, the new Butler heavy wall 5/16" one's have been issue free at up to 26psi.
Are they flexing around?? likely are but they are still straight.
What lift, spring pressure and rocker ratio are you going to be using?

charlie66 · 03-15-2015, 01:20 PM

Quote:

Originally Posted by blaktopr

It's going to take work. Not easy especially with guide plates. How bad are your current pushrods flexing and touching the head? How many more pounds per square inch does 30 to 35 lbs of boost add to the valve? 70 something? Tom? So if the pushrod sees 300 lbs closed with boost and valve spring pressure why can't 3/8 120 wall work. Call butler and see what they say.

Here are some pictures. what do you think . Are they flexing and hitting?

Exhaust is on the left and intake is on the right....

These r the butler .116 wall at 9.500...

charlie66 · 03-15-2015, 01:28 PM

Quote:

Originally Posted by v869tr6

Are you having issues now?
All the size advise and not one person asks what the cams specs are?????
My baby cammed engine started bending stock replacement pushrods at 20 psi, the new Butler heavy wall 5/16" one's have been issue free at up to 26psi.
Are they flexing around?? likely are but they are still straight.
What lift, spring pressure and rocker ratio are you going to be using?

I am having issues now.

I do think they are flexing around and they r still straight...

.580 lift. 310 on the seat 680 open. scorpion stock ratio rocker arms .

grnmnstr · 03-15-2015, 01:30 PM

Fit the biggest diameter pushrod you can, on any application, regardless of cam specs. This is the race section, not street.
We run a 7/16, double taper, .135 wall pushrod with our Tigers, and we still do not get full lift (could also be the aluminum rockers, but that is another issue)

Yes, it takes a while to clearance the pushrod hole. You must check it through the entire range, rotate the engine twice to make sure it clears every where. .010 - .020 clearance is good.

Even though the pushrod is not breaking it IS flexing, which means you are not getting all the lift out of the cam, thus, losing power.

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