308 heads

[Alphabet Soup]

Hello, have any of you guys ever used 3/8" pushrods with 308 heads and 1.5 rockers?
I have to make shorter pushrods and have a bunch of 3/8" BB odd ball length ones I can shorten,
rather than messing up the small block ones. Thanks, Gene.

 

[middleagecrisis]

The only way to know is to mockup and check for any interference. I'd shorten one and check various locations to see if you have to do any grinding. Also check the rocker cup to make sure the pushrod end is seating correctly.

 

[Professor Fate]

Since they were originally used on roller cam 360s, they already have enlarged pushrod holes to gain clearance with the taller roller rockers; so you stand a chance depending on what lifters you're using. But as has been said, the only way to know for sure is to mock up a couple.

 

[rmchrgr]

No way dude, don't even bother. I have higher-end aluminum heads that were designed with larger pushrod holes and those can't fit 3/8" pushrods. 5/16" fit but even those are tight on a stock 59º 340 block with a medium lift roller cam and 1.6 rockers.

I get that you have them on hand and want to try and use them but it's not going to be worth the effort. 5/16" pushrods will be sufficient with most any iron head combo. 308 heads are limited in how much power they can make so 3/8" pushrods would be total overkill and completely unnecessary.

 

[Newbomb Turk]

I use 11/32 in iron heads and that’s the smallest diameter I want to use.

You can get 3/8 in a speed master head and other like it with a little grinding.

You can do 3/8 in a 308 if you do some grinding.

If I didn’t already have 11/32 pushrods for my junk I’d be using 3/8.

 

[Alphabet Soup]

Ok... looks like I'm ordering some pushrods. Heads are already on the motor, so grinding is out of the question.
Thanks for the replies!

 

[Newbomb Turk]

Ok... looks like I'm ordering some pushrods. Heads are already on the motor, so grinding is out of the question.
Thanks for the replies!

lol yup, probably a bad idea to grind on them now.

You should be ok with 5/16 but especially on big blocks 3/8 is the minimum if I can get them to fit.

I know without grinding you can get a 7/16 pushrod in a TF head. That’s the way it should be.

 

[MOPAROFFICIAL]

Go for it 'if' you need them.

I run 3/8 in my x heads, real close but nothing is touching... but the clearance were talking is like .025 between the hole and the pushrod

 

[Alphabet Soup]

I use 11/32 in iron heads and that’s the smallest diameter I want to use.

You can get 3/8 in a speed master head and other like it with a little grinding.

You can do 3/8 in a 308 if you do some grinding.

If I didn’t already have 11/32 pushrods for my junk I’d be using 3/8.

Where do you get 11/32" pushrods? Who supplies them?? Thanks, Gene.

 

[Newbomb Turk]

Where do you get 11/32" pushrods? Who supplies them?? Thanks, Gene.

Manton has them. I think Trend may have them but I’m not 100% on that but Manton Im 100% on. They have them.

 

[Alphabet Soup]

Manton has them. I think Trend may have them but I’m not 100% on that but Manton Im 100% on. They have them.

Thanks, I will look. Jim @ Racer Brown lent me some the correct length but they are 3/8". There is room in the 308 heads for 3/8" but it's scarry close!
Does anyone know off hand, do 1.6 rockers move the adjusting screw closer to, or further away from the shaft? Gene.

 

[gzig5]

Thanks, I will look. Jim @ Racer Brown lent me some the correct length but they are 3/8". There is room in the 308 heads for 3/8" but it's scarry close!
Does anyone know off hand, do 1.6 rockers move the adjusting screw closer to, or further away from the shaft? Gene.

1.6 should be closer to the shaft than 1.5, all else being equal.

 

[Newbomb Turk]

Thanks, I will look. Jim @ Racer Brown lent me some the correct length but they are 3/8". There is room in the 308 heads for 3/8" but it's scarry close!
Does anyone know off hand, do 1.6 rockers move the adjusting screw closer to, or further away from the shaft? Gene.

Of you can do a little grinding and fit that 3/8 pushrods I’d do that in a nonosecond.

Im a firm believer Im running the biggest pushrod you can fit, even with SFT stuff.

 

[Alphabet Soup]

Of you can do a little grinding and fit that 3/8 pushrods I’d do that in a nonosecond.

Im a firm believer Im running the biggest pushrod you can fit, even with SFT stuff.

I would do that, and I think I could do what little I need with a round hand file. But of course, the heads are already on the motor, and I am not sure about reusing Cometic gaskets.

 

[Newbomb Turk]

I would do that... but of course the heads are already on the motor, and I am not sure about reusing Cometic gaskets.

In that case the 11/32 is your best option. And Manton makes a very nice part.

 

[Alphabet Soup]

OK, new info... it looks like 3/8" pushrods will fit in 308 heads with the lobe lift I have. There isn't much room to spare, but enough.
It also seems that I was using the wrong plunger height in the checking lifter I was using. It made things a little closer.
Thanks for all the input, Gene.