'79 F-100 w/ 300 six, what size studes in head, 3/8 or 7/16?

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'79 F-100 w/ 300 six, what size studes in head, 3/8 or 7/16?

Postby thunderb » Thu Jan 19, 2006 4:25 pm

'79 F-100 w/ 300 six. What size studs are in the head, 3/8 or 7/16?

I have some ticking lifters and am looking to do the chebbie rockers when I replace the lifters.
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Postby THE FRENCHTOWN FLYER » Fri Jan 20, 2006 11:44 am

The press-in studs are 3/8, so they may be tapped out for 7/16-NC threads very easily. The pedastal mounted stamped style are held down with 5/16 bolts.

It is a good idea to mill the bosses down to maintain proper rocker angularity. Good luck.
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Postby thunderb » Fri Jan 20, 2006 11:53 am

Thanks for the fast reply. I didn't specify that i wanted to use chebbie 250/292 six stamped rockers. I like cheap and easy.

I am wanting to know the size of the rocker arm studs so I know what size 292 chebbie rocker to get, 7/16" or 3/8". My truck is a '79 300 with the origional motor.

I'm not wanting to do any machine work to the head such as pulling studs and retapping them so now I'm wondering...the chebbie six rockers aren't a direct bolt in?

I'm just looking for an easy bolt on since I have to replace my worn lifters anyway. I was told my head uses stud mount rockers by the autoshop teacher where I work. I let his students put on some vlave cover and lifter gaskets for me.

So, if I am understanding correctly, the rocker studs are 3/8", they are pressed in, and if I get 3/8" 292 chebbie rockers, they will bolt-in with no modification, right?
Last edited by thunderb on Fri Jan 20, 2006 12:13 pm, edited 1 time in total.
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Postby THE FRENCHTOWN FLYER » Fri Jan 20, 2006 12:12 pm

Standard production Chevy rocker arms are 3/8 pivots. Aftermarket roller rocker arms are available in either 3/8 or 7/16 fulcums (all of which will require that the bosses be tapped to 7/16-NC.)

Do your stucs have 3/8-NF nuts or 5/16 NF nuts that bottom out on a shoulder on the stud? You will probably need the ones with the 3/8 nuts as the 5/16 nuts may not position the lifter plunger properly when torqued.

I suggest you buy ONE Chevy rocker arm assembly, pull the valve cover and play around with the installation, rotating the crankshaft through at least two revolutions to see if there any issues. Good luck.
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