Generation III Internal Engine - 3/8" Pushrod Clearance

Do 243 castings have the clearance to run 3/8 pushrods without rubbing issues? All I can find is info on the TFS heads not having the clearance...

Info with 11/32" dia pushrods. 3/8" might rub slightly on a few holes, but it sounds like a little rubbing is OK.

http://ls1tech.com/forums/generation-iii-internal-engine/1472763-pushrod-head-hole-clearance.html

Info with 11/32" dia pushrods. 3/8" might rub slightly on a few holes, but it sounds like a little rubbing is OK.

http://ls1tech.com/forums/generation-iii-internal-engine/1472763-pushrod-head-hole-clearance.html

11/32 was my fall back but I really wanted to run the straight 3/8 or even the dual tapered 5/16-3/8 manton rods if I could get the clearance.

What heads were you running on that combo, and were they milled at all? Thanks for the info!

11/32 was my fall back but I really wanted to run the straight 3/8 or even the dual tapered 5/16-3/8 manton rods if I could get the clearance.

What heads were you running on that combo, and were they milled at all? Thanks for the info!

That was on my '02 Z06 with stock LS6 (243 heads).

I think vettnuts was running bigger pushrods than 11/32, but he might have hogged out the pushrod hole ... can't recall.

11/32 .120 wall is all you would need with a Hyd roller.

I get mine from Manton.

Tim

I haven't seen 3/8 work on the setups Ive worked on, and what most of use are running for parts, stock rockers,. No big milling, or angle milling the heads, no shaftmounts, ot crappy rockers out there with guild plates, or adjustable cups. I open the holes up to run 3/8 pushrods on heads Im setting up. But I'm running the 11/32 on stock heads
http://ls1tech.com/forums/dynamometer-results-comparisons/1516724-more-power-cam-only-setup.html

I haven't seen 3/8 work on the setups Ive worked on, and what most of use are running for parts, stock rockers,. No big milling, or angle milling the heads, no shaftmounts, ot crappy rockers out there with guild plates, or adjustable cups. I open the holes up to run 3/8 pushrods on heads Im setting up. But I'm running the 11/32 on stock heads
http://ls1tech.com/forums/dynamometer-results-comparisons/1516724-more-power-cam-only-setup.html

Ive been following your threads ever since I went with a streetsweeper cam about 3 years ago. I have the smaller HT version, but all other mods are very similar. I understand the 11/32 are ~50% stiffer, but did you test or notice a difference in the 11/32 over 5/16?

I run YT roller rockers, ls7 lifters, and PRC dual springs. I havent had an issue pulling my current setup to 6600 rpm, but Im looking to eek out a few more HP while correcting my preload which is a bit high.

I'm running 3/8 with 243's

I'm running 3/8 with 243's

Are your heads milled down or did you have work done to the pushrod channels?

Heads are milled .020. Running ls7 lifters with .030 preload. Stands are milled .040 to correct wipe. Using stock rockers with .650 lift on both lobes and running PAC beehives

That was on my '02 Z06 with stock LS6 (243 heads).

I think vettnuts was running bigger pushrods than 11/32, but he might have hogged out the pushrod hole ... can't recall.

I have AFR heads, which won't fit straight 3/8". I went with the Trend double taper, which are machined from a single piece billet of steel rod. See this link: Link (http://forums.corvetteforum.com/c5-tech/2492581-an-investigation-of-pushrod-stiffness.html)

I have AFR heads, which won't fit straight 3/8". I went with the Trend double taper, which are machined from a single piece billet of steel rod. See this link: Link (http://forums.corvetteforum.com/c5-tech/2492581-an-investigation-of-pushrod-stiffness.html)

Excellent post at the link, thank you for taking the time to compile that info.

We use a lot of 3/8ths on 243s with oem rockers and YTs and they usually do clear believe it or not. If we are setting up heads we will put them on the Bridge port and open them up a wee bit but many fit without work. most other heads they hit on the port on the intake rocker.