Which pushrods to use with Harland Sharp RA's
04-11-2013, 03:11 AM
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Which pushrods to use with Harland Sharp RA's So I got some nice heads that I am putting on. I bought them second hand, and they came with some Harland Sharp rocker arms. The rocker arms are the SLS17 series (factory LS1 replacement with no valve clearance or valve cover clearance issues, 1.7:1 ratio)
On the website it calls for using shorter pushrods if you have an upgraded cam. I am currently running a TSP 228r cam. I have some brand new 7.4 pushrods that I was going to use, is this a smart idea? Or should I switch to a shorter pushrod length?
If this is too much of an issue, I will just sell the R/A's and use my factory set from my old heads. I wouldn't have bought these, they just happened to come with the heads.
On the website it calls for using shorter pushrods if you have an upgraded cam. I am currently running a TSP 228r cam. I have some brand new 7.4 pushrods that I was going to use, is this a smart idea? Or should I switch to a shorter pushrod length?
If this is too much of an issue, I will just sell the R/A's and use my factory set from my old heads. I wouldn't have bought these, they just happened to come with the heads.
04-11-2013, 03:06 PM
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From everything I have been reading, they sound like more hassle than they are worth in power adding. I'm just gunna use stock rocker arms and sell these. It seems like it won't help much in my set up and they aren't great unless you have a fully built motor making at least 800 wheel. And I would rather use my 7.4's that to buy new ones.
04-11-2013, 03:34 PM
#5
That doesn't prevent you from needing to measure for pushrod length.
Why? Tolerance stackup. Deck height has a 0.010" tolerance on it alone, then add in variations in ACTUAL head gasket thickness, cam base circle diameter, valve seat depth, and lifter cup heights. Then take into account that all this stuff grows when it gets up to temperature. This is nothing to gloss over.
Seriously though, the tool you need is $20 bucks. Or you could use the "known length method" since you already have your 7.4's to take measurements with (free). There's isn't really a reason to forego this measurement. The number of threads created about valvetrain noise, collapsed lifters, broken springs, etc. is insane. Probably a solid 3/4 of those cases were preventable if they would have taken the time to double check their valvetrain geometry instead of throwing in 7.4's and running it. I don't mean to preach, but I've seen a lot of these threads around lately and I'm just trying to save you a headache down the road.
Why? Tolerance stackup. Deck height has a 0.010" tolerance on it alone, then add in variations in ACTUAL head gasket thickness, cam base circle diameter, valve seat depth, and lifter cup heights. Then take into account that all this stuff grows when it gets up to temperature. This is nothing to gloss over.
Seriously though, the tool you need is $20 bucks. Or you could use the "known length method" since you already have your 7.4's to take measurements with (free). There's isn't really a reason to forego this measurement. The number of threads created about valvetrain noise, collapsed lifters, broken springs, etc. is insane. Probably a solid 3/4 of those cases were preventable if they would have taken the time to double check their valvetrain geometry instead of throwing in 7.4's and running it. I don't mean to preach, but I've seen a lot of these threads around lately and I'm just trying to save you a headache down the road.
