99 2500

According to VinciPerformance website, the crane rockers require .100 longer pushrods than what the kit supplies when installing on engine with AFR heads. Wouldn't adjusting the rockers make up the difference for the greater deck height of the AFR heads?

smask04C5

iTrader: (1)

No, using the 7.250 supplied pushrods on AFR heads will affect valvetrain geometry. AFR heads require 7.350 pushrods to maintain geometry. I am installing AFR 205's on my vett, milled to 62 cc, and will use a 7.325 pushrod.

99 2500

Thanks for the info.

99 2500

Just thought of another question, why doesn't AFR recommend a .100 longer pushrod to use with the stock rockers when installing their heads? You would think that if it would affect the crane rockers it would do the same to the stock rockers.

TT_Vert

iTrader: (12)

i have some hardened 7.350" pushrods ill sell for $90 shipped. They have 1 startup on them (maybe 20 seconds run time). I was trying to pinpoint a valvetrain noise.

Dave

99 2500

Just trying to find out why the Crane roller rockers require .100 longer pushrods when people don't seem to be having any problems when using stock rockers with no change in pushrod lenght.

99 2500

Bump, maybe mrr23 has some input on this post.

Squintz Palladoris

iTrader: (1)

The Crane rockers need a SHORTER pushrod. They come with 7.250" and should work fine with your AFRs.

Brad

mrr23

iTrader: (3)

because the deck height on the AFR heads are .100 thicker than stock heads is why. this brings the rockers .100 higher up than stock. and this brings the geometry off. and that's why roger vinci makes a rocker kit specifically for people with out of the box, unmilled AFR heads. they figured all this out when they started the PROJECT AFR corvette. the vinci/crane kits comes with 7.250 pushrods. so, with the taller deck, they need to make them that much longer as well to keep the geometry for the rockers correct. if you have any questions regarding proper pushrod length with your motor, just give them a call.

as far as why AFR doesn't recommend longer pushrods when using stock rockers, you'd have to ask them.

http://www.vincihighperformance.com/...20PAGE%20.HTML it's all on the site.

99 2500

Thanks mrr23, now I know the reason why they recommend .100 longer pushrods.

Tony Mamo @ AFR

iTrader: (13)

Guys...

I should have hopped on this thread a little sooner...

First off our rocker stand heights are extremely close to a factory LS6 casting (within .015)....The fact that our decks are thicker has no relation to the height we chose to machine our rocker pads at. When we first tested our heads on the dyno a long time ago we simply swapped out a set of LS1 heads and dropped on a set of 205's without changing pushrods and everything was fine (preload was almost identical).

I think what's more important in determining pushrod length (and is never spoken about) is the camshaft base circle diameter....which can be different from cam to cam even if the manufacturer remains the same, let alone switching cam manufacturers.

AFR's policy due to this situation and many others is NOT to recommend any type of pushrod length (there are too many variables)....what we do recommend is to get an adjustable pushrod and see what you're individual set-up requires....If you don't have the means or know how to check then enlist the help of someone who does. Even the same combination isn't a guarantee that the exact same pushrod length would be required (although a lot more likely).

With my heads milled almost .030 and our 224/228 cam, I ended up using a 7.350 length pushrod with Crane 1.7 rockers. If you have a similar set-up and are using our cam, there is a good chance you would require the same , but the bottom line is don't call AFR looking for pushrod length because we will not provide you with that information....EVERY set-up must be check if you are looking for maximium power and maximum reliability and long life from your valve train.

Tony M.

99 2500

Thanks Tony, appreciate your input.