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-   -   Anyone have 1.7 roller rockers under stock valve covers? (http://www.ifsja.org/forums/vb/showthread.php?t=186048)

rang-a-stang 09-22-2018 07:29 PM

Anyone have 1.7 roller rockers under stock valve covers?
 
I plan to buy my rockers here in the next couple weeks. I see conflicting info on the interwebz about whether or not 1.7:1 aluminum rockers will fit under stock valve covers. Anyone running them?

wiley-moeracing 09-23-2018 05:10 AM

I had to run aftermarket valve covers for clearance with the rockers.

Full Size Jeeper 09-24-2018 05:43 PM

Hey Rang, What is the benefit of going with a different ratio rocker. Is this something the machine shop suggested? I don't Know anything about valve train geometry, but will you have to change the length of the push rod too? Really interested in hearing what this will do, I have no idea.

rang-a-stang 09-24-2018 09:58 PM

yeah, I already expect to have to buy new pushrods anyway so if I am going to install 1.7's, I need to do it now. Having the extra length in the rocker opens and closes the valves faster and you get extra lift out of them, too. My cam has a little less lift than yours (I think you said you got the Comp Cams 270, right?) and Comp Cams said my springs can handle the 1.7s with my cam (CC 268) but I really want to keep the stock valve covers on it.

BJs has spacers:
http://www.bjsoffroad.com/AMC-V8-Val...ch_p_1689.html
and there are some other companies out there with them but I don't want to spend another $100 on them. If only 1.6's fit, then that's what I'll buy.

Full Size Jeeper 09-25-2018 08:30 PM

Gotcha!!!!!!!!!!!

rang-a-stang 09-29-2018 01:29 PM

After much pondering on theAMCforum, I am going to order 1.6's (like yours).
http://theamcforum.com/forum/would-y...537_page1.html

wiley-moeracing 09-29-2018 04:27 PM

You don't just throw in 1.7 rockers, you have to check valve spring clearance, valve clearance to pistons, new valve springs for the higher and faster ramp rate, push rods, etc. yeah you can bolt them in but will they work?

Full Size Jeeper 09-29-2018 08:54 PM

Hey Rang, All the math and calculations required to make these kinds of changes is beyond my ability, and the fact this very well might be the last engine I ever put together make me go to the people that do it for a living every day. I was at my friends machine shop the other day and asked him about putting the 1.7 rockers in your motor. He said you would see no noticeable gain that you could feel. He also said the higher ratio rockers puts more pressure on the valve train, and will in fact cause the cam to flex more than the the 1.6 effectively erasing any gains. Most of what he said went right over my head, but one of the things he said was that a lot of times when going with higher ratio rockers (on race engines) you go with a thicker cam blank to help stop the flex in the cam. In fact he said on the dyno with no other change other than a larger cam blank (same cam grind) you will see real horsepower gains. On some circle track engines he builds, they limit the amount of lift and duration on the cam, but not the cam blank size. This is one way to gain the upper hand in the horsepower wars. Your set up will be a fine up grade from the stock worn out setup you had.


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