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-   -   283 rockers (http://www.hotrodders.com/forum/283-rockers-226713.html)

Mertz 12-01-2012 03:42 PM

283 rockers
 
I have decided that the stock stamped rockers are not good enough for my build and want to use some roller tips like I did on my 350. The heads have a narrow slot for the pushrods. The cam is a MTC-1 low lift with new z28 valve springs. The pistons are .030 in the hole. The heads and block have been decked (0.017) and I used a .028 head gasket. Can I or should I use 1.6 rockers? Do I need to get self aligning rockers?

Richiehd 12-01-2012 04:13 PM

Quote:

Originally Posted by Mertz (Post 1617922)
I have decided that the stock stamped rockers are not good enough for my build and want to use some roller tips like I did on my 350. The heads have a narrow slot for the pushrods. The cam is a MTC-1 low lift with new z28 valve springs. The pistons are .030 in the hole. The heads and block have been decked (0.017) and I used a .028 head gasket. Can I or should I use 1.6 rockers? Do I need to get self aligning rockers?

Regular rockers will work but you may have to lengthen the slots for the 1.6 rockers. Myself , I would just put a good set of 1.5 roller rockers on or if you just want better accuracy, a set of Comp Cams stamped rockers with roller tips. These come in a 1.52 ratio and work well on the 283. They are priced right too. I think you might like a thinner head gasket too (back to that "quench" thread)

BOBCRMAN@aol.com 12-01-2012 06:15 PM

If you go to roller rockers. Be advised that modern extruded aluminum roller rockers won't clear the stock stud boss on most older (73-earlier) press in stud heads. Either cut down the boss or relieve the bottom of the rocker fulcrum.

Mertz 12-01-2012 06:17 PM

I will stay with the 1.5s and get the roller tips. They work pretty good on my 350. Do they need to be self aligning? I don't think they were on the 350. Head gaskets are on and I am still at .058 quench. I believe it was good to be between .040 and .060. I would have like to be tighter but I think I am still at 8.5:1 compression with the power pack heads and the decking.

vinniekq2 12-01-2012 07:42 PM

what did you end up building? sounds like a 200 hp 283? with a small cam the stock rockers are fine,buying roller tip rockers are a waste of money,nothing gained for how much spent?

Mertz 12-01-2012 08:17 PM

I was not getting a good pattern on the valve stem with the stock rockers. I know I am not going to gain a lot in hp but I want to have some good valve geometry and I am not getting that with stock rockers. I am going to use roller tip stamped rockers so they aren't that expensive. I have been told with my set up and the mods I have made and a 4 bbl carb I should be at 270 hp or a little more. Stock the 4 bbl versions could make 270. Roller tips with the correct geometry could add 10 to 30 hp. That comes from getting the valve opening at max height with the right size pushrods and correct lash.

vinniekq2 12-01-2012 08:30 PM

I think your expectations of the engine are quite high. starting with 195 hp,add 10 for 4 bbl and maybe 12-15 for the cam,where else is the power coming from? not trying to make you mad or argue,I just do see the power?If that engine pulls to 6,000 rpm,260 hp would be a very good achievement . what do your heads flow?did you use 1 5/8 headers?

Mertz 12-02-2012 08:27 AM

I would think that some port work on the heads and the balanced rotating assembly would add some. I would be happy with 260.

MouseFink 12-02-2012 09:37 AM

Quote:

Originally Posted by Mertz (Post 1617986)
I will stay with the 1.5s and get the roller tips. They work pretty good on my 350. Do they need to be self aligning? I don't think they were on the 350. Head gaskets are on and I am still at .058 quench. I believe it was good to be between .040 and .060. I would have like to be tighter but I think I am still at 8.5:1 compression with the power pack heads and the decking.

Do not use self aligning rockers if your heads have push rod guide slots or guide plates. There is misalignment between self aligning rockers, slots or guide plates and the push rods will bind.

vinniekq2 12-02-2012 10:45 AM

the camshaft you are using is way too short in duration to take advantage of the rpm range where the 283 can make power.


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