Guest FBody Addict Posted December 31, 2004 Report Share Posted December 31, 2004 i put 1.6 roller rockers on my 305, what kind of hp gain will this add (i'm thinking 5-7 but i'm probably wrong) and how will it effect economy Quote Link to comment Share on other sites More sharing options...
MrMeanGreen Posted December 31, 2004 Report Share Posted December 31, 2004 depends on the cam and what ratio the rockers were you replaced. 5-7 is a good guess nothing you'll really notice without supporting mods. <--- Dave posting Quote Link to comment Share on other sites More sharing options...
smokin5s Posted December 31, 2004 Report Share Posted December 31, 2004 Originally posted by Formulate: depends on the cam and what ratio the rockers were you replaced. 5-7 is a good guess nothing you'll really notice without supporting mods. <--- Dave posting+1 now put a big cam in there and it'll make the cam quite a bit better... if you put bigger RR's on but don't do any custom tuning then you won't have the HP gains if you would tune it. Quote Link to comment Share on other sites More sharing options...
KlubFoot Posted January 1, 2005 Report Share Posted January 1, 2005 how do roller rockers affect performance? as in why can you achieve a gain in hp with different ratio rockers? Quote Link to comment Share on other sites More sharing options...
Guest FBody Addict Posted January 3, 2005 Report Share Posted January 3, 2005 it is the measurement of how much the rocker arm multiplies the cam lobe opening the valve more letting the piston pull more air in with less resistance as it goes down in the cylinder(so when you buy your cam it actually gives you the amount of lift w/1.5's, for chevy at least)(im tired and hopefully this makes sense) a regular rocker arm drags across the top of the valve stem, creating drag, so you put a roller on there and get less drag on the motor hopefully adding hp i dont know about your fords there as to putting different ratio rockers, but the chevy smallblock usually uses a 1.5:1 but some performance gains can be added by using a 1.6:1 big blocks can even use a 1.7 i believe in short, a quick way to give your cam a little more lift fixed the backfiring, found a huge hole in the rubber connector on my intake oh yeah, i got a fun one coming up, cyl-cyl head gasket leak, any type of head gasket recomended im thinkin graphite Quote Link to comment Share on other sites More sharing options...
smokin5s Posted January 3, 2005 Report Share Posted January 3, 2005 Originally posted by American Badass: how do roller rockers affect performance? as in why can you achieve a gain in hp with different ratio rockers?just to reiterate what John.... allot of stock SBC's come with 1.5 ration Rockers... if you change it to a 1.6 ratio, then that allows more lift on your cam.... more lift = more air which means, gas, etc... can be put into the combustion chamber which means more power. roller rockers also cause less friction thus more power.... hope that helps. Quote Link to comment Share on other sites More sharing options...
desperado Posted January 3, 2005 Report Share Posted January 3, 2005 Hmmm, where do I start with this? Oh yeah, read my sig, then finish reading this. Please understand that this may or MAY NOT be a just swap in some new rockers sort of thing. And if it's not, you will fuck things up royally!! First off, if you change rockers, you are changing valvetrain geometry. Short explanation is that the holes in the heads where the push rods come through may NOT be wide enough for the pushrod to not rub. If the rods touch the walls, they WILL bend. Second, you will be increasing the valve lift, which will also increase the open pressure of the valve spring. This will put additional load on the rocker stud, which if they are stock are pressed in. They can be pulled out by the increased pressure. This coupled with the fact that some roller rockers require guide plates that are held into place with screw in studs, it's best to get the heads tapped for screw in studs. So now you have the heads off the motor to get the press in studs pulled and the heads tapped for screw in studs. Pull the valves, and have someone pocket port the heads. It's easy enough to do and will show noticable improvements. Also, since they are apart, get some new valves and springs and get a valve job done. Yes, this is an investment, but good heads will make good power, and heads are hard to scre up when you blow a motor. So they are portable to the next small block Chevy that you build as well. Quote Link to comment Share on other sites More sharing options...
Dave1647545494 Posted January 3, 2005 Report Share Posted January 3, 2005 get a felpro head set for that 305 it'll be fine Quote Link to comment Share on other sites More sharing options...
Guest FBody Addict Posted January 4, 2005 Report Share Posted January 4, 2005 any idea the cost of having all that work done on a junk pair of stock heads or would it be cheaper to order an oem head and pull the studs and tap those for screw ins cause i think with a core charge a reman is rather cheap i know i cant use em with this engine but a pair of brand new cast iron vortech heads are 275 a piece any good perimeter bolt sbc heads on something i could pull out of a yard that would flow better then the ones on thier now, just as a slight upgrade, but still retain the 9.5:1 compression? i cannot use heads from a 350 because of the 64 cc combustion chamber that my heads lack Quote Link to comment Share on other sites More sharing options...
desperado Posted January 4, 2005 Report Share Posted January 4, 2005 Not sure where you are getting the 64 CC chamber size. Damn few small block heads have a 64 CC chamber, most are 75 or 68 I believe. If have the time to go head hunting, the castings that are the most desireable are the 461X, the 461, the 462, 291, 292, 186 and 187 and the 492. These are all the "Double Hump castings" and I have listed them in the order of how desireable they are the first ones being the most sought after and performance ready. One of the biggest falacies is the 2.02 valve in a chevy head being better for performance, typically, without MAJOR reworking of the head, the 2.02 valve will only flow as well as the 1.94 and in many times due to shrouding of the valve by the head and in some cases (especially with bores under 4.00) the block. You need to be aware of this, due to your current motor displacement. As far as cost for redoing a set of yard heads. I only know what I charge for a basic pocket porting, $50 a head. I may still have the tools to do the screw in studs which is $40 a head if I can find the tools. I do NOT have the equipment for valve jobs, so that would need to be done elsewear. Also, for 275 each, do the vortec heads have valves and springs or are they a bare head? That's not a bad price for a complete head but if you are going to need valves, springs, keepers, and the like it would be wise to add all that up to see what it's really going to cost if you are on a budjet. Remember also that the most badass shortblock, will only make as much power as the heads will allow it to. Heads are KEY to making power. The bottom end need only transfer the power to the back of the motor, but the heads are where it's at. You should be the most concerned with the heads and how they flow. Then the rest of the intake and exhaust tract. That is where the power is. The ONLY thing more important than the heads is the cam. The cam WILL dictate EVERYTHING about the motor, and in fact the entire driveline, including gearing, shift points, required stall of the convertor if it's an automatic car and launch RPM on a stick. Cam design dictates compression ratio, intake and exhaust sizing and to a large degree the timeing of the motor for best performance. So we get back to what my sig says, the long version is, buy a book, learn as much as you can about what makes em fast, and how to do it on the cheap, Here's the reason for learning to do performance on the cheap. Every car, and every motor has a budjet. Everything costs something, if you learn to stretch everything that you spend, you have more to spend. And in that reguard, you can build more for the same amount of money. Quote Link to comment Share on other sites More sharing options...
Dave1647545494 Posted January 4, 2005 Report Share Posted January 4, 2005 if you put vortech style heads on it you gotta change the manifold too. just an fyi. Quote Link to comment Share on other sites More sharing options...
Guest FBody Addict Posted January 12, 2005 Report Share Posted January 12, 2005 i knew about the manifold plate, and scoggin dickey (sp?) makes a manifold plate for the TPI motor for vortech heads, and yes, they do come direct from the general with springs, valves,etc..., and you can get aluminum heads for about 750 apiece i did some checking and found that the springs are a general sbc spring that are used on engines with higher cam lifts than mine and going from a 1.5 to 1.6 ratio should be fine on the small cam with stock springs and press in studs i have checked the pushrods for wear marks on the sides and have not seen any more scratching than what probably occured during installation, no sections or bands of wear, so i am fine there ultimately, if something goes wrong desp, it's no ones fault but my own Quote Link to comment Share on other sites More sharing options...
Nitrousbird Posted January 12, 2005 Report Share Posted January 12, 2005 Are all GEN-I SBC's and 305's push-in studds?? LT1's and LS1's are screw in studds stock. Quote Link to comment Share on other sites More sharing options...
Guest FBody Addict Posted January 12, 2005 Report Share Posted January 12, 2005 pretty sure, i can stick a pair of vise grips on one of the studs and try to turn it out, but would that spin a press in stud and loosen it? Quote Link to comment Share on other sites More sharing options...
2Turboz Posted January 12, 2005 Report Share Posted January 12, 2005 The aluminum l98 vette heads are all screw in.. starting in 87 or so.. would be a semi cheap good upgrade... Quote Link to comment Share on other sites More sharing options...
desperado Posted January 13, 2005 Report Share Posted January 13, 2005 OK, Not ALL SBC's have press in studs. Aluminum heads are ALWAYS screw in. Some of the OLD first gen stuff were screw in, but once the smog shit went on em, they got press in studs in the iron heads. THe LT-1's both the iron and aluminum heads had screw in as well. I dont' know about the vortec heads for sure. But ANY of the roller cammed motors would be screw in. Easiest way to tell, if the base of the stud against the head has sholders on it like a bolt, it's screw in, if it is a straight side, all the way in, it's a press in. Quote Link to comment Share on other sites More sharing options...
Guest FBody Addict Posted January 14, 2005 Report Share Posted January 14, 2005 the thing with these particular 305's that the heads they put on them have a smaller combustion chamber in diameter because this is not a destroked 350 the bore is in fact smaller in diameter than a standard 4" bore Quote Link to comment Share on other sites More sharing options...
twistedfocus1647545489 Posted January 21, 2005 Report Share Posted January 21, 2005 If you do go w/ the Vortec heads.. make sure that when you buy rocker arms you get the "self-aligning" variety. Also, as far a the pushrod slot in the head goes, you can buy a "louis-tool" to use as a guide and lengthen the slot yourself (it's more of a length issue... the 1.6 rockers work by moving the rocker fulcrum inboard and it brings the pushrod a little closer to the stud end of the slot)..and of course the aformentioned Vortec style intake. I think the studs (although pressed in like mentioned above) are pinned, which would make them okay for some smaller-end aftermarket cams Side note: I think the valve springs are good for .470ish lift(my memory is not so good at times though) Quote Link to comment Share on other sites More sharing options...
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