roller rockers?

been looking at some and i first off let me say that i dont know much about them. What is better? 1.5, 1.6 or 1.7 ratio? i would generally assume that 1.7 is.

so which ratio is "better"?

 

Its mostly what you want. 1.7 will give you the most lift, but do you have the springs for it? It will not effect duration or any other measurement.
Alot of guys do run a higher ratio on the exhaust side just to make up for poor ports.

 

1.7 will make your cam feel bigger. But you will DEFINITELY need to make sure your heads and springs are set up for that much lift before you slap these bad boys on.

I love mine, but rebuilt the heads to handle the extra lift.

 

FOrd all come with 1.6, chevy uses a 1.5. As long as you dont have a huge cam you can eun the 1.7 rockers without worring about your springs or anything else.

If you cam is at .500 or smaller and you dont spin the engine above 6500-7000rpm, you should be fine.

 

ive been looking at 1.5 which have a max of .600 lift on the cam, and max 550 lbs for the springs. The cam i got i have no clue what it is but i know its brand new in the engine when i bought it. Im thinking about having my heads rebuilt and putting 1.5's rockers on it with 430 lb springs. Would that be good??

 

You should run the rockers and springs recomended by the cam maker.

 

fords use 1.6 rockers stock. so all cam specs are usualy based on 1.6 rockers. there shouldnt be any problems going to 1.7 roller rockers. the stock springs should not have a problem. if your changing springs get the ones recomended for the cam your using.

 

Dont use the 1.5 rockers...You will loose valve lift with em.Go 1.6 or 1.7 ratio.I have 1.7:1 magnums in my 302 mav with .487 int/.496exh lift with plenty of room on stock 58 cc heads and flat top pistons with a zero decked .030 over stock block.

 

hmm alright. I have no idea what cam i have though. I bought the engine from a guy who got it from a guy that died. Its been fully rebuilt and i took it all apart and found out its as clean as an engine could ever be. The guy that died put a new cam in it and like i said, i dont know what it is.

 

You can use a degree wheel to find out your cam specs and measuring lift is no problem. Of course this is usually done on engine assembly so its not very practical if its all together. Used to double check all cams I installed. Wow thats a long time ago.

 

If you don't know what your cam is you can messure the lobe lift of it at the lifter ,(from with the lifter down all the way on "base circle of cam" to max lift point of lifter with a dial indicator) you may be able to even rig a way to check it at the top of the push rod if the engine is together and in the car but I don't know how acurate the reading will be. then you can multiply that number by whatever rocker arm you want to use to get your max valve lift(IE; .450 lobe lift x 1.5 rocker = .675 valve lift)then you must check piston to valve clearance from that lift. wich usualy is the closest on most cams between 10degrees before top dead center and 10degrees after top dead center in overlap of the camshaft. and you also need to check for spring coil bind ,spring pressure open,valve stem seal clearance, and rocker arm geometry to the valve tip just to cover the main things to check for, not that odd things like push rods rubing etc. can't happen, but are not as likely doing a rocker swap. and as a general rule stay .100 of an inch away min. from piston to valves,sping to coil bind, retainer to valve stem seal at max lift, etc. some race only stuff can get closer but most street and performance cams don't even get that close, as most have said the ford rockers used mostly are 1.6 and almost always have room just to put the 1.7 rockers on, adjust and go with out problems. but its a good idea to check everything. best of luck with your rocker swap.

 

dang, thats a lot of stuff to check. If i were to take the whole engine into a machinist, would he be able too do all that? Not saying im going to do that, but i do want my heads port and polished and all that as well.

 

honestly theres about a 90% chance that you can put 1.7 rockers on and have no problems with the springs. if it was me i would just put the rockers on. once you get them bolted on just turn the motor by hand. watch the springs to see if they bind or still have a gap inbetween the coils. while you turn i over see if you feel the motor hit any solid hard spots. that would be the valves touching the pistons. one again i realy doubt that you will have any problems with just puting the 1.7s on.

 

yes a engine machinist should be able to check all of that if you took your engine to them. and some do port and polish work on cylinder heads as well, but see who is good in your area and if they flow test your heads before and after any port and polish work to your heads on a flow bench. if they do custom or performance work, some are just production type rebuilders. I am not trying to over load you with things to do ,but just give you an idea on how much can get involved in a project such as changing the rockers if you are unsure if all the components will work together its a good idea to check them to see. as much as stuff costs these days I hate to see any one spend hard earned money on something to later have problems that maybe could have been solved before it cost them more money.and I agree chances are you can put the 1.7's on and not run into a single problem,I'd put them on and start turning the engine over by hand and start checking to see if you have any problems with the springs binding or anything else and go from there.

 

Most cams will have a grind number on them.