gt-titan Posted September 23, 2013 Report Share Posted September 23, 2013 well i picked up a crane cam and was told that if i put it in the 305 i have that it would cause the valve to touch the piston.... it is a 465/488 lift.. 114 deg cam..... he said because its a 305 with a smaller bore(witch we know) that it would open the valves to much.....is he full of u know what ,or is there any truth to this...i dont think the cam is that big... Quote Link to comment Share on other sites More sharing options...
Mattsv8 Posted September 23, 2013 Report Share Posted September 23, 2013 Some gm old motor hit at or arround .491" best way to tell get a check spring set and dial indicator once its in. Simply install a lifter with piston at tdc 0 lash set indicator on top of the retainer. Go to .050 before max lift 0 indicator and push valve down record reading do same max lift and .050 after. Usually the exhaust is closest. The bore diameter would only be a factor for a combo with 2.10 or larger intake valve. Quote Link to comment Share on other sites More sharing options...
Green Bastard Posted September 23, 2013 Report Share Posted September 23, 2013 If your taking the heads off, get some clay and roll it out to 1/4" thick, cut some strips and lay it on top of a piston. Then you bolt the head on (with the head gasket, does not have to be torqued though) and roll the motor over. Take the clay off the piston and cut where the valves touched in half and measure. If you measure what the clearance is supposed to be or more then your good to go. Make sure to use a couple of solid lifters though on the piston you have the clay on. Fwiw, the bore size shouldn't have anything to do with how much lift an engine can handle. Quote Link to comment Share on other sites More sharing options...
SinisterSS Posted September 23, 2013 Report Share Posted September 23, 2013 so its a 224/234 @.050? first things first, is your 305 a roller setup or flat tappet? the stock 305 heads are garbage for flow, on top of that your gonna have to change out the push rods, valve springs, the money your gonna spend there you'd be better off getting a 5.7L but if piston to valve clearance is a problem you can get some notched/dished pistons, also stick with the stock 1.5 ratio rockers you change out the cam and go up to the 1.6 ratio your gonna wipe the cam lobes. The real question is: what is the ultimate goal here your trying to accomplish? Quote Link to comment Share on other sites More sharing options...
gt-titan Posted September 23, 2013 Author Report Share Posted September 23, 2013 so its a 224/234 @.050? first things first, is your 305 a roller setup or flat tappet? the stock 305 heads are garbage for flow, on top of that your gonna have to change out the push rods, valve springs, the money your gonna spend there you'd be better off getting a 5.7L but if piston to valve clearance is a problem you can get some notched/dished pistons, also stick with the stock 1.5 ratio rockers you change out the cam and go up to the 1.6 ratio your gonna wipe the cam lobes. The real question is: what is the ultimate goal here your trying to accomplish? i dont know if my motor is a roller motor....i fig it was a flat tapped....the motor is a 92 out of a camaro rs.....my goal right now is to just mess with this 305 until i get the 355 done.. im going to put a cam and gear drive in it..i just really want to play with this motor a little im not looking to build a 305 but its got a leaking intake gasket and prob leaking around the timming cover so if i take it down to fix the leaks im going to put in a cam and gear drive just to make it sound good... Quote Link to comment Share on other sites More sharing options...
gt-titan Posted September 23, 2013 Author Report Share Posted September 23, 2013 If your taking the heads off, get some clay and roll it out to 1/4" thick, cut some strips and lay it on top of a piston. Then you bolt the head on (with the head gasket, does not have to be torqued though) and roll the motor over. Take the clay off the piston and cut where the valves touched in half and measure. If you measure what the clearance is supposed to be or more then your good to go. Make sure to use a couple of solid lifters though on the piston you have the clay on. Fwiw, the bore size shouldn't have anything to do with how much lift an engine can handle. im not taking the heads off ... but thats good info thanks.....and when he said because of the bore size and not the stroke i fig he has no idea or i had no idea ....lol Quote Link to comment Share on other sites More sharing options...
Cordell Posted September 23, 2013 Report Share Posted September 23, 2013 This whole thread sounds like nobody has any idea. Let me start by saying that I have no experience modding an old 305. However, I have to agree with Craig (sinisterSS) as this is a huge waste of time, but if you are concerned with PTV clearance you'll have to pull the heads and check it. Since you seem to not care about this motor I guess you could just stick it in there and see what happens. As for your questioning some guys comments, you need to know the differences in the 350 and 305, I mean the bore, stroke, shape of piston, size of valves, and size of chamber, as this will help you understand how PTV clearance will be checked. Honestly I doubt its an issue but I don't know. Usually when people talk about 305 clearance issues they are refering to the valves being too close to the cylinder wall when changing heads. Go do some research on how the geometry effectgs the engine components in general, and then get some numbers for yourself so you can figure it out. Quote Link to comment Share on other sites More sharing options...
gt-titan Posted September 24, 2013 Author Report Share Posted September 24, 2013 This whole thread sounds like nobody has any idea. Let me start by saying that I have no experience modding an old 305. However, I have to agree with Craig (sinisterSS) as this is a huge waste of time, but if you are concerned with PTV clearance you'll have to pull the heads and check it. Since you seem to not care about this motor I guess you could just stick it in there and see what happens. As for your questioning some guys comments, you need to know the differences in the 350 and 305, I mean the bore, stroke, shape of piston, size of valves, and size of chamber, as this will help you understand how PTV clearance will be checked. Honestly I doubt its an issue but I don't know. Usually when people talk about 305 clearance issues they are refering to the valves being too close to the cylinder wall when changing heads. Go do some research on how the geometry effectgs the engine components in general, and then get some numbers for yourself so you can figure it out. ok man thanks for the info....will do.. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.