Posted By: n20mstr
larger magnum cam...longer pushrod?? - 09/26/10 01:33 AM
since the stock vavletrain is non adjustable...if i put a bigger cam in a magnum smallblock, will it need alonger pushrod??
larger magnum cam...longer pushrod??
Posted By: joedust451
Re: larger magnum cam...longer pushrod?? - 09/26/10 02:18 AM
Quote:
since the stock vavletrain is non adjustable...if i put a bigger cam in a magnum smallblock, will it need alonger pushrod??
Shouldn't. You can always gets adj. rockers fairly cheap, are you planning on changing springs? You really should to match the cam so you don't float the valves,just be awhare the factory bolts are small & could break if spring pressure gets too high. Are these factory magnum heads?
Posted By: n20mstr
Re: larger magnum cam...longer pushrod?? - 09/26/10 02:22 AM
all stock valvetrain, yes changed the springs, now if the cam is larger than the base circle is smaller....is it normal for there to be a little "lash: in there, gets taken up when the engine is started again and the lifters pump up that lil extra???
ALSO i lost one of the stock keepers, cant find it any where...any one got just one?? stick in an envelope and mail to me?? lol boy do i feel dumb
ALSO i lost one of the stock keepers, cant find it any where...any one got just one?? stick in an envelope and mail to me?? lol boy do i feel dumb
Posted By: joedust451
Re: larger magnum cam...longer pushrod?? - 09/26/10 04:26 AM
Quote:
all stock valvetrain, yes changed the springs, now if the cam is larger than the base circle is smaller....is it normal for there to be a little "lash: in there, gets taken up when the engine is started again and the lifters pump up that lil extra???
ALSO i lost one of the stock keepers, cant find it any where...any one got just one?? stick in an envelope and mail to me?? lol boy do i feel dumb
Yeah, ide say the base circle should be that different that it couldn't make up the difference, i had my stock cam re-ground from bullet cams, i'm sure they trimed down the base circle a tad.
Maybe Patrick will have what you need, hopefully he sees this & chims in, or you can PM him, i'm sure he will help you out.
Posted By: polyspheric
Re: larger magnum cam...longer pushrod?? - 09/26/10 04:31 PM
1. this has nothing to do with duration, so a new cam may require nothing at all.
2. higher life doesn't always mean a reduced base circle, a non-welded regrind always has a reduced base circle
3. base circle reduction needs more length: 1/2 the reduction
4. more lift needs less length: 1/2 the lift increase
5. final result depends on how the cam is ground and the rocker ratio
2. higher life doesn't always mean a reduced base circle, a non-welded regrind always has a reduced base circle
3. base circle reduction needs more length: 1/2 the reduction
4. more lift needs less length: 1/2 the lift increase
5. final result depends on how the cam is ground and the rocker ratio
Posted By: n20mstr
Re: larger magnum cam...longer pushrod?? - 09/27/10 12:49 AM
Well i stuck a feeler gauge in there, and .025 get the rocker nice and tight, A little math, 6.925 + .025 + looks like the Hughes 7.050 pushrods will work great....lets hope the stock rockers last a lil while...the cam is from Scott brown and its 580 lift , mopar perf springs
Posted By: StrkrDart69
Re: larger magnum cam...longer pushrod?? - 09/27/10 02:09 AM
With that much lift I hope you had the valve seal to retainer distance checked. Magnums do not have alot of retainer to seal clearance over .500 lift. I would purchase adjustable rockers, and use an adjustable pushrod checker to find out what length pushrod you need. Remember to check the rocker wear pattern on the valve stem tip. 
Posted By: joedust451
Re: larger magnum cam...longer pushrod?? - 09/27/10 02:55 AM
Quote:
With that much lift I hope you had the valve seal to retainer distance checked. Magnums do not have alot of retainer to seal clearance over .500 lift. I would purchase adjustable rockers, and use an adjustable pushrod checker to find out what length pushrod you need. Remember to check the rocker wear pattern on the valve stem tip.
, if you didn't have the guides cut down i don't think .580 lift will work.
Posted By: patrick
Re: larger magnum cam...longer pushrod?? - 09/27/10 01:55 PM
Quote:Quote:
all stock valvetrain, yes changed the springs, now if the cam is larger than the base circle is smaller....is it normal for there to be a little "lash: in there, gets taken up when the engine is started again and the lifters pump up that lil extra???
ALSO i lost one of the stock keepers, cant find it any where...any one got just one?? stick in an envelope and mail to me?? lol boy do i feel dumb
Yeah, ide say the base circle should be that different that it couldn't make up the difference, i had my stock cam re-ground from bullet cams, i'm sure they trimed down the base circle a tad.
Maybe Patrick will have what you need, hopefully he sees this & chims in, or you can PM him, i'm sure he will help you out.
if it's a regrind, that's how they get more lift, reduce the base circle, so there is a possibility to need longer pushrods. if you do, these are nice and cheap:
http://www.summitracing.com/parts/CCA-7828-16/
dependng on who's specs you believe, they're .018-.036" longer than stock magnums...
sorry, don't have a spare keeper....maybe try get one from a junkyard, or maybe hotroddave40, or rockauto lists sealed power VK216 for the magnums...
Posted By: MR_P_BODY
Re: larger magnum cam...longer pushrod?? - 09/27/10 02:06 PM
Quote:
Well i stuck a feeler gauge in there, and .025 get the rocker nice and tight, A little math, 6.925 + .025 + looks like the Hughes 7.050 pushrods will work great....lets hope the stock rockers last a lil while...the cam is from Scott brown and its 580 lift , mopar perf springs
Check the MP springs before you use them... I bought a
set that were good to .640 lift(according to MP) and
tested at 63# at 2" seat pressure
