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rocker clearence problems

6K views 11 replies 7 participants last post by  painted jester 
#1 ·
i have built a 383 stroker sbc. my problem is my aluminum heads have big *** springs and my rockers are rubbing on my spring retainers . idont have money to redo the springs , i have competition products aluminum heads stainless valves big *** springs and aluminum rockers which i have ground on for clearence on spring retainers . how much can i grind ? and will valve caps help me to corect this issue ?
 
#2 · (Edited)
I little grinding on the rocker is probably ok but I would not have done any grinding. Next time sell what you have and buy the right ones. Am I reading this correctly...you ground the retainer? or the rocker? Are you sure you have the proper retainers for the springs? A pict would help a lot

Scorpion has an aluminum roller rocker than will clear large springs.
FOR EXAMPLE...IF you're running guide plates and a want 1.5 ratio use Part number SCP1000 for full sized and SCP1037BL for narrow. The narrow help clearance problems with center bolt valve covers. Both will allow the use of a 1.625 diameter spring.
 
#3 ·
idont have money to redo the springs
Then where is the money coming from to fix the motor when the whole shebang goes BANG?
Premium rockers such as CompCams, Crane, Iskenderian, Scorpion, Harland Sharp, Crower and others will have plenty of clearance for big springs and retainers. Offshore rockers, not so much.
 
#4 ·
Valve lash caps have been used on Ford and Mopar for years and I use them on GMs they save your expensive valves tips from wear and give a little bigger surface area for the rocker to ride on! But your valve tips must be high enough so the caps don't hit your retainer locks and you may have to get shorter push rods depending on valve train geometry and the thickness of caps needed !
But the best way you should do it is get the right rockers!!

Jester
 
#5 ·
A list of the actual parts as in whose heads, springs and retainers, and rockers would be helpful. Different makers of parts need some different solutions to interference problems so it's good to know what we're starting with.

Before grinding on the parts the question another question which is did you set the sweep on the stem follow this tech article >>> COMP Cams® - Sorry... <<<. Getting the valve train geometry and the push rod length correct is the first thing that needs to be done. Some aluminum heads require a .100 inch longer push rod just as a starting place for this excercise. If you're currently optimized a lash cap can help but that requires going back through the push rod length exercise. Anytime you have heads with .100 longer or higher valve stems than OEM you also run the risk of not enough thread lenght on the rocker studs, just be aware that this can happen, it doesn't always mean this occurs. There are longer studs available if necessary. You will need an adjustable push rod checker for this and if you're running really stiff springs you may need to pull it apart to put checking springs on because checking push rods are not as strong nor as stable as regular push rods so they can bend or break when pushing against heavy spring pressures.

Grinding on rockers, while done, gives everybody concerned the worries, these things are highly loaded and do break. Grinding removes metal needed for strength and leaves scratches that are stress risers which is a place cracks start that lead to part failure. Same with retainers.

Bogie
 
#6 ·
Grinding removes metal needed for strength and leaves scratches that are stress risers which is a place cracks start that lead to part failure. Same with retainers. Bogie
Yep, cracks don't start down inside the part, they start on the surface of the part.

Polishing and shot-peening will go a long way toward insuring the structural integrity of a stressed part.
 
#7 ·
I'd find out what springs are.. you didn't say what type cam you are running.. but if the heads are set up for a roller cam and you try to run a flat tappet.. you'll think getting the correct parts now is cheap..
the springs should be matched to the cam.. start with that.. what cam.. and what springs came with these heads (open pressure and seat pressure and at what installed height) then see what the cam grinder is calling for springs.. they'll list what open/seat pressure to use with cam..

start there.. you might be changing the springs anyways.. I'd never grind on a rocker.. seen tomany break..
 
#8 ·
I ordered Patriot heads a few years ago, they showed up with a big spring that wouldn't clear my Harland Sharp rockers, springs were for a big roller, I called, they blew me off, I called back, name dropped Yellow Bullet, they sent me new ones with the right springs, t-shirts, stickers, and a packing slip to send the old ones back no charge. Was kinda funny
 
#9 ·
i ground on the rockers which are pro comp 1.5 roller rockers . the geometry for pushrod length is correct , i had the engine built at rams racing engines but have always had this clearence problem . he never made it right by me . it was built in 07 and i havent even put a thousand miles on engine . my heads are porofessional products angle plug aluminum , cam is pro comp .05 under for stroker crank clearence 515 lift in. 505 ext. only problem is rocker to retainer clearence . thanks for your reply !
 
#10 · (Edited)
no help.. what springs.. what part# rockers, if the heads were fully assembled units what part #
you didn't answer if the cam is roller or not..
how do you know the geometry is correct??
smaller base circle cam and alum heads will= not standard pushrods..
never mind if the engine deck was milled..
something's not right.. where does the rocker roller touch on the valve tip through out the whole motion , you might need to put a solid lifter in one spot and turn it over by hand, as the monster springs will bleed down the hyd lifters give you a false reading..
I'd break down and for *****s and giggles order one comp rocker (35-45 bucks,) and not the cheapest one either.. put it on and see if your problem is gone.. if it is.. you know you need new rockers.. buy a set and you now have one spare unless you have a buddy with a rocker hanging around to use to check..
my gut says the heads are units set up for a high lift roller cam. and your running a flat tappet.. and the spring installed height is to high
 
#12 ·
oldbogie:

You mentioned valve tips being .1 longer! Ive had a customer that tried to send back a set of aluminum heads because the valve tips were too short!! They were a deal from E.BAY and he couldn't get his money back.

Ive also had a set of heads done for a 440 Mopar with rocker arm shaft valve train where they came back with the vale tips different lengths higher then the keepers when checked with a straight edge, I sent them back to the machine shop and instead of fixing the problem they ground the tips to level them out! And I couldn't install Scorpion roller rockers that normally would have lots of clearance and even the Mopar lash caps hit the keeper locks!

If the OP could post some pictures we could better judge his problem!

Jester
 
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