Rebuilt my 350 sbc and used summit racing part # 152123 iron heads. The head said it takes up to a .520 lift. I installed a Melling 22135 cam and all the matching parts springs, retainers and keepers except for the Howard retro roller lifters. I'm also using 1.5 roller tip rockers. Did all my measurements. Pushrods seem to come out to 7.100. Spring heights are 1.720 + or - .008. Retainers to seal Clearance is .571 leased of all the valves. .571 - .490 valve lift = .081 for clearance. Problem is when I set my preload and swing the engine over it looks like the retainer is hitting the seal on the exhaust valve. This is with the checker springs. Am I doing this right? Should I trust my measurements? Cam lift .313intake .327 exhaust valve lift .470 intake .490 exhaust.
Retainer to seal measurement. SBC
- Thread starter Bubbagum
- Start date
there could be nothing wrong with your measurements or valve train,its simply that most heads are not machined perfectly identical on both the intake vs the exhaust valves, and your exhaust valves might be a different length than the intake valves ETC.
you could very easily have the valve seals installed a bit higher on the exhaust valves as the valve guide or the head casting or machine work on the heads you have or the valve stem length or the head casting could be marginally different, as most machine shops will not take the effort to make everything match perfectly, on the intake valve seals or head machine work,
shims under the valve springs and OFFSET valve keepers and OFFSET valve spring retainers are BOTH available that allow the installed height to remain the same yet move the valve retainer .050 higher WITH EITHER or .100 higher with BOTH, on the valve stem. Id suggest talking to your local machine shop machinist as to your options, simply because if the valve retainers contact the valve seals when the engine runs it will result in damaged valve seals OR MUCH WORSE!
your options are several, swap to a longer stem exhaust valve,
(while this works its expensive and requires the heads have the seats remachined)
have the exhaust valve seal area on the heads re-machined to lower the valve seal location, maybe .080
(MOST COMMON CURE)
use different design valve seals
(different brands and styles do result in different clearances in some cases)
use different shims and offset valve keepers or off set valve spring retainers or both.
(very common cure for that issue)
but ideally you want to get the valve spring retainer at full lift to leave about a .060 clearance from the valve seals
related links that might help
both offset retainers and valve locks exist that will allow .050 added height,or clearance, but be aware added space reduces the valve spring pressure, unless you use shims to get the installed height back to the ideal installed height
http://garage.grumpysperformance.co...ng-height-load-on-a-l98-383.14592/#post-77688
http://garage.grumpysperformance.co...tched-valve-spring-required.13774/#post-77425
http://garage.grumpysperformance.com/index.php?threads/what-springs.11352/#post-51835
http://garage.grumpysperformance.co...-loads-and-installed-height.10709/#post-46658
http://garage.grumpysperformance.com/index.php?threads/valve-guide-cutting.8382/#post-29239
both offset retainers and valve locks exist that will allow .050 added height,or clearance, but be aware added space reduces the valve spring pressure, unless you use shims to get the installed height back to the ideal installed height
you could very easily have the valve seals installed a bit higher on the exhaust valves as the valve guide or the head casting or machine work on the heads you have or the valve stem length or the head casting could be marginally different, as most machine shops will not take the effort to make everything match perfectly, on the intake valve seals or head machine work,
shims under the valve springs and OFFSET valve keepers and OFFSET valve spring retainers are BOTH available that allow the installed height to remain the same yet move the valve retainer .050 higher WITH EITHER or .100 higher with BOTH, on the valve stem. Id suggest talking to your local machine shop machinist as to your options, simply because if the valve retainers contact the valve seals when the engine runs it will result in damaged valve seals OR MUCH WORSE!
your options are several, swap to a longer stem exhaust valve,
(while this works its expensive and requires the heads have the seats remachined)
have the exhaust valve seal area on the heads re-machined to lower the valve seal location, maybe .080
(MOST COMMON CURE)
use different design valve seals
(different brands and styles do result in different clearances in some cases)
use different shims and offset valve keepers or off set valve spring retainers or both.
(very common cure for that issue)
but ideally you want to get the valve spring retainer at full lift to leave about a .060 clearance from the valve seals
related links that might help
sellecting valve springs, and setting up the valve train
read thru these links and their sub links https://garage.grumpysperformance.com/index.php?threads/reasonably-safe-valve-train-clearance-for-new-383-sbc-cam-instal.13109/#post-110492 https://garage.grumpysperformance.com/index.php?threads/valve-train-clearances-and-problems.528/...
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valve spring installation questions
I am in the process of installing the required springs recommended for my cam on my vortec heads. My first question is, on a cast iron head do I need to add a hardened steel shim to every spring pocket to protect the head or can I install a spring directly against the spring cup if the installed...
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valve train clearances and problems
you might want to read thru these links and sub links it will help you avoid costly mistakes http://www.summitracing.com/parts/pro-66830/overview/ https://www.harborfreight.com/multipositional-magnetic-base-with-fine-adjustment-5645.html...
garage.grumpysperformance.com
both offset retainers and valve locks exist that will allow .050 added height,or clearance, but be aware added space reduces the valve spring pressure, unless you use shims to get the installed height back to the ideal installed height
http://garage.grumpysperformance.co...ng-height-load-on-a-l98-383.14592/#post-77688
http://garage.grumpysperformance.co...tched-valve-spring-required.13774/#post-77425
http://garage.grumpysperformance.com/index.php?threads/what-springs.11352/#post-51835
http://garage.grumpysperformance.co...-loads-and-installed-height.10709/#post-46658
http://garage.grumpysperformance.com/index.php?threads/valve-guide-cutting.8382/#post-29239
reasonably safe valve train clearance for new 383 sbc cam instal
how much lift can one safly in a 383 with speed pro flat top with 2 valve relief pistons with a quench of .038 before you have to really worry about PVC. i know you should really check any time you change to a bigger cam my buddy has a vega with a 383 in it and its a pain to get engine out. its...
garage.grumpysperformance.com
youve installed 1.6:1 ratio rockers and the pushrods rub...
youve installed 1.6:1 ratio rockers and the pushrods rub...in the guide slots in the cylinder heads, this is a comon problem,easily solved... YOU NEED A louis tool, YOU WANT ABOUT .060 CLEARANCE, IT MAKES THE JOB EASY https://www.summitracing.com/parts/pro-66485 its used to hold a drill in...
garage.grumpysperformance.com
both offset retainers and valve locks exist that will allow .050 added height,or clearance, but be aware added space reduces the valve spring pressure, unless you use shims to get the installed height back to the ideal installed height
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