will this be too much lift?
#1
Member
Thread Starter
Join Date: Dec 2004
Location: burbank IL
Posts: 164
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1982
Engine: 350
Transmission: 350
will this be too much lift?
I recently put a crane cam in my 91 z28 (350) with a .480 lift im now wanting to buy a set of 1:6 rockers which will bring me up a little above a .500 lift my question is, will i smack a valve or how bad will i be risking valve float at higher RPMs ? I have 100% stock heads. What do you think?
#2
TGO Supporter
Join Date: Jul 2003
Location: Grand Rapids, MI
Posts: 4,803
Likes: 0
Received 0 Likes
on
0 Posts
Car: Z28
Engine: Sb2.2 406
Transmission: Jerico 4 speed
Axle/Gears: Ford 9" 3.60
Yes it will be too much lift. Factory heads tend to max out lift wise around .480". You will neither valve float or hit v-p clearance issues. Rather, your issue will be guide boss to retainer clearance. At about .480" the bottom of the retainer will hit the top of the guide boss physically halting any further opening of the valve. If the cam and rocker arm still want to open the valve beyond that point, things are going to break.
#4
TGO Supporter
depending on the head you shouldn't have any clearance issues around the valve guides untill well over .500, more like .55-.60 you will have problems with the springs being to small and weak for your application. you'd need to machine the spring seats larger, maybe, and buy springs to martch your cam. if you machine spring seats go ahead and have the guides cut down and sizes for positive seals. really a good plan to have the work done even if you don't do anything with it now since the cost is small for the guides and seats and you can use it later without needing to pull the heads. with the larger springs you'll have problems with the pull out studs, but since they're junk even for stock applications it's no great lose to replace them and up grade to screw ins. again depending on timing and the pistons you use there shouldn't be any valve to piston clearacne issues untill around .65. since there are so many variables it's always best to mock things up and check.
Thread
Thread Starter
Forum
Replies
Last Post
TX-SleeperC5
Engine/Drivetrain/Suspension Parts for Sale
1
09-24-2015 03:13 PM
1Aauto
Sponsored Vendors
0
09-23-2015 01:09 PM
1Aauto
Sponsored Vendors
0
09-23-2015 01:00 PM