rdmypny

X303 i have an E303 and i want the X cam it hits pretty good but i want a little more

Joel5.0

Always, always check for PtV clearance and second MJR46's. BTW.... total valve lift has nothing to do with a PtV problem possibility. If he's a beginner, he needs to get exposed to the real requirements to set his engine right, not patronize shortcuts that could become surprisingly expensive.

mjr46

Please stop with the misinfo!!! if you are refering to a small cam as smaller than the stock h.o cam I concure but any choice above that requires matched components or expect less than desirable max performance out of your mismatch of components, and lift will have nothing to do with Ptv the stock h.o springs are barely adequate to handle that cam, I've already attempted such early on and found out I couldn't get past 5500 without floating the valves with an e-cam and stock springs......and yes as lond as your not building a race engine with .600+ lift you still do have to worry about all I stated!!! wanna know what would of happened had I not checked for ptv like you stated since my cam was less than .600 lift (comp xe 282 cam of .565/574 lift)......had I followed your advice knowing better, I'd of destroyed my heads and pistons, I need not go any further explaining that one.........with cam swaps ptv should always be checked because it's not about lift but cam timing and when the opening and closing of the valves are occuring during the piston cycles.....max lift doesn't occur at tdc...........beginner or not it is key to understand why checks are made, there is no such thing that wham!! after reaching a certain level of performance and cam selections that all of a sudden you now need to be aware of performing proper checks....just some food for thought

lxman1

My stock 163K valve spring let my E303 got to 6200 with no float.
Probably won't do it forever, but I usually shift @ 5800 with no problems.
The E303 is an old design but would work pretty good with your application. It's is really strong from 2500 to about 5800 in my car, but I have stock, untouched E7 heads and an budget intake (Explorer Cobra style) with a 70mm MAF and 70mm Edelbrock/BBK TB.
If someone would like to donate a set of GT40X heads or something that doesn't require piston mods, I would greatly appreciate it. Having a family and raising a handicapped child, takes about all of my engine fund money

87Stallion

THanks for the info guys. I still haven't made up my mind. I dont want to sacrifice low end to gain on the big end.

Venomantidote95

ok well since lift dosent have any affect on ptv clearance, then you could have a valve hit the piston without the camshaft in the engine???? if you put your cam in and preset your rocker adjustment and put number 1 to tdc and completly rotate the camshaft (timing chain removed) and not have clearance issues you can have them at normal engine running perameters? ie: normal vlv timing (duration) id ic/ eo ec please enlighten me i`m fairly confused! i was pretty sure if a vlv wouldn`t hit at tdc then it wont hit anywhere from 4-40* b4 or after tdc! if the piston isnt there to be hit how can you hit it? if you can better help me understand your veiw please elaborate on the subject.

Joel5.0

Check this write-up on the subject, it even has a simulation of the valve events vs. piston position during the exhaust-to-intake cycle changeover cycle (overlap), which is the real "PtV Danger Zone".... as shown below.

Venomantidote95

taht is a great article for a domed piston setup, every diagram shows a dome piston, his stock engine dosent have domes, and the part about checking clearance if you push on the rocker additional length (lift) and make it hit what else can you ask for! teh example was i believe ex vlv fully open and intake vlv starting to open (overlap), and push extra on the ex vlv ?? go figure.. as for the stated spring pressure different subject from mjr46 yes old worn out springs are (worn out) get new ones, but i havent had a case myself or heard of one where an e cam caused ptv problems, i absolutly agree with all this in a dome setup just cant digest with flat top vlv relief pistons that is the reliefs job unless you have too great a lift! with the different angle heads i could see possible issues but not a normal consistant problem, but i am young and have less experiance than most on here probably, only about 8yrs, only build 9 complete engines with more than i can remember HCI swaps and have never had and issue but to each his own! i know what has worked for me have a great day gentlemen!

mjr46

I have .200 dome pistons in a motor of mine and the dome has nothing to do with ptv vs the flat top becasue of where the placement of the dome is on the pistons I have. The relationship of the valve reliefs on my .200 dome set up is in the same locations as my 347 flat top pistons........the blanket statements with which you made that have been taken issue with are
"As long as your not building a race engine with a .600+ lift cam you dont have to worry about all this " I don't even know where to begin with that statement????? all I can say is so much untruth in that and it may be due to a lack of understanding of what the purpose of such checks are.......and this statement "you wont even need to check piston to vlv clearance!"..........irregardless of cam size I don't teach nor preach improper or unnecessary techniques.....I do this for a living not for kicks and giggles...maybe with your small builds the checks have been pointless from your view but at what point will you see the need...most likely after you have screwed up an expensive engine because you failed to understand the importance, the point I am trying to make is the theroy and checks is the first step anyone should learn in their progression to becoming a good technician or even a backyard builder.....this is why there are so many crappy techs out there now!! they don't understand theroy and operation....Please don't take offense to any of this it's meant to be informational.....and btw early on in my carrer I felt it wasn't important to do all checks and with a 512 lift flat tappet cam I thought ptv was for dummies and now have saved in my tool box as a reminder 2 bent push rods and a destroyed cam