As some of you know I'm building a 383.

For the cam I have an XE230/236.

I was going to get 1.7s but I just learned I could even go with 1.8s and still have .100 of clearance for piston to valve.

Any kind of problems I could run into with .612/ .630 lift?

Obviously I will have to go with shorter pushrods to correct the valvetrain geometry.

Any other down sides?

 

Downside would be no vacuum for accessories. Rough idle and probably surging. It may also have a clearance issue with connecting rods. Not sure, haven't seen that problem but heard it's an issue with large lift cams and stroker cranks.

Incidentally, your push rods will more than likely get longer not shorter since larger cams have a smaller base circle so that they can fit through the same bearings. I find very often they stay the same length. Check them first before buying them.

 

I have the same xe cam in my car running 1.6rr's and I have surging problems in 5 and 6 gear just riding around town, but on the + side of that the car flat out hauls some A-- . Now as far as clearance goes you will have to clearance the rods for that cam and then get the rods rebalanced, I also had to clearance the block alot !!!!!!

good luck with your project

 

Sorry I couldnt resist to ask....are you two also members of the "380rwhp Stroker LT1" crew? I dont understand why you guys run such small cams in such large cubic inch engines. Hell, the 350ci engines even like cams like the gm847, cc306, xe233/239+ etc.

Edit....on the topic note. Damn, thats a lot of lift. I guess as long as you got tall valve covers, good springs, etc....that youll be fine. Just make sure you dont skimp on any of the necessary parts.

Maybe you should run some thick *** head gaskets also to prevent the valves from smacking into the pistons ...but then there goes your optimum quench height/distance.

 

excuse my ignorance.
But exactly is surgging and what causes it?

 

I have .150 of clearance with the XE 230/236 and 1.6 rockers.

Do you have a stroker? What cam do you run? How streetable is your car?

 

I wouldnt. I dont see the need. There was a reason that cam was made with that lift, more lift doesnt always = more power. You need to speak with a knowledgeable engine builder or a cam grinder, or even a head guy, you will most likely cause so much turbulence in there that you will actually hurt performance, but I could be wrong, not to mention how unstable the valvetrain will be unless going with shaft mounts.

Dont take it all from me though, post in advanced or speak with an expert.

Edit, just noticed you were the one posting about shaft mounts, so throw out unstablility, but you are still looking at large amounts of unwanted turbulence, so speak with someone like Compcams, LLoyd eliot would be an excellent guy to talk to as well

 

Its all in my profile there killer

 

I think you would need to look at your head flow sheet to see if you need that kind of lift. If the heads continue to increase in flow to 0.650 and higher, the extra lift will generate more power. If the flow stalls as .550-.600, you aren't going to see much of anything in the way of flow increase.