Cam question

[prophiseer]

Ah, well . . . didn't really want to start another thread on this, but anyways . . .


Seeing as how I'm planning on relocating to a different place of employment within the next few months, I was wanting to go ahead and finish up some upper end work for my 3400 GA while I still have access to valve grinding equipment, porting equipment, and great deals with our neighborly machine shop.

So, along with porting a set of heads and manifolds that I have, matching them all, installing LS1 springs and doing some valve work . . . I was wanting to throw in a mild cam. I figure I'll save a more aggressive cam, along with obtaining a 3500 UE for while I build up the spare 3400 block I've got laying around, which won't be for a while. I'm just looking to squeeze a little more out of the stock 3400 motor without having to swap engines yet.

My question: what grind would be recommended for a little extra umph in the motor's upper end? Preferrably something that won't cause me to HAVE TO reprogram the PCM (DHP unit, BTW), as I currently don't have access to that kind of equipment (or a chasis dyno for that matter - and the few shops that do around here charge ungodly prices for access [think $300, just to put the car up for one pull]). I still plan on using the OE 1.6 rockers - although, I am toying with the thought of 1.8 - and I'm not looking to have to order any custom pushrods, if I can safely get away with the stock units, great; but if not, then I can measure out what I'll need.

So, any opinions?

[gectek]

well the prob is you wont be able to run higher lift like i am with the LS1 springs...IIRC. but i think running slightly higher dur like maybe in the 203 area and lift in the 470-490 will give very impressive gains with no idle problems or reprogramming. i am looking at 206/210 dur and 500 lift for mine using the 1.6 rockers, and i know thatll give alot better top end and keep my good bottom end with better midrange power. where r u looking at the 1.8s from? very interesting. i wouldnt go that much though, IMO 1.65 or 1.7 would be more than enough as long as they are roller style. staying with the lower dur and higher lift will keep the smooth idle and be better in the mid and high.

[prophiseer]

that's pretty much what I'm loking to do. The 1.8 rockers was just an idle thought really, as I feel the stock 1.6 is perfectly fine for this project. I'm not going all-out, hell, I don't even plan on pulling the motor for a cam swap.

[gectek]

yah just drop it down a little and take the cover off and do it through the wheel well. thats what im gonna do. also look at the lifters to make sure they are ok. with my mileage im changing all of them out. and ill have to look at the bearings as well, but with my normal oil change interval im hoping they will be ok.

[prophiseer]

same here, I figure if need be, we have the equipment to cut a portion of the front "frame" out from the tire well, then weld it back up. I'm planning on swapping in a new set of OE lifters as well - when the LIM gasket blew a year ago, they were alright, but 160k miles now dictates otherwise to me.

So, a bit lower duration and higher lift, huh? And you'd figure that strengthens midrange and improves upper?

[gectek]

well i know really, i am taking engine rebuild and theory this semster and basically designed my own cam with some help. so give this situation where u keep same duration, then u gain lower end power and also the higher lift helps the mid and top end...so add a little duration in there and itll help out the mid and top more, but keeping the dur advancement small and keeping the lift at max will help out the entire range.

[prophiseer]

yeah, I understand. We don't really get into cam setups at our shop, so I'm not all that experienced in this area, y'know? Anyways, I was kind of looking for numbers that others have run . . . y'know, a setup that defi works. The car will still be on the street, too, but anyways . . .

So, between what research I've done, and your recommendation, I'm thinking 205in/210ex with a lobe lift of 305. Don't think I can run the LS1 springs, though, eh? But this should run the stock lifters and pushrods without a problem, unless I'm wrong . . . You get the impression, though, that cam setup will work alright with the heads having been decked .020"?

[gectek]

yah thats no prob on that...the .020 wont raise the CR that much or take the head height down too much either...just make sure to get custom pushrods. and i dont think anything over 500 will work with the LS1 spring. also ur going to the outer limits of the computer with that much dur...i would stay on the safe side with about 206 on both. or 203/205

ull def need custom rods or else u may not get all of the lift u want from the cam...and the lifters will work no prob. i think the coil bind on the LS1 springs wont allow more than 500, but 300 lift will be ok IMO, what i would do is check coil bind and then go with max lift, because the lift will have no driveability issues, its the dur you should be worried about. i would go with close to max lift to get the power nice...i think i would go with 480 up to 490 if you can.

[prophiseer]

Seeing as how I'm not sure right off the top of my head, how do you figure what the lobe lift translates into with 1.6 rockers?

Do you really think there's a need for a slightly longer duration on the exhaust with a stock bore and stroke? And I figure the lift I should keep the same for both intake and exhaust lobes, correct?

As to the LS1 springs, it's not like I NEED to run them to be happy . . . I'd rather go with whatever will be best for the setup.

Damn, sorry to sound so repetitive on this, just trying to make sure I get all the figuring straight.

[gectek]

lobe lift x rocker ratio equals actual ratio lift at the valve

[SappySE107]

http://www.60degreev6.com/store/index.php?act=viewProd&productId=70

updated with more info.

[gectek]

the ls1 springs are ok...also the duration will help top end alot where these engine choke out, and with a higher flowing exhaust and intake, the dur and lift will help that out alot. the exhaust and intake lift dont have to be the same, it really depends on the setup for the lift and combination, but staying the same doesnt hurt really, alot of people like to run more exhaust than intake and some intake over exhaust, but its really up to you and what you might find out in a simulated dyno. but if you are more comfy with the lift the same then thats ok, i dont see it hurting this engine since you arent trying to squeeze every ounce out of it.

[gectek]

the 1211 grind looks good for what you want...actually pretty perfect. but for some reason i want a little more lift. thats just me

and also i like a little wider LSA for stock and just in case i wanna run any nitrous

[prophiseer]

Gec ~ thanks for all this info so far, it's really helping iron-out a lot of my thinking on this

Sappy ~ thanks for pointing that out, I haven't look at the site store in a long while


Yeah, I was thinking the 1211 would be alright, especially if I do decide to put those shiny-new LS1 springs I've got laying around to use. I'd say the lift should be alright for my taste in this endeavor . . . at least, the combination of a mild cam, plus ported&matched heads and intake manifolds, the polishing of the exhaust manifolds, plus the valve work I think will really yield a highly noticeable difference over how the car runs now with a mostly stock setup. I'd like to get my hands on a 62mm TB (over my 60mm unit), and I *might* bump up the injectors a notch from 19# to 21# - I doubt it, though.

[gectek]

i would run the newer FPR with the newer injectors and harness, and IIRC a new cam sensor. thats me though. it would be running better with those at a lower %DC than ur lower pressure ones...but that may take some tuning IDK on that one