First I have a 92 Camaro B4C with a 355 TPI, world class T5 , it has 081 heads on it now and I have a set of 416s laying around that I ported and polished, with 1.94 in/ 1.5 ex, milled .010, and am looking for a cam to install with my engine rebuild due too a bad piston slap from when I bought it a month ago from the previous owner. should i increase the combustion chamber size after cc' ing the heads to lower the compression a little, possibly get the 350 head gasket and check to see where i have extra room to enlarge the comb chamber?
main thing is Im worried about valve clearance, how much lift can i have without worrying about the valves getting blasted by a piston. Also with my high compression what type of duration should I look for, ive read 112 LSA is best for the TPI
I plan to port the intake, runners and plenum, it alreay has a K&N intake, airfoil, gutted air boxes, headers with dual cats through single muffler, and plan to install a 3.73 posi i have, also plan on getting full MSD setup... also have adj. fuel press reg
but for right now what type of duration and lift numbers should I be looking at for a cam, do you consider this mildly modified like i read for cam selection charts that say "for mildly modified engines" or should I be looking for more than mildly modified cams

thanks for any help
tim

 

well i just bought this one off of ebay

int= .479 Exh.=.501 with 1.5 roller rockers

Dur.= 222 232 @ .050

what do you think?

 

What's the LSA?

Unless the cam was specifically designed for TPI, I'd guess your TPI won't be too happy with it. But, some PROM tuning should make it happier.

 

ya it was designed for TPI
LSA 114
what do you think
Speed pro 1152R
specs link

 

Hey TexasB4c are you going to make it to the houston meet this saturday? Sure would love to you see that car of yours.

 

the car is out of comission for the next month or two while i do an engine overhaul, i bought it with a bad piston slap, then i need to get a paint job and do a little bodywork...
keep me informed on any other upcoming events..... youll see me a tthe track as soon as i get it finished
BTW do you know where i can find the Houston Raceway Park safety rules and tech stuff the link at their website for all that stuff doesnt work

tim

 

ok i just got done cc'ing my heads (416's) and found them to average 65cc, they were milled .010 i ported and polished them, installed 1.94 intakes and unshrouded the comb chambers
does 65cc sound right? i had a mL dropper and had to convert it to cc and found out that mL are pretty close to cc's so that was a waste, am i right about 65mL equaling 65 cc?
what type of compression ratio will i have with a 355 and and 65 cc combustion chambers?
and from the previous question do i need to worry about max valve lift since i have a hydraulic roller setup?

thanks
tim

 

You need to worry about the valve lift, but not because a piston is going to hit a valve.

You will almost certainly have the retainers smacking the top of the valve guides, if not coming uncomfortably close to it. From what I've been told, you should have atleast a .025- .035 gap for comfort. Don't quote me on that though, I'm not sure.

By the way, you didn't mention anything about valve springs. I sure hope you weren't hoping on running that cam with factory valve springs.

Once you get beefier springs (neccessary, not an option), you are going to pull out your rockers studs since the factory ones are pressed in. You can either machine the heads for screw in studs, or pin the rocker studs in place with roll pins. That will keep them from pulling out.

Do a search on google for compression calculator, and you'll be able to figure out your compression. Your going to need to know more than the infor you have posted though.

As far as the cam, its too big for TPI. You will make more power with a smaller cam and take advantage of the strong bottom and midrange. Your current cam peaks when the TPI falls on its face. When your manifold works well, your cam is starting to make power. Not an efficient combo. Especially if you aren't planning on doing some prom work.

Any way, thats just my .02.

 

thats a little big for a mild hop up.
It will probabily require chip tuning.
TPI systems don;t like increased overlap (it confuses the computer)
That cam would be for a max effort TPI with a high stall converter and high rear gearing.

I would get one with about 210-215 intake duration and 218 220 exhaust duration max.

Stock TPI is all about low mid range torque keep the cam small so its on the same page as the induction system.
.501 lift will require new valve springs and may require guide boss maching to get clearance (retainer/ seal)
This is more lift an you need.

 

If your 416 heads are now 65cc's (with the sweeped out chambers) than your compression ratio will not be too high on a 355ci motor with flat top pistons.

the 416s will work, but for a TPI motor I like the centerbolt valve cover heads. (081/083)
stock 350tpi motors use the 083 head (64cc-1.94x1.50))but the (305) 081 head (58cc 1.84x1.50) will work fine as long as you up the valve size. Once you've fitted these heads for the large valves the chamber size will also increase ( deshrouding)
They will flow the same as ported 416's or ported L98 083 heads would with equal valve size and porting as all the ports are esentually the same.

So essentully they all have the same performance potential
(with mods) but the centerbolt valve cover heads are a direct fit to your TPI car. And the valve cover gaskets don't leak.

 

im not sure what type they are but ive got dual springs, the type with the center coil also, i plan to have them checked also,
what type of rocker studs do i need to get, i plan on getting roller rockers later on
lets see......
i plan to get 3.73's for a broken 3.73 posi i have on my porch LOL
and theres a local guy from the boards here that does chip tuning so i plan to get that done too, im a student at UTI so ill be running the dyno while tuning it hopefully and ill be posting my results so everyone can see, and as i do more ill post more dyno ...... and track times
well im stuck with the cam mentioned above...
i saw all the cams tpis had and looked at the hotcam and some other TPI cam specs and went with this one which had a little more than the hotcam and a little less than the ZZ 9X by TPIS

int= .479 Exh.=.501 with 1.5 roller rockers

Dur.= 222 232 @ .050

i have headers with dual cats flowing into a single flowmaster, ill be doing a flow check on those 416 fullly ported and polished 1.94/1.5 heads and ill post the results for that, and ill be porting the plenum and runners, the air boxes were gutted from before with K&N filters, and i just bought ram air boxes off ebay for 14 bucks, i have an adjustable fuel pressure reg. .......your saying all that wont be enough flow for the cam I bought?
if not what else could i do besides getting a mini ram or super ram

thanks for the tips so far
tim

 

It's not so much a matter of not enough flow. Well ported 305 heads will flow enough but that cam is getting to the radical side of a TPI motor. TPI motors are all about midrange torque. The cam timing has to match the intake manifold tuning effect. Once you get that big in camshaft you need to shorten the runner length of the intake to work together. (LT-1or super ram manifold) Porting the plenum and runners will help flow but the tuning (runner length) is all wrong. The larger duration cams that TPIS use in their modded motors are more for the Mini Ram or a Super Ram.

For roller rockers with polylocks I would install screwin studs. They come in 3/8" and 7/16".

For upgraded ball /gambnut rockers with or without a roller tip I would just pin the stock studs. If you plan of 1.6 rockers be sure to lengthen the pushrod slot in the 305 heads a little.

 

guess ill have to have to try it out, i cant afford adifferent cam now, ill post my results to see how it goes....
speed pro has it listed as 2000 - 5500 rpm range with fair idle
well im only paying 91 w shipping for the cam

thanks so far
any other suggestions would be great

tim