I still need to buy a cam for my 305 rebuild and have selected one with these specs 420 intake valve lift, 443 exhaust lift, .50 duration 204 intake and 214 exhaust with a 112 lobe spread.

Do I Need More Or Less Cam for more street speed..... any cam grind Suggestions??

I want a cam that will make my setup as fast as possible 0-80mph and street speeds / daily driver. I think this cam looks pretty good. I want more power so I was going to switch from my 86 peanut cam to the better 85 cam grind.....but i figured I might get more speed out of a more agressive cam.

It will go into a NON-ROLLER 305 with the parts I already have: .40 over stock type pistons, 416 milled heads fully ported with 3 way valve job and new set of stock springs.

My car is a 86 tpi with 3.73 gears and an automatic. I have great exhaust with headers (not on yet) and no catalitic converter. Stock tpi setup with good intake system including: ported plenum, airfoil, gutted maf and offroad k&n airfilter.

In short...(too late) I dont want to loose power by over or under camming the engine.

Here is a pic of my heads

 

Too small - go to at least 212 degrees of intake duration IMO. The exhaust can be from 216 to 220 easily with no probs, and use at least 112 degrees of separation. Get as much lift as possible. I'm basing my decisions on 1) TPI, 2) Gear. You'll thank me when you go bigger. Get a higher stall converter - even on a stock cam, more converter helps. With a 212, I'd go no smaller than 2200, more like 2600 RPM stall (it'll stall less on a 305 most likely though).
Enjoy!

 

Those specs look similar to to a 350 grind.
A stall converter would let me use a bigger cam like that but wouldnt I have to do other mods like different valve springs and upgrade the ignition to rev the 305 motor over 4000rpm?
I have heard that the stock tpi runners and setup is not good enough to support higher rpms, is this true?

I found a grind close to what you suggested:
1) Camshaft, Hydraulic: Except Roller Lifter;.435" Valve Lift; Intake;.455" Valve Lift; Exhaust;All Durations Measured At .050";209 Degree Intake Duration;216 Degree Exhaust Duration;114 Degree Lobe Spread;1 Per Car;Mpg Performer²requires Stock Valve Springs And Hydraulic Lifter

IMO its kind of big for a 305, but I have limited camshaft experience. Thats why I have so many questions.

Whats the deal with cams that have the same intake and exhaust duration (single pattern)? Will a single pattern be better or worse for this tpi 305?
Thanks

 

IMO, still on the small side for the mods you have going on.... The duration is close to the range that should work well, but it needs more lift. You've upgraded the intake and exhaust side of the system so much it would be a shame to not take advantage of it with the camshaft.

Do you have flow numbers on those heads? What ratio rocker arm will you be using?

 

Not bad, when I chose the cam for my GTA I actually went to small I think. I could have gone with more duration and not had a hard time with it.

I bought the lingenfelter 211/219 cam. 112* lobe sep, and about .500"/.525" lift with 1.5 rockers. Now that I have my setup together, I realise I could have easily gone higher and still not gotten to outrageous with my upgraded TPI.

Probably should have gone for the 216/224 cam. With 1.6 rockers I could have had as much lift as I do with this cam. But this cam will make enough power for 12's if I get the intake/exhaust/heads to go with it. Right now its just a AS&M SS tpi setup, with ported L98 (3 angle valve job), LT4 valve train, headers and full exhaust, no cat. Probably enough for a mid 13, maybe a little better.

 

Think of an engine as a big air pump.... Of course every engine seems to be different, but in general a dual pattern cam is employed when the intake side of an engine flows much better than the exhaust side. Thus they will work much better on relatively stock setups. Upgraded components like heads, headers, intakes, TBs, etc. will tend to balance the abilites of each side of the engine's system.

Cylinder pressure also plays into which will work better on a given engine as well since the exhaust has the benefit of the piston pushing the gasses out of the cylinder and is much less dependent on the actual flow abilities of the cylinder head/headers/exhaust in comparison to the intake which sucks air in through the cylinder head/intake manifold/throttle body/carb/etc. How much pressure the engine can build directly relates to how good the engine is at evacuating exhaust gasses from the cylinders.

But there is plenty of debate on which one works best as a blanket statement. In your case I would be leaning towards maybe a slight split pattern cam but nothing too outrageous as I think the flow abilities of your setup are fairly well balanced for your target operating range for your engine.

All IMO of course and I am no cam expert .

 

The stock TPI is a better match for a 305 than 350 and works pretty well to 5000 RPM, maybe a little more. You should be able to turn over 5000 RPM with the stock ignition and vavle springs. Limit on my car was about 5700 RPM before valve float. Would you benefit from upgraded ignition and fresh springs? Sure, but you shouldn't have to make those changes unless the stock parts are too worn or weak. You should run fastest with shift points between 5000-5300 RPM with your exhaust, heads, gear, and planned cam upgrade.

 

I dont have flow #s for the heads, I basicly took all the bumps out, port matched everything, polished exhaust, trimmed back valve guides and took a TINY bit of material from the bowl area.
The head studs are for 1.5 rockers and I have new stock springs, so I wanted to use them if possible to help the budget. I was thinking of a inexpensive set of 1.5 roller tip rockers, but I have not decided yet. Id be happy to hit 5000rpm, but have never gotten there stock because of the cursed peanut cam.

I am tempted to go bigger, but I keep worrying its only a 305 and you guys are running 350's on steroids .

Whats my ECM gonna think about these crazy changes? I have not gotten into re-programming proms yet. I assume that changing to anything like different springs, 1.6 rockers, and or big cam would make the computer throw a fit.

 

Im running a 215ish - 220ish cam in my 383 qith around .500 lift:-)

Heres the best cam recommendation I can give you. How will your car be used? All street? All race? Or little street with a lot of racing? Pick accordingly and be honest about it.

TPI pukes at 5k, maybe 5.5k tops(depending on runners etc)

Bigger isnt always better, drive 300 miles a week for work, a hotcammed 350 is a POS under those conditions:-) Ask me I know, I built it and tuned it and everything in between.

Buildind a 383 now and even a smaller cam and a blower in its future lol should drive twice as nice and make more power eeverywhere, especially once I boost it

later
Jeremy

 

Quote:"Heres the best cam recommendation I can give you. How will your car be used? All street? All race? Or little street with a lot of racing? Pick accordingly and be honest about it."



It will be all street and highway, very little race (once or twice for track times only)

 

Good news!!! I found what looks like GMs original TPI performance cam. It is still for sale at scoggin dickey. Here is what it listed for 350 TPI F-bodys and corvettes. QUOTE:

"Chevy IROC-Z, 206/216Duration @ 0.050, Hydraulic Roller
This GM Performance Parts Hydraulic roller tappet camshaft was originally used in 1987 350 cubic inch Corvette and IROC-Z Camaro’s.
Mild camshaft can be used in all 1986-99 305-350 engines originally equipped with a hydraulic roller camshaft. It can also easily be used in non-roller 1986-99 305-350 enignes when used with lifter kit 12371042.
Can be used with a stock computer in most applications, or in a non-computer controlled engine.
Camshaft
Specifications
SDPC Part Number: 14093643
Manufacturer: GM Replacement Parts
O-Lap : 202/206
Lobe Separation : .403"/.415"
Lift (I/E) : 115
RPM Range : Idle-4500
Recommended Spring : Hydraulic Roller "

My 2 previous choices were close to this because I was selecting grinds that were similar to stock. All of the different stock TPI cams seem to follow the same pattern including this GM IROC cam. I am leaning twoards the 204 int, 214 exh cam I mentioned earlier because it is almost exactly the same, just smaller (better for a 305, right?) and 4 times cheaper. I would also have to buy a aftermarket roller conversion kit to get the IROC cam to work.
Also I have another pic, intake ports

 

Depends on what you want the car to do. How fast you want to go?

 

I just want to finish up what I already have with a good cam to match. So I want to pick one that will go as fast as possible without any more mods or new parts.


I still cant believe I am making such a fuss over a 305

 

I had the 204/214 cam, and a 212/212 comp cam as well in a 305. Of the 2, the 204/214 was better. I think the 212/218 that comp sells or something like that with a split pattern would work best, and I cant see any reason that duration in the 212-215 area and .450+/- lift on the intake wouldnt work real well with that type of setup. If you can get a cam with a little more lift, even better.

 

Thanks for all the replies.
Max, I like the comp cam you suggested a lot.
212 218 lift of 4.44 and 4.44, 1500rpm to 5500rpm lobe Separation 114 degrees.
And the lesser version of it at 206 212 4.25 and 4.40 lift, 1000rpm to 5000rpm lobe Separation 112 degrees .

Both are recommended for TPI motors and are listed as computer compatible. I kind of want the bigger one 212 218..... but I am worried by a quote that they had for the bigger cam Quote "Application Notes Recommended for TPI motors with modified computer."
My concerns are:
1)Will it work ok for city and highway driving without a modified computer? (I have not gotten into prom burning yet)
2)Can my stock valve springs, 1.5s, stock runners and intake handle the higher RPM range?
3.8TransAM QUOTE: "TPI pukes at 5k, maybe 5.5k tops(depending on runners etc)"
What would I have to change to get these higher RPMs up to 5500? A different runner length like the SLPs, or something else?

Please let me know what you think,
Thanks again!

 

You will need aftermarket runners, AS&M makes the best runners out there. I have them

SLP's can be made to flow just as well, maybe better but they need to be cleaned up out of the box pretty bad. Though they are better than stock.

A ported base is nice, aftermarket even better, and a ported aftermarket base is the best. ^_^

The plenum will need to be port matched to the runners for the best gain. As well as some porting around the area the throttle body bolts to. Vader has a good article on how to port the plenum, pictures and all.
___________________________________

Ofcourse, in an ideal world everyone who wished to keep TPI would ditch the factory setup and get one from www.firstinjections.com for some real power!

*note - Apparently Ken is updating the site and the usual pages are down.

 

I need to get a cam soon and still cant decide between the comp cam 206-212 duration with 4.25 and 4.40 lift or the comp cam 212-218 duration with 4.44 and 4.44 lift.

I have decided to KEEP the STOCK runner / base combo on my 305(i already port matched it)

I still need it to be a daily driver, 20 miles to work and 20 miles back home.

I will probably get rhodes lifters to help but im not expecting miracles from them.

Is this 212 218 cam to much for a daily driver 305 with some mods?

 

No.

Man, this thread makes me feel like the cam I have sitting here is wayyyy too big. 222/232 @ .050", .479int/.501exh lift, 114LSA.

Original plan was to put that into my 305 with an LT1 intake and ported LT1 heads (hopefully flowing about 260int/190exh at .500") with 1 5/8" headers, a 3000-3200 stalled T/C, and very many nicely tuned chips.

The new plan is to use this cam with the same intake and heads, possibly larger headers, and a 350 block bored .030" over with 10:1 forged pistons, also with a 3000-3200 stalled converter

 

I would probably pick the extreme 212 218 duration and around 444 lift for my 305 but I get freaked out that its too big for a 305 (even with my mods) when I compare it to the stock 350 tpi cam that is much less with its 207 213 duration and 415 430 lift.

I am going to call the comp cam help # and think I will go with whatever they recommend.

Ill post the recommendation after I get to call.

 

They always err to the small side... not that its always a bad idea, but I think you'd be good with the 212/218.

I have a LT4 hot cam I'm going to throw in mine one of these days, so dont go thinking a 212 intake duration is too much. All a 206 intake duration is going to get you is stock performance. Yawn.

 

I have a all forged 383 stroker that i am wanting to put into my 88 iroc. The specs on the roller cam are 290/300 adv duration, 222/230 @.050, .468/.480 with 1.5 rockers, 110lsa.... It has 1.6 rockers so the lift is actually .499/.512 at the valve. I've been told that this setup will not work with a prom. Just wanted to see if anyone could help.

 

Holy old post revival batman!

with a 383 you could probably get a running car out of a MAF system using that cam, but I don't hold much hope of it actually running RIGHT.

You'd need it tuned, badly. My car ran ok when I did heads/cam/intake/headers/exhaust on my TPI, my cam was a mild lingenfelter cam though, idled no problems at 500 to 600rpm. 211/219 @ .050" duration on a 112lsa with .500"/.525" lift.

There was a ton more power left in the car though.

 

I have the Comp Cam Magnum 270H Cam Kit for my 305 TPI , but its still not installed yet along with the headers also, its the - 224/224 @.050, .470/.470, 110 LSA

which I was told the this is the largest cam that can be used with stock heads and converter, and I was told its suitable for the 305, cuz I'm basically just trying to take the 305 to the limit in performance without exchanging other components over and keeping the heads.

But I'm also wondering if this cam is a bit much for the 305, or just fine for a daily street driving car.

 

The heads are 1.94/1.6 valve size. They are older small block heads. The compression is 10.5:1