N8MAN1068

I've finally narrowed myself down to 2 cams:

cam 1.) 224 int., 234 exh dur. @ 0.05 , .477/.490 113lsa

cam2.) 224 int, 234 exh dur @ 0.05, .465/488 112lsa

engine:
85 305, int/exh gasket matched alum. L98 heads, hooker 2460's with a mpp2 right before the cat. converter. planning on a lt1 intake this spring, 3.42 rear, stall will be matched to the cam by phoenix trans., going to be going on the juice at the track too.

no worries about emissions, and i'm playing around with tunerpro_rt for reprogramming.

thoughts?

thanks guys.
and yes, i did say a 305.

FlamedROC

My vote is on the #2 cam...seems just right for a 305!!

Jason

gixxer9

Your power will be soft, especially down low, with either of those cams until you install the lt1 intake. Even then it probably will not be optimal because of being a 305 (small bore, 350 stroke) 305's just do not like to rev. You would think it'd be a good, high revving motor like ford's 302, but the 305 is the opposite of the 302. You'll be ok though, but can I ask whats keeping you from going 350? My IROC was a 305 originally also, and it just didn't seem to be worth the effort to build a 305, in part, due to the above limitations. I'm not saying that a 305 can't be fast, but want to point out that the entire package must work together flawlessly, and the heart of that package is the cam. Personally, I would go with a hot cam which would work well with the lt1 intake, and moderate heads. Good luck with whatever you decide to go with!

gixxer9

I forgot to mention that the cams you are picking from would also like at least 9.5-1 compression. What's the compression on your motor?

JakeJr

Lot of cam for a 305. Plenty of trade-offs, but I'm guessing you're aware of that.

Jake

Roostmeyer

iTrader: (3)

Iron or aluminum l98 heads? Stock bottom end? For a 305 this seems like too big of cam, expecially before you get the lt1 intake. Throwing the numbers in desktop dyno I'm showing peak hp at aroung 6500, probably a little high to stop valve float with hyrdaulic flat tappet friendly springs. If you made it a solid tappet or roller cam it would peak around 6000. I'm thinking about putting a similar or slightly larger cam in my 406 build until I go roller but i really don't know how a big hydraulic flat tapet cam does above 6000 rpm with the weaker springs.

N8MAN1068

alum. l98 heads.
I ran the same info through DD2000 and mine says it's making peak at 6200rpms, which is fine, b/c it's just past where i want it to be, but 6500 is too much.

staying 305 b/c i already have one, and haven't had time to go find a 400sbc yet. Yet. Plus, I want to see how much a stock bottom end 305 can take before it goes boom.
the car won't be ran until it's finished, so no worrying about 'this cam is great for lt1 intake, but will suck for tpi, etc etc'. i can't go hot cam b/c it's a pre '87 block...hydraulic. not hyd. roller. the springs in the heads are left over from a comp. 280? cam swap.

stock compress is 9.5-1, but may drop a bit with the alum. l98 heads. I plan to run some thinner head gaskets to combat this. I'd shave the heads, but once i'm done with this setup, i'd like to sell them.


cam 1. is a comp. cams nitrous hp. cam, since i've heard they make incredible gains w/ n2o
cam2 is an elgin recommended by competition products($50!)

JakeJr

You can easily go with a retro-fit hydraulic roller setup in your block. I've been doing it that way for well over 20 years, long before GM came out with hydraulic roller blocks.

Remember, too, for the best times you shift above your power peak; that's why it's so important for the engine not to fall off sharply after peak power.

It's the torque and HP the engine will see AFTER the shift that keeps the car accelerating briskly. The old "area under the curve" lesson.

Rule of thumb is 10% but trans gearing effects that.

Jake

N8MAN1068

what 10% rule of thumb?

tranny wise, i have a th350
i always figured in a 20% loss from fly to the wheels, if that is what you're referring to as a rule of thumb...

JakeJr

No, the shift is made at 10% above the power peak.

Allows the engine fall back into the meat of its torque curve AFTER the shift is made.

Also, for the absolute best times, the shift point (rpm) should be different depending on which trans gear you're in and into which gear you're shifting. RPM drop varies depending on the trans gear differences.


For example in a 700R4 1st gear is, what 3.09 but and second is 1.63, which is a serious drop. The shift from second to drive would be 1.63 to 1.00 which is much less of a drop so the engine RPMs won't drop as much.

You really need to play with shift points to find which ones work for your setup.

Jake

John Millican

iTrader: (1)

I'm running a cam about as big as the second one you listed in my 383! Maybe I need something more if 305's can run that cam.

FlamedROC

OK First you will never see 6000+ RPM's with a stock TPI!!!!!! They fall flat on their face at or around 4800 RPM. Even with heavy porting of stock TPI components guys are lucky to come close to the 6000 RPM mark.

Why are you goin to waste money on buildin your 305 just to watch it blow up. Waste of time, although a good excuse for a 350+ c.i. swap. Just seems dumb to me


Actually alum. heads raise compression but like you said a thick head gasket will take care of it!


Unless u plan on running nitrous that cam will be a waste of money and time get one that works better for TPI like one from TPiS.

Sounds like maybe a little more reserach on your part for what cam would work better for your application


Jason

JakeJr

[SNIP]Originally posted by Fbirdta878787
OK First you will never see 6000+ RPM's with a stock TPI!!!!!! They fall flat on their face at or around 4800 RPM. Even with heavy porting of stock TPI components guys are lucky to come close to the 6000 RPM mark.


Jason [/SNIP]

I can send you a Diacom trace of my engine over 6300 rpms. That's where I decided to shift.

I ported my TPI setup using the inspiration from MadMax.

Jake

FlamedROC

Yea send it over!! I wanna see it I know its possible to squeeze 6000 RPM out but only with alot of porting/Aftermarket runners/TBs which he hasnt claimed to wanna do any of it. So I was sayin he'll never get that RPM out of an otherwise stock TPI.

Jake-I bet that yours pulls into that RPM range, but at what cost and what all have u done to get there. See where I'm goin with this? You cant just slap a cam in and expect to see your RPMs climb higher and still make power. You have to open up the air ways to allow it to breath that high!

Unless he's sayin that these RPM numbers are for the LT1 intake then I missed something. But it is my understanding that a stock TPI unit is being used.


Jason

gixxer9

Actually, if he installs L98 heads on his 305 he will experience a drop in compression due to the larger combustion chambers.... 305 heads I believe are 53 cc, L98 heads have 58cc..

MrDude_1

just cause you can spin a engine that high, doesnt mean its making power there.

my L03 can spin past 6k.... doesnt mean its making the most power that it can...

N8MAN1068

this post is still up? lol

the 2 cams are pretty closed matched. one has more lift but a looser lsa, the 2nd has a tighter lsa but less lift.

I choose these 2 patterns because I do intend on spraying the engine.
I believe the 305 heads are still 58cc, so compression should remain close to the same.
the intake i'm going to use is the lt1 intake with read the entire post.

Again, i'm doing this on the 305 just as a 'what if' scenario. Really, the only expensive part is the intake. Only thing I'm out at the end of the endeavour is a few hours of time and a tired old 305.
Everything I'm using i plan to use on my next and more cubically enhanced motor.
Running a larger than normal cam will give me something to play with while i learn prom tuning.

Christ...mention 305 and anything past the normal upgrades and all kinds of fun stuff happens.

It'll just be fun to see the responses to 'which cam for a lt1 406 w/pro topline etc etc.'

JakeJr

I just emailed you the trace.

Okay, I understand what you're saying now.

Exactly right. The ability to carry the rpms high is one thing; the ability to still make acceptable power up there is quite another.

In my case it was an experiment just to see if the engine would keep pulling when I carried it well above its power peak. When it crossed 6300 I'd had enough and shifted.

I deliberately built my engine for low and mid range torque, not high RPM HP. All I wanted, in this WOT experiment, was a SOTP feeling of how the engine performed when I carried it well above it's power peak.

So, yea, it'll rev up there. Question then becomes how much power is it making.

As far as mods, I just followed MadMax's lead and removed the dividers from the runners and intake manifold in as far as I could reach. I also did the plenum according to TPIS's recommendation and "eye-glassed" the plenum openings too. Most of the other mods are listed in my sig.

Take care,

Jake

FlamedROC

Here I am shootin him down and I forget hes running a 305 already...What a dumba$$. I'm not tryin to slam ya cause ur messin w/ a 305, Its all good in my book but I just didnt see the merit in doin what u were planin on.

Now that I know that you plan on puttin the squeeze in everything is a lil more clear. As for the heads crompression will stay the same but is 9.5:1 to high for nitrous? Well maybe not cause they have kits for stock TPI guys w/ that compression to use nitrous. I think I'm thing turbo or something. ANYWAY now that you mention a 406 LT1 I think that cam will become to small for your application. Plus the addition of nitrous to the 406 will want more.

I dunno man I think you should just hold of on the cam part and swap the LT1 intake over onto your 305 and play with it there. Then when it comes 406 time then you should build your motor and decide on a cam from there.

Jason