mr_posey

Ok,
for the record you can call me Jeremy.

Here is my sitution people.
I own a 85 firebird which came with a 305 ho engine 5 speed
t tops, front disk rear drum.

Here is my problems, or rather help with clairification.
I have recently swapped a 355 with mildly ported 305 heads into
my car. am running a cam, old style one that is between a edelbrock rpm and torker. the cam I am using is a Sig Erson.
the engine runs strong, am using a edelbrock performer
due to hood clearance problems.
the engine or car rather flat hauls *** one up to speed. power comes on at about 22-2500 rpms, you can feel it.
I wanted more seat of the pants feel off the line, am wondering if it is my rear end thats robbing my torque, or the cam.
with the stock engine, it felt differrent, more torqy. I know that I am buidling more torque and hp with this set up, but i think it is building it too high up. my question is should I re gear my rear end, or swap out cams, but I LIKE the feel and sound of my cam now, just want more bottom end off the line, ie from stop light to stop light.
was thinking about installing a gm perfomance corvette cam shaft
is this a mistake.
also, I am running 2-1/2 inch exhaust thru stock manifolds strait back, no cat, flowmaster muffler.
could I be starving my engine with the tiny 305 valves.
anyways need some suggestions. this is the first engine build I have done own my own. had the block put together for me, bottom end that is, all I had to do was install it into my car and bolt up exhaust intake etc.
thanks for the help.
the reason I chose to use the heads is becuase the machine shop said that these little valve will build a broad torque curve.
thanks
Jeremy

five7kid

iTrader: (14)

Welcome aboard.

Gears. You moved the powerband up with the cam. Although it would be nice to know exactly what cam you have, because the description leaves out important details.

Your machinist didn't do you any favors with his valve advice. 1.94's would have helped the engine breathe.

What have you done with the exhaust?

ljnowell

#1 First thing I would say is ditch that exhaust. It cant be helping in any way whatsoever. Headers and a good catback, or some true duals, whatever is your taste.

#2 As Five7 said, you need some bigger valves. Definately. The engine you have is designed to make power up top, and the valves probably arent letting it, at least not very effectively.

You would probably definately benefit from gears too, but who wouldnt.

RB83L69

If it's really the HO motor (8th VIN digit would be "G"), it should have come with a better exhaust already, than what you're talking about putting on there. You'd be downgrading your car.

Put 3" exhaust on it. Use a cat. It costs nothing in terms of power, and probably might save you some trouble someday. Plus, if you do that, you can buy an off-the-shelf exhaust, and it will just fit perfect and bolt up to everything, and be right.

The manifolds are killing you even if they're HO (VIN "G"). They choke a 305, let alone a 350 such as your motor. Get a good-quality set of application-specific headers, such as SLP or Edelbrock; NOT generic ones. Get the ones for L69 if that's what you have; the 4-bolt cat that goes with it; and the corresponding cat-back. Or, get the headers for a 350 TPI from 88 or so, and the cat and cat-back for that. Do it all as a set, all at once.

You have a pitifully mis-matched cam for the rest of the motor. Just all-around bad. I'd suggest getting rid of that, and putting in a Comp XE262, or a similar grind from Lunati or Crane. You DON'T want ANY cam from GM. Not even if it comes with the magic "V" word associated somehow. That word adds no power.

Little valves don't make a broad torque range. That's just bad advice, period. Even the most pathetic smogger 350s from the 70s had 1.94" intake valves. That's what should have been done with those heads.

Again, if this is really a VIN code "G" car, you have 3.73 gears. You're already set up right in that department.

I'd suggest getting rid of the Performer (basically stock replacement) intake; a ZZ4 one would be perfect. You can pick those up brand-new as take-offs from people buying the ZZ4 and putting on some other intake like TPI or whatever.

What is the 8th digit of your VIN? That would help to determine what the car already has, or at least should have, and what the correct next steps should be.

mr_posey

ok, after digging and looking heres what I have

vin code H,
cam specs of:@.50 intake 221/225 lift @ 50 499/ 510.
I orginaly had a super victor jr on this engine, have had the performer on for about a month now.
have the old stock 305 manifolds on it now. minus the air tubes that came off of them. plugged those.
have 2 1/2 inch back now, going thru a flowmaster.
the front bumper on the drivers front and on the back of the car
say formula 305, so do the doors.
anyways, the pistons are sealed power speed pro 9:73:1 4 dish pistons.
the block is bored .30 over, have had the rotating mass balanced,
the block bored to match the pistons crank and flywheel lightend
and using crower replacement 1:5:1 ratio rockers,roller tip.
it .runs, it feels good, but I am sorely dissapointed in it considering the money I have paid out.
its not what I was looking for. yeah I can beat a muustang, but that isnt that hard.

I live in sandiego, by rancho sandiego/alpine, dont know where everybody lives, but if you want to email me, come by assuming you live in the same state. city.

RB83L69

OK.... that helps.

Vin code "H" = the lowest output motor of that year. It's the LG4, the base-model 4-barrel.

There was no Formula that year IIRC, so ignore the stickers on the doors. They contribute very little to the reality.

Get the headers, you'll need the cat since you're in SD (I used to live in Carlsbad / Vista / Oceanside BTW), so get the whole exhaust system for a 350 TPI car from about 88 or 89. Make sure whatever headers you get have the AIR tubes because your car won't pass inspection without them.

I don't recognize the cam from those specs. The .050" numbers and the lift are pretty moderate; but if it's one of those old ones with 60° more "advertised" duration than .060" duration, it'll be a pig down low. I'd still recommend the cam I listed.

Your old intake might have been a Super Victor, or a Vic Jr. One or the other but not both. In any case, when you changed it, you went from WAY too much intake for the rest of the motor, to WAY too little. Keep in mind, being in an "enhanced" area for emissions controls, every "device" must be installed and appear to be operating, in its factory location; that means EGR, AIR, the computer, etc. etc. etc. The cam ties into that: too much cam will make it very difficult indeed to get it to pass emissions inspection.

RB83L69

Oh, I forgot:

You probably don't have 3.73 gears. That car would have come with probably 3.08s. So, gears will make a HUGE difference to its off-the-line acceleration.

five7kid

iTrader: (14)

3.23's were stock in '85 with LG4 & a 5-speed (had to be a Trans Am, though).

VIN code "H" - hope the machinist didn't tell you that stood for "HO".

Air cleaner and exhaust are killing you. As RB said, choke a 305, let alone a 350.

I'd go for RB's cam and intake recommendations, too.

(FWIW, lived in Lemon Grove from '86-'94.)