undead_undead

Heres the run down;
this motor has 67,000 original miles on it, and i definetly want a bit more power out of her, so i can get through college .
My ideas are:
1992 305 TPI heads, Port Polish
LT4 Rocker Arms
LT1 Cam
Dual Snorkel intake (have it already)
Edelbrock TPI Headers (have them already too)
chip tune.

What else do you guys i think i need to complete this setup? i just want a streetable 305 with decent power and good reliability, and i believe this is the route to take. i'd really like to have some input on this!

ShiftyCapone

iTrader: (7)

TGO wlecomes you!

Take some time to read through the stickies at the top of the page. In there you will find what makes these cars tick. If you are a novice to chip work I would stick with basic mods for now. Your dual snorkel intake along with those headers are a great start. I would compliment both of those with a 3" cat-back and high flow cat.

I would also consider some suspension mods and a gear swap. Those two things alone don't add power but they can make your car faster and tons more fun to drive.

Dewey316

Go with more cam. I'm running one bigger than the LT1 cam, and I wish I had gone with more.

Ohh, and start on the computer tuning now, before you swap heads/cam. What you learn now, will be invaluable once you do the swap.

undead_undead

thanks for the welcome, i actually been lurking these boards for a while now; i posted pictures of my car the other day you can check them out
https://www.thirdgen.org/techbb2/sho...hreadid=307406

kdrolt

The stuff you already have is fine. You should use a low-restriction exhaust in addition to the headers you already have.

You are starting from an LO3 TBI, so that means you already have the 187 heads that have fairly low mileage. It's been proven that the swirl port heads for the 350 (193 casting suffix) are (a) decent heads if they are ported and so (b) they will flow as well as, or better than, the LT1/L31 heads as proven by dyno tests. Since the 193 and 187 heads are virtually the same casting (with the exception of the smaller intake on the 305 , 1.84" diam on the 305 vs 1.94" on the 350) then I'll propose that you keep the low-mileage heads you have and port them the same way Fast355 ported his 193 heads. The 081 heads (305 TPI) will also flow well after porting, but you will need to buy them and you may need other work done on them due to the (unknown) mileage/wear. IOW you could benefit from better-flowing heads but you don't need huge airflow from them because it's a 305 with a mild cam. The cheap route is porting what you already own. Port the intake manifold too because it has to come off the car to remove the heads.

Skip the LT4 rockers. That's $250 worth of double rollers that won't really provide much power gain when using a fairly mild cam with mild valve springs and loads, over what you can get with 1.6 stamped steel self-aligning rockers from Elgin or Sealed Power. The power gain comes more from the valve lift than it does from friction-reduction, especially on a mild engine. $80 vs $250 --- you make the call.

The cam choice is fine, but you will still need to retune the ECM. For the others that advocate a hotter cam, they won't have to live with ECM tuning of a hotter cam but you will. Stay conservative for now.

undead_undead

what kind of power do you think this combo would make? i already have taken care of the driveline (rear end, tranny)
3.42 gears, and a transmission that shifts slightly harder than before (corvette servo, 9C1 valve).

kdrolt

Assuming that the ported 187s respond to porting like the 193 heads did, then they should flow at least as well as the L30 Vortec heads (used on 305 engines --- do a search, there are flow numbers for them here on TGO). That engine was rated at 230 fwhp when using the Bcar LT1 cam. The Fcar LT1 cam is worth another 20 hp (per GM's rating) so at the conservative minimum I'd say 250 fwhp. With 1.6 rockers to increase the valve lift you might go 260. That would run you low 14s in the quarter and it satisfies your desire for low-cost but decent performance.

weberflorida

iTrader: (2)

Dewey,

How is your rearend and tranny holding up to that hp and tq from the spray?

Have you done any tranny work or any upgrades besides the posi and gears in the rear?

Later brother,

Bill

Dewey316

The rear is pretty solid, and has had no problems. I have a studs and a girdle on it, along with richmond gears, and the posi.

So far everything is holding up, I've run three bottles of the spary thru it, that included dyno runs, track time, and a few goes on the street.

I haven't run on DR's yet though, only street tires. I haven't cut better than a 2.2 60' with it, and haven't been hitting the spray until 2nd (with no traction, it does no good to use it out of the hole.)

Dewey316

double post.

TWICEtheRICE

Better flowing heads, headers, larger intake like performer RPM (w/ TBI adapter plate), matched cam, and goto the TBI section and click on the sticky for TBI mods. I bought a chip programmer for $50 off ebay and TunerPro is free.

Then buy a nitrous kit to bolt on (100hp is okay). Seriously.

Goodluck!

I know how it feels to be on a college budget (5 years). Maybe get another student loan to buy HiPo 350, cause a 305, is just garbage.

weberflorida

iTrader: (2)

Dewey,

That is cool that the rear is holding up. I have been babying mine until i can do some mods mainly the posi, gears, and girdle. Does the girdle really make that much difference in the strengthing process?

Bill

3rdgenstm

Hate to bring up an old thread, but I am considering the same combo.

My L03 is .030 over, P&P stock heads (that were done about 4000k miles ago), Hedman headers, full Dynomax header back exhaust, all emissions, stock TBI and manifold, and stock chip. I have an LT1 cam from a 95 Z28 I want to install along with better springs. I have a 3.23 to swap in place of the 2.73 and a B&M shift kit for the 700R4.


I wanted to swap to the 081 heads, but from what I have read, that wouldn't help much(??). True? I can pick up a pair for under $100, but if they offer little help I'll keep the hund-o for something else.

I was looking at some 1.6 rollers but I gather that a stamped rocker w/ roller tip will have a better hp/$.

Do the gains from the Edelbrock intake justify the cost?

Thanks

Dewey316

Bill,

I guess I didn't see your post last time. In theory it helps, the reason people gernade their rear end, is that the case flexes, then the gears doesn't line up right, and stuff breaks. Adding the bracing of the gridle, should help keep things in place.

kdrolt

a. ported LO3 heads & modified exh means you are pulling a lot more air through the engine. So the (stock) cam is the weak spot but it should still run really well (mild cam, great heads, exhaust.... a recipie right out of Lingenfelter's book) .... but it probably doesn't because your using the stock chip, stock injectors, stock FP. So your engine probabluy doesn't run as well as it should.

b. have you any performance metrics (GTech, track, dyno, head flow data, fuel economy) for the combo you are running right now, as is?

Use the Bcar LT1 (or L31 Vortec) retainers, locks, and springs. The springs are the same diam as the ones used on the LO3, and the retainers will eliminate the heavy rotators used on the LO3 exh valve. Don't use Fcar springs/hardware because they are larger diam OD (which won't fit the LO3 spring pockets).

None of the flow data, stock or ported, on swirl port heads shows that they are much different than the flow data on non-swirl versions. Ported swirl port heads run well, at least as well as similarly modified non-swirl. And so do unported swirl port heads:

Lo-tec had stock LO5 heads in his car (per this thread), and Dewey316 has stock LO3 heads in his car (another thread) --- and they both ran well even without porting. In both cases they dealt with the main offender for perfomance: the stock exhaust. So IMO (based on the results of other TGO members) you will spend more money but gain very little by replacing the heads you have.

What you need to do is to get a new chip, either now or after you get the LT1 cam/springs/retainers/locks installed.

IMO yes, stamped SA 1.6 are a better hp/$$ choice.

Also note that GM doesn't use roller-tip rockers in the LS1-family engines. IMO there isn't enough friction reduction there to warrant the extra cost and the potential for reliability problems

The roller tip also doesn't completely roll: it's a mixture of rolling (because there is a bearing) and non-rolling (because the roller has inertial mass and the tangential friction acting on it is small. Mech Engr/physics analysis of what happens at the roller is enough to prove how they behave. So IMO roller-tip rockers aren't worth it.

Roller pivot might be useful but not for practical friction reduction at the cam lifts and forces from an LT1 cam. If you used a bigger/hotter cam, then full steel rollers might make sense, but otherwise either keep the stock 1.5s are go for the stamped SA 1.6s.

After seeing the gains Fast355 has made in several TBI exercises using the factory intake manifold, I'd say no.

3rdgenstm

Thanks for the great info!

You brought up the stock injectors. Will the stockers keep up with the cam? Shifty has suggested to me to go ahead and change the pump to a Walbro unit when I do this, but I don't think I asked about the injectors? If they need to be changed, any recommendations? (I am not real 'up' on FI parts).

I was going to have a new chip made after I do the swap. But, I think I may go ahead and get one and have him reburn it afterward.

No, I haven't done any kind of testing with it, so I don't have a baseline other than factory specs.

The springs I bought are ones Shifty had listed in the sticky for the LO3.

I won't waste the money on the 081s and intake, but instead use that money to get a set of 1.6 rockers.






I have done so much work to this thing to get it back to somewhat glory, and now I am ready to start tackling performance and suspension. My main objective was to get it running and sell it when I bought it 3 years ago. I rebuilt the engine with stock components since I didn't think I was going to keep it. Then I did all the cosmetic work-- new paint, weatherstrip, interior parts, carpet, etc. I finsihed that up a couple of months ago and am now ready to do some better performance mods.

Thanks again

weberflorida

iTrader: (2)

Oh ok right on. I am thinking of doing the rear end girdle just to try to help to hold it together. Sounds good.

Bill