Hello everyone.
I have a 89 camaro in Australia with a 305. It used to be TBI, now its full time LPG.

I want to return it to gasoline only for performance value.
I just want to firstly acknowledge from my prior research that i seem to see that the 305 is not widely liked. I also wish to note that i know there is no substitute for cubes.
HOWEVER,
this engine is in great condition and since it owes me nothing, I'd like to see what i can get out of it. Later i will replace it with a higer cube engine. But hopefully that will be alot later on, once i blow this one up! I've always had big blocks and I'd like to see what this can do.

My setup right now is a stock 305, hyd roller cam version. The only non standard thing on it is the brand new L98 Corvette heads.

With the obvious need for returning to gasoline and headers, what setup would be required to get 300+hp? Can this be done easily?

What cam / intake is advised? From owning big blocks, i really like tourqey engines, high rpm really doesnt do much for me. I like having the ability to fry the tyres on command.

With whatever cam / intake that is recommended by you all, are there needs for a different valve train setup from standard? any porting need to be done to the stock L98 heads? What carb is best? What about the computer / distributor?

After hearing these recommendations, what about gearbox and diff? It is a 4 spd auto, and seems to have really low gearing suited for hwy use? At what HP will gearboxes, tailshafts and diffs need strengthening over stock?

Also, with the LPG installation, the fuel system was removed. What pumps / lines would be needed for what i am looking to obtain.

Maybe my expectation of something that is tourqey, can spin the wheels easily with the car in motion, and something that would run into the low 14's or high 13's is unrealistic from this engine. OR it may be that the amount of money needed to spend on it would be the same as getting a crate 350. I dont know. I'm hoping you can help, with advise biased towards the 305 not 350. I really look forward to hearing your suggestions!

Back to gasoline you say..

add a good old Holley 600 cfm 1850 carb on their 300-36 true high-rise if it will fit under your hood and set of 1.625" dia, 4-tube long headers and..................

CAM!!!!!!!!!!!!!!!

9 to 1 CR. or so here!!

Install a good old CC 260HE cam in it OR Lunati's VooDoo 256 cam if you want SOTA!! Now more HP, and if your compression ratio is up to about 10 to 1 CR., then go w/ the 268HE or Voodoo 268 cam.....

Sounds like you have a 200 or a 700 4-speed auto tranny so you should be fine, imho..

More here that I've saved through the years............................................. ................................................

I found the old article telling about the maxed out combo for a 305 so here goes. It was in Hot Rod Action Series Volume 2, Number 1, early 1984 booklet.

They started w/ a stock 9.5 to 1 CR. shortblock, cast pistons and all! Then added 350 rods b/c the 305's are too skinny!!

They made a 10.6 CR. 305 using -041 number heads that were reworked to 59 cc w/ 1.94"/1.5" valves. Deck height is .035" w/ a stock 305 head gasket, so is close to say the least! Intake ports were untouched w/ only bowl work done. They taped up the pistons and ground some exhaust valve clearance so the valves had enough room! Did some bowl work on the exhausts too. Manley Pro-Flo valves.

The cam was a CC magnum 292H w/ 244 duration at .050", 110 lobe centers and 501" lift. They used .100" shorter pushrods to correct the valve train geometry.

Headers were 1.75" four tube w/ 23" collectors and a pair of Supreme Super C turbo mufflers!

Carburetion was a Victor Jr. and a reworked 650cfm Holley double-pumper!

Ignition was an MSD-6A and an MSD extra duty distributor(?). A 4" K&N filter. A windage tray and crank scraper in the pan!

Here are the Engine dyno numbers!

3500rpm - 210hp -- 314t - .398 BSFC
4000 - 243 -- 319 - .394
4500 - 270 -- 320 - .411
5000 - 316 -- 331 - .417
5500 - 361 -- 344 - .419
6000 - 376 -- 335 - .444
6500 - 378 -- 305 - .451
6850 - 386 -- 296 - .461
7200 - 402 -- 287 - .479

Here it is!!

From a 1995 Chevy High Performance article.

305 Engine Build-up.

1 ’69, 041 double hump 1.94”/1.50” valve heads cut to 59 cc’s. Bowls blended and only the exhaust ports polished.
2. Manley Pro-Flo valves, PN 11560 intakes and PN 11559 exhausts.
3. CC 292 Magnum hydraulic cam, 292/244, 110/106, .501” lift.
4. 350 rods rebuilt with good bolts and nuts.
5. L-69, 9.5 to 1 CR. LU5 fuel injection short-block engine with stock head-gasket gives 10.6 to 1 CR. Or a
6. LG4, 8.6 to 1 CR. engine will give 9+ to 1 CR.
7. Deck height was .014” down with stock four valve notch cast pistons.
8. Quench was about .035”.
9. Hooker 1.75” four tube long headers with 3.0” collectors. PN 2110 for a Third Gen. car.
10. Holley 650 double pumper PN 4777 and an E-brock Victor Jr. intake.
11. 4” K&N open filter.
12. Good Electronic ignition

The little bugger made like 402hp up top!! They ran it until she spun a bearing or just came unglued!

AND

An old RHS, Memphis, TN, 305 motor build-up that makes right at 300hp. http://www.goingfaster.com/spo/290hp305.html
Chasis Dyno Test
7000rpm --- 300hp

And Hotrodding the 305!
http://www.goingfaster.com/spo/modthel03.html

And an article from mw66nova
http://www.thirdgen.org/techboard/organized-drag-racing-autocross/394788-new-bests-two-walter.html
new bests for two Walter Racecraft 305's!

well, Kody and I were able to get out to the track for one more night of racing tonight before we called it a season. i was totally stoaked at the times we got as i totally didn't think we were going to do as well as we did. remember, these cars are 100% daily driven and 100% naturally aspirated. race weight for Kody's car with him in it: 3255, race weight of my car with me in it: 3220

i'll start with Kody's car cause i haven't really told many folks about it. combo is super simple:
-305 out of ssean92's 1992 RS
-416 casting heads with backcut valves
-lt1 cam
-crane energizer aluminum roller rockers
-hedman longtubes with manderal bent y-pipe into a 2.5" dynomax catback with homemade cutout
-holley street dominator intake (the smaller of the two, basically a performer) and an edelbrock 1406
-2100 stall converter w/ 700r4 and 3.23's with a 275/50/15 mt ET Street Radial.

previous best was in the upper 15.2x range, tonight with the cool air it went 14.67@93.7mph. we went from a 28" tire to a 26" tire and rebuilt the carb and added more timing. the car needs some more gear bad. timeslip for that pass looked like this:
r/t: -.123
60': 2.205
330': 6.166
1/8: 9.441
mph: 75.20
1000': 12.276
1/4: 14.678
mph: 93.73

we were hoping for some 14.9's, so to get a high 14.6 out of the car was like walking on sunshine.

now for my car. alot of you know that the solid camshaft that was in the car was hurt and i put in a used 280H cam that my friend Eric gave me. i totally didnt' expect to even break into the 12's and i did that at the shootout we had back in the end of september with a 12.97 @ 103mph. air was SUPER nasty that weekend and i was trying to run a 13.0 index class so i wasn't looking to go blazingly fast anyhow. the previous best for my car with the solid cam in the 305 back in may was a 12.50@106.8mph. that was with hotter weather, a water pump drive kit and manual steering. this evening the car had full accessories (water pump, alt., and i put the powersteering back on) so i was going to be happy with 12.7's. i figured that would be possible because of the cool air. after screwing around on a few runs trying to get reaquanted, i clicked off a 12.42@107.49mph! the timeslip for that pass looked like this:

r/t: .088
60': 1.694
330': 5.035
1/8: 7.862
mph: 86.33
1000': 10.328
1/4: 12.425
mph: 107.49

after that pass we decided to see how fast we could actually get the car to go. i knew that the powersteering was worth atleast .1 so i snatched the ps pump belt off the car and proceeded to go 12.39, followed by a 12.34, and then finally a 12.31@108.48mph!!! that pass looked like this:

r/t: .150
60': 1.678
330': 4.994
1/8: 7.797
mph: 87.05
1000': 10.240
1/4: 12.318
mph: 108.48

as you can tell, i'm so pumped about it that im writing a thread about it at 1:18am to tell ya'll. anyhow let me know what ya think. oh, and check out a pick of Kody's ride all ready for the track wearing the mickey t's!



pdq67

There's a read... Also, check out superchevy.com. They have a tech article that they made 300 horse by only modding the top end. Good read

Thanks for the quick reply!

Is the 600 holley best as DP or Vac Sec? I've had better luck in the past with vac sec...

Also, with the L98 heads, and idea of the CR? It is an 1989 305, with stock internals. The heads had never even been off this thing!

With those cam recommendations, would you personally recommend lower diff gears, or will the stock diff gears be stufficient to light the tyres through first and second? Im running a 4 spd 700, are the cams aggressive enough to warrant a stall convertor?

I am somewhat concerned about hood clearance. With the air filter housing on their now, there is a recess in the heat insulation to let it fit in.
Are there any good low profile intake manifolds that will serve the required purpose?

Brent
Were your pistons flat top- dome- or dished--- when you changed heads?
The L98 heads show to be 56cc, which is good, helps keep the CR up on a small disp engine.
With -5cc flat tops, I'm showing 9.5:1. But I didn't research the pistons, and -5 could be wrong.

mec sec vs vac sec is a taste thing on the street I think.

Don't overlook nitrous for your 305. A 50 or 75 shot a few seconds at a time is not going to hurt a stock engine.

Hood clearance...... I think you're screwd, but idunno for sure.....

That's what I was thinking -- N2O

I agree with PDQs cam recommendation. Something right about 260* advertised and 215* @ .050. For a carb and manifold combo I would suggest the Performer RPM and a Holley 600 Double pumper (or a 660 Street Avenger, or a 625 Edelbrock).

PS. For a fuel system and lines -- 3/8" streel lines and a Holley Blue pump should do just fine.

I think from memory the pistons, they were dished a little. I know that they did have valve recessed cut into them, but i seem to remember that they were dished slightly
The only problem with nitrous is that it is illegal here on the street. We are alot more relaxed about performance and emissions here than in the States, but Nos is something that can land you in deep $h!t if they find it connected in your car.