So my friend wants to build up his little 89 trans am 305 little by little. So with my knowledge of cars, i told him to start off with a cam and intake. He already had somewhat of an exhuast and his 3.42 gears. The cam i was looking at is a comp cams roller grind, the biggest availible for the tpi motors. It spec'd out at max of .502 lift. Will that clear the pistons? Also, i dont know which intake to use. I have seen a accel, and herd of a few others. Which is the best? Also, on a set of heads. What is up with this i hear about 350 heads not bolting on? If this is the case, is it because of the big valves? I may just have to grind away some of the block to clear like they do big blocks? Ever hear of that? I want to run a set of AFR's for now because soon we are going to make this little 305 scream with a D1SC. Why 305, well someday down the road this babe will be a 383. No, we are not saving and building all at once so that is not a option. So you tell me where else i can get a cam and a nice intake. I know i will need a tune and nice injectors soon then. That will not be a problem. I will be replacing the torque converter soon to with a nice 3000 stall to get this joker outta the hole quicker. I tried reading up on some of it, and couldn't find much but "why do this to a 305" type bullcrap. We are going to do it no matter what it takes for now. Just plase point me in a direction for a nice high flowing intake and cam, I dont care if its to big for the motor now, it will always switch over to the 383 that he will have someday. So thanks for your time and please give me some websites and your insight on what i have just blabbed on about for a few minutes. Thanks, Justin

 

What, does no one of this board know?? Do i have the wrong section?

 

Basically everyone that would have posted would say "swap in a 350". Sorry.

 

Yup, just sparing you the completely logical, fiscally prudent 350 case which you don't want to hear.

Decent 350 heads won't fit a 305 because the valves will smack the block deck...305 bore dia is too small.

 

Thats sad everyone would say 350 because thats all they know how to say. Never mind, ill jus figure out some things on my own..

 

Take a 305 and spend $2K on it and tune it to get max HP. Now take a 350 and do similar mods and tune it just like you did the 305 and I garuntee the 350 wins every time.

I don't know why everybody gets so pissed off when a 350 is suggested. First, its a direct fit, and only a trained eye "might" notice the difference. Motor mounts, transmission, intake and exhaust all swap over.

Second, 350s are a dime a dozen. Manufacturers are too busy raping us on LS1 stuff to worry about overpricing SBC parts.

Third, fuel mileage maybe? No dice. My 357 w/ Trick flow heads, LT4 Hot cam and other misc got the same gas mileage as my bone stock 305: 18 MPG.

Fourth, its no freakin' suprise that more cubic inches usually makes more HP. So when you slap on "high flow" heads, and gnarley camshafts, the 350's larger displacement can better utilize it and make more power with it. So I don't see what the big damn deal is.

If you want to be "challenged" and make tons of power with small engines, dazzle us all with a Turbo V-Tec in your F-body

 

I agree it's sad, but I guess we'll disagree (for now) about why...check back later with a dyno printout if you don't mind some giggling.

You've got people here with engineering degrees, automotive/marine industry experience, and more wrench time than most shop mechanics posting volumes of actual data on why the GM 305 is a cripple.

The bore:stroke geometry and availability of optimized cylinder heads is something you aren't going to change by wishful thinking.

Choose to believe it or not, it's not my $$ and we all get a free laugh eventually.

 

I was in the same position. 305, want fast, not alot of cash I wanted to sink into the car at the moment. Well the amount of work to change a cam while in the car is almost as much as a full engine swap. Put a stock 350 bottom end in, bolt the 305 top end (port the TPI while its off), get headers while everything is apart. When its together it will completely rape a 305 with similar mods. You could do all that for $500 easily.

 

You guys must know that in a sprint car class, you must not run any bigger than a 305 or some cubes like that. So what do people run? A 305. What am i going to do? I dotn care what makes more power, i am going to be different, just like i was with my big block in my car. Yeah, i coulda have built a 406 that made 500 hp. But why. Great, the 305 makes more power.. Everyone knows. Now lets talk about how you build a nice 305 for guys that have rules to there cubic inches.

 

Not sure what sanctioning body you're referring to, but I have some experience there...in the Midwest Sprint Car Series a GM V8 is allowed up to 363ci and in USAC you get 366ci.

So what do people run? Not a 305.

Those are the two big sanctioning bodies, so were you talking reality or inventing some "facts" to try to support your case?


Different would be a V6 or some other rare/unique powertrain as mentioned by GMTech above. You are going to be what Honduh kids call "slow".


What sanctioning body is this engine being built for?

I'll throw ya a bone here and mention the NASA Camaro Mustang Challenge has a 305ci engine limit, but they also regulate modifications. The cars aren't street legal so exhaust is where they go for power, which you can't do much of on a street car.

The SCCA Trans-Am series was 310ci back when I cared about it, but again you're talking about carb'ed track cars with no street legality, and in this case a lot more $$ than you and I would throw at a project.

 

Your opening post said you were upgrading to a 383.

 

Then why the hell are you doing cam, heads, intake and "soon to be" D1SC???????

 

I have to agree w/ everyone here. If someday it's gonna be a 383..save your money, buy the 383 and don't waste it on a 305. In fact when i bought my 350 the place i bought it from told me to take the 305 and fire it into a dumpster somewhere, they didn't even want it.

 

Instead of bashing him to death, you could try and give him some actual answers or ideas :-)

I wont argue if wanting power, to just drop the 305 and go to a 350 or 383. I also wont argue that just dropping in a 383 or a 350 is always as cheap as everyone makes it sound.(I am discounting good used engines, because they are out there if u search) U can rebuild them fairly cheap and there are many good stroker kits that wont kill u out there also. Just hard for a lot of folks to have that much $$$ to plunk down on it.

In the meantime there are plenty of things he can do depending on what his ultimate goal is.

He could swap heads and gain some there as well as use them later on another 350 or even a 383 depending on his end goals.

Headers, intakes, runner, etc are also all able to be swapped very easily to a new combo.

So can a new stall converter and a properly built trans.

If you are for sure upgrading your engine cubic inch wise, focus on parts and pieces you can use on your 305 now as well as your new engine later.

I would also suggest dabbling in some prom burning now that you ahve a stock car to play with. Lot easier to learn now then figuring out how to make it run with any real mods.

later
Jeremy

 

Yes, it doesnt matter about anything. I dont care what anything allows, argue about it. I dont care. I want to know what i can do to this 305 and what people have done to make them run good. Yes, a 383 will be down the road. Will it all switch over? Yes, Are we going to wait? Hell no. So get over it. If all you have to say is drop in a 350, go somewhere else and keep the people in this thread who have a brain.

Stall converter Will be after the engine will get tuned, we already decided that. Intake, i dont know what to use, Holley, super-ram, mini-ram? It loks as if i am limited to 1.94 heads after calling afr and speaking to one of there techs. Anything more will hit the bore. Now what i want to know is on the 4.25 BBC motors with 2.3 vavles, you must clearence the deck of the block with a grinder. Call it stupid and everything you want, but every good engine guilder who builds race engines do it. Hell, i know of 8 468 motors running high 7's with stock block, but crete on the bottem to stiffin things up. So has anyone ever clearenced the valves on there 305 to clear? Since i am not much of a 305 guy, i have herd that the valves of a size of 2.02 will not clear. Please tell me if you have gotten them to clear. The cam, will be a roller, and i want around .550 lift with a good torque curve. I want a nice lsa for the supercharger. Now the duration with this fuel injection engines may screw with it. This is what i need your help on.. How much duration to keep it from running **** rich and junk.

If you want to keep arguing, i will take my post's elsewhere for help and someone who wont tell me for a 350 bs. A 302 block would be much better to start out with, but things are not looking good.

 

I plan to eventually build a 383 to replace my TPI as well. I've been trying to only buy mods now that I can re-use on the 383.

This is what I did/am planning to do:

1.6 rockers
Longtube headers
Nitrous
Modified LT1 intake

I started with a 350, but you get the gist of what I am saying. A cam and heads will help the HP output of a 305, but you'll have to buy heads and cam again when you go 383. You can make enough power to blow the bottom end out of the 305 with nitrous, and you didn't waste time or money on parts you'll be basically throwing away when you build the 383. You might be able to sell the used parts to re-coup some of the initial cost, but the performance market for the 305 is pretty soft.

If you do plan to S/C the 305, just do that instead of heads and cam. Like nitrous, you can make all the power the bottom end will handle with just a blower. Why swap the heads to make 200 HP NA, and then add a blower to make a total of 400 NA; when you could of just added the blower to the stock 150 HP NA, pullied the blower a little differently, and still arrived at the same 400 HP?

My advice is to stick to mods that will still be useable on the 383.

The intake issue has been beat to death. Try searching for more info, but FWIW I am going to use a modified LT1 intake. As for a cam the LPE 219 or a copycat thereof is a tried and true cam. I'm not sure it'll work in a 305 (never looked into it, since I don't have one) but some internet searching would probably yield that inof pretty easily. It might be a tad small for the 383, but it'll make good power and be streetable.

Good luck.

 

I hear that you can shave .040" off the deck of vortec heads to get a 10:1 compression ratio on a stock 305 bottom end. then you'll either need a vortec baseplate, have your stock one modified(which I'm planning on trying on an 86 TPI soon), or have the heads drilled and tapped for the stock baseplate and portmatched. 89's had roller cams right? maybe put the GM hot cam in it. dur 218 218 lift .525" .525" (.490" with stock rocker arms I think) also make sure the valvesprings can handle the lift of the cam. SDPC sells vortec heads modified for high-lift roller cams. Then tune away. I'd put that combo with a good intake and exhaust around 300hp at the crank. maybe get aftermarket intake runners because vortec heads outflow the tpi runners. intake runner of vortec heads @.500" lift flows 239cfm each; stock runners flow like 203 cfm each.
If you want to get fancy there are a few 335 stroker kits for those blocks. Or if displacement is a concern, get a block with a 4 inch bore and destroke it to 3 inches to make a high rpm 302 chevy like the old Z28's.
You can probably tell that I've thought this over a little. I was in your position 3 years ago, but guess what I did.

with shaved heads and inverted dome pistons in your 383 you'll be around 10.4:1 compression ratio. then put some bigger valves in the heads.
I don't know much about the different models and brands of superchargers but I think a SC that makes... say... 10 psi on a 305, may only make 6psi on a 383. Just for example, no proof that I know. From what I understand a supercharger flows a constant airflow at each rpm. So it forces the same amount of air into a smaller engine causing higher boost levels. I could be totally wrong though. and to change the airflow at each rpm you use different pullies. but I hear tons of problems with belt slip when the pullies start getting smaller.

 

So then does anyone know Max lift at the valve you can use on a stock 305? I want around .560 lift, will that clear?