305 questions (Wrath, post here)

[MBood82]

Can a 305 be made into an engine displacing 350 cubic inches?

[nblehm]

why? 350 blocks/motors are a dime a dozen

[wrath]

Nope, afraid not. A 305's bore is 3.736". It's the main reason they're so aenemic. The bore is so small that you have to run small valves or you end up shrouding them. That's why 350 heads don't work so well on 305s. Combine that with poor castings and they just plain don't make much power.

The motor is designed to produce torque, much like Ford's 5.4L. The stroke is really long compared to the bore size on the two motors. This creates a good opportunity for torque but it makes it really difficult to fill the cylinders.

Valvetrains are swappable between the two. Decent 305 heads (off trucks and 305HOs) will make a little more power on a 350 than a set of smog 350 heads. I mean little bit. If you port the crap out of those heads you can get them to flow what a good non-smog 350 head will. Basically, with stock parts except for cam and porting, a 305 is good for about 275 usable horsepower or 315 drag-only horsepower. The heads just aren't up to the task. Cranks are not swappable without balancing.


You can stroke a 305 to 334/337ci. Basically you're going from a 3.48" crank to a 3.75" crank.


And 350s are getting rare in Michigan. It's to the point now that most 350s you find in Michigan are TBI350s out of 87-95 Chevy pickups and they want 200-300 for them. This is especially true after the last year and a half of high scrap prices. 305s are dime a dozen though.

[Vetteboy]

I helped put a V8 into a early 70s I-6 nova...turned out it was a 305. And I bolted my Holley 650 CFM double-pumper on it. :bang:

The thing sounds GREAT...two Flowmaster 40s and a worn valvetrain give it an awesome exhaust tone, and it sounds (and looks) cam'd because it runs funny. The first time I took it out, it was all rumbling and shaking, then I stepped on it, and it barely gets out of its own way. The 305/powerglide combo can't even out-do the factory rear drums when trying to powerbrake it...it either rolls the fronts or just doesn't do anything but torque up against the busted-*** leaf springs.

Then I noticed the throttle wasn't traveling all the way. I adjusted the linkage, romped on it...and nothing happened again. Because it was already getting too much fuel from the too-big carb I had on it.

Bottom line - not impressed with the 305. Another friend of mine has one in a '92 Camaro RS with the 5-speed (apparently they didn't offer the 5-speed in that generation with a 350, only the 305) and he's got the heads redone, a new chip for the TBI, regeared to 3.73, full headers and dual exhaust...and it's exactly as fast as my '79 Corvette L-82 was with a 350, 4-speed, original motor + mild cam, and 2" factory exhaust.

[nblehm]

Bottom line - not impressed with the 305. Another friend of mine has one in a '92 Camaro RS with the 5-speed (apparently they didn't offer the 5-speed in that generation with a 350, only the 305) and he's got the heads redone, a new chip for the TBI, regeared to 3.73, full headers and dual exhaust...and it's exactly as fast as my '79 Corvette L-82 was with a 350, 4-speed, original motor + mild cam, and 2" factory exhaust.

the tbi 305's blow asss...my car easily pulls any tbi 305 rs camaro by 2-3 car lengths

[MBood82]

I asked because I'm lookin at a Camaro, an 87 with a carb, that originally had a 305 in it. The guy claims it has a 350 now but the block started out as a 305. I knew the blocks were different but I didn't know if you could still make the 305 a 350 cubic inch displacement motor easily enough or not. I figure the guy probably was told the car had a 305 in it originally but has a 350 now and he got it wrong. I'm hopefully gonna take it for a test drive later today and check it out. It could be a trade for my Jeep.

[nblehm]

And 350s are getting rare in Michigan. It's to the point now that most 350s you find in Michigan are TBI350s out of 87-95 Chevy pickups and they want 200-300 for them. This is especially true after the last year and a half of high scrap prices. 305s are dime a dozen though.

really wow... I got like 4 4 bolt main block/crank/heads sitting in my garage :lol:

[MBood82]

shipping to 04901?

[razorbackME]

I asked because I'm lookin at a Camaro, an 87 with a carb, that originally had a 305 in it. The guy claims it has a 350 now but the block started out as a 305. I knew the blocks were different but I didn't know if you could still make the 305 a 350 cubic inch displacement motor easily enough or not. I figure the guy probably was told the car had a 305 in it originally but has a 350 now and he got it wrong. I'm hopefully gonna take it for a test drive later today and check it out. It could be a trade for my Jeep.

Check that thing over well...those cars tend to get abused. He's probably full of shiit on the engine. He may not even know what he has.

[razorbackME]

You can stroke a 305 to 334/337ci. Basically you're going from a 3.48" crank to a 3.75" crank.


Yeah, but that's a waste of time really....the small bore shoruds valves, as you said, and you can't do anything about that.

Also of general note as that the TBI trucks have heads that are completely worthless. Half of the approach to the bowl is completely blocked in a crude attempt to induce swirl.

However, the blocks have the bosses for all of the retaining hardware for the factory roller cam, even though trucks got flat tappets, so the block itself isn't a bad blace to start a build up.

[MBood82]

Check that thing over well...those cars tend to get abused. He's probably full of shiit on the engine. He may not even know what he has.

Oh, I plan on fully checking it over. It sounds like he's only owned it for a short amount of time and mostly commuted with it, the previous owner had a shop do all the work.

[wrath]

Yeah, but that's a waste of time really....the small bore shoruds valves, as you said, and you can't do anything about that.

Also of general note as that the TBI trucks have heads that are completely worthless. Half of the approach to the bowl is completely blocked in a crude attempt to induce swirl.

However, the blocks have the bosses for all of the retaining hardware for the factory roller cam, even though trucks got flat tappets, so the block itself isn't a bad blace to start a build up.

Yeah, TBI truck heads are none too impressive... but neither are the cars. You can fix both with a die grinder to a limited extent. TBI truck heads are even worse as there isn't much you can do with a 1.84" intake valve.

Didn't matter if it was provisioned for roller or not, all trucks got flat tappet... but not all had provisions for roller. All warranty blocks do. One of those peculiar things GM did.

On another note, that Camaro probably has a 305 in it if it had TBI.

[MBood82]

The camaro left the factory with a carb, according to the seller. Since I checked and that was an option that year, I"m assuming that is the case.

[wrath]

Get the VIN number and the RPO codes out of the glovebox. Thirdgens are notorious for various motor swap cobbles. Kind of like a SWB Jeep and wiring cobbles.

[MBood82]

got a place I can do a search if I get the numbers?

[razorbackME]

If it had a carb, it was a factory 305 car. The only 350s were TPIs, and all of those had autos, so if it's a 5 speed, then it had to be a 305 or worse.

Of course, this assumes it wasn't actually a V6 car or something.

8th digit of the VIN will tell you the factory engine, and if it was equipped with a carb, the 8th digit will be H. "8" is the only engine code for this year that will tell you it was a factory 350 car, but it would have been TPI in that case. "S" is the code for the V6, just in case you run into that.

[wrath]

wrath.com/rpo

You can look up the VIN on thirdgen.org.

Borg-Warner wouldn't make a T5 that was strong enough for a TPI350 so that's why GM didn't use them.

[MBood82]

cool, thanks.

[razorbackME]

Borg-Warner wouldn't make a T5 that was strong enough for a TPI350 so that's why GM didn't use them.

Yeah, the T5 was a POS.

[HotSEXJ]

wait, trade an EIGHTY SEVEN camaro for a 97+ Cherokee???????

Huw-WHAT!?

http://img.engadget.com/common/images/0130471947182347.JPG

[MBood82]

you forgot your IMG tags

see my thread in the for sale forum, it explains a little better.

that 87 isn't necessarily the one I'm gonna go for but it's certainly worth looking into.

[jeepthing]

I used a 305 in a 67 Nova wagon. 3.36 gears, no posi, turbo350 trany, crane272 cam installed straight up, stock worn out 305 heads, performer intake 1" spacer ,holley 780 vac, cheapy headers 2.5" exaust,3250lbs car good for 13.98@101.7 at the track on 6" wide radials . freshen the engine, some porting , 3.90 gears, posi, 13.69@101.1 .. this was just a scew around engine and i had little money into it all used parts except rings and bearings. but if i was to spend some money i would of used a 350. it would of cost about the same to compleatly rebuild and it would run faster and have more torqe than a 305. :thumbsup: :)

[razorbackME]

I used a 305 in a 67 Nova wagon. 3.36 gears, no posi, turbo350 trany, crane272 cam installed straight up, stock worn out 305 heads, performer intake 1" spacer ,holley 780 vac, cheapy headers 2.5" exaust,3250lbs car good for 13.98@101.7 at the track on 6" wide radials . freshen the engine, some porting , 3.90 gears, posi, 13.69@101.1 .. this was just a scew around engine and i had little money into it all used parts except rings and bearings. but if i was to spend some money i would of used a 350. it would of cost about the same to compleatly rebuild and it would run faster and have more torqe than a 305. :thumbsup: :)

And I think that's a very good example of how NOT to build an engine.

[wrath]

And I think that's a very good example of how NOT to build an engine.

And what is your reasoning behind this?

[KILLER"B"468]

And I think that's a very good example of how NOT to build an engine.


For a worn out engine it sure got down the track fast. Some people don't have all the $$$ to do it the right way or other priorities for their $$$. I am a Big block freak, but it also is neat to hear how other's made stuff work with little to no expense.

[razorbackME]

And what is your reasoning behind this?

Because all of the parts are completely mismatched...huge cam, big exhaust, all on a 305 with stock heads.

Besides, mid-13s isn't what I would consider fast these days.

[WagoneerXJ]

Because all of the parts are completely mismatched...huge cam, big exhaust, all on a 305 with stock heads.

Besides, mid-13s isn't what I would consider fast these days.
It is for an old Nova wagon with very little money into it :thumbsup:

[wrath]

Because all of the parts are completely mismatched...huge cam, big exhaust, all on a 305 with stock heads.

Besides, mid-13s isn't what I would consider fast these days.

You need the cam with a lot of duration so it'll breathe... and about a 113° LSA to make a 305 happy. The only thing that bad about his setup was the carb was WAY too big. The rest of it is the same kind of stuff people put on bone stock 350s that make less power and move less air.

Sometimes it's kind of fun to beat people with your bargain basement setup, especially when they have a lot of money tied up in it. And when you don't have much tied up in yours you tend to beat on it a little harder than necessary. :D It's not ideal but sometimes it's a lot of fun... and sometimes you can prove a point. :lol:

[razorbackME]

You need the cam with a lot of duration so it'll breathe... and about a 113° LSA to make a 305 happy. The only thing that bad about his setup was the carb was WAY too big. The rest of it is the same kind of stuff people put on bone stock 350s that make less power and move less air.



Except that the increased duration moves the powerband way up where the heads can't breathe anyway. And 2.5" dual exhaust on a stock 350 is too much, and it just compounds the problem on this 305. The cam and exhaust want to make power at high rpm, while the heads can't flow jack. I'd venture to say that with a milder cam and a smaller exhaust, this car could have been faster, if he could put the power to the ground.

[wrath]

The heads can breathe if the valves are open longer for a larger amount of lift aka "square lobe". Most 305 cams are completely different than 4" bore cams. The 305, due to its cylinder mimicking a caulk tube, requires a certain lobe separation angle. The problem with the 305 and a wild cam is that it is more pronounced due to the small bore/long stroke and you end up with a narrow powerband.

It's true that a set of 1.5" primary headers and 2.75" single exhaust would be ideal for a 305... and 2.5" exhaust flows worse than a 2" or 2.25" exhaust for such small amounts of exhaust gases. But, for what he was doing (el budget-o) it was sufficient. I run dual 2.25" and 1.625" headers on my .060" over 305.

[nblehm]

Besides, mid-13s isn't what I would consider fast these days.


:rolleyes:

what do you drive again? since you seem to know/have better crap then everybody.... does your sh!t not stink either?

[hwm3]

:rolleyes:

what do you drive again? since you seem to know/have better crap then everybody.... does your sh!t not stink either?

He drives a 16sec Laser. :bow:

http://stalcup.us/jbrannen/Thahizzle/photos/photo32.jpg

[razorbackME]

:rolleyes:

what do you drive again? since you seem to know/have better crap then everybody.... does your sh!t not stink either?

I have had fast cars before, I just don't have any now. I'd love to, but I have 2 cars plus a company car, and I honestly can't justify having another car to park in the driveway. Plus, having a jeep is money pit enough; having something fast would be compounding the problem.

And I say mid 13s isn't fast because it's getting to be where there a decent number of cars that'll run 13s right off the showroom floor. I know of several guys who have run 12s in bone stock camaros or firebirds, and that's in the Memphis heat.

Oh, and I think that the Laser making it down the quarter in 16 seconds is giving it too much credit.

:D

[KILLER"B"468]

I know of several guys who have run 12s in bone stock camaros or firebirds, and that's in the Memphis heat.

I have been racing for a long time and I say no way on the 12's in the "stock" camaro's & firebirds.... Unless they are juiced with 250horse or more. A vette off the showroom floor will have a tough time breaking into the 12's

[wrath]

I have been racing for a long time and I say no way on the 12's in the "stock" camaro's & firebirds.... Unless they are juiced with 250horse or more. A vette off the showroom floor will have a tough time breaking into the 12's

LS1 F-bodys run 12.6 bone stock all day long. A set of Nitto 555Rs, manual electric fan, a SLP lid, and SLP full length headers = 12.2 all day long. Throw a cam in it, LS1edit the computer, and 11s are possible. You can even do this at Orlando Spin World, check out fuelslut.net.

I suggest whoever told you this learn how to drive.

[razorbackME]

I have been racing for a long time and I say no way on the 12's in the "stock" camaro's & firebirds.... Unless they are juiced with 250horse or more. A vette off the showroom floor will have a tough time breaking into the 12's

Then you haven't been paying attention, or no one up there can drive. Some of the slowest of these cars has been 13.2s that I have seen (assuming the driver knows what he's doing). I know several that have run 12.8s, and that's 100% stock...no NOS, no mods, and on the factory radials, not sticky tires.

I haven't seen anyone run 12.6s, but it gets a hell of a lot hotter down here than it does where wrath lives, so I could see that as a possibility.