305 Builds

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305 Builds

Post by Roadcaptain S3 on Sat Feb 11, 2017 8:50 am

Everybody calls them "Boat Anchors", including us. But I've only got 45,000 miles on mine so I've been looking into "what if".
We all know that the guv mandated de-tuning engines right when GM was designing and building the G3 cars. I'm looking through a bunch of old articles and discovering  more than a few folks have turned 305s into respectable (and some down right mean) engines.

Super Chevy Mag:
http://www.superchevy.com/how-to/engines-drivetrain/1412-how-to-mod-a-305-with-bolt-ons-add-168-rwhp/

They got 259 HP and about the same TQ out of a 76 Elky for around $2300. I crunched the numbers a little, and it can be done the same way for less than 2k using some cheaper parts (Summit headers vs Hooker etc) and skipping some of their steps.
260 HP is about the same as the 94-96 Impala SS and the 87-93 Fox Mustangs. To get the same HP crate 350 plus exhaust would run you closer to 4k if you do all the work yourself.


They got 360 HP out of this one.
http://www.superchevy.com/how-to/project-cars/sucp-1007-305-small-block-engine-build/


300 HP
http://www.hotrod.com/articles/ccrp-9903-305-chevy-small-block-engine-build/

I've been thinking about a crate and or dropping in an LS. But the idea of keeping my orig 305 and playing sleeper, all while gaining hundreds of HP for cheap is really beginning to make sense. And I can do all of these bolt-on upgrades in my garage with hand tools in half the time of a total swap.

Thoughts?
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Re: 305 Builds

Post by bracketchev1221 on Sat Feb 11, 2017 10:35 am

I don't buy into magazine dyno numbers. They want you to buy parts. But on the flip side being an engine builder and drag racer, I do have a desire for the odd and different. So if building a 305 isn't the norm but what you want to do go for it. I would look at cost because a hydraulic roller conversion for an early block can get expensive. That may limit you to flat tappet. When I did my nova 355 it was like 400 just for lifters and 300 for the cam.
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Re: 305 Builds

Post by 73ss on Sat Feb 11, 2017 11:39 am

I always felt that the 83~88 4bbl HO motors ran fairly strong. Some even say they would out-run a 305 TPI motor. They also got help from a 3.73 out back. If you are dead set on a 305, look for the HO heads (Monte SS, Z-28, etc.) they got smaller chambers & a 1.84 intake, up from the bread & butter 1.72. The biggest hurdle with a 305 is the small bore which limits valve size. 2.02 heads wont clear, the valves will hit the bore. I dont think a 1.94 valve will fit either.
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Re: 305 Builds

Post by brownbomber77 on Sun Feb 12, 2017 9:36 am

You'll be much happier doing an LS swap if you're going through the trouble... For $2300 you can buy an entire LS engine and 4L60E trans AND have enough left over for a cam and a tune that will put 325 to the wheels

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Re: 305 Builds

Post by Roadcaptain S3 on Sun Feb 12, 2017 9:51 am

I agree the LS swap has it's appeal. I've got wheels on the way, then a bumper swap/tuck to do, then I'm gonna make a decision

I talked to my best friend/engine builder yesterday, of course he poo-pooed all over the idea. He's one of those guys that thinks a VW should have a 400 horse SBC. I have a 383 sitting in his shop that I pulled from my 75 Laguna years ago and he screeched and pointed at it. I had forgotten about it.

But the 305 build is kinda turning into a thing now. I might do it just to see how much we can squeeze out of it.
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Re: 305 Builds

Post by Limey SE on Sun Feb 12, 2017 11:57 am

CAPTAIN I SAY FULL STEAM AHEAD 44564 Original mileage 305 sitting between my rails of the SE also Lets see this get done

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Re: 305 Builds

Post by bigredlaguna on Sun Feb 12, 2017 12:26 pm

Lol, I can completely visualize the stop, screech, and point at YOUR engine in the corner!
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Re: 305 Builds

Post by ant7377 on Sun Feb 12, 2017 1:18 pm

Just my opinion but I would not waste my money. The machine work will cost you the same as any other small block and with all the LS swaps being done now you can probably piece together a good 350 or 383 for the same or a little more.
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Re: 305 Builds

Post by Roadcaptain S3 on Sun Feb 12, 2017 1:59 pm

bigredlaguna wrote:Lol, I can completely visualize the stop, screech, and point at YOUR engine in the corner!

His eyes were all bugged out too.
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Re: 305 Builds

Post by Roadcaptain S3 on Sun Feb 12, 2017 2:15 pm

ant7377 wrote:Just my opinion but I would not waste my money. The machine work will cost you the same as any other small block and with all the LS swaps being done now you can probably piece together a good 350 or 383 for the same or a little more.

No machine work. All bolted on to a 45xxx mile block. That's one of the reasons I'm seriously considering it. It's stupid to **** can a perfectly good engine and replace it with a used-pieced together 100000 mile truck motor. I'm not knocking the LS swap, I think it's great.
BUT, it's a lot bigger job (and can be a lot more expensive) than many think. Gas tank, fuel pump, oil pan, ecu, bungs in the exhaust etc etc. Everybody says "Oh just throw in an LS" like its simple. First you have to source the right engine, then find all of the other stuff you're gonna need, then spend a ton o time getting it done. I admire the guys that do it.

It looks like 305s can generate a lot more power than most think just by bolting some stuff on with hand tools in the same time it would take to sort through the wiring on an LS.  

I sorta feel like we've all been brainwashed to hate the 305, so nobody even tries it. GM used them for years for a reason.
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Re: 305 Builds

Post by fasrnur on Sun Feb 12, 2017 2:57 pm

Go for it roadcaptain. I myself had one in my S10 for a while. It was okay, but nothing like the 350 I replaced it with. The 305 was not stock, but did have a mild cam in it, an intake with a quadrajet and that was about it, but it just didn't trip my trigger. It had to go! That was my experience with one, but yours might be completely different.

How does that saying go? "There is no replacement for displacement?"  Very Happy

Jeff....
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Re: 305 Builds

Post by Limey SE on Sun Feb 12, 2017 3:52 pm

I am in With The Captain on this Build I have 44xxx bone stock original and short of the New Heads, No machining to motor will have to be Done I have the 600cfm, 4 barrell intake, Longtubes and 2.5" exhaust already So would only be cost of Heads.

I wonder how different the 84 SS 305 H/O heads would be than the S/r Heads ?? I can get a set real cheap from a friend that decided to leave his 350 alone

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Re: 305 Builds

Post by pila on Sun Feb 12, 2017 3:55 pm

Let's see......383 crank in a 305 block....    Need some pistons, Very Happy Unless you can mill .135 thou off of some piston tops !
I did it on 400 pistons, to use 5.7 inch rods. Back then there were no pistons available to do it...Had to put valve notches in them too of course...


Last edited by pila on Sun Feb 12, 2017 3:59 pm; edited 1 time in total

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Re: 305 Builds

Post by Roadcaptain S3 on Sun Feb 12, 2017 3:59 pm

Displacement if you're gonna race it.

Nothing makes me giggle more than guys that build 500 HP engines so they can sit next to it and tell everybody how fast it is.
Like most of the 396 Chevelle guys.
I see all these yappers talking about their fast cars, but all of the tracks around the country are closing.
Weird.

I ain't racing. I figure 250-400 horse is adequate for a street car weekend cruiser. I had that 96 Imp SS that was factory 260 HP and it scooted. It probably weighed more than my 77.


I figure I'll give it go just to see. Then if I hate it, I'll build the 383.
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Re: 305 Builds

Post by bigredlaguna on Sun Feb 12, 2017 5:20 pm

The most limiting thing about the 305 is head selection. Even the "vortec" generation 305's didn't get the good combustion chambers. I'm sure you will hit your goal for power with the right cam. If you can't find a set of the HO heads, just blend and equalize the ports of your original heads as best you can, good valve job and blend the transition cuts etc.

I understand what you are wanting to achieve. Even though the same work done on a 350 will give greater results, that isn't the point of this exercise. The 305 built right will definitely get the big car moving. I just think it will be more impressive with the right gears and an overdrive transmission. Gears are a small engine's best friend.
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Re: 305 Builds

Post by Roadcaptain S3 on Sun Feb 12, 2017 8:11 pm

I'm reading quite a bit about it. The 305 is fairly popular with some rodders. Looks like most are talking about World Products Torquer heads being better than Vortecs. Seems the Vortecs may be prone to cracks and have to be bored out a little?
Also looks like the Comp xtreme energy and Crane cams are popular. Summit apparently makes a generic version of both for cheap.
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Re: 305 Builds

Post by Limey SE on Sun Feb 12, 2017 8:25 pm

keep talking Captain LOL

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Re: 305 Builds

Post by bracketchev1221 on Sun Feb 12, 2017 9:16 pm

I would stick with the trick flow 175 cc heads. The 1.94 valve is perfect for that size bore. I try to stick with about 52% bore diameter for intake valve. I like the comp extreme energy cams, or the lunati voodoo series. Also the weight savings will be a help with the aluminum heads. Try to get the compression over 10:1. Also don't be afraid to spin the rpm up. 6-6200 is probably good with the shorter stroke.
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Re: 305 Builds

Post by Roadcaptain S3 on Sun Feb 12, 2017 11:26 pm

Thanks Ray.

That means more coming from a guy that actually DOES race his big HP 70 Chevelle, instead of just yapping about it. Thumbs up
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Re: 305 Builds

Post by bracketchev1221 on Mon Feb 13, 2017 7:33 am

Look, I know machine work costs the same and yeah you could build more inches. But to me there is a challenge in building an engine. I agree, the world is overrun with 700 hp 12 second cars. Everyone and their brother is building a 496 that makes 700hp and there isn't a small block that doesn't claim to make 425 hp. Build what you want. The challenge is taking an engine and finding gains in it and finding the combination that works. When I worked at McBetts racing engines, the majority of their business was circle track motors. So it was cool to have a strict set of rules and see how to make the most HP within them. My car being a bracket car, if I want to go faster I can just build a bigger engine. But then the goal is trying to make what I have quicker. I was recently involved in a project that was going to be based on a 396 BB and trying to make 6-650 hp with it. There aren't many of them around any more, and it was going to be different than the common 454 based engine. Unfortunately, the engine broke a valve and broke a lot of stuff before it was able to be pulled from the car. So there wasn't anything left to start with.
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Re: 305 Builds

Post by dynchel on Mon Feb 13, 2017 7:54 am

Even basic stuff makes a difference.  Pull the converter (or at least put modern replacements) with good flowing exhaust..Good ignition parts ,plugs, wires, maybe a msd box.  Hi flow air filter.  Maybe look around to shave a little weight (these cars are pretty heavy) & if this doesn't work, the same parts will work on your 383.
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Re: 305 Builds

Post by Roadcaptain S3 on Mon Feb 13, 2017 5:37 pm

bracketchev1221 wrote:Look, I know machine work costs the same and yeah you could build more inches.  But to me there is a challenge in building an engine.  I agree, the world is overrun with 700 hp 12 second cars.  Everyone and their brother is building a 496 that makes 700hp and there isn't a small block that doesn't claim to make 425 hp.  Build what you want.  The challenge is taking an engine and finding gains in it and finding the combination that works.  When I worked at McBetts racing engines, the majority of their business was circle track motors.  So it was cool to have a strict set of rules and see how to make the most HP within them.  My car being a bracket car, if I want to go faster I can just build a bigger engine.  But then the goal is trying to make what I have quicker.    I was recently involved in a project that was going to be based on a 396 BB and trying to make 6-650 hp with it.  There aren't many of them around any more, and it was going to be different than the common 454 based engine.  Unfortunately, the engine broke a valve and broke a lot of stuff before it was able to be pulled from the car.  So there wasn't anything left to start with.  

Amen. A challenge.
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Re: 305 Builds

Post by Roadcaptain S3 on Mon Feb 13, 2017 5:43 pm

dynchel wrote:Even basic stuff makes a difference.  Pull the converter (or at least put modern replacements) with good flowing exhaust..Good ignition parts ,plugs, wires, maybe a msd box.  Hi flow air filter.  Maybe look around to shave a little weight (these cars are pretty heavy) & if this doesn't work, the same parts will work on your 383.

This car was 100% stock w/ 44,000 miles when I picked it up. The first thing I did was dump the catalytic converter. You would not believe how much difference just that made.

And like you said, I'm not even counting dual exhaust as part of the budget, I was gonna do that regardless.
I'll keep ya'll posted as I go. I'm finishing up my wrangler project at the moment. Once that's done I'll start updating my build thread with wheels bumpers engine etc.

If I can find a dyno around here, it will be really interesting if I can do before and after tests.
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Re: 305 Builds

Post by dynchel on Mon Feb 13, 2017 5:51 pm

I know they early converters were very restrictive (and heavy). I found a shop that made me a "delete" pipe for my mom's '76 camaro (305 2bbl). You could feel a difference and definitely hear it.
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Re: 305 Builds

Post by Damon23 on Mon Feb 13, 2017 7:39 pm

For the money I don't know why anyone would build a 305 when you can buy a create motor cheaper. Unless you wanted numbers matching or for the fun of it. Either way you go you'll have a good reliable motor.

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Re: 305 Builds

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