performance of a 305?
Registered User
Joined: Jun 2003
Posts: 573
From: Just outside of "D-town"
Re: performance of a 305?
Originally Posted by NastyTA
I'm not here to get in a pissing contest with any of you. Just offering my opinions, experience and what I've come across. I think you'll find the consensus being that most don't want to mess with the 305, not saying it's junk or can't make power, just not worth it in most cases.
noones trying to unzip here buddy..if you start out with a 305 it can be made to perform, even though it wasnt designed as a performance platform..with a 350 those parts will make atleast another 30-40 hp and 50+ lb feet....alot of people feel the way you do that a 30 is a waste. and it is if you have nothing to start with..if you dont have a core then theres no point in going with a 305 especially when 350 are easy to come buy and you can build one CHEAP..my point is that a 305 can make some good power and torque, just that most people dont give it the time to figure it out and really try to extract the most from it..they say "its a 305 its gonna be a dog"....when id beat LT1's and run with LS1's to 75mph i got a few people to respect it...but it was also becasue of my driving ability..as i was running 14.1's with only a 96mph trap speed when the LT1s i was beating were trappin 99-101
Registered User
Joined: Jun 2004
Posts: 379
From: Bloomingdale, IL
Re: performance of a 305?
Honestly man, if you're going to go through the hassle of rebuilding an engine, don't do a 305. I'm building up my 305, but every single part I put into it (except maybe the cam) will go onto a 350 someday. I'm also hoping to run low 13s on motor this year with my 305. But if/when I blow this shortblock to smithereens, I'm definitely going to rebuild a 350...no sense in spending rebuild money on a 305. Go ahead and buy bolt-ons and stuff that will work on a larger motor, but if you have to tear into the shortblock (aside from cam), then its not worth it.
Oh and by the way...to figure out if its a 305 or 350, check those casting numbers....or just pull a head and measure the bore. If its 3.75" then its a 305. If its a 4.00" then it may be a 350...or a 327...or a 377. Never know.
Oh and by the way...to figure out if its a 305 or 350, check those casting numbers....or just pull a head and measure the bore. If its 3.75" then its a 305. If its a 4.00" then it may be a 350...or a 327...or a 377. Never know.
Registered User
Joined: Feb 2005
Posts: 3
Re: performance of a 305?
Originally Posted by NastyTA
What the heck are you doing to get 300hp out of a 305? I'm not trying to be a d!ck, but it's extremely hard, if not impossible. If you're going to spend the money to build a motor, start with a 350. High 13's on the motor are tough with a 5.0L and mid to low are even harder to come by N/A. You'll just be disappointed. You can make a nice cruiser with a 305 but you'll be hard pressed to get those times. You'll need a good set of aftermarket heads, a good size cam, and enough machine work and small parts that will make it more economical to leave that block in the woods. If it's back there, someone put it there for a reason. Before you do anything you first need to find out if it's a 5.0 or 5.7L motor. Look on the drivers side of the block above the bellhousing and if it's a newer roller motor it will say 5.0 or 5.7L. If it's older you will find casing numbers that you'll have to look up on mortec.com to identify. Then you need to have a good machine shop check a few things before you go further. The block needs to be degreased and magnafluxed to check for cracks. Then the bores need to be mic'd to see if they're out of round and to see if it's been bored before. The line bore needs to be checked to see if the block is twisted. If it checks out OK, you'll spend 300-500 on block prep, you'll need to find a rotating assembly, a set of heads, cam, lifters, valvetrain, oil pan, timing cover, oil pump, and all kinds of other parts that would take too long to list. I think your best bet is to find a complete 350 out of a truck or something and start from there. You can pick them up for <300 at a junkyard or on the forums. You'll still need all the machine work, heads, cam and stuff like that, but you'll have a block, crank, rods, all the little bits and pieces and you'll know what you're starting with. Or you could always buy a crate motor for 3-4000$, stick it in the car and go. Sorry so long, but I don't want you to make a mistake.
Start with the oil pan up.
High volume High pressure oil pump.change the 5.7rods to 350 light weight 6in rods ,go with a true "flat" top piston. Machine for 0 deck clearace.Have the pistons top ring come as close as you can to the top of the boreSelect a moderate "roller camshaft" and lifter set. A roller set will give you about 45 more horsepower over stock.Run a "true" double roller timing chain or even get the gear set.Hardend pushrods ,roller rockers.Stock 305 heads have a 58cc combustion chamber cut it down to about 52-54cc and install 202 valves. Nothing bigger because you haven't got the piston size to run the larger valves.
Run a quality intake. Holley or Eldorbrock. Opinions vary.Run a good 750 carb. Adjust jet size accordingly.Run a good quality "hot" coil to burn the extra fuel.Have a set of headers on it.With the above set up expect around 350 to 400 HP from a 305 , no $h1t.
Registered User
Joined: Oct 2004
Posts: 100
From: Littleton, CO
Originally Posted by chevyguy926
your definitely right but im not looking for a super screamer i just want a consistent 12-11 second camaro
Registered User
Joined: Apr 2003
Posts: 1
Re: performance of a 305?
Yeah you'll never hit 12-11 second times with an N/A 305, sorry. Build something bigger that'd make it much much easier.
Of course you can't bore a 305 to accept 350 pistons. You'd have to bore the block like 0.25" you won't be doing that with any small block.
you can`t even bore a 305 block to accept standard 350 pistons without more than likely hitting a water jacket
Registered User
Joined: Jul 2004
Posts: 29
Re: performance of a 305?
I'm out of my 305 as soon as I can. It's a good motor for a driver but I won't spend money on it. I'd rather spend $$ and see "more" results then messing around with a motor that has limited potential.
just an opinon.
just an opinon.
Registered User
Joined: Jun 2003
Posts: 573
From: Just outside of "D-town"
Re: performance of a 305?
Originally Posted by MY91Y84
i personally know someone with a 410 horse 305 TPI motor...hes runs a TPIS base, runners and plenum STOCK ported 083 heads and a SP-L98 cam (also TPIS)...and a set of 1 5/8 smoggger SLP headers...runs 12.2's on motor and 11.7 on a 90 shot...gotta know what your doing before you diss the little 305...just for fu(ks sake my VERY mild TPI 305 ran 14.12...only mods were a K&N filter flowmaster MUFFLER and the EGR walls ground down...
[QUOTE=BronYrAur]Yeah you'll never hit 12-11 second times with an N/A 305, sorry. Build something bigger that'd make it much much easier.QUOTE]
i still dont know what the hell the problem with reading every post before you reply...i mean seriously it only makes you look like a fool...now read what i typed again
NEVER SAY NEVER
Thread
Thread Starter
Forum
Replies
Last Post
F'n1996Z28SS
Cars For Sale
8
Aug 23, 2023 11:19 PM
oldschool
Parts For Sale
16
Feb 9, 2016 09:21 PM
bossco
Automotive News / Industry / Future Vehicle Discussion
4
Nov 29, 2014 10:18 AM