Throw the 305 out if you want a high revver and build a 350. Besides that, to build a high revver that will hold together we`re talking money. Cam change, head change, intake change, exhaust change, gear change, etc. You can build a mild 350 for it with a rev limit of 6000 rpm with Vortec heads and you`ll be shocked at what it`ll do with almost 50 more cubic inches. Don`t waste your time with a 305.

 

As DV says....but it will only rpm as high as the valve train allows it. I don't understand this "RPM' thing unless you just want to run around town doing burnouts and trying to impress folks with a 305. If an engine makes its power at say 5500 then anything more is just a waste of time, gas and engine wear.

 

Throw the 305 out if you want a high revver and build a 350. Besides that, to build a high revver that will hold together we`re talking money. Cam change, head change, intake change, exhaust change, gear change, etc. You can build a mild 350 for it with a rev limit of 6000 rpm with Vortec heads and you`ll be shocked at what it`ll do with almost 50 more cubic inches. Don`t waste your time with a 305.

I could'nt agree more. :thumbup:

 

Hey, I have an 87 Camaro with a carb'd LG4. It's a roller block as far as I know, and I'm pretty sure it has a decent bottom end since it's an 87 block, but I'm not sure what the absolute limits are. I'd like to get away with changing rod bolts and pistons, which will be stock size hypers.

After doing some reading, I've found that the 87+ rods are good for 480 HP (in a 350, not sure if they're different, even though they're both PMF), the crank for 425 (nodular iron), but the RPM limits were not given. As far as I know, rods are prone to breaking from RPM rather than compression So, what can I spin the 305 to, assuming the top end will be able to support whatever the bottom throws at it? I've heard of the stock cranks being reworked and able to spin 7,500, but if I were to do that I'd just buy another crank for a bit more $.

Edit: CR won't be over 10.25

Anyway, summary: Max RPM 87+ roller block 305?
I'm thinking just shy of 7k, 6.8k or so.

Thanks :mwink:

You'll have to be more specific about exactly what mods you made that are worth 480 horse. Because that would include a lot of work on the top end of the motor, which dictates in large part what your RPM limits are (valve springs/mass of valve train etc).

I would note, however, that with cast pistons and stock rods, even if you do have the valve train, cam and ignition to carry you up to 7 grand, you're going to be in trouble with that bottom end.

There will be guys telling you "I rev a stock SBC to 7 grand all the time and its fine!" There are probably a few. Doesn't change the fact that in general its pretty clearly not a good idea, and I've seen more than my share of stock motors blow up and much lower RPMs than 7000. You could chance it, but ask yourself this, do you really want to take a chance of a 20 dollar stock piston breaking loose and destroying a 1200 dollar set of heads?

K

 

That's out of my budget, and I'm not really looking for a high revver, so to speak. (At least I don't think 65-6800 is considered a high revver) I'd like to know that safe limits of what I've got with minor improvements. I really only have money for cam, heads, and new rear gears.

I've driven a 98 viper, I know what cubes can do, it was fun until I spun out in an intersection an almost ***** myself. :embarrass

 

I rest my case. Go right ahead with your plans. What killer mentioned was the gospel. I`m out.

 

You'll have to be more specific about exactly what mods you made that are worth 480 horse. Because that would include a lot of work on the top end of the motor, which dictates in large part what your RPM limits are (valve springs/mass of valve train etc).

I would note, however, that with cast pistons and stock rods, even if you do have the valve train, cam and ignition to carry you up to 7 grand, you're going to be in trouble with that bottom end.

There will be guys telling you "I rev a stock SBC to 7 grand all the time and its fine!" There are probably a few. Doesn't change the fact that in general its pretty clearly not a good idea, and I've seen more than my share of stock motors blow up and much lower RPMs than 7000. You could chance it, but ask yourself this, do you really want to take a chance of a 20 dollar stock piston breaking loose and destroying a 1200 dollar set of heads?

K

I haven't done anything yet, that was just saying what I've read in one of Vizard's books. I'm not going to buy the valve train until I know what the bottom end can support with ARP rod bolts on PM rods, stock size hyper pistons, and stock nodular iron crank.

I'd like to make sure this will work before I go and spend the money on heads and cam that are way too big for what I'll be able to do.

I figured the 305 would be able to spin a couple more RPM due to the lighter pistons, in comparison to a 350. If my limits 5,500 that's fine, too. I just want to get the right setup the first try.

 

i'm really not sure if they are a true roller, i have a 87'Z8 that originally had a LG4 305 4bbl in it, but ive never torn it down. since i have put a 355 and now a 385 in it. if well balanced the original GM parts are capable of decent power, not sure if as much as you mentioned by these are numbers i would shoot for with a 305. i do agree with DV. it will take a bunch of money to make that 305 run high rpms, and even then it still wont make a bunch of power, it may make decent tq but the 305 has a small bore making it much harder to make good power out of them. no matter what you do to the bottom end the heads will still fall off after 4500rpm, even if you get a set of 416 HO 305 heads and have them reworked you still will have problems reaching over 6k. a set of vortecs with the 1.94/ 1.6 or 1.5 exh valve wont fit too well in the standard bore 305 the 416's are about the best you could shoot for, i cant remember GM made a set of vortecs with 1.84 int valves, if so they should be able to fit in the bore.

i you really dont want to go through the hassle of building another motor but just want to make the one you have a little stronger then look for the 416's have them cleaned up P&P'd, get a very mild cam (no more than 208 duration @ .050) performer/ RPM intake, keep the Q-jet carb if still working well, a set of headers and true daul exhaust, if you do all this you should be getting 250+hp and 300+tq it may rev to around 5500 till it starts falling off quick. then get rid of the stock 2.73 gears and get a set of 3.42's and get a shift kit in the 700R4, it will feel like a completely different car.

but if you want real power you will need to go to the 350 block

 

6500-6800 is high reving in a stock sbc, i have scat 9000 crank, with eagle sir rods and KB pistons in a .040 383 makeing over 500hp and i still wont rev it to 6500 (dont want to see my money go through my hood) i have hit 6300 in it during a burn out but i dont like to hit over 6200 ever

 

Thanks for all of the responses, by the way. It's hard keeping up with them all :smash:

For what it's worth, what I had in mind for the top was a slightly worked set of 113s, stock rods with aftermarket bolts, a comp 280HR in at 2* advance, 1.94/1.5 valves, magnum rollers, beehive springs, RPM air gap, 570 CFM carb vac secondary carb.


Edit: But since that was shot down rather quickly :nono:

How would 113s, stock rods, a comp 270HR straight up, and an air gap with a 500 CFM carb do? Should make power to 5.8-6.1k. Or should I just find something that'll cap at 5,500 and be done with it? I can have the 113s for cheap, and I like them because of the exhaust flow and high velocity intake port. That's the only reason I keep bringing them up.

 

that cam is advertised to 5000 RPM operating range in a 350. That puts you at 5500+ for your power peak (if you have the heads to support that) and you usually ride about 300 RPM past the power peak before you shift, so that's 5800 R's for you, roughly speaking.

You mentioned earlier about 10:1 compression, are we still thinking about that or has that changed?

I wouldn't be pushing this motor very hard in terms of RPM. 5500 is the standard limit, 6000 is an occasional thing but to be honest with you, I wouldn't push a stock bottom that hard, and I don't.

You're not going to be getting very close to 480 horse with this motor as far as what I'm reading. With your 133 heads, stock compression, this cam a decent intake and some exhaust in a 305 I'd say 220-250 horse would be a pretty liberal estimate. Numbers don't matter as much as how it feels when you drive it. If you like the car then don't worry about dyno numbers.

Also speaking of numbers that you may be too concerned about: RPM does not necessarily = power. I was a little confused why you were looking for a specific RPM limit for this motor from the beginning. Last, even when we do start talking about high RPM power, the 305 is not a great revver (not bad but not great) and doesn't breathe as well as similar sized motors.

Another thing I'll mention is that I think an 87 camaro is a pretty heavy car. I think you're going to be disappointed with that cam in a 305 because its going to be a little soggy on the bottom. Stall converter helps, but then you're moving further into the build...

As mentioned before, you may want to just ditch your 305. By the time you start talking about putting a cam and heads on a motor you already have it out of the car (if you're doing it right). Get a 350 core and build on that, you'll be much further ahead. I'd be willing to bet you could do heads and a cam on your 305 and you'd be slower than if you just dumped in a stock 350.

Best of luck-

K

 

http://www.hioutput.com/tech/400hp/400hp.html

 

http://www.hioutput.com/tech/400hp/400hp.html

It would be cool to blow somebody's doors off with a 400 horse 305 as above. Might make some money at the strip with that motor!

I may be beating the dead horse here, but I just wanted to give my 2 cents on a few points about the above build should you choose to go that route:

• Those heads are pretty high-dollar, maybe more than you'd need to make similar power from more cubes.
• That's a pretty high-revving motor: 7200 RPM for max power. They said they did it on a stock bottom but if you read the connecting rod section they actually changed them out, so now you're looking at a full rebuild.
• The compression is very high, and may be tough to run without pinging on the street (borderline), so that's something to consider.
• That car has a huge cam and a single plane intake which will make it very soggy below 2500 RPM.
• Sort of touched on this before, but given the stress of the RPM and power on stock rods, I think reliability is limited.
• A minor point, but an MSD ignition was installed to carry the RPM for that build. A larger-cube motor could live at lower RPM and you could save money by using the stock ignition.

Anyway, good luck either way. I find myself compelled to post on this thread because I went down the same road myself with a 305-car and found out that I was much happier with more cubes after I'd done a good amount of work to the 305 already...

K

 

I'd love to ditch the 305, but if I built anything else up, it'd be a 377 or a 434 and I'd go all in on it and end up with a $5000+ engine that'd blow my trans and rear, and that's why I'm kind of stuck on the 305 for now. No point on building up the front if the back can't take it. That said, it'd be stupid to build it up twice. And hey, if this engine craps out, I can pick up a JY 350 or a GW for 1500.

I've looked at that build, but one thing I've heard is that it's called "Deadly Lessons" because it ended up losing a rod. It seems like there was more potential in that engine, the headers were a terrible choice in my opinion, but they were just shooting for peak power. Not a fan of the carb choice either.

One thing about that build is that it's a pre-87 305, meaning the internals were much lower quality. It's also flat tappet, I believe.

With the 87, the rods are much improved, as are the crank and pistons. The fact that it's a roller with more aggressive lobes leads me to believe I can make the same power by 65-6700. Then I could stick with an RPM air gap, over a single plane.

I think I'll go for it. What the hell? :evil: Rod bolts, pistons and rings or just new rings depending on what's in there.. Will have to change what heads and cam I'm going with, though.

 

im no engine expert but i agree with ditching the 305...imo there junk

you can pick up a 350 on craigslist for 100 bucks or so, throw a 70 dollar cam in it, find some pistons, new rings, freshen it up and have fun

if you do blow it up your only out 400 bucks or so

on the stock gm parts i've always had good luck, i've ran 3 motors with gm stock bottom ends(all had aftermarket pistons, cast), and i've turned them all to 7000, one was a 406, one a 355 and most recently a 361

lots of ppl have told me they won't hold up, and they are pry right as i don't have that much experience, but im not scared one bit to run the stock bottom end

but lots of ppl have told me im stupid for building 2 bolt main blocks to

 

now after looking it up the LG4 is not a roller block, in 87 and up the roller 305's were the LB9/L98 TBI motor, the LG4 is the same motor put in the camaro's from the early 80's till the last year in the camaro in 87.

if you were to look at the cam specs from the LG4 you would laugh. i really dont think you will ever see 6500+rpm out of a 305 without $$$$ into the heads. i mentioned before you should look for a set of 4416 HO 305 heads, have them cleaned up and a little porting and polishing. look for a mild cam with a advanced duration around 208-214 get one with a LSA around 110 and maybe a lift around .420 ish. get a nice dual plane intake and i mentioned keeping the Q-jet carb, they are a great carb but they get a bad rap, ask a carb guy they will tell that a Q-jet has good performance attributes and great street attributes, it may need to be tweeked a little and you'll have to fine someone who knows what they are doing. a set of headers and true duals.

if you want a referance to look at then look up the L69.

after all this you may get up to 250-270hp and good tq.
you'll want to replace the factory gears as they are likely 2.73's, find someone selling 3.23's and posi carrier from another 7.5 rear.

i still say replace the motor with a 350