Thread: my 305 putting out 304 HP

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it's only a 1/4 in smaller bore. usualy those who rant about how sorry they are dont have any idea what they are. just repeating stories. it's all the smog junk that hurt them.

yep, like I said before, dollar for dollar a 350 will make more power....but that doesnt mean you cant make a 305 be a stout performer if done right.my 86 Elcamino ran 13.70s with a mild 305 & 3.08 gears

With my 305 I went to a show 35 miles away and even though I burn 93 octane, I get 21 miles to a gallon which Is about 10 more than I get withmy 2000 Dodge Dakota with the 4.7 engine. Nothing wrong with a 350 we all know its a great engine, but I got the 305 with the vehicle and it works great and yeo I have put alot of money into it, but it was woth it.

Well lets disect the 350 an the 305
350 Crank 3.48 stroke mains 2.45 rods 2.10 Bore 4.000
305 Crank 3.48 stroke mains 2.45 rods 2.10 Bore 3.740

Rods 5.7 long with a 2.10 pin hmm same exact rod
Crank is the same an the rods the same so y not just came it up an get some aluminum corvette 350 58cc heads an slap em on there an see what happens.
305 with 210k on it an going strong.
I will post some dyno graphs of the 305 engine that i am got put together an now adding a t4 turbocharger to it.
So to all the 305 engine hang on to them. They are fuel efficient

FMhellraiser Here I'll post some more pictures of my 305. As far as how long your 305 will last thats up to the owner. Over 100,000 miles I would say your engine might(and I say might) be do for some new parts. Heck I had 85,000 miles on my 305 before i bored it .060 over which is alot for that engine, but I've never had any heating problems and even though I don't run a mechanical fan because of space limitiations, the 2 electric pusher fans I have mounted on the front never come on unless I'm sitting for long periods of time.

Cad, I used the L-98 vette aluminum heads on my 305

Well guess I will just have to wait and see how much longer it lasts. I also understand that this 305 of mine (since it;s an 84) has I think 8:1 compression which is horrible from the things I have read. Dave on CHR here told me to buy new 350 heads and shave them. But what about if I wait when I rebuild this motor and just get new rods, pistons, etc and change the compression by different pistons? What would you do about this? I am thinking to run 9.5:1 compression?
I will keep the 305 though, no need in changing it when nothing is wrong with the thing.

To increase compression ratio, there are different ways of doing so.
1.You can mill the deck which will put the pistons closer to the deck, reducing the clearence volume, or you can mill the heads, which reduces the chamber volume which will increse your compression.
2.If you use dome pistons with no other change you can increase your compression ratio.
3.Head gasket thickness will increse or decrease your compression using thinner or thicker gasgets.

There are different formulas for working out what you want in compression ratio, but I don't have any of them available. Maybe other can help you .

Thanks Chevy 37. The only thing that would be hard for me to do since I am bad at math and all is learning how to figure out what compression I will get and learn how to buy what pistons, gaskets, heads, etc to get what compression I want. Hard to explain but I think you will know what I mean.

Originally posted by FMXhellraiser
Thanks Chevy 37. The only thing that would be hard for me to do since I am bad at math and all is learning how to figure out what compression I will get and learn how to buy what pistons, gaskets, heads, etc to get what compression I want. Hard to explain but I think you will know what I mean.

FMX, I use the compression ratio calculator thats at www.campbellenterprises.com/pistons.htm It tells you your cubic inches, your compression ratio, plus will tell you how much HP you need in order to turn a certain 1/4 mile ET.... Check it out.... hope this helps.....
I use to have a 305 that was mildly built in my '84 Camaro, plus it had Nitrous on it. It ran good..... In fact I now have a '94 Firebird with a 350 & YOU have 19 MORE HP than I do!!! Billl

Thanks for the site man. I can't use it yet because I dont know the thickness of the stock gaskets or the CC's in the heads and the other ones. All I know is the bore is 3.740 and stroke is 3.48. lol

I'm not a chevy guy but if you have a 305 build it. I built a 302 ford that puts out 289 rwhp and 298 rwtq (all motor) at the last dyno time. Since then I changed carb and picked up .15 in the 1/8 mile. so I'm confident that that little 302 is doing 300 rwhp now. Moral of the story build what you have and don't let anyone f??K with your good time. Everyone (ford guys) keep telling me to build a 347. I've got three kids a mortgage and two ex wives. I can barely afford and extra pop at the end of the month. The 305's bore is a little small but hp is all about the Heads, cam, intake. JMO. enjoy.

later

Dennis kelley

Good point. I have a 302 in a F100 and everyone wonders why I dont put a big block in a big heavy truck. Well I am only 18, no job right now, going to college... No money. The 302 runs strong enough and not like I need a big block with heaps of power. I wont go down the street with the pedal to the floor racing every second... Waste of gas.

Well I'm new to web forums like this so go easy on me if I screw this post up.

Just throwing in my 2 cents on 305's great engines, alot has already been said, but biggest limitations on the TBI version in the caprices is the runners in the heads and the exhaust manifolds.

Stock LT-1 exhaust manifolds, Camshaft, and Valve springs/retainers are supposed to give a nice boost to a TBI 305. Nearing Impala SS performance but with a couple extra mpg.

My 1992 caprice has a 305/700r4/2.56:1. Modifications are a K&N air filter, synthetic oil, bosch platinum plugs (cured misfire above 4300 rpm), 1/4'' injector spacer, 40 series flowmaster, 16'' electric cooling fan and a resonatorless tail pipe.

Haven't had it to the strip since the plugs and injector spacer but it's best time is a 17.4 @ 80.9mph. Sure it's not the quickest or fastest but it weighs 4200 pounds before you put 200 pounds of me in it.

The best part is the 23 or so mpg it gets in the city and regularly 28-29 on the highway, occasionally low 30mpg.

I'm actually working on getting a 305/700r4 out of an '86 caprice to put into my 82 "El caprice" (4 door turned into a 2 door truck with 4 inch chop)

The "El Caprice" now has a '73 Olds 350 with 210,000 miles in this car and lord knows how many miles it had on it when it was put in (junk yard engine installed in '84). has a worn out 700r4 behind it. Single digit fuel economy in the city, needs rebored.

Just for the sake of mention, I also have an '85 caprice in the middle of a frame off "resto mod" so to speak. Body should be back on Saturday. It's getting a 1976 cadillac 500/700r4. Read of similiar combos getting mid to high teen mpg, IF you can keep your foot out of it... Fuel economy is not what this car will be about.

Welcome to CHR. Looks like the El Caprice is a big project.