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BlownBirdy 12-12-2003 07:31 PM

Stroked 305
Alright, I know that I am going to get chewed on this one, but maybe not.
I am building a stroked 305, .060 over with a 3.75 inch stroke for about 334 cubes. I have had the block tapped for four bolt mains with the outer two bolts digging into the block at a 22 degree angle. I think it will hold. I plan to use a World Castings Torquer 305 head because the 58cc chamber should boost compression. The engine was rebuilt to stock specs about 900 miles ago, and just isn't cuttin' it. It is going to be rebuilt again. On and off I am working on a 383 stroker with a blower, but for now I would like to see this 334 come alive because the blower is going to set me back a lot financially. My question regards connecting rods. I plan to use a Scat crank and rods, but I am confused on the size. From what I understand, the pistons I am getting will work fine with a 3.75 inch stroke and 5.565 inch rods, but I was wondering how the motor would react to 5.7 or 6.0 inch rods. I am planning to run over 10.1:1 compression, but I don't want to go crazy because this is a Street/slight strip car. If I use the longer rods will I have clearance problems or is it just a matter of too high compression. The only reason I ask is because the deck height is 9.025 inches, just like a 350, and that works fine with teh 3.75 crank and 6.0 rods. Is it a matter of combustion chamber size? What about other combos like a 3.48 inch stroke with a 6.0 inch rod? Maybe It would be best to go with the recommended 3.75 crank and 5.565 rods. Anything anybody can offer will really help.

badknuckles 12-12-2003 07:46 PM

if you want to boost compression late model camaro 305's with high output heads were 55cc with 1.94 1.50 valves. those would boost your compression work well for me

KeithB123 12-12-2003 07:59 PM

I like the 334 or bored out 305 idea! Seriously. You must compare cost.

My worn out 305 with boltons and a 3:73 rear did a 14.7. You all can say whoopy but that engine had 165,000 miles and most newer stock stangs are in the 14`s! So with a cam and heads, with the puni 305 bored out.....that car can get low into the 13`s without a power adder. Be easy with that cam.

I would put in a Comp extreme 262 and a 600 cfm carb with that set up.

I believe the 6 inch rods will work. The reason you DO want the 6 inch rods is because you CAN run a higher Compression Ratio!! ..the higher the CR the more power you will have...because the piston will be dwelling a little longer when it is firing.

Don`t listen to the Bull**** you hear on the 305. You can make a 305 respectable...the problem is ...if you spend that much money on a 350, you will be 100 horsepower or soo higher.

Good Luck, keep us informed! 12-12-2003 07:59 PM

Have you checked the price of pistons for a 305, 5.7-6.0 rod setup? I haven't checked for stocked pistons of these combinations, but you are probably looking at a $500.00 bill min.

BlownBirdy 12-12-2003 08:09 PM

Camaro heads
I don't mean to be difficult, but if you would have either a casting number or year to look for that would really help. The 305 that is in the car right now is a 1978 sbc 305 block with numbers matching heads. Are these the same heads you are referring too?

I figured it would be expensive, but I only found two pistons made for a 305 that is .060 over. Summit Racing sells the Sterling pistons I was referring to in my original post for 14.69 per piece. Any idea on the quality of these? Then again, I would probably have to buy rings wrist pins, etc., which would add to the cost. I know JE pistons makes a piston for a 305, but I don't think it is a stroker piston. It is a +.060 piston to be used with a 3.48 stroke and a 5.7 rod. I know that JE Pistons are expensive, but if I could use them with the factory crank and rods, it might offset the cost, maybe not. They have a compression height of 1.560 and yield a comp. ratio of 10.1:1 with a 58cc head. If i use the 55cc head, the comp would be a little higher, and I could save some money through the use of the stock crank and rods.

stepside454 12-12-2003 08:09 PM

I used the L98 HO Aluminum vette heads on my 305 I had in my 86 Elky. they have 58cc chambers 1.95/1.5.
I had the comp cams 256X in it. car ran 13.70s with 3.08s . worked real well. Another great, maybe better option for 305 is vortec heads.
I had KBpistons in mine & with 58cc head came to right at 10.2:1. I was real happy with it.
Dollar for dollar 350 or more makes more power than the 305, but the 305 can perform if done right.

badknuckles 12-12-2003 08:11 PM

no the heads that came on a 78 305 are large chamber low compression heads with fairly small valves.
high output heads are the way to go look for an iroc or some monty ss's have high output 305's.
getting a set of these heads is cheap i picked up a set for 30$
the big money was getting them machined.
l98 iron heads off of a 350 ta or camaro had 70cc's.
the aluminum off of the corvettes were 64 cc's with 1.94 1.50 valves very good heads

BlownBirdy 12-12-2003 08:16 PM

Thanks KeithB123 for the info.
I was actually going to ask about cam next. I like your choice cuz I wanted something comp cams makes. Would a 1.6 roller rocker with pushrods +.100 work if I drilled the rod ports they didn't hit the sides of the heads, or would I have problems with piston to valve clearance. I have also heard of using 1.6 on the intake and 1.5 on the exhaust to offset the smaller exhaust valves. Any thoughts? If i used the 6.0 inch rods, would you suggest the 3.75 crank or the lower compression 3.48?

Thanks everyone.
I know that I can make more power per dollar with the bigger cubes, but i could still have fun with the smaller motor. I knew it could be done.

badknuckles 12-12-2003 08:19 PM

let me know how it works out for you sounds like a cool project curious to see it done:thumbup:

KeithB123 12-12-2003 10:33 PM

I hope you go through with this to shut alot of people up.

1.6`s will hurt nothing! ..include the rollerside, even better. $$

+ .100 pushrods is not a matter of working..."Is it the correct size?" That is not a`s a measurement that will not make the engine faster.
This must be correct.

Luci or Double would have to comment on the other questions....just a little bit to far advanced for my 101 !! smile!!

machine shop tom 12-13-2003 07:58 AM

This is a build that I always thought had promise. As far as piston go, Keith Black has one , KB186, that works with the 5.7" rod. Should be around 10:1 with the 58cc head. I would be very careful in choosing a camshaft to try to avoid too much cylinder pressure. Stay away from torque cams or mileage types. Look for something that produces mid-range hp. If you buy aftermarket heads, make sure to have them checked out, as many need milling and a valve job right out of the box.

killerformula 12-13-2003 08:44 AM

First I really have to commend you for going through with a plan like this, it really takes some skill and know-how. I know you're probably dead set on building this motor, but the principles behind it don't really work that well. Your motor is going to have a long stroke so its not going to rap that well... maybe 6000 or so. Second its got the 305 bore which is small (3.5 if I'm not mistaken) so you lose the advantage of a big bore too. Take, for example, a 327. THey're great engines because they have strong cranks and a short stroke that allows them to rap really well. Same concept in a 340 too. With this setup I think you're defeating yourself for the extra cubes. Why don't u trade somebody for a 350 block and build a 383! Honestly you're talking the difference of 50 cubes here, it would be well worth the trade!

If you go through with the 305 stroker I hope it all goes to plan. I just had to give you the advice we all were thinking.

Good luck either way!


machine shop tom 12-13-2003 08:52 AM

Second its got the 305 bore which is small (3.5 if I'm not mistaken)

305 bore size is 3.736.

3.736 + .060 = 3.796"

Still not a whole lot, but more than you were thinking, Killer.

BlownBirdy 12-13-2003 10:55 AM

Bore Size
I get what you are guys are saying, and I know that there is a lot more power available in other motors. I am not really building this for an all out race engine though, and I figured that by building a stroked 305 I would get a decent amount of power without running over 6k in traffic. Cops can hear an 6000 RPM engine well enough....I have been told so many a time. I think that by building a 10.1 or 11.1 334, it might work out ok. As for the 383 idea, I have a block sitting in my garage as we speak. It is taking some time to build because I am making sure I do it right. It is an early 70's 350 block I got from a guy who used to done some work for the race engines used by John Force. He gave me the rusty 350 core for free! Score! My plan is to do it .060 over, so it would probably be like a 388 when I am done. I am using a Scat forged crank, H-beam rods, and JE inverted pistons. To top it off, I am adding a Weiand 6-71 blower and two HOlley 4150 HP 600cfm carbs. The only problem is the expense of it. This is why for right now I want to do the 334. Thanks for the advice.

P.S. THe stock bore of the 305 is 3.736, you were right Tom. Punching it 60 over will result in a 3.796 bore. As you said, not a lot, but slightly more effective than stock.

machine shop tom 12-13-2003 10:58 AM

One more thing while I think of it. I wouldn't go more than .030-.040 oversize. Those cylinder walls are none too thick.

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