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Author Topic:   305 chev
posted January 11, 2004 05:33 PM
Need lots of help just getting into some Dirt track racing and have to run a 305 with stock intake and carb.Track is 1/3 mile would like some idea as to what to run for a cam pistons crank and where I can get good parts for one also some idea as to what gears we should run any help would be appreciated. Thanks irk

posted January 11, 2004 05:48 PM
Can you run anything else besides a 305?

dan ferry
posted January 11, 2004 06:38 PM
if ur stuck running a 305i wouldnt be too upset all the others gotta run em too right. find the 305 heads with 601 casting # and there is one other good flowing 305 head i cant find the papers but someone will know. put good valve springs on that match the cam u go with.we will need to know a little more info on the rules. what type of piston and fuel theyre gonna let u run. u can get the copression up on those pretty easy with a flat top and some machine work but all for nothing if u gotta run pump gas. is there a lift or vacuum rule 2 or 4 barrel. i popped my 355 and used a fresh 305 for a couple weeks and finished 5th and 7th you can get them to run but i wasnt limited on cam and could run flat tops. let us know what u cant do

posted January 12, 2004 03:56 PM
Hey, I'm building a 283 and can't wait to try it out. The guys at the track said it'll run ok on our class (283 - 318 cu for the class). To get 302 off a 283 you have to bore out .060 if I remember correctly. 283's made after '57 don't have enough material to to go that big if I remember right.

Some tell me it won't be the best engine for roundy round racing, but it was cheap, and I got one of those nascar type engine run stands out of the deal too.

Good Luck

posted January 12, 2004 05:01 PM
i ran a 307 for a couple years was a pretty good little motor no power house by any means but was good on a sloppy or realy dry track we used a 480/480 cam from crane believe the # was 10007 with 1.6 rockers she worked pretty good. like the others said tho just some hyperutetric flat tops and reconditioned stock rods with good bolts and a set of valve springs should do you just fine and not to hard on the wallet either. that would give you a motor just like mine but mine is a 350 ands i have less then 500 bucks in it

posted January 12, 2004 06:54 PM
If you take a 283 crank and a small journal 327 block is about the easiest way to make a 302.

posted January 12, 2004 07:35 PM
Thanks to all who has replied I am not right sure of the rules at this time but they were talking of a vacuum rule you can run a 4bbl and headers and we are planning on flat top pistons we could run a 283 but the 305 was here and most are running them will find out how much vacuum we can have and get back to you

posted January 14, 2004 12:05 PM
take a 305 put a 267 crank in it a replacement cam for a 1978 4 wheeldrive blazer and 305ho heads and turn it about 6500 and it will fly

posted January 14, 2004 05:43 PM
Here is a article I found hope it helps.

Lunati's 343 hp 305 Build-up


Using traditional hop-up techniques, Lunati's goal was to achieve maximum performance at an affordable price from the 305 small-block in a non-emission-controlled environment. The engine should be capable of running on the street, with decent idle characteristics and low-end torque. For longevity and practicality, the engine ought to develop peak power at around 5500-6000 rpm. finally, the package needs to be reasonably priced because the high-buckers would just as soon spring for the larger displacement small-blocks.


All 305 blocks have two-bolt main caps and use cast cranks. The Lunati 305 rotating assembly consists of a standard 3.48-inch stroke cast crank turned 0.010- or 0.020-inch under, indexed and balanced. Reconditioned stock rods are fitted with Mr.Gasket SPS bolts. Both crank and rods are supported by Michigan77 bearings, and are kept oiled by a Melling standard M55 oil pump.

Silv-O-Lite Keith Black Signature Series pistons (PN 144) were chosen. Manufactured from high-silicon alloys, they combine light weight with superior detonation resistance and (compared to forged pistons) permit tighter wall clearances for improved oil control and quieter operation. On under-4.100-inch bore engines, Silv-O-Lite piston skirt clearances can be set as tight as 0.0015 to 0.0020 inch; yet their rigid skirt design and high-silicon alloy permits running the piston "looser" than a traditional casting if desired--as high as 0.0045 inch. These pistons yielded a 10.26:1 compression ratio, used with a 0.038-inch-thick head gasket, 0.010 piston (down) deck, and a 60 cc combustion chamber.

Silv-O-Lite pistons come machined for Spirolock piston pin retainers. Usually, floating the pin requires bushing the rod. But to keep costs down while retaining the floating pin feature that allows the homebuilder to assemble the rods onto the pistons himself, Lunati runs the floating pins "steel-on-steel," with no bushing. If that worries you, remember that Chevy did the same thing on the '69 Z28 302's and warranteed them for 50,000 miles. The key is maintaining 0.0003 to 0.0005 inch of pin-to-rod clearance, not to mention drilling the rod for pin oiling.

Another depature when using the Silv-O-Lite pistons is piston ring end-gap. These pistons make more horsepower by reflecting heat energy back into the combustion chamber. As a result, the top ring runs hotter and requires more clearance than usual. According to Silv-O-Lite, increasing the ring end-gap does not affect performance or oil control because normal end-gaps are realized at operating temperature. Conversely, failure to provide sufficient end-gap can cause a portion of the top piston land to break, as the ring ends **** and lock tight in the cylinder. Silv-O-Lite provides a "recommended ring gap" chart with its pistons for varying applications that recommends multiplying the bore diameter by approximately 0.0065 to get the recommended ring end-gap on a normally aspirated non-computer street engine. On Lunati's 0.030-over 305 (total bore= 3.766"), the end-gap with the chosen Speed-Pro plasma-moly "file-fit" 5/64-5/64-3/16 ringset ended up at 0.025 inch for the top ring and 0.014 for the second.

Cylinder Heads

Lunati used "generic" 305 iron cylinder heads (casting number=14014416, used on LG4 and HO engines), replacing the 1.84-inch stock valves with larger 1.94-inch valves, but kept the stock 1.50-inch exhaust valve size, treating both to a "good' standard valve job. They also ended up gasket-matching the heads and doing a little bowl work before installing Lunati high-performance springs, retainers, locks, screw-in studs, and pushrod guideplates.


Lunati installed one of its Streetmaster hydraulic non-roller-tappet grinds that offers reasonable idle quality with just a touch of that performance "rump-rump" so dear to our hearts. At least that's how it behaves in a benchmark 350; the cam is a tad more radical in a smaller displacement motor. To compensate for the engine's small displacement, the cam was installed 4 degrees advanced, and uses 1.5:1 ratio long-slot rockers.

Lunati SM-225
Lift @ valve Advertised duration 0.050 duration Int/Exh seperation Intake lobe seperation
0.477" 275* 225* 108* 104*

Why not use a smaller cam? Lunati says it's hard to move air through a small-bore motor with a restricted valve area like the 305. You need a bigger cam to make this small cylinder work, but there are limits due to the small displacement. Fortunately, the relatively long stroke for this displacement engine helps low-end torque, so the engine isn't all that cam sensitive.


Edelbrock's Performer RPM intake was used. This manifold pulls through 7000 rpm, but it's divided plenum also makes it work at low rpm. It has exhaust heat passages, but no EGR provisions or divorced choke stove pad. Edelbrock says the manifold is not 50-state smog-legal on most emission-controlled applications. The tall plenum won't clear the stock hood on late-model Camaros, either. Holley's model 0-4776 600 cfm double-pumper carb was used.


Lunati used a pre-computer ACCEL Blueprint HEI distributor with conventional mechanical and vacuum advance, along with ACCEL's in-cap, high-intensity coil and spiral-wound 8.8 wires. The ACCEL unit comes with extra mechanical advance weights and springs, and the vacuum advance is fully adjustable. For the full-throttle dyno test, the unit was run as delivered.

Test Results

Lunati's engine was tested on Dynotech's SuperFlow dyno using a generic set of 1 5/8-inch primary tube headers. The best results were obtained with the stock jetting and 38 degrees total timing, where a peak of 343 corrected horsepower at 6250 rpm was observed. The peak torque output of 356.2 lb-ft occurred at 4250 rpm. The engine made over 1 hp/cubic inch from 4500 through 6500 rpm, the highest rpm tested. It made over 300 lb-ft of torque from 3000 rpm (the lowest test point) through 5750 rpm.

Through all the tests, the engine idled smoothly at 750 rpm. Dynotech's technicians believe the engine would have more potential with less restrictive heads. They also think that the engine would perform better with a 650- or even 700-cfm carb, albeit at the cost of additional bottom-end sogginess.

Racing gas with a 108-octane level was used for all tests. This gas is not generally available for street cars. Assuming the use of 92- or 93-octane unleaded, you could get by with a true 9:1 to 9.5:1 compression ratio street motor when using cast-iron heads. The generally accepted rule of thumb is that you lose 12 to 15 hp for each point drop in compression-- so an otherwise identical 9 1/4:1 engine would be down about 15 hp from the results reported here. This lost power could be easily regained by using aluminum heads fitted with bore-clearing 1.94/1.50 or 1.55 valves, such as those offered by GM or Air Flow Research. Not only do the heads flow much better than 305 iron castings, but aluminum's superior heat-rejection characteristics allow 10:1 street engines on available unleaded premium pump gas. In any event, the end result is a 305 that will surprise quite a few late-model 350 owners.

Dyno Test Results
Lunati's engine was tested on Dynotech's SuperFlow engine dyno, using the 200 rpm/second acceleration test schedule. All values are corrected to 29.92 inches Hg, 60*F dry air.Test fuel was 108 octane race gas. Peak amounts underlined.
Speed (rpm) Torque (lb-ft) Power (hp)
3000 324.3 185.2
3250 333.7 206.5
3500 342.0 227.9
3750 347.0 247.8
4000 352.1 268.2
4250 356.2 288.2
4500 351.9 301.5
4750 340.2 307.7
5000 333.8 317.8
5250 324.4 324.3
5500 313.0 327.8
5750 306.2 335.2
6000 297.3 339.6
6250 288.2 343.0
6500 258.4 319.8



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