Thread: LE9 305 rebuild

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looking at rebuilding my old 305 and looking to see if you guys thought this would be a good combo. stock 4 bolt block 60 over, 10.5 comp, stock cast 14010201 heads cleaned up and rebuilt with a mild port polish and valve job, 1.9 int & 1.6 ext valves,1.6 roller tip rockers, summit sum k1103 cam, performer intake and 500 cfm afb rebuilt and tuned or a 600 eddy if the afb's not quite enough

Is there any particular reason you have to build a 305??? GM has some great prices on 350 ci crate engines assembled similar to what you have described doing to your 305, and the GM engines come with a warranty!!!! Just an option to consider.....

Originally Posted by Dave Severson

Is there any particular reason you have to build a 305??? GM has some great prices on 350 ci crate engines assembled similar to what you have described doing to your 305, and the GM engines come with a warranty!!!! Just an option to consider.....

I had typed a very similar reply, saying "Why are you putting money into a 305??", but then deleted it. If it were me I wouldn't spend a nickel on a 305 engine, especially one already 60 over...

its not 60 over yet as it stands its never been touched and i just want to keep the 305

I've built quite a few 305 s. Because the parts interchange with a 350, it's cheap. You can easily propel two tons of Detroit Steel for about 18 mpg.

But around here, more respect is given for 8 mpg engine which would rip the car in half if it actually connects, or ridiculous over the top engineering to make a 302 stroker.

Nope, you won't get any respect building a 305.

not looking for respect or to go fast down the track just to rebuild my trucks engine so its a little funner to drive around town and still get ok mpg. i use the 360 in my dodge to suck gas and haul ass the chev stays on the street where it belongs

With today's oil having no zinc in it, tough to make a flat tappet cam live... Might want to consider a hydraulic roller, better efficiency and longevity! .060" is about the largest overbore to do on a sbc, might want to drop that to .030" and save room for one more overbore someday should you need it. For the street, hypereutectic pistons are great. Connecting rods should have new rod bolts installed and be resized. Just depends on how much money you want to put in the engine on what will work best for it. I'd still check with Chevy on a 305 crate engine, too. Lots less downtime then overhauling the existing, and usually a 3 year warranty with the engine!!!!

i dont like create engines i prefigure to build my own. and the over bore is nothing the le9 305 was built with a gm lm1 create engine 350 4 bolt block and cam just bored for the 305 instead i have plenty of meat to spare if i really wanted i could bore it to a 350 no problem

Well, if you already know what you're going to build, I'd say there's not a lot of reason to bother with any suggestions. Good luck.

Can't disagree with Dave on this one. The only comment I have is I'd drop the compression ratio down into the 9:1 range based on the fuels we have available today, to support running 87 octane pump gas; and I'd dump the flat tappet cam for a hydraulic roller based on the oils we have available today. Other than that, I'd wish you best of luck on the build. You seem to know what you want, and you're satisfied in the value you get for the dollars you're going to spend.

Chevy 305...Mighty Mouse in Underdog's costume!!



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I had an 85 chevy K10 with a 305. Replaced it with a 350 and a Shaun Murphy quadrajet and the mileage went up 2-3 mpg. Truck zeroed the AZ emissions test except for CO at idle where it was .01 percent. Had dual exhausts with Corvette cats.

Yeah, I hate to knock someone's plan as it is your money and time but these were probably the worst performance small blocks Chevy ever put out. If you want small cubes find an old 307. Bigger bore/shorter stroke; much better engine. Hot Rod built one of these years ago that got something like 25mpg in a full size Monte Carlo.

Originally Posted by falconvan

Yeah, I hate to knock someone's plan as it is your money and time but these were probably the worst performance small blocks Chevy ever put out. If you want small cubes find an old 307. Bigger bore/shorter stroke; much better engine. Hot Rod built one of these years ago that got something like 25mpg in a full size Monte Carlo.

Puttin' Perfume on a Pig...307 Tech?!


Both Tech Tip are from Fat Hack a HAMB member who likes playing w/the odd ball motors....joe



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