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Old 01-26-2013, 09:31 AM
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305 chevy sluggish

Hello any ideas on how i can pep up a 1979 305 motor i cant even get a chirp from the tires. I have a 350 a/t and 348 gears.

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Old 01-26-2013, 09:36 AM
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Have you checked the timing and advance mechanisms? Do the work, is timing correct?
Is the exhaust breathing freely? Could be plugged at the cat.
Engine could be tired, but for sure if it is a stock 2 barrel engine the cam is puny .
Not to mention the cam timing is probably retarded for emissions.
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Old 01-26-2013, 09:51 AM
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It has a lopey mean sounding cam, shorty headers 4 bbl carter carb, passing gear works on q,The timing and vacuum seem to be good it has a nice curve 10 BTC and 40BTC at 2500 rpm gets good accel but wont turn the tires.
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Old 01-26-2013, 09:53 AM
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Its installed in a 32 chevy coupe that weighs 2700 lbs the rear diff out of a 73 -80 vette.
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Old 01-26-2013, 11:23 AM
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Lumpy lopey most likely means cam is bleeding off too much compression at low rpms. The thumper cams are known for that. They sound cool...but thats about it.
You could put a 2500 stall in it, that would liven it up.
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Old 01-26-2013, 03:44 PM
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First, you did not mention the type of car you are driving. If the 305 is stock and the tranny and converter is all original, you will never spin the tires. The work on a 305 will be so much you better off of getting a 350 from a junk yard and sell the 305. 350 are a dime a dozen. Don't bother spending money on aftermarket auto parts.

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Old 01-26-2013, 04:28 PM
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a stock 305 has a low 8.6:1 cr. camming it up makes it real sluggish at low rpm.

You need stiff 4.10+ gears and a 3500+ stall to get a cammed up 305 going.

try recurving the distributor for 24 to 26deg at idle....a limited 10deg advance curve and no more than 36deg BTDC at max mechanical advance. You cannot get this curve by just swapping the advance springs.
You need to limit the travel stop of the advance system. This allows increased idle timing, yet avoides excesssive max advance.
40deg max timing is way too much and 10eg at idle is not enough for a cammed motor.
Cammed 305's don;t get busy till 3000+ rpm. It wants rpm. (gears converter stall)
needs 10:1 compression ratio.

If you buy a 10" "3500 stall converter" and install it, you will see about 3000 rpm stall behind a 305.
if this 305 has factory dished 305 pistons the compression ratio will be way too low for a high perf camshaft.

Nothing that a Weiand 142 blower and 7 psi boost won;t fix.
A great way to wake up a low compression over cammed 305. You will have a whole new opinion on 305's and their ability
to roast tires.

Its very easy to over cam a 305. especially with a stock torque converter and stock- mild gears and low compression.

no such gear ratio as 3.48:1. What is the real gear ratio? What is the rear tire diameter?

Last edited by F-BIRD'88; 01-26-2013 at 04:36 PM.
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Old 01-27-2013, 08:43 AM
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I think i'll agree that the305 is a dog. Had one in my nova when i bought it new. Latter years i tried everthing to get that thing to run. Sold it to make room for a 355 motor and it realy ran good. I then took the rear and put 3.42 posi in, and 200 4r tranny. Then it turned out better. Now i'm putting 3.73 gears and a better torq converter. Good, better, best. never let it rest. MY motto for a hot rod. ...
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Old 01-27-2013, 08:45 AM
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late 70s and early 80s sbc s were nothing to write about.All the parts are low performance.When I bought my 81 vette the original engine was warmed over,cam,holley manifold,holley carb,small tube headers. I test drove the car,felt ok,bought it.Tuned it,enhanced the carb,upgraded the ignition etc. The best combination of tune netted 205 horse power and almost 280 pounds torque at the wheels.
After thinking of what I could use from the original engine,I ended up replacing everything. I went a little over board.
Point Im making though,that 79 305 does not have a lot of potential,at least not for cheap.
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Old 01-27-2013, 10:23 AM
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305's respond to hot rodding just like any other SBC.

Compression, head port flow, valves, camshaft, intake, exhaust. You will be changing everything
but the block and crank with better stuff.

Like all small cid sbc engines a hot rodded 305 needs a stiff rear gear and a very high stall as the power band will be up high and you have to rev it up. Just like a 302 or a 283.

You can also supercharge it. Makes it act and perform like its 100 cubes bigger.

One way to do it.
http://www.hioutput.com/tech/400hp/400hp.html

needs a 5500 stall custom race converter and 5.xx series gears.
revs to 7500 rpm.

Last edited by F-BIRD'88; 01-27-2013 at 10:33 AM.
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Old 01-27-2013, 11:55 AM
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Man you have to do alot to those little cu inch motors to get any real power. there is no substitute for cu inches. Not to mention, the high the horse power, higher the revolution, the greater the wear. there is also a comfort side also. I like my power and get up and go, but there is the comfort i like when i drive. That is why i stuck with a automatilc with four forward gears. That overdrive gives you alot of options for gear ratio.
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Old 01-27-2013, 12:05 PM
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Wow

Now thats why I joined hot rodders thank you to everyone for the sincerely great ideas. And the gears are out of a 73-80 vette with the 350 trans it feels like it wants to shift again at 55 mph.
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