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Choppy/Loppy Flat Tappet Cam for Stock 305 H.O. L69

3396 Views 121 Replies 12 Participants Last post by  BogiesAnnex1
After removing my lifters and inspecting them, I have learned that I need to replace my camshaft and my lifters...

If I'm going to replace the camshaft then I want to do it possibly with something a little better than stock...

I wanted to sound choppy/lopey...

What is a good camshaft and lift a kit that will make my engine sound a little more choppy ?
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More lift and more duration to get a choppy idle increases force on the springs and valve guides all of which are already old. Messing around with a hot rod cam is going to get you into spring replacement and likely a head rebuild to restore the valve guides and seats. You can’t do guides without doing seats both head and valve if the valves are salvageable. Valve wear is seat and stem. Stems usually wear a long time as they are hard chromed but the guides in the head take the beating as a result of the harder surface on the stems. The theory here is refinishing guides is less costly than replacing valves but in this engine that’s still based on 1950’s economics which aren’t true today.

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After removing my lifters and inspecting them, I have learned that I need to replace my camshaft and my lifters...

If I'm going to replace the camshaft then I want to do it possibly with something a little better than stock...

I wanted to sound choppy/lopey...

What is a good camshaft and lift a kit that will make my engine sound a little more choppy ?
A lopey 305 with a stock converter and rear gears is going to be a REAL turd on the street. Just put a stock or near stock cam in it and save to build a 383, a transmission/converter, and a rear end.

Figure $10 per horsepower for the 383 engine.

For your 305 engine, why not put in some sort of an original spec hydraulic cam for a 9:1 compression low performance 327? Someone else might know what this would be, or maybe something better that will retain a little bit of torque on the low end and work with the low compression of your 305.



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Choppy idle means high revs to get power. You have an intake, heads, torque converter, compression, ECM, valves, and exhaust that are all perfectly suited for idle-4000. If you put in a choppy cam that is suited for 3000-6000, you'll have a real boat anchor. You'll have to change all of the above to match the choppy cam or you'll just have a 10mpg slug that makes less power and torque than what you have now.
 

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Choppy idle cams are soooo obsolete. The sound of the 1960’s never produced all that much power against the cubic inches. Much was made of getting 370 SAE gross horsepower from the LT-1 350 with 11 to 1 compression. So rather than refining the engine they turned to a cam that barely closed the valves 312 degrees total duration with only .458/.485 inch lift and 242/254 duration at .050 lift. These needed 100 plus octane fuel and a 750CFM to reach 370 Hp. Plus vehicles like this only came with manual 3 or 4 speed transmissions and rear gear ratios started at about 3.5 and went up from there 3.89 and 4.11 being common. Try spending a day listening to your engine spinning at freeway speeds. Automatic transmissions behind performance engines were something occasionally seen as experiments at the race track, not available from the OEMs behind performance engines.

Today the emphisis to make power is preserving compression pressure on less compression ratio since hundred octane plus fuel is not at the corner gas station. So combustion chsmber design has changed a lot to increase the efficiency of the burn. For Chevrolet these Ricardo (heart shaped) chambered heads first show on the 1992 LT1 and the 1996 LT4 in aluminum and iron for the 94 L99 Gen II engines. The 1996 L31 Vortec introduced this chamber to pickups with conventional block first then heads cooling. The LT1, LT4 and L99 are reverse cooled which routes coolant to the head first and returns from the block. Gen II blocks, heads, intakes, ignition, coolant pump are not interchangeable with the Gen 1 engines with the exception of the aluminum heads can be modified back to conventional coolant routing with some welding, remachining and creative external coolant returns.

The aftermarket industry has picked up on the ideas of the Ricardo chamber and manufacture heads from moderately priced imports to very expensive domestics that blow away anything from the 1960’s using much less can duration and lower compression ratios suitable for 89/91 octane E10 unleaded at the corner station. A cam timing like the Comp XE268H with 268/280 overall degrees having 224/230 at .050 and .477/.480 lift through a 1.5 rocker at the valve will easily produce 390 SAE gross crankshaft power using L31 heads and a 650 CFM carb. With a 750 CFM carb and attention to valve train details its almost impossible not to get 420hp from a 350 all on 9.5 to 1 compression. This makes a lot of torque and power under 6000 RPM that is very automatic transmission friendly and does not need a high stall converter, higher than your 1400 but nothing crazy getting into 1700-1800 stall is sufficient. The exhaust note on this cam rumbles but is pretty smooth at idle but in an engine built to todays knowledge base when it comes on it is gang busters to use the old phrase.

If you’re not building like this as I outline above but rather for rumbly idle exhaust sound you will spend a lot of time looking at the other guy’s tail lights. So you need to get out of this 1960’s think and get modern. In the words from my teen years “you gotta get hep man”.

Like I’ve said the devil is in the details, for all the words I’ve used this is still like skipping stones across the pond. Since this an early build for your history you need to talk to us before tearing into things and buying parts. You need to start with a realistic power goal and realize that changes in engine power are sooner or later effect the driveline and chassis. The first issue is getting the power the next is component survival further down the line. Big power numbers especially in terms of torque will make you learn transmissions, driveline and rear axle technology very quickly soon followed by concepts of the suspension, frame and body. You will find that big power numbers have to be controlled or you crash, I’m wishing you discover the former before suffering the latter.


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A L-79 or L-82 clone cam is a good cam for a 305 SBC. Either one will give you the desired sound at idle. In a 305 either one take off will feel about the same with a stronger 2500 to 4500 mid range.


Here is one of those cams in a .010 over 305 with Edelbrock Torker intake, long tube headers. 4v carburetor, HEI etc. The L-79 camshaft is easy on the valve train.
 

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A L-79 or L-82 clone cam is a good cam for a 305 SBC. Either one will give you the desired sound at idle. In a 305 either one take off will feel about the same with a stronger 2500 to 4500 mid range.


Here is one of those cams in a .010 over 305 with Edelbrock Torker intake, long tube headers. 4v carburetor, HEI etc. The L-79 camshaft is easy on the valve train.
L79 was a 11.0:1 compression engine. Just sayin'!

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L79 was a 11.0:1 compression engine. Just sayin'!

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I'm clear on the compression of that engine.

I recomended that camshaft it because it is easy on the valve train and just works. It's not a end all - cure all but it's easy to find and cheap to buy. I am sure there are better cams available. Much like women and barbecue everyone has a favorite.
I've used those cams in 350, 327, & 305 engines without any issues. These were definitely not 11.0:1 compression engines. I'd be shocked if they were 9.0:1.
I also recommend the L-82 camshaft which has larger lift numbers than the L-79 camshaft but GM listed that engine at 350CID, 210 hp and 9.0:1 compression.
The OP can do as he pleases I only offered what has worked for me. The truck in the video was a 305, 700R4 with a 2.70-ish rear end. It is a pleasure to drive.

The OP stated "I wanted to sound choppy/lopey..."
 

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Anyways, another way to get choppy/lopey is to switch to manual choke; When you want chop, close the choke up. Back to normal, open it up......

Not saying anyone SHOULD do this, i'm just saying this is a way to get choppy / lopey without messing with the cam.....
 

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Anyways, another way to get choppy/lopey is to switch to manual choke; When you want chop, close the choke up. Back to normal, open it up......

Not saying anyone SHOULD do this, i'm just saying this is a way to get choppy / lopey without messing with the cam.....
Turn the idle mixture screws in a bit to lean it out. Make it sound like It's got a hot cam. And when you get tired of it or the exhaust burns your eyes turn them back out. Easy and inexpensie.
 

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Turn the idle mixture screws in a bit to lean it out. Make it sound like It's got a hot cam. And when you get tired of it or the exhaust burns your eyes turn them back out. Easy and inexpensie.
Yeah, this too.

i /we suggest this if you want to "make noise" at the traffic light without having make any major modifications to the engine which could adversely affect performance/driveability.

(i've just realized how immature this is.......)
 

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Anyways, another way to get choppy/lopey is to switch to manual choke; When you want chop, close the choke up. Back to normal, open it up......

Not saying anyone SHOULD do this, i'm just saying this is a way to get choppy / lopey without messing with the cam.....
I'm going to actually admit to doing this when I was 19. Back when you would cruise the town in your car on the weekend. When you go by the fast food places where everyone would congregate..... a little extra choke and it would sound wild!
 

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If you have an L69 engine that is starting to get tired, why not just put a similar cam back in? Comp makes a "factory muscle" cam for the L69. Factory Muscle 195/202 Hydraulic Flat Cam for Chevrolet Small Block. Hotter cams are going to require at least new and stronger valve springs. It has to run better than a flat original cam.

One thing I have never seen in your posts - does this vehicle have headers?

How about taking a photo of the RPO code list that is pasted in your glovebox. We can tell your rear end gear from that amongst many other things.
 
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