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Old 09-03-2004, 10:35 AM   #1
websparks
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Default Bolt-On Horsepower?

Looking for ideas on "bolt-on horsepower" to get my 76's stock L-48 at 190 horse up to something in the range of 300+. I'm planning on pulling the engine out in a month or so and want to start getting lined out to minimize "stand-time".

Not looking for anything too radical (like cutting holes in the hood ... ), but this 190 is just too anemic. All ideas are appreciated.



Mike
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Old 09-03-2004, 10:43 AM   #2
SteveG75
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Heads - Something nice like AFR's. 64cc chamber will get you up to abot 9.5:1 compression
Cam - 210-220@.050 lift range works good for a 2000-5500 rpm power range (Comp XE262, Comp HE268, Crane Powermax 272 are all popular)
Good intake - Performer RPM is popular, Weiand 8004 is also good.
Ignition - Adjust timing per Lar's tech paper
Carb - Rejet/tune Q-jet or go for a Demon
Exhaust - Headers to true duals. Dynomax Cerama-coats are a good deal.

I did all this the first time round and the car pulled hard and still got 18-19 mpg.
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Old 09-03-2004, 11:17 AM   #3
Beasley's 76
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When I went through this two years ago after comparing costs and seeing what could be done. I decided to replace the L-82 in my 76 with a GM Crate Motor 350HO 330HP. I was able to order the Vortec Long block that came with a nice set of Chrome Valve Covers, I added the Edlebrock intake and a Holley 650. I could have reused the Old Carb but chose to go with everything new. The Engine, Distributor gear and Flywheel costs me $2289 including shipping from Bobby Murray Chevrolet. My corvette is now my most dependable vehicle in the driveway now, that includes a Honda Accord. For the two years since I put the engine in I have had no problems and it has performed beyond my expectations. I installed new Headers and Flowmasters and it sounds great, the cam lopes good and has great response.

My only complaint with my car is no A/C and without an overdrive it sucks taking road trips, I run about 3500RPM at 70-75 mph.
I'm about to install a T-56 6 speed within the next two months and I can't wait to get it installed have two extra gears for Interstate driving!

You can view my motor under the pics on the new upload page once it gets back up and running.

Hope all goes well!
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Old 09-03-2004, 11:25 AM   #4
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Cat, heads, cam, ignition. These are the mods I would make first.

These are the basic mods that later C-3's need.

The factory cat is VERY restrictive so that needs to be addressed first. The heads are the biggest limiter of power after that on any engine. These 2 changes allow you to make other mods that will work. The L-48 cam is designed to work in station wagons and 4 door sedans so that needs to be addressed. Even the '69 350/350 cam would be an improvement and was designed to work with the Vette vacuum accessories. That cam is worth considering. The ignition is pretty good as is but the curve setup is for emissions so that is a low budget easy mod.

The cost/benefit ratio gets higher after that.

-Mark.
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Old 09-03-2004, 11:41 AM   #5
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Holley makes Systemax kits.... cam & Intake or cam, heads & intake
one of those kits with some headers looks like a pretty simple & cost effective way to bolt on some serious HP.... The one kit claims 425hp last time I looked!!!
Good luck & have fun building up your toy!!!
John
Link to kit info

Last edited by jcswm; 09-03-2004 at 11:49 AM.
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Old 09-03-2004, 11:52 AM   #6
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[QUOTE=SteveG75]Heads - Something nice like AFR's. 64cc chamber will get you up to abot 9.5:1 compression
Cam - 210-220@.050 lift range works good for a 2000-5500 rpm power range (Comp XE262, Comp HE268, Crane Powermax 272 are all popular)
Good intake - Performer RPM is popular, Weiand 8004 is also good.
Ignition - Adjust timing per Lar's tech paper
Carb - Rejet/tune Q-jet or go for a Demon
Exhaust - Headers to true duals. Dynomax Cerama-coats are a good deal.
QUOTE]
I'm supposedly sitting at about 350hp using Dart 180 Iron Eagle heads with 64cc chamber, flat top pistons, Comp XE262, Performer EPS intake, 9.7:1CR, stock HEI ignition per Lar's, Holley Street Avenger carb
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Old 09-03-2004, 11:52 AM   #7
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First I go with a nice set of headers, it is a mod that you WILL feel a difference with. Second I go with a cam and intake and maybe a head swap.

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Old 09-03-2004, 11:56 AM   #8
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Quote:
Originally Posted by Corey_68
First I go with a nice set of headers, it is a mod that you WILL feel a difference with. Second I go with a cam and intake and maybe a head swap.

Unless you upgrade your exh system you will be chocking all your other mods, prolly get about 20-30 hp and torq from headers and true duals. Then when you move on to other mods you will get the full benefit from them.
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Old 09-03-2004, 05:39 PM   #9
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Nitrous......
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Old 09-03-2004, 05:47 PM   #10
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Quote:
Originally Posted by jcswm
Holley makes Systemax kits.... cam & Intake or cam, heads & intake
one of those kits with some headers looks like a pretty simple & cost effective way to bolt on some serious HP.... The one kit claims 425hp last time I looked!!!
Good luck & have fun building up your toy!!!
John
Link to kit info
There was a guy at carlise that bolted on the same kit, made 250 rwhp on a 79 L48, so thats about 300 flywheel

MAtt
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Old 09-03-2004, 06:08 PM   #11
mandm1200
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Quote:
Originally Posted by Fevre
Unless you upgrade your exh system you will be chocking all your other mods, prolly get about 20-30 hp and torq from headers and true duals. Then when you move on to other mods you will get the full benefit from them.
I can't argue with your logic, as that is the first thing I done (upgrade to headers and true dual exhaust). The exhaust will have to be modified to something less restrictive.
Someone else mentioned the 350/350 cam. I haven't seen someone mentions that cam before. I had a mid 70's Camaro that I installed that cam into, along with some other mods like intake and headers. It made a world of difference. Good performance and sounded good.
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Old 09-03-2004, 06:15 PM   #12
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my plan

882 casting heads, 2.02 and 1.6 valves, mild porting by me
edlebrock torker intake
edlebrock performer carb
shorty headers, 2.5"duals, H pipe
stock HEI recurved
cam, I have a 327 350 cam and lifters but i migth get a newer better profile.

expected hp, a bit over 300 at the flywheel

so its not the best set up combo, but if i were to tell you what i paid for each item i dont think youd argue with me on it

MAtt
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Old 09-03-2004, 08:20 PM   #13
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Quote:
Originally Posted by pillowmeto
my plan

882 casting heads, 2.02 and 1.6 valves, mild porting by me
edlebrock torker intake
edlebrock performer carb
shorty headers, 2.5"duals, H pipe
stock HEI recurved
cam, I have a 327 350 cam and lifters but i migth get a newer better profile.

expected hp, a bit over 300 at the flywheel

so its not the best set up combo, but if i were to tell you what i paid for each item i dont think youd argue with me on it

MAtt
882 heads are prone to cracking. A dual plane intake MIGHT be better suited. Why shorty headers?
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'76 L-48, 4-Speed, 3.36
383 with Eagle 3.75 crank & 5.7 SIR rods
Speed-Pro Hyper 12cc dish pistons
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Internally balanced
Comp Cams XE274 cam & Roller Tip Rockers w/Crane Posi-Locks
Accel distributor
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Edelbrock Performer RPM Intake
Correct Stock Q-Jet with professional (Lars) rebuild
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Old 09-05-2004, 11:55 PM   #14
websparks
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So what's the best way to get around the cats?
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Old 09-06-2004, 08:36 AM   #15
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Exhaust-
http://www.corvettefaq.com/c3/ganeyexhaust.htm

Cam & intake at same time.

Heads.
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Old 09-06-2004, 10:45 AM   #16
76REDSTINGER
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i just switched from a TM-1 single plane to an EPS performer dual plane
BIG difference on throttle response, low end better

also on sizing a carb i read that if you are drawing less than 1.5 in/mg
at WOT the carb is too big.........any one else seen this?

any opinions on World S/R heads ? just chased down the casting NO's on mine.

also noticed the no performance crate motors under 400 HP have a carb bigger than 650 cfm........bigger isnt better, if you cant use all the fuel.

R.
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Old 09-06-2004, 11:02 AM   #17
Uriel
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Those Holley Systemax kits look pretty cool. I have a '77 that's basically stock (L-48 with the smog stuff removed, dual exhaust) and I've been thinking about some upgrades. I think my valve guides are on their way out (some blue smoke on start up) and I figured it would make sense to rebuild, get new cam/heads/intake/headers at the same time. Now as a newbie, it really is overwhelming the amount of choice in parts that are available and to me this kit seems like a godsend. Trouble is I don't really want to spend too much money. It'd be the top Systemax kit I'd be looking at but how would this cope with the rest of my setup? I'll be getting a rebuild kit for the bottom end, will I need an expensive one with forged companents? Will the Systemax kit be ok with my block (2-bolt I assume?). What about the stock 4-speed manual 'box and read end? I'm prepared to spend some cash getting this kit and having the engine rebuilt and am not that bothered if it doesn't make near the 400HP they claim when used with the rest of my gear (can upgrade other parts at a later date), but I wouldn't want to spend all this and have the 'box fall apart or shatter the rearend or whatever...
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Old 09-06-2004, 11:02 AM
 
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