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Old 03-02-2011, 05:28 PM
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Muscleing Up a 350 Vette Smog Engine

Somebody asked a similar question about the same thing, only putting it in a Hot Rod. I'll ask it again, only the engine is in a 77 vette. The current engine is I THINK an L78(?), but it IS a 180 HP 350. What I'd like to know is what sort of HP could I expect to pull out of this engine with an Edelbrock package...heads, cam/lifters, intake, carburetor. Is the juice worth the squeeze, or is there a more cost effective way to acheive the same results. And the hood needs to close. Thanks, guys...

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Old 03-02-2011, 05:31 PM
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400 hp as long as the compression ends up being 9.5+. As long as its a low rise intake the hood will close.
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Old 03-02-2011, 06:43 PM
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i'm not sure if you will be able to get the hood to close with a performer rpm intake, you may have to use a performer intake. i dont know exactly what the cost is, but personally i would rather go with a set of RHS pro tokers (vortec style) and about a 212-216 duration @ .050 cam (should have around .450" lift) with a 600 vac sec carb.

rhs heads = 800.00
cam/lifters/pushrods = 200-225.00
performer intake = 150.00
gaskets = 75-100.00
carb = 325.00
est. totall = 1750-1850.00

and i would say this combination would be good for around 325hp/ 365tq which is a very fun street motor, and you wouldn't have to change your stall nor gears for it either
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Old 03-02-2011, 08:09 PM
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I'd essentially agree after doing lots of research to do the same thing to my 81 350 weak sister.

I don't want to swap pistons (shortblock is sound) so am going with smaller comb chambers to up compr ratio, a good set of Vortec style heads, but
aftermarket, a Comp Cams hydr flat tappet cam (you have to use the right
kind of oil for flat tappets so it's got enuf zinc, and that is NOT Rotella! See
the BobIsTheOilGuy forums for what production oils do have enuf zinc.)

The RHS heads are great and flow better in mid lift than the Ebrocks.
Strictly for cost purposes I'm going with these

You'll definitely have to use a Performer vs a Performer RPM intake for
hood clearance.

Dart Vortec style heads are also very good. Problem is not likely to find
either Dart or RHS used. A good used option would be the regular
Ebrock Performers if budget is important.

A very interesting exercise is Comp Cams Camquest on their website -
you plug in the basic parameters of your engine and then how you want
to use it etc and they offer a range of their cams they feel would work.
They then show a likely dyno result for each of the suggested cams.

You need to know what rpm you want the torque peak and the hp peaks
to occur, and be realistic. I'm putting a limit of low 5k max on mine so the
engine lasts - it's surprising how small changes in cam specs and affect
the torque curve especially.

Many people have a tendency to over-cam and end up with a mismatch
for a combo that doesn't run worth crap.

And coordinate your torque peak rpm goal with your vehicle overall
gearing. I'm going 3.31` or 3.08 gears with a 2200 stall and a 1.84
low gear 200-4R. In OD that'll be 1600 at 58mph and 2200 at 78 mph
for good trip gas milege, but with the lower 1st & 2nd gears in the 200
trans vs a 350 or 400 trans I'll still get a 25% reduction in overall 1st
gear from stock.

Good luck!

Opinions freely offered!

Just fyi your pistons have a 9.9cc dish and are about .025" deck height.
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Old 03-04-2011, 10:12 AM
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its probaly an L48....getting 350 hp and 425 ft lbs is easy.....just like you said add cam, heads, dual exhaust with x or h pipe, aluminum intake and aluminum water pump, ministarter to reduce weight the stock intake is pretty good any way.....dump cats and all smog add a 700r4 and rack and pinion throw in a removable rear window and you now have my 77 vette.

dont just haphazardly throw this together go buy a book on engine builds that has actual dyno results and just duplicate one of those builds. vortec heads will kick ***!
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Old 03-04-2011, 05:04 PM
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I don't want to come across as some Holy Joe. But removing the smog equipment may not be the best thing to do.

I used to be able to get my '68 Elco through the visual inspection with the open element air cleaner that was on the car when I bought it. Now, no place that does state inspections will give my car the thumbs up with that on the car. If I don't have a thermostatic air cleaner I fail. The muffler shop that made the stove so it'd work with headers now has a big sign telling customers not even to think about asking them to remove the cats from their cars, and explaining the hefty fines that not only a business but any individual can face if they remove the smog equipment from a vehicle originally so equipped.

There was a local place that had to pay a quarter million dollar fine last year for playing fast and loose with the rules about emmissions testiing, and now every place around here that does testing or even the visual inspections is making sure to dot all their "i"s and cross all their "t"s.

I don't believe removing the smog equipment is really necessary anyway. GM cats back in the '70s were garbage, but they've come a long way since then. You should be able to put together a decent exhaust with a high flow cat. Air pumps don't rob much hp.

JMHO. YMMV. Etc., etc. I realize that a lot of places exempt cars over a certain age from testing. Which leads people to believe here that such cars are exempt from emmissions controls, period. Not true; it is illegal under federal law everywhere, and it may be illegal under your state law, to remove that equipment.

I don't know of any individuals who've been fined for doing so, just businesses. I wouldn't be surprised to hear about it. A lot of states are strapped for cash, and this would be one way to collect some.
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Old 03-04-2011, 06:38 PM
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As 34ford said it's probably an L48 with 180 Hp although there was also an L82 which had forged crank, larger exhaust, and a few other upgrades to give 210 HP. Only about one in eight '77 Vettes had the L82.
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