yes I have, while impressive for the craptacular 80s pony car, it still didnt compare to the L98. The 305 in question was about as powerful as a blue flame 6. It really was a disgrace to the Chevy V8 family.

 

What year vortech heads are the best to put on a 77 350 l-48 engine? Will the stock exhaust manifolds bolt up to the vortech heads? I understand that the intake manifold is different.

 

I guess I want a clarification to the original question. How much power do you want? Does the 305 run OK, or does it need rebuilt? How much money do you want to spend? How original is the car? How important is originality to you? Are you interested in fuel injection or do you want to stay with a carburetor? Are you going to do it yourself, or pay somebody else?

I think if these things were known, we would have a better idea where to steer you. My point with staying with the 305 was that if the bottom end was OK you could fuel inject it and it would jump up a level in performance. Then you could save up and build a 350 and you would already have the fuel injection stuff done, just change injectors and PROM and you would be at yet another level of performance. You may want 400 HP now, I don't know.

 

Buy a new set at GM the are cheap ... but you will need a matching intake manifold. The manifolds cost a little bit more the HP is worth it on a budget.

Otherwise you can find a decent set of 305 heads before 1987... the best are early 86 to 84 Z28 HO heads. They have 1.94 valves and 58cc chambers. Mild port job and put them on your stock 350! This will give you a nice bump in compression and HP. (you can still use a standard manifold.)

Chevy vortec heads started in 95 or 96 to 99, but they are center bolt. (so you need the different manifold) Found on 350 trucks. Factory Hp jumped from 210 to 255 during those years mostly from the heads.

 

IIRC Vortec heads started in 1992 with the LT1.

 

True... but that head (LT1) will not fit a GEN I SBC without heavy mods.
LT1 head is the Gen II sbc. Your Truck head will bolt directly to the GEN I...just the intake will not fit... centerbolt heads.


Some casting of 305 heads (58 cc and 1.94 valves)... IROC and Z28 HO are good heads for a Smog 350. It will raise the compression to about 10.5 from the 8.8 or 9.0 to 1 smog engines. Mild porting will help it flow... stick the adv 266 or adv 270 hyd camshaft in it... you have a go street smog motor... Just need to run 93 in it.

 

Ah, they were still using the Gen I block on trucks in the mid 90's? I thought they were all on Gen II blocks by then.

 

I've had two Chevy 305s (one in an '85 Trans Am and one in a '78 Firebird I currently own that is being replaced with a Pontiac 455). I found it is more prone to detonation than the 350, they don't like to rev, and are generally gutless. You should buy a boat, use the 305 as an anchor, and then drop in a nice 350.

 

Or use the 305 as a boat motor. Works great for those.

 

I would like to stay as original as possible, but as for the 350 my friend is wanting to build it for me and pretty much for free, that is including giving me the engine and installing it. The car is totally original and the 305 has 119,000 miles on it and runs ok, with all that I have read so far it looks like I will go with the 350 and donate the 305 to my friend as a Boat Anchor. Thanks for all the advice so far reading all the different suggestions helps a great deal.

 

Don't get GEN II and Vortec motors confused...

Vortec motors are GEN I short block engines with new style heads (vortec) and slightly different intake manifold with TBI

A GEN II engine is a reversed cooled, opti spark, fuel injected, small block. LT1


Lots of C3ers do a vortec set up on the stock smog engines. vortec heads intake and decent hyd cam... to make cheap power.

Doing a GEN II swap would be a LT1 motor from 92-96 vette or 93-97 F-body or B-body in the 90's

 

Ah, that all makes it a bit clearer now. Now what I'm curious about is what was the point of the reverse cooling?

 

Agreed the 305 is definately boat anchor material. Build the 350 Corvettes were made to run. !!! That's my 2-cents

 

Wait your buddy is building you a 350 and is willing to put it into you vette for beer and you had to ask us if that's the right thing to do?
What's wrong with this picture.

 

check out this offering sent to me via email


"The YearOne Power Crate 350 has the power you need for the car you love.

The four-bolt main seasoned 350 block has been bored 0.030 over. It uses a nodular iron crankshaft with hypereutectic pistons connected with powdered metal connecting rods.

A dual plane aluminum intake allows good idle quality and excellent street driveability while providing plenty of low-end torque. Ported Vortec cylinder heads, 1.6:1 ratio rocker arms and a hydraulic roller camshaft round out this excellent engine.

The fully balanced and blueprinted PowerCrate 350 has been dyno tested to produce 400-plus horsepower* and 440-plus ft./lbs. of torque* with a pump-gas friendly 9.5:1 compression ratio. The engine comes with a 12-month/12,000 mile warranty.

You will find more features and specifications on this engine, along with an engine test graph, by scrolling down to the bottom of this e-mail.

You can have this YearOne exclusive engine for only $2990.00 (plus shipping).

To take advantage of this offer click Part # CT350PC1, add it to your shopping cart and enter the code EM611 during checkout.

But hurry, this offer ends midnight EST on Wednesday, February 15, 2006.

Another exciting special offer from…


Your Friends At YearOne


Please note:
Enter the promotional code EM611 at checkout
This offer is good until midnight EST on Wednesday, February 15, 2006 "

YearOne Power Crate 350 Specifications


*Dyno tested with 1-5/8” headers and 750 CFM carburetor.
400+ horsepower and 440+ ft/lbs of torque
Produces 12hg inches of vacuum at 800 RPM. Perfect for power brakes
Good idle quality with plenty of low end torque
9.5:1 compression ratio – pump gas friendly (92 octane recommended)
Fully balanced and blueprinted with harmonic balancer and flexplate
Dyno tested and supplied with printout of your engine’s output
Utilizes a 4-bolt main seasoned 350 block bored 0.030 over with nodular iron crankshaft
Hypereutectic pistons connected to powdered metal connecting rods
Ported Vortec cylinder heads with 2.02 int./1.60 exhaust stainless steel valves
1.6:1 ratio rocker arms with heavy-duty valve springs
Hydraulic roller camshaft with .520” valve lift and 218 int./228 exhaust duration @ .050
Includes a dual plane aluminum intake for excellent street driveability
High tensile strength fasteners installed throughout the engine
12 month/12,000 mile warranty
Engine includes oil pan, timing cover and valve covers

 

I originally posted the question because I did not know if I would be making a mistake by taking out the original engine and replacing it. ( For Future resale value) If I would ever plan to sell it. And since I am new to corvettes I just wanted to check with people who know the most.
Thanks for all the advice.

 

Look do what 99% of all late year C3 owners do. Take out the low hp motor put it in the deepest part of the garage and put in a high hp 350 motor. You will be happy and have piece of mind that someday 40 years from now some young kid who has been born yet will buy your vette as a collector item and pay you $100,000 because you kept the 305 all these years. Then you will wake up.

 

MANY LOW Hp vettes are modded... The emission years are not valued by collectors (except 25th and silver cars, low power big blocks, maybe a L82 4 speed)... you could actually increase the valve with a tastful and proper engine upgrade to a smog year vette... (say Late model engie swap or ZZ4 crate motor)

Because NOW you have vette looks with vette performance!

You could get more for 76 L48 with a T56 and LT4 engine... than a bone stock L48 with a th400. Both clean both with working accessories.

Unfortuately a 305 vette will only carry as much value as a guy off the street is willing to pay for the lowest output v8 produced... which Kalway just paid.

just my .02

 

The coolant was run throught the heads...first... then down into the block to offset detenation from the High compression LT1 and LT4 engines made in 92-97 (GEN II motos)

bad thing about this design is ...if the water pump leaked it could kill your ignition system (ie.. opti spark)

 

I think a 305 Corvette would be a neat project. I have owned several 305's. They were all very reliable torque motors. You can go here for some ideas.

http://www.hioutput.com/tech.html

Remember, all the nice equipment you slap on that "worthless" 305 will also fit on the 350 short block you replace it with. In a few years.

BigBlockk

Later.....