I’m new around here and have done some searching and reading before I registered to post. I’ve got a 90 RS Convertible with the stock L03 305 with the stock 4 speed overdrive transmission. I bought the car this summer, it was complete and unmolested…only problem it had a rod thrown through the block when I bought it. So the car has just sat inside and I’m in no real hurry to do anything yet.

After reading some of the threads on L98’s I’ve determined that I’m probably not as ambitious as most when it comes to performance. I won’t be turning any quarter mile times or anything like that. I’ve got a 305 block that I could rebuild but I just don’t want to. I want to order a crate 350 and be done with it. So here is my question what crate 350 should I order?

I want an engine that is a “bolt on.” I want to take the 305 out, take the TBI, distributor and other stuff of the 305 and put it on the new long block 350 then put it right in the car. I want to use the same transmission, fly wheel torque converter etc... Performance is not a big deal to me, I don’t care if is a bone stock crate motor with 200 hp or a something else. I just want it to be inexpensive and to be a 350 “bolt on” replacement for the 305 that will pass emissions.

Thanks for your time.

 

Welcome to the board. I know you said you searched but there is a good link that may answer some of your questions...
https://www.thirdgen.org/forums/tbi/...-350-swap.html
Later.

 

That post was very helpful...what 350 should I buy then? The Passenger Car 350 or the 290HP 350?

Here are the two engines I'm considering:

From Crateenginedepot.com


1971 - 1985 Passenger Cars and Lt Dty Trks 350 (LM1) New Goodwrench Engine 10067353 Description GOODWRENCH COMPLETE 8 CYLINDER ASSEMBLY: The 10067353 universal 4 Bolt main block 350 is a brand new long block used to cover most GM applications from ‘1970-1985. It is our lowest priced 350 and is great as a small block replacement or V-8 retrofit into any vehicle. This brand new crate engine comes with a GM nation wide warranty and is covered for 3 years or 100,000 miles when used in applicable GM vehicles. Check out our Warranty Information for full details. The specs of the motor are as follows: ·(4) Bolt main block with a (2) piece rear main seal. ·Cast Iron Crank. ·LT/LT4 Powdered Metal connecting rods. ·Cast Pistons, (dished). ·Hydraulic flat tappet cam, (.383” intake / .401” exhaust) and a 112-degree lobe separation. ·Cast Iron Cylinder heads with a 76cc combustion chamber. (Non vortec design) ·8.5:1 compression ratio. ·Left or Right hand dipstick. ·(4) Quart oil pan. ·Timing tabs for a 6 ¾” or an 8” balancer.

OR

350 Crate Engine 290 HP HO 12499529 Description Our lowest priced Performance crate engine. Quite simply, the 290 HP 350-cubic-inch is the best small-block crate engine value offered by GMPP! With 290 horsepower and 326 lb.-ft. of torque, it makes a great replacement engine for countless GM vehicles, while its all-new construction provides peace of mind over salvage and rebuilt engines. The 290 HP is packed with good stuff, too, starting with the four-bolt-main block, aluminum pistons, and a hydraulic camshaft. The durable iron cylinder heads process healthy amounts of air to deliver strong torque across the rpm range and great mid-range horsepower. Delivered as a long block assembly, you add items like an intake manifold, carburetor, ignition system, starter, balancer and water pump—all available from GMPP. Build it up to suit your needs, as the economical 290 HP will leave plenty of change on the table! Our lowest priced crate engine.
This HP 290/350 is the best value crate engine from GM Performance Parts, with 290 horsepower @ 5100 RPM, and 326 lb-ft. of torque @ 3750 RPM on 87 octane fuel.

The HP 290 horsepower will provide great durability because of its 4-bolt mains, PM steel rods, strong cast aluminum pistons.
The camshaft has .450" intake and .460" exhaust lift with hydraulic flat tappets.
The cast iron cylinder heads have 1.94" intake and 1.50" exhaust valves wit 76 cc combustion chamber. These heads have the conventional 90 degree with 12 bolt intake manifold attaching design used from 1955 thru late 1980 12 bolt postion @ 90° to the intake/headflange.
This engine was designed to work with the following components:
intake manifold 10185063.
HEI distributor 93440806.
balancer 12551537.
flex plate 471529.
Bolt on the starter,water pump, fuel pump, and your ready to run.

This 350 engine is not intended for marine use, and should be used in 1979 and earlier pre-emissions street vehicles or any off road usage.

The difference in price is only about $300 bucks, but would the HO 350 pass a smog test? It should pass a visual inspection.

 

Vortec heads lead to problems with the EGR valve function.

Consider this one http://www.sdparts.com/product/12513...cBDL0557K.aspx . Closer to a bolt-in, might have to do a little PROM tuning.

The first two you listed have 2-piece rear main seal, low compression, and flat tappet cams. And, the heads have 90 degree angle bolts for the center two intake mounts, while your manifold has 72 degree angle for those bolts.

 

As "straight drop ins," go you are actually looking at only a few options with no tuning. Especially if you are passing a smog test.

Easiest is a 350 TBI engine from an 87-95 TBI GM truck. You put your accessories on the front and you are done.

You can also put a 350 TPI spec engine (stock) from 87-92 with your accessories, your intake, and a 350 TBI unit from a truck (or at least those injectors in your TBI unit.)

I'm pretty sure those will pass. I passed the L98 under the TBI in a 90 firebird years ago in CA but the tests may be tougher now. We passed later with a 400 and a custom chip!

Good luck!