350 CID Engine Detail

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General Information

Note: The information contained in all of the "Engine Detail" sections should be read before proceeding with modifications, etc., because some information that applies to all engines, or all small blocks or all big blocks, might not be duplicated in every section.

The 350 was built from 1968 through 1980, produced from 160hp to 320hp, and was installed in just about every car Olds built in that period at one time or another, including the Cutlass/442, Delta 88's, 98's and Toronados, and the Omega. You can get a quick estimate of the year of the engine by looking at the 1" high casting number on the lower-left corner of the block and/or head.

Watch out for windowed main webs on 1977 and later blocks. This limits sustained or occasional high RPM usage. All diesel 350 blocks are solid main webbed.


1974 350: 180 [email protected] 3800 RPM; 275 Ft-lb Torque @ 2800 RPM

[ Thanks to Matt Cremean, Bob Barry for this information ]


First, congratulations on not getting sucked into the "gotta have a 455" mentality!

A set of mildly-ported 2.00"/1.62" early small-chamber heads will let you spin into the higher RPM range. The only non-factory part you may be interested in is an aftermarket cam and intake, and a high-volume oil pump. If Edelbrock can get 370hp from such a combination, where only the intake and exhaust are non-stock, then you certainly can, and it will bolt to your existing transmission, and the holes for the frame mounts are already drilled, and it will look completely stock, and it will go strong for 200,000 miles.

Any '68-'72 350, with mild modifications makes a reliable and strong street engine.

[ Thanks to Bob Barry for this information. ]

Short Block:

Don't try to go for max cubes with the overbore. Simple reason, if something happens and you have to overbore again you'll have to chuck the block.




If you really want to dust 5.0's, go with the Performer RPM. The Performer is supposedly no better than a stock Olds intake.

[ Thanks to Mike Bloomer, Bob Barry for this information ]


I just rebuilt my '72 350 about 3 months ago. I used new cast pistons, edelbrock performer intake, and a melling camshaft. Melling, you say? Well i just so happened to look in one of their catalogs one day and noticed the specs on one of their cams. The exact same as the performer, only mucho cheaper. I have a toro oil pan, melling oil pump, nodular crank, stock rods, oil galley restrictors, cloyes true roller timing chain, moly rings, and #7 heads with new exhaust valves, springs, ect., and I ground down the AIR bumps in the heads.

I'm running a quadrajet out of a '80 or so eighty- eight. Distributor came out of a '78 toro. I love the way the engine runs! I ran the edelbrock specs through a program of mine, and it says im making around 290hp. I'll definitely believe it as i have outrun several 5.0s even with an auto and 2.29 gears. I had very few problems with the install into my '78 cutlass.

[ Thanks to for this information. ]

Tuning / Power Boost

In 1970, the 350's had 9.0 CR with a 64cc head. In 1971 the CR dropped to 8.2 with the same cc. This was accomplished with a "dish" in the piston. This carried over until 1973 when the CR dropped again to 8.0 BUT with a 79cc head. This means that the dish was gone but the large chambers in the head caused a further drop in CR. Going from the stock 79cc heads to the earlier 64cc will bring the CR up to around 9.2 but with the thicker head gaskets than stock you can figure on about 9.0:1 "true" CR. This will definately wake up that motor and with a cam, 4bbl, and dual exhaust you should get 250 HP net easily as long as the bottom end is in good shape. I would definately take a look at the bearings. Since they were used to only 8.0 CR, jumping up a full point might hammer them pretty quick if they are already worn. Some plastigauge works wonders.

[ Thanks to Mike Bloomer for this information. ]

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Submit corrections and additions to this information to The Olds FAQ Compiler.