How to tell the difference between 305 and 350???

Discussion in 'Engine / Swaps etc.' started by evan, Sep 22, 2006.

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  1. evan

    evan Not-quite-so-new-guy

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    I'm starting my parts search for my engine build so I need some advice. When I go take a look at a used engine, how can I tell the difference between a Chevy 305 and a Chevy 350?
     
  2. ONE EYE

    ONE EYE Greasemonkey

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    http://www.mortec.com is the best way unless you have a casting number book around. theres about 50,000,000
    010 blocks out there. thats the most common 350 chevy made.
     
  3. bananaMC

    bananaMC Not-quite-so-new-guy

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    i believe the oil dipstick is on the driverside for 305 and passenger for 350 at least thats the diff between my blazer and camaro.
     
  4. evan

    evan Not-quite-so-new-guy

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    I don't think that will apply in all situations because the 305 in my 78 c10 had the dipstick on the passenger side.
     
  5. ONE EYE

    ONE EYE Greasemonkey

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    the dipstick is on the drivers side on (i cant remember the exact year) engines up to 1980 or 1983. its on the passengers side for all years after that, 305 and 350. engine size is also cast into the motor right where the tranny bolts up and on the side of the block above the oil pan rail. newer motors are cast with 5.0L, 5.0G (high output) or 5.7L.
     
  6. clean8485

    clean8485 Royal Smart Person

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    ONE EYE is pretty much right. Telling the difference can be a challenge, especially if you're dealling with engines that were produced in the same year, or close to the same year. The later engines do have the 5.0 or 5.7 numbers cast into the block in the bellhousing mounting area on the driver's side, which is one way to tell. In 1986, GM went from a 2 piece rear main oil seal to a one piece seal, and oil pans will vary because of this change, and in 1987 they went from perimeter bolt rocker covers to center bolt rocker covers. There are other changes that were made over the years as well. Probably the best way to tell would be to get your hands on a good small block Chev reference book that has listings for both casting numbers and stamping numbers, then compare those numbers with engines that you're looking at. Its not always a 100% sure-fire way, but its about as close as you can get. Hope this helps.
     
  7. pontiacgp

    pontiacgp Rocket Powered Basset Hound

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    If you do check the casting numbers there are blocks that based on the casting number is a roller cam engine but don't be fooled, the roller cam engines were only put into a few high performance cars.
     
  8. SBCregal

    SBCregal Master Mechanic

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    i thought most 87 and up cars were roller cam?
     
  9. clean8485

    clean8485 Royal Smart Person

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    Roller cam engines were fairly common in a number of applications from the late '80s up 'till GM stopped building what I will call the "traditional" small block Chev engine. They were used both in remaining applications on cars, and in light duty trucks. They weren't in everything, but as I said, they were fairly common. You can tell a roller engine by either removing the intake manifold and checking for the metal lifter retainer plate, or by removing the front cover and looking for a camshaft retainer plate.
     
  10. 85 Cutlass Brougham

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    By far the easiest way would be to pull a head and measure the bore. A 350 will have a 4 inch bore ( as would a 327 or a 302) while a 305 will have a 3.736 in bore. The difference is very pronounced once you know what you are looking at . Now , the 400 has a 4.126 in bore, and 3 freeze plugs ( or at least a boss for the center plug even if it isn't drilled) plus a 3.75 in ( IIRC ) stroke as compared to a 3.48 in stroke for a 305 or a 350 , a 3.27 in stroke ofr a 327 or a 3 in stroke for a 302. All but the 400 use a 5.7 in rod ( the 400's is shorter 5.565 IIRC). AS for the differences in years, the earliest small blocks made from 55-56 had no oil filter boss, 57 was the first year for that, early Chevy II blocks had a relocated oil filter boss that is higher in the block ( and are front sump IIRC), in 1979 or 80 the dipstick went to the passenger's side and about the same time GM went from a 168 tooth flywheel to a 153 tooth: be sure to use the right starter! Also, transmissions designed for the 153 tooth flywheel sometimes won't work with the 168 tooth piece ( T-5's come to mind...). Also, a 400 is externally balanced and can't use the neutral baalnced flywheel of other small blocks without either rebabalcing the engine or flywheel. Finally, GM switched to the roller cam block between 86 and 87 with the introduction of the one piece seal block. However, not all engiens made in these years are roller cam; rather, they all have provisions for the cam valley spider to be installed and can use the factory roller cam valevtrain if it is installed.
     
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