chevy small block (305) rebuild

Discussion in 'DIY Marinizing' started by ericklee, Oct 10, 2006.

  1. ericklee
    Joined: Oct 2006
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    Location: Tampa, Florida

    ericklee New Member

    I have access to a 305 out of a late 80's firebird. It is free to me with all the accessories. It runs but has a thrown bearing, so will need at minimum a lower end rebuild anyway. Disregarding the essential need of installing a marine starter, alternator, ignition, coil; what is the least I can spend to marinize? any specific kit suppliers in mind? Pistons, rods, bearings, rings, high torque cam, etc.. and... do I need to change out the intake manifold? I presume yes if its aluminum, but am not sure. I have read the past threads on marinizing and I realize there are a lot of folks against it. I should mention I have a searay 23' cruiser with a 305 "mercruiser" chevy we just installed after the previous one had the #3 rod go through the block and oil pan (nice).
    I didn't own the boat at the time, but I am sure it was scary. This rebuild is not for that boat, just a project for a future hull in the 20-23' range and I want something that will be OK for recreational use only and take such a boat 27-32mph, no more.
     
  2. Jimbo1490
    Joined: Jun 2005
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    Jimbo1490 Senior Member

    An auto 305 is not a good block to use for marine duty. Hell the hotrod guys don't even like them. Too thin among other things. Start with a different engine. There are no good marine parts in a auto 305. The duty cycle is the problem, the boat speed is irrelevant.

    Jimbo
     
  3. grumpygrady
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    grumpygrady landlubber

    for the same price to rebuild it you can do a 350 ci
    northern has rebuild kits starting at 169.00 for a 350
    and a 2 bolt main is the best one in terms of strength
     
  4. curtis73
    Joined: Mar 2002
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    curtis73 Junior Member

    You can probably score a 350 block for cheaper than you can repair the spun bearing on the 305
     
  5. Verytricky
    Joined: Oct 2005
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    Verytricky Large Member

    I have had a problem with the VOLVO (GM) small block, aparently made in Mexico, and blew apart at 450 hp.

    I have been told to get an American cast block.

    Is this just rubbish, or is there truth in this?
     
  6. grumpygrady
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    grumpygrady landlubber

    yes and no
    a good casting is a good casting mexico or american
    but 2 bolt mains blocks are stronger and heavyier than factory 4 bolt mains
    we us the 2 bolt and machine a 4 bolt cap on them
    they are good for 900 +hp
    factory 4 bolts good for 400 or 500 max
    now these are in land vehicles
     
  7. grumpygrady
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    grumpygrady landlubber

    you need to make sure that you have a good block before machine work
    holes centered,, cam centered ,webs about the same , no cracks etc

    the same things that should be done on any motor rebuild
     
  8. fasteddy
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    Location: gainesville ga

    fasteddy Junior Member

    The only place I'd use a 305 on a boat is as an anchor. Too thin walls and iffy cranks, and lots of casting core shifting. Never saw one with the cam bore centered in the block boss.
     
  9. l_boyle
    Joined: Sep 2006
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    l_boyle ol' can of sardines

    305 is not a good choice for marine use..... unless you like to be stranded out in a deep bay, from a blown engine.. I am Chevy lover by heart, but believe me those 305cu. are the poorest designed block along with 400cu...
    I have used 283 cu, before, I love that engine, it may be low on horsepower.. oh boy look at the rpm output... I can redline it at 6,000 al the way across the lake and without any problems.. A guy offered a large sum of money for it, I sold it to him for 2 grand... Darn, I miss that engine... It was a "screamer"....
    Look for 327, 350, in small block... And 366, 396, 454 in large block... 396 is a hard running engine ever made in the large block for chevy... Also hard to find a 396 complete or bare block also these days...
    Please, take all of our advices... stay away from 305 cu, if you can... We all are trying to save you griefs and embarassments, okay...
     
  10. fasteddy
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    fasteddy Junior Member

    Chevy never made a 396. They did make a 400 that they called a "396", but it was just to scam the insurance companies, who were charging a monster premium for muscle cars with engines = or > 400ci...

    400sbc's were ok if you got rid of the cast crank and drilled steam holes in the right places in the replacement heads. Probably the worst all time sbc was the 267. 283's, like the 327's, were almost all small main bearing blocks. The most common warranty claim was for broken cranks on those engines, which is why GM redesigned the block with bigger journals for the 350. 400's are even larger. IMHO, the 301 is the hardest winding sbc, but very rare. First Z28 Camaro motor.
     
  11. Jimbo1490
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    Jimbo1490 Senior Member

    This is a false statement. It is true that from 1969 onward, what they called a 396 (4.0925" B X 3.76" S) was actually a 402 (4.125 B X 3.76 S) which was a 396 bored ~.030". From 1965 to 1969, they were actually 396 CID: I know because I owned several during the late 70's and 80's when they were still quite common. I tore down and rebuilt every one of my muscle cars and the original bore size certainly did not escape my notice. This is really old news, not some kind of new revelation. The old HP Book "How To Hotrod Your Big Block Chevy" covered this in their first edition published back in the early 70's.

    Jimbo
     
  12. fasteddy
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    fasteddy Junior Member

    Dang, I guess that means I'm not perfect. What a disappointment...

    Good catch, jimbo.
     
  13. l_boyle
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    l_boyle ol' can of sardines

    However, as you said... There are 396 "big block"... 366, 396, 454's share the big block series... I am telling you this.. I had one in my old 1968 chevy 3/4 ton pickup, I rebuilt it to factory spec... 4.096" bore x 3.76" stroke, while 454 have 4.250" bore x 4.00" stroke.. And that how I found out that I have 396 instead of 454 in my truck... Dude, learn more chevy before barking okay... Another thing, there is no such thing as 301 in chevy small block... The first Z28 camaro that came out with "302" in 1967...
     
  14. fasteddy
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    fasteddy Junior Member

    "302" in 1967...

    Which measured 301.44ci. I round down....
     

  15. Fisean
    Joined: Nov 2006
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    Fisean Fishaholic

    327

    Had a 327 in an older Camaro that kicked but until the harmonic Balancer fell off, and damaged the crank....oh this is a boat question:eek:
    I have been extremely happy with my 190 hp FORD 302 powered 2170 Carver.
    Something tells me if you use a car engine, there will be lots of things that need to be changed, starting with the camshaft. I remember back in the day, when I first started tinkering with boats, I had a 1963 Belmont Jet that the motor blew up in, replaced it with a 350 4 bolt Chevy, and had some top end issues....replaced the cam with a RV cam???....ran at 55 mph all day long! This probably hasn't helped much....but good luck to you!
     
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