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283 w/305 compression?

Discussion in 'The Hokey Ass Message Board' started by Shaggy, Apr 18, 2009.

  1. Shaggy
    Joined: Mar 6, 2003
    Posts: 5,208

    Shaggy
    Member
    from Sultan, WA

    What's the ballpark compression for a 10 year old 283 with 305 heads and flattops, i dont know anything else about the motor other than i'm dissapointed with the "RV" cam that was in it

    I put it in my OT daily and I'm looking to get a new cam for it with a bit more power, Hydralic, any suggestions?? Also the Wiend Stealth intake seems a little big any suggestions there?? I have a 450cfm holley that i love

    If it was a 327 i'd lean to the L-79 cam, mabey a little less, but i dont want to over cam this motor, and i dont know that i have the compression for one of them
     
  2. Rudebaker
    Joined: Sep 14, 2007
    Posts: 1,598

    Rudebaker
    Member
    from Illinois

    "Ballpark" about 9 to 1. Depends on which 305 heads, what head gasket, deck height, etc.
     
  3. Rich Rogers
    Joined: Apr 8, 2006
    Posts: 2,018

    Rich Rogers
    Member

    Cam wise I think something around 268 dur and 450 to 480 lift. It shouldn't be very lumpy and would wake it up pretty good. 450 cfm carb may be a bit small but should work alright as long as your not looking for best performance. I really liked the Eddy performer intake when I had it on the 55. Seems the rpm range was like 1500 to 5500rpm.
     
  4. Little Wing
    Joined: Nov 25, 2005
    Posts: 7,501

    Little Wing
    Member
    from Northeast

    a 10 year old 283 ??
     

  5. Rich Rogers
    Joined: Apr 8, 2006
    Posts: 2,018

    Rich Rogers
    Member

    Yeah I saw that :D but figured he must have meant rebuilt 10 years ago:rolleyes:
     
  6. Shaggy
    Joined: Mar 6, 2003
    Posts: 5,208

    Shaggy
    Member
    from Sultan, WA

    Rebuilt 10 years ago, low miles since, figured some people would know what comp ratios would be avalible then

    As for carb it is fine now, i really cant reach the end of it, but it might be small with more cam
     
  7. A 66 Power Pack 283, blueprinted to NHRA minimum specs, is over 11 to 1 comp.
     
  8. tommy
    Joined: Mar 3, 2001
    Posts: 14,757

    tommy
    Member Emeritus

    According to the Motors manuals most stock 283s were in the 9.25- 9.5 CR unless it was fuel injected and then it was 10.5 The last injected 283 was in the 1961 Corvette. Possible but doubtful. I have no idea how the 305 heads would affect the CR up or down. I believe that 9.25 would be a safe assumption for a garden variety 283.
     
  9. Montechris
    Joined: Nov 15, 2004
    Posts: 523

    Montechris
    Member

    305s had 58cc heads so compression is probably higher than stock
     
  10. Rudebaker
    Joined: Sep 14, 2007
    Posts: 1,598

    Rudebaker
    Member
    from Illinois


    The 283 Power Pak heads were also 58cc, they were rated at 9.5 to 1 but that was usually a bit optimistic.
     
  11. carcrazyjohn
    Joined: Apr 16, 2008
    Posts: 4,844

    carcrazyjohn
    Member
    from trevose pa

    Change the carb.use either a 600 rochester or an edelbrock or an afb .you could use a holley but you will have to change the power valve to either a 9.5 to a 10.5 Learned this many'many years ago while playing with a 307.Try that before a cam.You should notice an improvement. 2102 cam
     
  12. 56sedandelivery
    Joined: Nov 21, 2006
    Posts: 6,675

    56sedandelivery
    ALLIANCE MEMBER

    The 601 casting number 305 heads are the ones with 53cc combustion chambers, and usually the same small valve sizes 283 heads came with. Those heads would give you the highest available C.R. with stock parts. I'm still trying to figure out how a "66 Power Pack 283 blueprinted to NHRA specs", could be anywhere near 11.0:1 C.R. (?). Butch/56sedandelivery.
     
  13. i think you should give it a try , you may not be disappointed ...that's basically what an Edelbrock Performer cam is
     
  14. I have a 283 with a RV cam that I'm not that thrilled with either. I have some 305 heads that I was gonna bolt on thinking it might "wake up" the RV cam but it sounds like it's just wishful thinking. What cam would be a good choice to give it a little rump?
     
  15. foolnhismoney
    Joined: Mar 18, 2007
    Posts: 18

    foolnhismoney
    Member

    you guys are missing the big picture here. there is alot of things to consider. The intake runner cc's are going to limit high end rpm. so though you get high compression your motor is just an air pump. the more air in and the more air out give horsepower. the 305 heads will be great on low end and an rv cam should be the best choice. I think you are hoping for more power that you are only going to get out of a bigger air pump(CID) with heads that have more cc's in the intake runners and the right cfm carb is important as well.
     
  16. Shaggy
    Joined: Mar 6, 2003
    Posts: 5,208

    Shaggy
    Member
    from Sultan, WA

    I like my holleys but never ran any other PV's other than stock, i'll try that
     
  17. Not to hi jack this thread, but since we are after the same thing I hope you don't mind.

    The thing with my motor is I'd be happy if it just sounded better. The horse power is second to that for me. I've heard that what is a mild cam in a 350 may be a bit much in a 283. Is this true?
     
  18. Rudebaker
    Joined: Sep 14, 2007
    Posts: 1,598

    Rudebaker
    Member
    from Illinois

    601 and 416's are the "good" 305 HO heads, they both have 1.84 intake valves vs. 1.72 on the 283 heads. They usually have 58cc chambers but that can varie, I've heard anywhere from 53 to 60 cc's. They flow close to the old 461 327/300HP heads on the intake side, not quite as well on the exhaust but still adequate for a moderate 283. A dual pattern cam or some 1.6 rockers on the exhaust would help that. The 305 heads don't have much material for shaving but you could run a thinner head gasket to squeeze a little more out of it, that would also close up your quench distance. Depending on what pistons they used your deck height could be anywhere from .005 to .025. I've seen a 350 with cheapo pistons that were .040" down the hole!

    This can be true, most modern cams are rated based on use in a 350. What would be a moderate cam in a 350 could be pretty lumpy in a 283. The 327/350HP L-79 cam is a good example, nice mld lope in a 350, really lopey in a 283. "Really lopey" being different things to different people.;)
     
    Last edited: Apr 18, 2009
  19. fergusonic
    Joined: Nov 11, 2007
    Posts: 221

    fergusonic
    Member
    from Kokomo, In

    I have a 283 +.060, flat tops, stock cam, headers, Quadrajet, 3.50 gear, 700r4 all in my '56 pickup : I consider it a dog.
     
  20. Hotrod Lincoln
    Joined: Apr 8, 2009
    Posts: 55

    Hotrod Lincoln
    Member

    There's a machine shop in Florida that's selling 58CC heads on Ebay with 1.75" intakes and 1.6" exhausts, screw-in rocker studs and guide plates. Thery're pocket ported, also. 283's love high RPM, 7,000+ or more. Get a set of .125" popup pistons, use a 305 degree roller cam with triple springs on the valves and a rev kit, and shift at about 7,500 RPM. The engine will sound like a bumblebee on steroids, and the 350's will only wish they could run that fast!
    Jerry
     
  21. Shifty Shifterton
    Joined: Oct 1, 2006
    Posts: 4,964

    Shifty Shifterton
    Member

    Engines are just air pumps right?

    If you do the math and assume a lot of efficiency sameness...... a 283 at 7500 rpm moves the same air as a 350 at 6050 rpm. 305 heads are notorious for choking 6000 rpm 350s, even with pocket porting.....Sure you wanna be taking on 350s? ;) The little winder would be cool, I'm jus sayin.....
     
  22. Shaggy
    Joined: Mar 6, 2003
    Posts: 5,208

    Shaggy
    Member
    from Sultan, WA

    That's what i'm building my 301 in my '65 camino for, but i just kinda want to liven up my daily, nothing serious i cant do in an afternoon, basicly just a cam. I realize the best thing i could do is not put this in a 3,300# car
     
  23. Hotrod Lincoln
    Joined: Apr 8, 2009
    Posts: 55

    Hotrod Lincoln
    Member

    Actually, the one I've been dusting 350's with is a destroked 305- - - -255 cubic inches. They can't figure out how I'm running 1,000 RPM faster down the straightaway than they are, no matter what gear ratio they run. We're restricted to a 350 CFM Holley 7448 carburetor, which chokes the 350's down to 6,200 RPM max. I'n turning over 7,000 with no problem, and 7,500 isn't impossible if I tinker with the gearing a little. The only thing the race determines is who's going to run second!

    BTW- - - -a quarter mile needs four turns and dirt on it to be a race track!
    Jerry
     
  24. Sorry. It's 10.53
     
  25. My '38 Ford pickup is running a 307 with 262/305 heads and flat top pistons. I don't know what the compression ratio is. It's not so high that it won't run on regular gas, but it's got plenty of power. Using an Edelbrock Performer intake and Holley 600. The motor came out of a '68 GMC pickup with 3 on the tree that only had 30,000 miles but was rusted all to pieces. I was able to just hone the block and go back standard size on the rings. It has whatever cam the General put in it at the factory. I put the 262/305 heads on it because they had the hardened valve seats for unleaded gas and also, unlike the 307 heads, had bolt holes in the ends of the heads for mounting accessories. This thing has gobs of torque and plenty of acceleration if you stomp down on it. I'm thinking the pickups may have gotten a different cam than the cars to give them more bottom end torque. I had a pretty good load of my sister-in-law's stuff coming back from Gadsden AL yesterday, came up that really steep hill on 278 in Cleburne County without downshifting. The truck is not geared extremely low. The rear is a 3.44 ratio 10 bolt out of a '74 Camaro that had a 307 and 3 speed, rear tire size is 215/70X15.
     
  26. Blair
    Joined: Jul 28, 2005
    Posts: 361

    Blair
    Member
    from xx

    I'm running a 283 with flat tops and power pack heads in my Model A. Granted it's a light car, and has 3.73 gears in the rear, but I am very happy with the performance of the motor.

    I'm running a COMP 282S (solid lifter) which is 236 at .050 on both sides. The compression is right at 9.0:1. The lash is set at .017".

    You would think that this would be too much cam, but the intake valve closes early (not super early, but earlier than most cams of the same total duration) which saves the compression. Being a solid, you can stand a little more duration as some is eaten up by the lash, although it is set a little on the tight side.
     
  27. I'm curious as to what the timing figures, specs, etc. are for an RV cam?


    My understanding of a true RV cam is that it's milder than a typical "stock" passenger car cam and delivers its highest torque/HP at low RPMs.


    Do any of the cam grinders advertise an RV cam?
     
  28. Shifty Shifterton
    Joined: Oct 1, 2006
    Posts: 4,964

    Shifty Shifterton
    Member

    The key for your very specific racing application is the carburetion restriction. The question here is a street application without 2bbl restriction and I think your glasses may be a little rosy.

    dirt track is awesome for sure!

    To the original question I think they'll work just fine as long as they're not cracked between the valves like so many 305 heads are.
     
    Last edited: Apr 19, 2009
  29. Hotrod Lincoln
    Joined: Apr 8, 2009
    Posts: 55

    Hotrod Lincoln
    Member

    With a 600 CFM Edelbrock, the engine turns 8,000+, and nobody can keep up. I've got just over $5,000.00 in the rotating assembly, 38 lb. billet crankshaft, H-beam rods, Honda-size rod journals, and a gear drive on the cam. The heads just make it breathe right at high speed.
    Jerry
     
  30. Truckedup
    Joined: Jul 25, 2006
    Posts: 3,974

    Truckedup
    Member

    Somebody said RV cam? I have a 305 in my old El Camino with #416 heads. The block is a 1990 roller cam version,Comp Cams mild roller,206-212 degree at .050 lift, .490 total lift.The block was decked to give an actual 9.25 compression with slight dish typical 305 pistons.Has a slight lope at idle,pulls nicely from 1500 rpm to around 5200.Probably 240 HP with decent fuel mileage and runs on 89 octane.
     

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