max valve size on 305
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From: Hayward Wi
max valve size on 305
hello all
well im dropping the deal on getting the 350 lol i found an deal on an 305 for like $100 no tax and stuff. verses the 350 for 300+5.5% tax so im going with the 305 for what im doing, but anyway what is the biggest valves that you could put in an stock 305 bore.
i know stock is like 1.71 I and 1.5 E could you pop 1.94 I and 1.5 E into it with out it hitting on the sides of the bore.
what is an good sight that has flow data for all or most all the GM SBC heads? 50s-90s?? i kinda want to see what this 305 has on it to see what i can do with the stock heads.
ryan
well im dropping the deal on getting the 350 lol i found an deal on an 305 for like $100 no tax and stuff. verses the 350 for 300+5.5% tax so im going with the 305 for what im doing, but anyway what is the biggest valves that you could put in an stock 305 bore.
i know stock is like 1.71 I and 1.5 E could you pop 1.94 I and 1.5 E into it with out it hitting on the sides of the bore.
what is an good sight that has flow data for all or most all the GM SBC heads? 50s-90s?? i kinda want to see what this 305 has on it to see what i can do with the stock heads.
ryan
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From: Hayward Wi
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From: Hayward Wi
ok sounds good. i think i might throw an old Q jet on it for ****s an giggles im going to look at the motor again on monday and get the numbers an tell the guy to hide it away for me lol. ie tell him i will take it as soon as the T engien is history.
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From: San Diego - Deep Within The State of CONFUSION!
That being said though, the only limit on valves is your wallet. We were using 2.02 intakes back when I was building 283's and 327's. 
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St. Jude Donor '08-'09
I think the 305's small bore (3.73) will only take a 1.94 1.50 valve. Even if they will take 2.02 1.60 you don't need them with 305 CI. Vortec heads are a good match for this.
Last edited by 63mako; Aug 30, 2009 at 12:45 PM.
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I had a set of Elderborck Rpm heads with 202 -160 valves on a 305 and the valves did kiss the top of the cylinder holes at upper rpm's ie 6000 grand. I got lucky and it didn't bend any valves, but the 305 did turn
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Personally I'd go straight for the 350 and not waste time, but with a 3.730" bore and a combined diameter of 1.94"+1.50"=3.440", you get .290" leftover to spread between 3 areas. The edge of each valve and the cylinder wall and the area between the valves. That's an average of .096" to play with. Add in larger valves and it just get's worse. Having valves close to the cylinder wall kills airflow.
2.02/1.60's only leave an average of .036" to work with!
Also be aware that many chambers on *normal* heads will overhang the bore size a lot and you have to really pay attention to head gaskets to get the seal right.
Hmmmnnn...that 350 will actually be worth something when you're done even if it is a play motor.
JIM
2.02/1.60's only leave an average of .036" to work with!
Also be aware that many chambers on *normal* heads will overhang the bore size a lot and you have to really pay attention to head gaskets to get the seal right.
Hmmmnnn...that 350 will actually be worth something when you're done even if it is a play motor.
JIM
Last edited by 427Hotrod; Aug 30, 2009 at 10:22 PM.
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From: columbus oh
Le Mans Master
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From: Seattle WA
St. Jude Donor '14
Someone once gave me the most direct advice for making an effective use of a 305: put it in a Mustang and then push it off a cliff 
Seriously, you'll spend exactly the same amount of money overhauling a 305 as a 350...for 45 less cubes. If you've got money to burn and want 50 less ponies, go for it.
Seriously, you'll spend exactly the same amount of money overhauling a 305 as a 350...for 45 less cubes. If you've got money to burn and want 50 less ponies, go for it.
Last edited by billla; Aug 31, 2009 at 03:57 PM.
Racer
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From: Corona Ca
Get the 350!
I am one of the few that see's nothing wrong with a 305, in the right application! I don't think your Vette may be it.
However, if smogging the vehicle is not an issue, or it doesn't need to be "numbers matching", I would never build anything smaller than a 350. Parts are so cheap and plentiful for these motors, they're almost free!
Also, I believe the chambers on 305 heads are smaller than 350 heads (smaller bore size), so once you are past the valve clearance issues, you have to deal with compression drop when using 350 heads.
If you really have to go with a 305, look for L69 (I think) HO 305 heads from a 84-88 Monte SS and some Z28 Camaros. If I remember correctly, slightly bigger intake valve (1.8-something?) and little better compression. But you'll cover that price spread you quoted between the 305 and 350 really quick and still not get the same power, or enjoyment,
Better still, go get the 350.
Best,
Tom
However, if smogging the vehicle is not an issue, or it doesn't need to be "numbers matching", I would never build anything smaller than a 350. Parts are so cheap and plentiful for these motors, they're almost free!
Also, I believe the chambers on 305 heads are smaller than 350 heads (smaller bore size), so once you are past the valve clearance issues, you have to deal with compression drop when using 350 heads.
If you really have to go with a 305, look for L69 (I think) HO 305 heads from a 84-88 Monte SS and some Z28 Camaros. If I remember correctly, slightly bigger intake valve (1.8-something?) and little better compression. But you'll cover that price spread you quoted between the 305 and 350 really quick and still not get the same power, or enjoyment,
Better still, go get the 350.
Best,
Tom
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From: Hayward Wi
yah i am looking at it tomarrow as for the 350 i would if it was an lilttle less and more complete and that some one with an real prodject wasent looking at it i guess an guy with an 1970s Camaro is looking at it as an posible 355 or 383 so im going to be the "MAN" here an let the guy who could realy use it have it.
as for the 305 i think from what the guy said it could be an "Hipo" one and it has an new starter, plugs/wires, and distributor, and it has like 1/3 of the miles the 350 has on it the 350 has like 220,000 on it lol and the 305 has like under 100,000
as for the 305 i think from what the guy said it could be an "Hipo" one and it has an new starter, plugs/wires, and distributor, and it has like 1/3 of the miles the 350 has on it the 350 has like 220,000 on it lol and the 305 has like under 100,000
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From: Hayward Wi
in our bumbfuxk town there is lol i have been after one for like 6 months now and that one just came up but that 305 will do im not after big power just an learner engine.
as for corvette i dont have one i almost had 1976 :
****ing mechanic lied to me so he could get it. im still looking for one hence my thred about vette owners in my aria was looking for help if i finde one and or look at it with me lol. dad dont know much about vettes.
i might be get a non big block Chevell though and work on that but i wont got for big power in it just enough to make Highway speeds and good MPG lol
as for corvette i dont have one i almost had 1976 :
****ing mechanic lied to me so he could get it. im still looking for one hence my thred about vette owners in my aria was looking for help if i finde one and or look at it with me lol. dad dont know much about vettes. i might be get a non big block Chevell though and work on that but i wont got for big power in it just enough to make Highway speeds and good MPG lol
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From: Seattle WA
St. Jude Donor '14
So you drive a bit 
Couple of hours to Eau Claire or the Twin Cities. I grew up in Burning Stump, Iowa...so I hear you...but they are out there!
Might be worth backing up and giving more background on what you're looking for vs. the orginal question of 305 vs. 350.
Couple of hours to Eau Claire or the Twin Cities. I grew up in Burning Stump, Iowa...so I hear you...but they are out there!Might be worth backing up and giving more background on what you're looking for vs. the orginal question of 305 vs. 350.
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From: Hayward Wi
actually i didnt drive there i but i did call and ask and they said 2 things there were an few but all fule injection ones and some 262s lol, guy told me that there getting scairse these days. said had i called like 4 days earlier i could have gotten an 350 for like 120 but an local hotrodder bought it for an 383 build.