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#1 |
screamin eagle
Join Date: Oct 2007
Location: westbury ny
Posts: 237
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surprise at the machine shop
sent my heads to the machine shop and it turns out they are 307 heads.My block is a 350.Was it common practice to put smaller heads on a 350?Turns out my friend has a set of 350 heads so I will use them instead.
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SCREAMIN EAGLE |
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#2 |
Hollister Road Co.
Join Date: Apr 2005
Location: Houston
Posts: 6,134
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Re: surprise at the machine shop
it depends. Some have a smaller chamber increasing the compression. 305's on a 350 is a common swap.
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#3 |
Special Order
![]() ![]() Join Date: Nov 2004
Location: Mt Airy, MD
Posts: 85,858
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Re: surprise at the machine shop
What size valves and what cc were they?
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"BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~ |
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#4 |
Registered User
![]() Join Date: Feb 2004
Location: Idaho
Posts: 4,034
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Re: surprise at the machine shop
Not super uncommon for their to be 307 heads on a 350, look at the harmonic balancer. You might be suprised there as well.
But they have definitely been swapped out at sometime.
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"Remember, They can Kill You, but they can't eat You, That's against the law!!!!!!!!!" |
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#5 |
screamin eagle
Join Date: Oct 2007
Location: westbury ny
Posts: 237
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Re: surprise at the machine shop
you think they would swap that as well?I'll have to look tomorrow
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SCREAMIN EAGLE |
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#6 |
Registered User
Join Date: Jul 2008
Location: TX
Posts: 737
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Re: surprise at the machine shop
Depending on what casting your 350 heads are you may be better off with the 307 heads. The combustion chambers are most certainly smaller boosting your compression ratio a bit.
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------------------------------------------------- Jim Garage fillers... 85 Chevy C10 Silverado LWB 07 Nissan Altima 2006 Mini Cooper S |
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#7 |
screamin eagle
Join Date: Oct 2007
Location: westbury ny
Posts: 237
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Re: surprise at the machine shop
the casting on the 350 heads are 387 3487
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SCREAMIN EAGLE |
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#8 |
Registered User
Join Date: Mar 2006
Location: kearney,nebraska
Posts: 443
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Re: surprise at the machine shop
the draw back to putting on smaller cid heads are that they typically have smaller valves to clear the cylinder walls and thus smaller ports to maintain velocity
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'70 k-10 longbox- mid 70's drivetrain 350/350 487x heads 10.1:1 flowmasters ,35's 3.73's auburn posi ,rear shackle flip. '72 short stepside U.S. forestry truck, '73 455 buick,400 turbo,dropped 2"-4 1/4" ,3.07 posi,:'89 silverado 1500 ,OK truck ,5.7 holley tbi ,trick 700r4 3.07 auburn posi ,and my '66 skylark ,'73 centurion and my '84 monte carlo imca stock car |
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#9 |
screamin eagle
Join Date: Oct 2007
Location: westbury ny
Posts: 237
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Re: surprise at the machine shop
block is a 350 I checked the numbers and measured the pistons-It has flat top pistons with a valve relief
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SCREAMIN EAGLE |
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#10 |
Registered User
Join Date: Oct 2008
Location: Livermore ca
Posts: 699
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Re: surprise at the machine shop
Are your pistons flat or dished? If they are dished I would stay with the 307 heads. Keep the compression up there. Are you sure that the motor is a 350? Check the casting number in the back while the heads are off.
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#11 |
Why does it taste purple?
Join Date: Sep 2007
Location: Cambridge Md
Posts: 621
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Re: surprise at the machine shop
Put some 350 heads on it and you will love yourself.
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