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305 heads on a 350?????

 
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kujomat
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PostPosted: Sat Mar 19, 2011 1:00 am    Post subject: 305 heads on a 350????? Reply with quote

I am putting together a 350 sbc and using a set of 305 head that have had 2.02 intake and 160 exhaust valves put (crammed) into them. My question is would a slightly dished piston help remedy some of the shrouding in the cumbustion chamber caused by the large valves in the small combustion chamber? If it would be a benefit, would it be worth the loss in compression over a flat top piston? Any other idea's to help make this thing "perk" Has to run on pump gas and cant do any porting.
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10sec.et
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1969 Oldsmobile Cutlass

PostPosted: Sat Mar 19, 2011 1:05 am    Post subject: Reply with quote

sorry, im no help here but welcome to SMOKEmUP Cheers .
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af2 wrote:
It seems we can look at our magical Balls and come up with a fix?

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Skunkworkx
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1968 Chevrolet Camaro

PostPosted: Sat Mar 19, 2011 7:48 am    Post subject: Reply with quote

You should be fine as is (pending what compression you end up with)... usually the valve gets shrouded by the cylinder wall. This is an "old school" trick to get compression up and make HP
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Paul P
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1971 Chevrolet Chevelle

PostPosted: Sat Mar 19, 2011 9:14 am    Post subject: Reply with quote

I would still un shroud the valve by taking a bit out of the chamber wall. If the valve is right up against the chamber wall flow will be compromised big time.
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2001 Focus 2.0 Zetec
stock cams, bolt-ons and tune
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1971 - Chevelle 408 SBC N/A
6.86@102.5 MPH 1/8mi
10.78@122 MPH 1/4mi
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squeeezer
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1991 Chevrolet Camaro

PostPosted: Sun Mar 20, 2011 2:55 pm    Post subject: Reply with quote

^^^^^^^^+1^^^^^^^^^
but i suppose that would be "porting huh??

"they" say a 1.94 int and 1.5-1.55 exh is all a 4" bore should ever take, after that its shrouding


but...................................

i keep seeing increases in performance with bigger valves in a 4" bore personally , all the way up to a 2.05 int and 1.6 exhaust(sounds like you are as big as you can go in a 305 head)

i imagine your poor flowing 305 heads have around a 55 cc chamber??? could be a little more
after you unshroud the valves via chamber work whats it gonna be 60 cc?????????? i dunno, but it will be a good increase in compression (but again that is prolly considered porting??)
then will it detonate????? idunno , what kind of pistons do ya have???
you must be in a engine limited race class (factory stock)????
no vortecs right???
some flat tops set up with proper quench clearance should be ok
IF you can run bigger cams
i think you will need a dish piston if you cannot use a cam to bleed high cylinder pressure

what casting # 305 head????the iroc z head????

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Paul P
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1971 Chevrolet Chevelle

PostPosted: Sun Mar 20, 2011 4:43 pm    Post subject: Reply with quote

squeeezer wrote:
^^^^^^^^+1^^^^^^^^^
but i suppose that would be "porting huh??


No that would be chamber work not port work.. Cool

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2001 Focus 2.0 Zetec
stock cams, bolt-ons and tune
15.63@87 MPH 1/4mi

1971 - Chevelle 408 SBC N/A
6.86@102.5 MPH 1/8mi
10.78@122 MPH 1/4mi
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squeeezer
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Joined: 02 Mar 2007
Posts: 2427
Location: new richmond WI
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1991 Chevrolet Camaro

PostPosted: Mon Mar 21, 2011 9:50 am    Post subject: Reply with quote

i tend to agree Laughing


but

rulz is rulz Crying or Very sad

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