350 heads on a 305 block - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Aaron104 · 11-10-2009, 06:17 PM

can you run 350 heads on a 305 block? if you can what are the pros and cons?

Longhorn Man · 11-10-2009, 06:25 PM

can't do it, the valves will hit the cylinder walls. (won't open)

**truckster** · 11-10-2009, 07:34 PM

Quote:

Originally Posted by Longhorn Man

can't do it, the valves will hit the cylinder walls. (won't open)

That would definitely be a con!

1-PU70 · 11-10-2009, 09:50 PM

Im running 350 heads on a 307.

turp mcspray · 11-11-2009, 12:16 PM

Depends on the valve size.
305 has such a small bore size, that the large chamber head will drop the compression.

71tahoe · 11-11-2009, 04:24 PM

Quote:

Originally Posted by 1-PU70

Im running 350 heads on a 307.

Even though it's 2 cubic inches, 307 std bore is 3.875 and 305 is 3.736.

pritch · 11-11-2009, 11:17 PM

"I got 350 heads on a 305 engine
I get ten miles to the gallon
I ain't got no good intentions"

What, no Drive By Truckers fans here?

rscam · 11-12-2009, 08:34 AM

I think they will physically fit. But the valves are so close to the cylinder wall they call it shrouding the valve. When the valve open the part that is close to the wall won't let any fuel in and vise versa for the exhaust.

silverstreak · 11-12-2009, 11:42 PM

I've been doing a little research on how to get a little more power from my 305. I've read some articles on swapping on some L30 "059" vortec heads (1996 - 2002 305) on an older block. It seems to be a good swap, but needs a "vortec" style intake as the intake mounting bolts are different and uses centerbolt valve covers. They also use specific rail type rocker arms and are limited to .430 max valve lift due to the retainers contacting the valve guides. Edelbrock makes a performer intake whick seems reasonably priced. They also don't have the exhaust crossover to keep the intake / carb heated in cold weather. So, I'm still on the fence on that decision.

Richard8971 · 11-13-2009, 12:05 AM

I have heard you can run 305 heads on a 350 but not sure on the other way around...

Hmmmm.

D

joedoozer · 11-13-2009, 01:20 AM

Find out what heads you have on the motor now, see if they are anything worth using. 1.94 intakes and a 64 or 67cc chamber will be just fine for a 305. Put a decent cam in it, something with lift around .430 to .450. The smaller bore of the 305, and the smaller intake runners will limit just how well it breathes. So duration would be a little more important than lift in your case. I would guess

.

Best bet is get as much information as you can from your vehicle. Weight, rearend gears, transmission, converter stall, exactly what the engine is (compression and so on). And call a tech line of some camshaft manufacturers. They can run the numbers and help you out. You will get some really good info from this site, and from tech support. But collect as much information as you can before you spend your hard earned money.

custom72c20 · 11-13-2009, 03:21 AM

Quote:

Originally Posted by turp mcspray

Depends on the valve size.
305 has such a small bore size, that the large chamber head will drop the compression.

You are correct. I have seen it done before.

11-10-2009, 06:17 PM	#1
Aaron104 Registered User Join Date: Oct 2009 Location: clovis ca. Posts: 19	350 heads on a 305 block can you run 350 heads on a 305 block? if you can what are the pros and cons?

11-10-2009, 06:25 PM	#2
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: 350 heads on a 305 block can't do it, the valves will hit the cylinder walls. (won't open)

11-10-2009, 09:50 PM	#4
1-PU70 Registered User Join Date: Apr 2000 Location: Bradenton, FL Posts: 1,036	Re: 350 heads on a 305 block Im running 350 heads on a 307. __________________ 1970 CST/10 402,700R4,3:73 posi,AC,PS,PB,TLT,PW,Buckets with heaters

11-11-2009, 12:16 PM	#5
turp mcspray Registered User Join Date: May 2007 Location: Rapid City South Dakota Posts: 2,359	Re: 350 heads on a 305 block Depends on the valve size. 305 has such a small bore size, that the large chamber head will drop the compression. __________________ Turp Mcspray New life for an old 2wd, farm blazer http://67-72chevytrucks.com/vboard/s...d.php?t=505987 My Blazer build http://67-72chevytrucks.com/vboard/s...d.php?t=342299

11-11-2009, 11:17 PM	#7
pritch Registered User Join Date: Mar 2004 Location: Hoytsville, Utah Posts: 3,365	Re: 350 heads on a 305 block "I got 350 heads on a 305 engine I get ten miles to the gallon I ain't got no good intentions" What, no Drive By Truckers fans here? __________________ '68 Panel Project Boogie Chillin' '68 C-10 Ol' Green Last edited by pritch; 11-11-2009 at 11:18 PM.

11-12-2009, 08:34 AM	#8
rscam Registered User Join Date: Nov 2005 Location: Monroe,Georgia Posts: 313	Re: 350 heads on a 305 block I think they will physically fit. But the valves are so close to the cylinder wall they call it shrouding the valve. When the valve open the part that is close to the wall won't let any fuel in and vise versa for the exhaust.

11-12-2009, 11:42 PM	#9
silverstreak Registered User Join Date: Mar 2009 Location: USA Posts: 255	Re: 350 heads on a 305 block I've been doing a little research on how to get a little more power from my 305. I've read some articles on swapping on some L30 "059" vortec heads (1996 - 2002 305) on an older block. It seems to be a good swap, but needs a "vortec" style intake as the intake mounting bolts are different and uses centerbolt valve covers. They also use specific rail type rocker arms and are limited to .430 max valve lift due to the retainers contacting the valve guides. Edelbrock makes a performer intake whick seems reasonably priced. They also don't have the exhaust crossover to keep the intake / carb heated in cold weather. So, I'm still on the fence on that decision.

11-13-2009, 12:05 AM	#10
Richard8971 Still livin the "dream" in '54 Join Date: Nov 2006 Location: Tucson, AZ Posts: 2,656	Re: 350 heads on a 305 block I have heard you can run 305 heads on a 350 but not sure on the other way around... Hmmmm. D __________________ Current build. 1954 Chevrolet 3800 "Ella" SOLD! My '67 stepper "Tangerine Dream" "Anything worth doing is worth doing right" James Dean “When you have eliminated all which is impossible, then whatever remains, however improbable, must be the truth.” Sherlock Holmes "There is no spoon." Neo

11-13-2009, 01:20 AM	#11
joedoozer is Certifiable Join Date: Feb 2008 Location: Hinesville, Georgia Posts: 160	Re: 350 heads on a 305 block Find out what heads you have on the motor now, see if they are anything worth using. 1.94 intakes and a 64 or 67cc chamber will be just fine for a 305. Put a decent cam in it, something with lift around .430 to .450. The smaller bore of the 305, and the smaller intake runners will limit just how well it breathes. So duration would be a little more important than lift in your case. I would guess . Best bet is get as much information as you can from your vehicle. Weight, rearend gears, transmission, converter stall, exactly what the engine is (compression and so on). And call a tech line of some camshaft manufacturers. They can run the numbers and help you out. You will get some really good info from this site, and from tech support. But collect as much information as you can before you spend your hard earned money. __________________ 1972 Chevy C10 LWB 350 Auto Blue with a white roof. Last edited by joedoozer; 11-13-2009 at 01:21 AM.



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