305 to 350 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

outacontrl86 · 04-03-2006, 04:42 PM

how easy is this swap? i got a 350 in my garage has all new bearings,rings and seals, the heads are another story could i use the 305 heads on the 350?o and will all the pullies bolt right up? and about how much time would this take to do? thanks

Jason915 · 04-03-2006, 05:03 PM

305 cylinder heads have smaller combustion chambers like 58cc or so and 350's up to 86 typically have 76cc so your compression ratio will be too high with the 305 cylinder heads. Most everything else should bolt right up. It's an easy straight forward swap.

86 GMG · 04-03-2006, 05:05 PM

305 to 350 staight cross over no mods yes the heads will bolt on and work but they will raise yor compression from 8:1 to 9:1 all pullies will work correctly.

jermasaurus · 04-03-2006, 07:37 PM

The 58cc heads are a nice swap for some low end power, especially if your using a cam that wants 9ish compression ratio or up. The downside to those heads would be that they cannot breathe very good once you get like 4000 rpm or so. Bigger valves would help, but the price of that may be close to just buying some vortecs.

Either way, its nice for the low end. I would use them.

-Jeremy

outacontrl86 · 04-03-2006, 07:42 PM

yea my 350 ones are shot but the 305 ones b4 i got the truck was rebuilt. my 350 has a .490 lift cam.too big??well if all works out i am going to use the 350 with the 305 heads thanks guys

04-03-2006, 04:42 PM	#1
outacontrl86 Registered User Join Date: Mar 2006 Location: long island Posts: 25	305 to 350 how easy is this swap? i got a 350 in my garage has all new bearings,rings and seals, the heads are another story could i use the 305 heads on the 350?o and will all the pullies bolt right up? and about how much time would this take to do? thanks

04-03-2006, 05:03 PM	#2
Jason915 Registered User Join Date: Jan 2005 Location: Colorado Springs Posts: 693	Re: 305 to 350 305 cylinder heads have smaller combustion chambers like 58cc or so and 350's up to 86 typically have 76cc so your compression ratio will be too high with the 305 cylinder heads. Most everything else should bolt right up. It's an easy straight forward swap. __________________ 1971 GMC K1500 SWB Fleetside, 4" skyjacker softride and, 14 Bolt FF, HD Dana 44 4.10's 1970 K5 TBI conversion lifted etc SOLD 1968 C20 camper truck SOLD “To ban guns because criminals use them is to tell the innocent and law-abiding that their rights and liberties depend not on their own conduct, but on the conduct of the guilty and the lawless.” Jeff Snyder

04-03-2006, 05:05 PM	#3
86 GMG Registered User Join Date: Apr 2005 Location: Tulsa Oklahoma Posts: 943	Re: 305 to 350 305 to 350 staight cross over no mods yes the heads will bolt on and work but they will raise yor compression from 8:1 to 9:1 all pullies will work correctly. __________________ square body trucks an addiction or an investment either way they consume all my extra time and money Last edited by 86 GMG; 04-03-2006 at 05:09 PM.

04-03-2006, 07:37 PM	#4
jermasaurus Registered User Join Date: Dec 2004 Location: New Lenox, IL Posts: 442	Re: 305 to 350 The 58cc heads are a nice swap for some low end power, especially if your using a cam that wants 9ish compression ratio or up. The downside to those heads would be that they cannot breathe very good once you get like 4000 rpm or so. Bigger valves would help, but the price of that may be close to just buying some vortecs. Either way, its nice for the low end. I would use them. -Jeremy __________________ 79 Jimmy slammed AKA James Down

04-03-2006, 07:42 PM	#5
outacontrl86 Registered User Join Date: Mar 2006 Location: long island Posts: 25	Re: 305 to 350 yea my 350 ones are shot but the 305 ones b4 i got the truck was rebuilt. my 350 has a .490 lift cam.too big??well if all works out i am going to use the 350 with the 305 heads thanks guys



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