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

yfs200p · 09-19-2004, 08:55 PM

Hey i was thinking about dropping a 350 in my truck. The engine comes with everything except a starter and alternator, so there is no major parts that need to be switched over. I was wondering if there is anything you guys know of that will have to be changed in order to go to a 350 from a 305. Will the manifolds bolt right up? and how about the motor mounts... will they need to be changed in any way? thanks alot, NICK

beaterC10 · 09-19-2004, 09:17 PM

Is the 350 the same era as the 305? I was thinking 86 was about the time GM went to a one piece rear main seal from the 2 piece. The flywheels don't interchange between the two styles. The other problem can be the dipstick. They were on the passenger side until the late 70s or early 80s, the later ones are on the driver side. This can cause a problem if the exhaust manifolds don't match the dip stick location. Everything else will swap over.

1986Silverado · 09-20-2004, 04:45 PM

Quote:

Originally Posted by beaterC10

Is the 350 the same era as the 305? I was thinking 86 was about the time GM went to a one piece rear main seal from the 2 piece. The flywheels don't interchange between the two styles. The other problem can be the dipstick. They were on the passenger side until the late 70s or early 80s, the later ones are on the driver side. This can cause a problem if the exhaust manifolds don't match the dip stick location. Everything else will swap over.

86 GM went to 1 piece rear main seals and the dipstick went to the passenger side, early models had dipstick on driver side

beaterC10 · 09-20-2004, 06:48 PM

One other thing I remembered is if the 350 has an aftermarket intake and you have air, make sure the manifold has the required threaded boss for the A/C bracket that attaches to the intake on the driver side.

You might also make sure the manifold has all the required bosses to mount the factory bracket for the accelerator cable. Some of the earlier aftermarket intakes didn't have all the required threaded bosses.

beaterC10 · 09-20-2004, 06:51 PM

Quote:

Originally Posted by 1986Silverado

86 GM went to 1 piece rear main seals and the dipstick went to the passenger side, early models had dipstick on driver side

I stand corrected on the dipstick location. I must have gotten condfused, my 84 has a 73 vintage 350.

1986Silverado · 09-20-2004, 07:14 PM

Quote:

Originally Posted by beaterC10

I stand corrected on the dipstick location. I must have gotten condfused, my 84 has a 73 vintage 350.

Yep alot of people get confused on that issue, your 84 engine would have had the dipstick on the drivers side also, I think.

jimfulco · 09-21-2004, 03:03 AM

I think the knock sensors are different.

cliffsta · 09-21-2004, 04:02 AM

manifold won't work period unless its a 4 barrel 305. I think GM went to 4 barrel 305 in like 83, but don't get me lying.

Jonboy · 09-21-2004, 04:57 AM

I think 80 was the first year for the pass side oil dipstick. 86 was first year for 1 piece rear main, 87 had centerbolt valve covers and little distributor.

hotrodhomi · 09-21-2004, 02:33 PM

I just did this on my 81 and the oil dipstick thing was a problem but then I also realized I needed new exhaust manifolds or headers to fit the different bolt pattern aka the 7th bolt. I solved it all by adding some edlebrock headers. now the exhaust bolts up and I can use the dip stick. Easy swap really. good luck.

SanitysBane · 09-22-2004, 12:39 AM

my 83 with a 305 had a 4 barrel

hotrodhomi · 09-22-2004, 01:08 AM

my 81 had one too! In fact I used my intake and carb off of the 305 to put on the 350

cliffsta · 09-22-2004, 01:21 AM

Yeah i looked today in LMC and 81 was first year for 305 to have a 4 barrel. GM called it a "high output" 305. My 80 has a 305, and its just fine for me

09-19-2004, 08:55 PM	#1
yfs200p E.H.F.D Engine #2 Join Date: Feb 2003 Location: East Hampton, NY Long Island Posts: 916	305 to 350 Hey i was thinking about dropping a 350 in my truck. The engine comes with everything except a starter and alternator, so there is no major parts that need to be switched over. I was wondering if there is anything you guys know of that will have to be changed in order to go to a 350 from a 305. Will the manifolds bolt right up? and how about the motor mounts... will they need to be changed in any way? thanks alot, NICK __________________ -NICK '72 K10 SWB Fleetside. Avocado Highlander 350-4speed-NP205 Frame Off Re-Creation '89 GMC V3500 C/C Flatbed Plow Truck 454/SM465/Np205 '15 Chevy 2500HD CCSB High Country Duramax '22 Tahoe Premier Duramax

09-21-2004, 04:02 AM	#8
cliffsta Stepsides RULE Join Date: Jul 2004 Location: Pineville, LA Posts: 1,921	manifold won't work period unless its a 4 barrel 305. I think GM went to 4 barrel 305 in like 83, but don't get me lying. __________________ 1981 Chevy C10 Custom Deluxe Stepside 350 V8, headers, side exhausts, 3-speed auto SOLD 1980 Chevy C10 Custum Deluxe Stepside 305 V8, Edelbrock Performer Intake, Edelbrock 1406 600CFM 4-barrel, TH350C. Bent rod. SOLD 1984 GMC Sierra Classic Longbed 6.2L Diesel SOLD 2009 Kawasaki KLX-250S too many mods for this signature 1999 Honda Accord EX 4-cylinder, 17" Motegi Wheels 215/45/17 Sumitomo tires, Tein S-Tech lowering springs, KYB GR2 shocks, Acura TL 20mm rear swaybar, debadged, blackhoused headlights, Short-Ram Intake Cardomain of the Accord

09-21-2004, 04:57 AM	#9
Jonboy Slots go on anything! Join Date: May 2003 Location: Richardson, TX Posts: 5,957	I think 80 was the first year for the pass side oil dipstick. 86 was first year for 1 piece rear main, 87 had centerbolt valve covers and little distributor. __________________ 1974 Jimmy- 5.3/4L80e/NP241

09-22-2004, 12:39 AM	#11
SanitysBane Registered User Join Date: May 2004 Location: Lubbock, Texas Posts: 2,121	my 83 with a 305 had a 4 barrel __________________ '96 Nissan Pathfinder '02 Firebird Trans Am. '88 K5 Blazer

09-22-2004, 01:21 AM	#13
cliffsta Stepsides RULE Join Date: Jul 2004 Location: Pineville, LA Posts: 1,921	Yeah i looked today in LMC and 81 was first year for 305 to have a 4 barrel. GM called it a "high output" 305. My 80 has a 305, and its just fine for me __________________ 1981 Chevy C10 Custom Deluxe Stepside 350 V8, headers, side exhausts, 3-speed auto SOLD 1980 Chevy C10 Custum Deluxe Stepside 305 V8, Edelbrock Performer Intake, Edelbrock 1406 600CFM 4-barrel, TH350C. Bent rod. SOLD 1984 GMC Sierra Classic Longbed 6.2L Diesel SOLD 2009 Kawasaki KLX-250S too many mods for this signature 1999 Honda Accord EX 4-cylinder, 17" Motegi Wheels 215/45/17 Sumitomo tires, Tein S-Tech lowering springs, KYB GR2 shocks, Acura TL 20mm rear swaybar, debadged, blackhoused headlights, Short-Ram Intake Cardomain of the Accord

09-19-2004, 09:17 PM	#2
beaterC10 Senior Member Join Date: Jul 2003 Location: Indianapolis, IN Posts: 1,277	Is the 350 the same era as the 305? I was thinking 86 was about the time GM went to a one piece rear main seal from the 2 piece. The flywheels don't interchange between the two styles. The other problem can be the dipstick. They were on the passenger side until the late 70s or early 80s, the later ones are on the driver side. This can cause a problem if the exhaust manifolds don't match the dip stick location. Everything else will swap over.

09-20-2004, 06:48 PM	#4
beaterC10 Senior Member Join Date: Jul 2003 Location: Indianapolis, IN Posts: 1,277	One other thing I remembered is if the 350 has an aftermarket intake and you have air, make sure the manifold has the required threaded boss for the A/C bracket that attaches to the intake on the driver side. You might also make sure the manifold has all the required bosses to mount the factory bracket for the accelerator cable. Some of the earlier aftermarket intakes didn't have all the required threaded bosses.

09-21-2004, 03:03 AM	#7
jimfulco Registered User Join Date: May 2003 Location: Shreveport LA Posts: 3,170	I think the knock sensors are different.

09-21-2004, 02:33 PM	#10
hotrodhomi Registered User Join Date: Apr 2004 Location: Sacramento Posts: 3,737	I just did this on my 81 and the oil dipstick thing was a problem but then I also realized I needed new exhaust manifolds or headers to fit the different bolt pattern aka the 7th bolt. I solved it all by adding some edlebrock headers. now the exhaust bolts up and I can use the dip stick. Easy swap really. good luck.

09-22-2004, 01:08 AM	#12
hotrodhomi Registered User Join Date: Apr 2004 Location: Sacramento Posts: 3,737	my 81 had one too! In fact I used my intake and carb off of the 305 to put on the 350



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