261 Jobmaster engine id - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Maynard57 · 03-17-2014, 04:17 PM

Trying to confirm what motor I have:

PO says its a '54 261.
Head has four side screws holding valve cover in place (not 2 on top like earlier 235), front breather cap a Fenton dual exhaust manifold.

Block casting number, right side, aft of fuel pump is:
3759365

Stamped number on flat machined block boss, near front of starter is:
F3I7L

Inline website says block casting is 1959 2 ton truck 261 motor.

Can anyone confirm 261 and year?
What is the F3I7L number (engine serial number?)
How can I id head (235 vs 261)?

Thanks, Maynard

Mac the Yankee · 03-17-2014, 04:40 PM

What's casting # on the head? An "848" at the end means it's a 235 head, and will give you higher compression.

Maynard57 · 03-17-2014, 07:12 PM

Thanks.

Head casting # is 3886850.

Motor runs good. Sounds healthy. No leaks detected but seems to "use" a 1/2 quart of oil about every 150 miles.

OrrieG · 03-17-2014, 08:06 PM

How long since it has been ran regulary? When I got my 64 Chevelle it was smoker for the first month I drove it daily, then the rings seated and I drove it about 60K more. If you watch any of the vintage shows on TV most of the trailer queens and museum pieces that do not get driven much smoke too.

Inliners.org has lots of info on the straight 6 and 8 motors.

dwcsr · 03-17-2014, 08:12 PM

Quote:

Originally Posted by Maynard57

Trying to confirm what motor I have:

PO says its a '54 261.
Head has four side screws holding valve cover in place (not 2 on top like earlier 235), front breather cap a Fenton dual exhaust manifold.

Block casting number, right side, aft of fuel pump is:
3759365

Stamped number on flat machined block boss, near front of starter is:
F3I7L

Inline website says block casting is 1959 2 ton truck 261 motor.

Can anyone confirm 261 and year?
What is the F3I7L number (engine serial number?)
How can I id head (235 vs 261)?

Thanks, Maynard

58-62, 261
Block possibilities
3739365
37369717
3769925
Head
3836850

Don't put a 235 head on it

Maynard57 · 03-18-2014, 12:03 AM

Thanks. Sounds like I have a 1959 261 with 261 head. It hasn't been run regularly for several years, at least the last 5 years. I'll change oil again and pamper it for a while to see if it slows oil burn.

Thanks.

03-17-2014, 04:17 PM	#1
Maynard57 Registered User Join Date: Jan 2014 Location: Foresthill CA Posts: 8	261 Jobmaster engine id Trying to confirm what motor I have: PO says its a '54 261. Head has four side screws holding valve cover in place (not 2 on top like earlier 235), front breather cap a Fenton dual exhaust manifold. Block casting number, right side, aft of fuel pump is: 3759365 Stamped number on flat machined block boss, near front of starter is: F3I7L Inline website says block casting is 1959 2 ton truck 261 motor. Can anyone confirm 261 and year? What is the F3I7L number (engine serial number?) How can I id head (235 vs 261)? Thanks, Maynard

03-17-2014, 04:40 PM	#2
Mac the Yankee Registered User Join Date: Nov 2012 Location: Winder, GA Posts: 274	Re: 261 Jobmaster engine id What's casting # on the head? An "848" at the end means it's a 235 head, and will give you higher compression.

03-17-2014, 07:12 PM	#3
Maynard57 Registered User Join Date: Jan 2014 Location: Foresthill CA Posts: 8	Re: 261 Jobmaster engine id Thanks. Head casting # is 3886850. Motor runs good. Sounds healthy. No leaks detected but seems to "use" a 1/2 quart of oil about every 150 miles.

03-17-2014, 08:06 PM	#4
OrrieG Registered User Join Date: Jun 2006 Location: Idaho Posts: 8,800	Re: 261 Jobmaster engine id How long since it has been ran regulary? When I got my 64 Chevelle it was smoker for the first month I drove it daily, then the rings seated and I drove it about 60K more. If you watch any of the vintage shows on TV most of the trailer queens and museum pieces that do not get driven much smoke too. Inliners.org has lots of info on the straight 6 and 8 motors. __________________ 1959 Chevy Short Fleetside w/ 74 4WD drive train (current project) OrrieG Build Thread 1964 Chevelle Malibu w/ 355-350TH (daily driver) Helpful AD and TF Manual Site Old Car Manual Project

03-18-2014, 12:03 AM	#6
Maynard57 Registered User Join Date: Jan 2014 Location: Foresthill CA Posts: 8	Re: 261 Jobmaster engine id Thanks. Sounds like I have a 1959 261 with 261 head. It hasn't been run regularly for several years, at least the last 5 years. I'll change oil again and pamper it for a while to see if it slows oil burn. Thanks.



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