 gcrkfrd
"6th Year" Platinum Supporting Member
Posts: 458
Age: 76
Loc: Neosho, MO.
Reg: 04-01-18
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03-11-23 06:28 AM - Post#2855626
Just bought a 79- 350, out of a half ton, low mileage, 57,603. Got it because, PO had discovered it was a Four Bolt, but had #376450-305 Heads on it. Motor had never had Heads off. Funny, how you never hear of GM Tricks until you own One.
1952 Styleline Sedan, 62-235, Drum brakes, Manual steering, 2" Drop, 8-60 AC, Glass packs, Two Carbs, and a Cast Iron PowerGlide-
Way out behind the Old School
Half a Dozen in a Row, all it needs for Her to go.
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 gchemist
Member #271 Senior Chevytalk Moderator
Posts: 25860
Loc: Austin, TX 78748
Reg: 05-09-00
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03-11-23 03:13 PM - Post#2855647
In response to gcrkfrd
Good block! Add some aluminum heads and cam. Block is barely seasoned.
'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles
'08 GMC Acadia 3.6L SLE
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Tony1963
Frequent Contributor
Posts: 2072
Loc: Orlando Florida
Reg: 07-09-18
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03-11-23 04:29 PM - Post#2855652
In response to gcrkfrd
I always thought that 305 heads on a 350 were going to give you a bump in compression, but also had the smaller 1.72 intake valves.
| People fear change because it threatens what they know, or what they claim to know. |
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Shepherd
Valued Contributor
Posts: 2848
Loc: Lake George, NY
Reg: 11-11-15
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03-11-23 04:54 PM - Post#2855653
In response to Tony1963
The 70's 305 heads were listed as 60cc's, not sure if they were used on 350's as that would raise compression as Tony said, but dished piston would lower that. According to Mortec, those heads were not OE on the 350.
Edited by Shepherd on 03-11-23 05:01 PM. Reason for edit: No reason given.
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Tony1963
Frequent Contributor
Posts: 2072
Loc: Orlando Florida
Reg: 07-09-18
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03-12-23 03:18 AM - Post#2855668
In response to Shepherd
I wondered about two things. The C10 with an emissions era 4-bolt main and the 305 heads.
I believe that you have a replacement engine in the truck.
| People fear change because it threatens what they know, or what they claim to know. |
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gcrkfrd
"6th Year" Platinum Supporting Member
Posts: 458
Age: 76
Loc: Neosho, MO.
Reg: 04-01-18
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03-13-23 11:43 AM - Post#2855720
In response to Tony1963
I do not know Mortec, but GM dealer says they did this trick, on well over 7000, 78-79 GMC, and Chevy Trucks. They were also using blocks cast several years earlier. Block is #3970010 casting-stamped
V0115TBA, Heads are casting #376450-
Sorry misread T, looked like a J-Lime Book says if it was a 72 TBA, it would be 250HP, but it's a 79, so 165HP--
1952 Styleline Sedan, 62-235, Drum brakes, Manual steering, 2" Drop, 8-60 AC, Glass packs, Two Carbs, and a Cast Iron PowerGlide-
Way out behind the Old School
Half a Dozen in a Row, all it needs for Her to go.
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Shepherd
Valued Contributor
Posts: 2848
Loc: Lake George, NY
Reg: 11-11-15
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03-13-23 01:24 PM - Post#2855727
In response to gcrkfrd
Mortec is a website that lists the cylinder head and block casting numbers, they list the head application and head cc's and valve sizes. They show that 450 head was a 70"s 305 combo only.
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Tony1963
Frequent Contributor
Posts: 2072
Loc: Orlando Florida
Reg: 07-09-18
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03-13-23 02:42 PM - Post#2855730
In response to gcrkfrd
the only way to "document" this for sure is to go to the GM Heritage Center and download their information for your truck and see if anything shows up as an engine option.
While the GM dealer can "say" lots of things, frankly that was over 40 years ago so how would you ever know for sure?
In fact, for 1979 on the base C10, Chevrolet didn't offer the 350, only the 250 inline 6 or the 305. If you opted for the "Big 10" (option code F44) then the 350 and 454 were available.
Better check your option tag in the glove box, that adhesive label that has all of the original factory options. Someone probably put an older 350 with those 305 heads on this truck.
There is nothing to suggest that the base C10 even came with a 350.
Is yours a "Big 10"?
https://www.gm.com/content/dam/company/n o_search/h...
| People fear change because it threatens what they know, or what they claim to know. |
Edited by Tony1963 on 03-13-23 03:27 PM. Reason for edit: No reason given.
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gcrkfrd
"6th Year" Platinum Supporting Member
Posts: 458
Age: 76
Loc: Neosho, MO.
Reg: 04-01-18
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03-13-23 09:28 PM - Post#2855753
In response to Tony1963
Check- The Lime Book
1/2 ton 4x4, 4 speed-- a Pickup Truck
I am not worried about documentation, or the opinions, of people, that think they know everything automotive. I've wrenched on Chevys, for over 60 Years, and I learn every day.
1952 Styleline Sedan, 62-235, Drum brakes, Manual steering, 2" Drop, 8-60 AC, Glass packs, Two Carbs, and a Cast Iron PowerGlide-
Way out behind the Old School
Half a Dozen in a Row, all it needs for Her to go.
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Edited by gcrkfrd on 03-13-23 09:57 PM. Reason for edit: No reason given.
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Tony1963
Frequent Contributor
Posts: 2072
Loc: Orlando Florida
Reg: 07-09-18
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03-14-23 02:20 AM - Post#2855757
In response to gcrkfrd
Due to prior "suggestions", I back up my statements with reference material. First, if yours is a 4x4 then it is a K10 not a C10. Based upon your initial remarks, it appeared that yours was a C10.
The K10 in 1979 would be equipped with either the 250 inline 6, the 350 or the 400 small block.
However, regarding "The Lime Book", the opening comment is as follows:
The author has made his best effort in the
compilation and preparation of the information in
this book. However, inaccuracies may occur.
The author makes no warranty of any kind with
regard to the information in this book.
Also, that #3970010 casting is very common as nearly every 350 I ever had showed that casting number. With the engine only at 165 HP, I doubt that any tricks were employed by the factory.
However, it is your truck so enjoy.
| People fear change because it threatens what they know, or what they claim to know. |
Edited by Tony1963 on 03-14-23 02:34 AM. Reason for edit: No reason given.
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