Differences between 69 350 HP & 70 LT1
Thread Starter
Racer
Joined: Feb 2007
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Differences between 69 350 HP & 70 LT1
I have a 1969 350 350 HP out of a 69 Vette in pieces and it seems to me that aside from the Hydraulic cam it seems to have all the good parts; 202 heads, 11;1 comp. pink rods, steel crank. Am I all wrong here or what?
Melting Slicks
Joined: Mar 2005
Posts: 2,838
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From: Austin TX
Solid vs. Hydraulic cam,..otherwise the shortblocks were the same. The heads castings were the same (041's?), and as Big G noted, the intake and carb were different.
You'd think a solid lifter, holley, and high-rise would all combine for more than 20 HP over a hydraulic, Q-Jet and it's cast iron intake.
The 350/350,..what a great motor!
You'd think a solid lifter, holley, and high-rise would all combine for more than 20 HP over a hydraulic, Q-Jet and it's cast iron intake.
The 350/350,..what a great motor!
Drifting
Joined: Dec 2004
Posts: 1,345
Likes: 3
Solid vs. Hydraulic cam,..otherwise the shortblocks were the same. The heads castings were the same (041's?), and as Big G noted, the intake and carb were different.
You'd think a solid lifter, holley, and high-rise would all combine for more than 20 HP over a hydraulic, Q-Jet and it's cast iron intake.
The 350/350,..what a great motor!
You'd think a solid lifter, holley, and high-rise would all combine for more than 20 HP over a hydraulic, Q-Jet and it's cast iron intake.
The 350/350,..what a great motor!
Le Mans Master
Joined: Jun 2005
Posts: 5,447
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From: Syracuse NY
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Advanced
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LT-1 Components
The heads were the #186 castings on these LT-1's. 2.020 intakes, 1.600 exhausts, and screw-in studs with 5/16" flat guide plates.
Same heads used on '69/'70 Z-28's. The '69's had no guide plates, they started on the '70.
The factory connecting rods had the letter "O" cast into the cap half and they are the "pink" series. The same letter "O" was used on the original rocker arms. Denoted slightly longer slots.
Harry P. Hunter
Same heads used on '69/'70 Z-28's. The '69's had no guide plates, they started on the '70.
The factory connecting rods had the letter "O" cast into the cap half and they are the "pink" series. The same letter "O" was used on the original rocker arms. Denoted slightly longer slots.
Harry P. Hunter
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Joined: Aug 2006
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From: North Augusta South Carolina
pink rods in '71 LT-1
I have a 71 LT-1 motor that was purchased across the counter from a GM dealer in the Feb-Mar time frame in 1971. It had (and still has today) the pink rods with all the correct codes and even the pink tint paint markings. I would believe that other than the 70 LT-1 corvette engine also contained these rods. GM was not known for their strict adherence to their own standards.
Le Mans Master
Joined: Mar 2004
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From: Little Rock AR
The LT-1 was produced with presed pin non-floating style rods and did not have the expensive babbit plated small end bore.
-Mark.
Team Owner
Joined: Apr 1999
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
The NHRA performance factor sheet shown above just includes balancing and blue printing the block. Real world HP - not factory. To get into the NHRA stock catagories every one cheats. 
Balance and attention to detail counts for a few more HP.
You have a nice 350
My 79 stock bottom end L-82 forged crank and rods never broke with many times over 7000 rpm with B&B and .030 flat tops. I still have it with smoked pistons. I used 200+ cc heads and single planes
Balance and attention to detail counts for a few more HP.
You have a nice 350
My 79 stock bottom end L-82 forged crank and rods never broke with many times over 7000 rpm with B&B and .030 flat tops. I still have it with smoked pistons. I used 200+ cc heads and single planes
Drifting
Joined: Sep 1999
Posts: 1,970
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The heads were the #186 castings on these LT-1's. 2.020 intakes, 1.600 exhausts, and screw-in studs with 5/16" flat guide plates.
Same heads used on '69/'70 Z-28's. The '69's had no guide plates, they started on the '70.
The factory connecting rods had the letter "O" cast into the cap half and they are the "pink" series. The same letter "O" was used on the original rocker arms. Denoted slightly longer slots.
Harry P. Hunter
Same heads used on '69/'70 Z-28's. The '69's had no guide plates, they started on the '70.
The factory connecting rods had the letter "O" cast into the cap half and they are the "pink" series. The same letter "O" was used on the original rocker arms. Denoted slightly longer slots.
Harry P. Hunter
Melting Slicks
Joined: Mar 2005
Posts: 2,838
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From: Austin TX
Clarification,..according to Colvin's "Chevy by the Numbers",..on 1970 Vettes, head casting number 3947041 was used for both 350 HP and 370 HP engines. Casting number 3927186 was used for 300 HP and 370 HP in 1970 (though the 300 horse head would have had smaller valves). And casting number 3927187 was a 350/350 Corvette only head.
FWIW,..
FWIW,..
Drifting
Joined: Sep 1999
Posts: 1,970
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Clarification,..according to Colvin's "Chevy by the Numbers",..on 1970 Vettes, head casting number 3947041 was used for both 350 HP and 370 HP engines. Casting number 3927186 was used for 300 HP and 370 HP in 1970 (though the 300 horse head would have had smaller valves). And casting number 3927187 was a 350/350 Corvette only head.
FWIW,..
FWIW,..
Not exactly. The 3927186 head was used for the base, 350hp and 370hp. According to the NCRS new tech manual. Also, 3927187(L-46) and 3973414(LT1) were spec'd and may or may not have been used.
I can say with absolute certainty, that at least one 3927187 was used on a 70 L46. THat would be mine. My other head being a "186 .
Last edited by dennis; Mar 28, 2007 at 03:32 PM. Reason: info
Melting Slicks
Joined: Apr 2002
Posts: 2,337
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From: Norfolk VA
I have a 71 LT-1 motor that was purchased across the counter from a GM dealer in the Feb-Mar time frame in 1971. It had (and still has today) the pink rods with all the correct codes and even the pink tint paint markings. I would believe that other than the 70 LT-1 corvette engine also contained these rods. GM was not known for their strict adherence to their own standards.
Advanced
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Pink Rods
You shouldn't count on identifying the rods any longer by the paint. Most of the it is gone by now due to working with and cleaning the rods. The caustic soda in most hot tanks will eventually remove the color.
If the letter O is forged in the caps they are pink rods.
If anyone happens to be wanting any of these original rods, with no damage ever, drop me an e-mail. I have friend who restores nothing but the Z-28's and LT-1's. He usually upgrades the rods and has a few sets around.
Harry P. Hunter