Critical Engine Build guidance problem. LT1/4 Engines
Thread Starter
Le Mans Master
Joined: Feb 1999
Posts: 9,946
Likes: 38
From: South Carolina
St. Jude Donor '03 & '05
Critical Engine Build guidance problem. LT1/4 Engines
Well I was putting my LT1 back together and did the timing chain as I always do with the dots on the crank sprocket and timing gear sprocket lined up. This is with #1 piston at TDC (top dead center). I was using the FSM and the HP books How to rebuild LT1/4 engines.
Well Look at the pictures and see what the problem is. This book , the HP is a convenient book, and so i thought a good one. Now I am wondering.
I use the FSM 99% of the time. For this build I was using the ARP bolt torques recommendations etc and JE pistons ring layout, so nothing critical is wrong. But when I saw this as I was putting the timing cover on, I noticed the timing marks (according the HP Books, which I didnt use for the timing marks)didnt line up with the FSM. SO, this is a lesson I have found and am putting out to everyone else. I will also send this to HP.
[IMG]http://i33.photobucket.com/albums/d80/Steve40th/Timing2.jpg[/IMG
Well Look at the pictures and see what the problem is. This book , the HP is a convenient book, and so i thought a good one. Now I am wondering.
I use the FSM 99% of the time. For this build I was using the ARP bolt torques recommendations etc and JE pistons ring layout, so nothing critical is wrong. But when I saw this as I was putting the timing cover on, I noticed the timing marks (according the HP Books, which I didnt use for the timing marks)didnt line up with the FSM. SO, this is a lesson I have found and am putting out to everyone else. I will also send this to HP.
[IMG]http://i33.photobucket.com/albums/d80/Steve40th/Timing2.jpg[/IMG
Last edited by steve40th; Jul 16, 2008 at 11:31 PM.
Thread Starter
Le Mans Master
Joined: Feb 1999
Posts: 9,946
Likes: 38
From: South Carolina
St. Jude Donor '03 & '05
The 12 o'clock crank and 6 o'clock cam are normal gm since 1955 I believe.
And I believe most have #1 at TDC when installing timing chain, thats why the books would give you different mechanical timings.
Race Director
Joined: Dec 2006
Posts: 10,383
Likes: 4
Both at 12 and the 12 crank/6 cam combo are the same mechanical timings. Both would have #1 at TDC. The 12/6 would be TDC exhaust and 12/12 would be compression. #1 and #6 are 180 degrees out of phase is the only reason that I mentioned it before.
I think this is one of those conversations that in person would take 5 seconds but through text I'm somehow not on the same page as you are.
I'm sorry if I added confusion to your thread.
I think this is one of those conversations that in person would take 5 seconds but through text I'm somehow not on the same page as you are.
I'm sorry if I added confusion to your thread.
Thread Starter
Le Mans Master
Joined: Feb 1999
Posts: 9,946
Likes: 38
From: South Carolina
St. Jude Donor '03 & '05
No worries. The error is me. The page I just so happen to be at was as I was installing the cover. If I had gone back a page, I would have seen the correct layout. The page I posted here is for installation of the Opti, which makes no sense why It should be where the picture is.
