LQ9 Question
Thread Starter
Teching In
Joined: May 2016
Posts: 5
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LQ9 Question I have a 1970 Nova with an LQ9 block and 862 heads. The cam that is in it now is the ***** Thumpa part number 54-601-11. The car does not have much torque until 4K RPM's or so. I am looking to do a cam swap. I am not sure which timing set is in the car or if the valve springs have been changed. I would assume so but I bought the car with the engine already in it. I am running a Victor Jr Intake and a Holley HP 750 CFM carb on it. It has a turbo 400 tranny and 3.55 posi rearend. I am running power brakes and steering. The car I believe was a track car before I got it because it had a 3,800 stall. I am going to use it as a street car so I swapped it out to a 2,200 stall.
Can anyone help with a cam selection? I'd prefer Comp if possible. The cam I am interested in is the 269LrR but it looks like I will need to upgrade the valve springs and maybe even the timing gear set. I'm not sure as I am new to LS motors on what all should be done. I don't have a ton of money at this time so if I can get by with what I have and just do a cam swap that would be perfect.
Thanks to all for any help.
Can anyone help with a cam selection? I'd prefer Comp if possible. The cam I am interested in is the 269LrR but it looks like I will need to upgrade the valve springs and maybe even the timing gear set. I'm not sure as I am new to LS motors on what all should be done. I don't have a ton of money at this time so if I can get by with what I have and just do a cam swap that would be perfect.
Thanks to all for any help.
TECH Resident
Joined: Apr 2014
Posts: 985
Likes: 12
Get ready to get flamed for using the COMP name on this site, it is not a vendor, so
you will hear every failure and some made up ones I'm sure, about Comp.
You will get, I wouldn't use anything but... You will see.
But some of the vendors on this site use there cores sooooo.....
you will hear every failure and some made up ones I'm sure, about Comp.
You will get, I wouldn't use anything but... You will see.
But some of the vendors on this site use there cores sooooo.....
Thread Starter
Teching In
Joined: May 2016
Posts: 5
Likes: 0
Sorry to bring up the Comp name. I didn't mean to offend. I have no idea if the 862's are stick or not. I would assume that the previous owner upgraded the valve springs when he put this cam in but I'm not sure. The only thing I've done is put the rocker trunion kit on it.
TECH Junkie
Joined: Dec 2012
Posts: 3,621
Likes: 1,335
From: Iowa
If i did the math right (i was using standard values for lq9 shortblock and 862 heads) with that cam you will have pretty wild dynamic compression and likely will have detonation issues if on pumpgas.
I'd bet something in the neighborhood of 226/230 113+0 would be plenty torquey around 2000-2500 and still carry well into the top.
The big motha whatever you have in there now is on a small lsa and very early icl with loads of exhaust duration. This means loads of overlap which equals plenty of lope or chop. in your case it probably sounds pretty cool but doesn't run worth a ****.
With larger displacement and lots of compression you have, it should still be noticable chop with that 226/230 creating 2 degrees of overlap at .050.
I'd bet something in the neighborhood of 226/230 113+0 would be plenty torquey around 2000-2500 and still carry well into the top.
The big motha whatever you have in there now is on a small lsa and very early icl with loads of exhaust duration. This means loads of overlap which equals plenty of lope or chop. in your case it probably sounds pretty cool but doesn't run worth a ****.
With larger displacement and lots of compression you have, it should still be noticable chop with that 226/230 creating 2 degrees of overlap at .050.
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I have one of those cams in a GTO and its a great sounding cam but hardly anything to write home about on the performance aspect of it. I dont race the gto i just cruise in it so the sound is nice.