Anyone ever broken a comp 921 spring?
Thread Starter
Launching!
Joined: Jul 2004
Posts: 200
Likes: 0
From: Gainesville, Florida
Anyone ever broken a comp 921 spring? I need total valvetrain reliability for daily driving and open track use (about 1 hour at WOT in a full track weekend). I thought I was going to have to go with a LS6 valvetrain setup with mild lobes, but some people told me these springs wouldn't ever break if I kept the lift and ramp down.
So, anyone broken one? Cost isn't much of an object. If an extra $300 keeps me from dropping a valve, I'll pay it.
So, anyone broken one? Cost isn't much of an object. If an extra $300 keeps me from dropping a valve, I'll pay it.
Last edited by Grant B; Sep 4, 2004 at 04:41 PM.
Teching In
Joined: Sep 2002
Posts: 44
Likes: 0
From: Lafayette, LA
I should know by tomorrow if I have one. Last pass down the track Monday, heard a pop.. then the car started to miss and bank 1 O2 sensor went extremely lean. Got out of it and coasted to the end of the track and back into the pits. Car went straight on the trailer and has been there since. I will be dropping it off this afternoon to have a local shop check it out.
Still ran a 7.28 1/8th letting up at the 500-550' mark and crossed the traps at 93 mph.
Mph prior to this was 98 with the car only shifting at 5800rpms. Still trying to get the shift points nailed witht the new 4000 stall and 3.90's. Had just about had the 1st-2nd gear shift point nailed down (6425) when I heard the pop just as I shifted from 2-3 (6250). I shut it down from there.
Still ran a 7.28 1/8th letting up at the 500-550' mark and crossed the traps at 93 mph.
Mph prior to this was 98 with the car only shifting at 5800rpms. Still trying to get the shift points nailed witht the new 4000 stall and 3.90's. Had just about had the 1st-2nd gear shift point nailed down (6425) when I heard the pop just as I shifted from 2-3 (6250). I shut it down from there.
TECH Resident
Joined: Apr 2003
Posts: 791
Likes: 0
From: Tulsa, Ok
i'm sure there are some, but everyone running these springs is running BIG cams, so it's kind of to be expected. that being said, i've got 7k on my springs with no problems and there are countless others with BIG cams and these springs without any problems. best springs on the market, IMO
Originally Posted by xaon
I've already seen one 921 replaced. Was on a 408 with a cam in the 245ish duration and .610ish lift range.
LITTLE CHEEEESE!!
anyways, i have not seen any 921's break before at all... Pretty nice spring actually!
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Verdad Gallardo Teching In
Joined: Sep 2002
Posts: 44
Likes: 0
From: Lafayette, LA
Well turns out no broken springs. #1 piston cracked around the skirt and has to be replaced as well the exhaust valve kissed the top of the piston. Now have to get the head cleaned up and valves replaced as well. Luckily it is not as bad as it could have been from looking at it.
Now just have to decide whether to replace the piston with another stock one or to put forged pistons in.
Now just have to decide whether to replace the piston with another stock one or to put forged pistons in.
