MY ride: 85' Monte base with chevy performance 350 HO motor as described:
https://www.gmperformancemotor.com/parts/19210007.html
Installed in 2011 and driven roughly 7,500 miles it developed a ticking sound in fall 2017 under the rear of the motor emanating form the driver side wheel well around cylinder 7. After much tinkering(adjusting valve lash, different weight oils and such) and a visit to a performance shop its been determined the engine isn't tearing itself apart and hasn't wiped a cam lobe or lifter. It' most likely a lifter still in operation but noisy and not draining completely.
Many people have basically said "just drive it", but I can't. The sound annoys me, makes the car sound off and undermines my confidence and enjoyment of driving it. So I've got a shop lined up to convert the valve train from hydraulic flat tappet to a hydraulic roller. It's an '86 and later block so it has provisions for a roller cam. The reasons for the conversion are obvious, if I'm in there and paying money, upgrade to newer, better technology. And Chevy Performance now sells my exact motor but with a roller setup as they seem to be phasing mine out:
https://www.chevrolet.com/performance/crate-engines/sp350-357-base
This engine in this incarnation is a light bump in power from 333hp/381 ft lbs to 357hp and 407ft lbs. Pretty much as you would expect. Since I'm paying to dive into the motor i'd like to reach these gains as well as gain the other benefits of a roller cam. The only hangup I see if my valve springs. I'm no engine builder so I need help here. The springs in my Vortec heads are Gm # 10212811. I can't find exactly what these are rated for lift wise, but I know the lift on the chevy performance roller cam would be 0.473 on intake and exhaust which is up from 4.35/4.60.
What has me worried is this Q and A from the Summit racing sight on the roller cam part # gm 12677151
Q:Will this cam work with a stock L31 vortec head without modification?
Asked by JOSHUA on December 26, 2017
A:
Thank you for your question Joshua. This camshaft appears to have a valve lift of 473/473. We usually do not recommend running over .450 lift on stock valve springs. Head work would more then likely need to be done to ensure you do not collapse a valve spring. Thanks again for your question.
But someone else replied with
A:
GM puts this cam in their 350 crate engine that is part number per part number the same as what came in the Vortec trucks/SUVs and Vans. Same springs, same retainers, same valves, same seals, etc. The 395' Ramjet cam is .460/.481" lift with the 1.6 rocker arms and uses box stock Vortec heads as well.
For me where some of the confusion is coming in in when Chevy first launched the roller version of the 350 HO they used my Vortec heads but now appear to have shifted to the fast burn heads. I found this when looking into doing the beehive spring setup:
NOTE: The conversion kit is intended only for Fast Burn heads and is not compatible with Vortec heads because of insufficient room for the spring seats.
My friend suggested doing a cam with lower lift, but what fun is that? Especially since I'm paying to dive into this thing. What would you guys suggest?
https://www.gmperformancemotor.com/parts/19210007.html
Installed in 2011 and driven roughly 7,500 miles it developed a ticking sound in fall 2017 under the rear of the motor emanating form the driver side wheel well around cylinder 7. After much tinkering(adjusting valve lash, different weight oils and such) and a visit to a performance shop its been determined the engine isn't tearing itself apart and hasn't wiped a cam lobe or lifter. It' most likely a lifter still in operation but noisy and not draining completely.
Many people have basically said "just drive it", but I can't. The sound annoys me, makes the car sound off and undermines my confidence and enjoyment of driving it. So I've got a shop lined up to convert the valve train from hydraulic flat tappet to a hydraulic roller. It's an '86 and later block so it has provisions for a roller cam. The reasons for the conversion are obvious, if I'm in there and paying money, upgrade to newer, better technology. And Chevy Performance now sells my exact motor but with a roller setup as they seem to be phasing mine out:
https://www.chevrolet.com/performance/crate-engines/sp350-357-base
This engine in this incarnation is a light bump in power from 333hp/381 ft lbs to 357hp and 407ft lbs. Pretty much as you would expect. Since I'm paying to dive into the motor i'd like to reach these gains as well as gain the other benefits of a roller cam. The only hangup I see if my valve springs. I'm no engine builder so I need help here. The springs in my Vortec heads are Gm # 10212811. I can't find exactly what these are rated for lift wise, but I know the lift on the chevy performance roller cam would be 0.473 on intake and exhaust which is up from 4.35/4.60.
What has me worried is this Q and A from the Summit racing sight on the roller cam part # gm 12677151
Q:Will this cam work with a stock L31 vortec head without modification?
Asked by JOSHUA on December 26, 2017
A:
Thank you for your question Joshua. This camshaft appears to have a valve lift of 473/473. We usually do not recommend running over .450 lift on stock valve springs. Head work would more then likely need to be done to ensure you do not collapse a valve spring. Thanks again for your question.
But someone else replied with
A:
GM puts this cam in their 350 crate engine that is part number per part number the same as what came in the Vortec trucks/SUVs and Vans. Same springs, same retainers, same valves, same seals, etc. The 395' Ramjet cam is .460/.481" lift with the 1.6 rocker arms and uses box stock Vortec heads as well.
For me where some of the confusion is coming in in when Chevy first launched the roller version of the 350 HO they used my Vortec heads but now appear to have shifted to the fast burn heads. I found this when looking into doing the beehive spring setup:
NOTE: The conversion kit is intended only for Fast Burn heads and is not compatible with Vortec heads because of insufficient room for the spring seats.
My friend suggested doing a cam with lower lift, but what fun is that? Especially since I'm paying to dive into this thing. What would you guys suggest?
