Where do you shift your BB
Melting Slicks
Joined: Jan 2003
Posts: 2,877
Likes: 13
From: Doha
St. Jude Donor '08
I don't think his valves are floating, when I had valve float the engine will just stop revving past 4500 RPM but it will not pop or make any unusual sounds. It may be ignition problem.
Drifting
Joined: Oct 2005
Posts: 1,527
Likes: 148
From: East London/SW Essex UK
Race Director
Joined: Jan 2000
Posts: 13,017
Likes: 2,261
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
All those factory hyd flat tappet motors should go 5500+ easily with no drama. Valvesprings can show up in many ways. Sometimes car just gets a little slower and only noticed on a timeslip. Sometimes they just nose over.....when they are really bad they will bang spit and belch at high RPM.
Since factory cams had light spring pressure anyway...and since there's no telling if they are really old, or if someone did a valvejob and sunk the valves a little and didn't shim them, or they have the wrong ones etc....it's worth checking the pressures on them.
Once you eliminate that you can chase other gremlins in electrical and fuel systems maybe.
JIM
Since factory cams had light spring pressure anyway...and since there's no telling if they are really old, or if someone did a valvejob and sunk the valves a little and didn't shim them, or they have the wrong ones etc....it's worth checking the pressures on them.
Once you eliminate that you can chase other gremlins in electrical and fuel systems maybe.
JIM
Pro
Joined: Apr 2008
Posts: 596
Likes: 6
From: Irving Texas
After drag racing my 1969 396 big-block camaro for several years.....my two cents are:
Pushrods!
The big blocks use two different size pushrods and a multi-angle valve arrangement...meaning there's more stress going on there than the small-blocks.
When someone says they are RPM limited, I usually think they are using points. But the popping is either the MSD box hitting the limiter or ignition or valve issues.
I've never bent any valves but have replaced my stock pushrods with cheapy parts and ended having to do it all over again. Trust me, the best investment I ever made was to buy a pushrod length checker and order the Comp Cams Magnum or HighTech pushrods.
You will not recognize your engine after adding an MSD box and these pushrods.
Pushrods!
The big blocks use two different size pushrods and a multi-angle valve arrangement...meaning there's more stress going on there than the small-blocks.
When someone says they are RPM limited, I usually think they are using points. But the popping is either the MSD box hitting the limiter or ignition or valve issues.
I've never bent any valves but have replaced my stock pushrods with cheapy parts and ended having to do it all over again. Trust me, the best investment I ever made was to buy a pushrod length checker and order the Comp Cams Magnum or HighTech pushrods.
You will not recognize your engine after adding an MSD box and these pushrods.
Thread Starter
Racer
Joined: Mar 2009
Posts: 331
Likes: 1
From: Brooklin Ontario
All those factory hyd flat tappet motors should go 5500+ easily with no drama. Valvesprings can show up in many ways. Sometimes car just gets a little slower and only noticed on a timeslip. Sometimes they just nose over.....when they are really bad they will bang spit and belch at high RPM.
Since factory cams had light spring pressure anyway...and since there's no telling if they are really old, or if someone did a valvejob and sunk the valves a little and didn't shim them, or they have the wrong ones etc....it's worth checking the pressures on them.
Once you eliminate that you can chase other gremlins in electrical and fuel systems maybe.
JIM
Since factory cams had light spring pressure anyway...and since there's no telling if they are really old, or if someone did a valvejob and sunk the valves a little and didn't shim them, or they have the wrong ones etc....it's worth checking the pressures on them.
Once you eliminate that you can chase other gremlins in electrical and fuel systems maybe.
JIM
Thread Starter
Racer
Joined: Mar 2009
Posts: 331
Likes: 1
From: Brooklin Ontario
After drag racing my 1969 396 big-block camaro for several years.....my two cents are:
Pushrods!
The big blocks use two different size pushrods and a multi-angle valve arrangement...meaning there's more stress going on there than the small-blocks.
When someone says they are RPM limited, I usually think they are using points. But the popping is either the MSD box hitting the limiter or ignition or valve issues.
I've never bent any valves but have replaced my stock pushrods with cheapy parts and ended having to do it all over again. Trust me, the best investment I ever made was to buy a pushrod length checker and order the Comp Cams Magnum or HighTech pushrods.
You will not recognize your engine after adding an MSD box and these pushrods.
Pushrods!
The big blocks use two different size pushrods and a multi-angle valve arrangement...meaning there's more stress going on there than the small-blocks.
When someone says they are RPM limited, I usually think they are using points. But the popping is either the MSD box hitting the limiter or ignition or valve issues.
I've never bent any valves but have replaced my stock pushrods with cheapy parts and ended having to do it all over again. Trust me, the best investment I ever made was to buy a pushrod length checker and order the Comp Cams Magnum or HighTech pushrods.
You will not recognize your engine after adding an MSD box and these pushrods.
Race Director
Joined: Jan 2000
Posts: 13,017
Likes: 2,261
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
No reason to pull heads to verify spring pressure. All you need to do is pull valve covers and use one of the tools that checks them by leveraging the rocker arms. If they are weak...just replace them or shim them possibly right on the car. Not hard to do.
My old 427 would *mysteriously* lose about a tenth and a mph at the track after 1-2 years of running with the solid flat tappet cams and beating on it regularly. After verifying everything else, a simple spring check showed they had lost some pressure. As soon as that was corrected it was instantly back in the game. Never felt it..or heard it...but since I was racing regularly it showed on the timeslips.
Interestingly...during a recent freshen up of my 540...I found the 6-7 year old springs had lost a LOT of pressure. They were fine a year or so back...but now were way down finally. Funny thing was that the car never slowed a bit even with 7500 rpm shifts and 9 sec 1/4 mile passes over 140 mph. Apparently the dynamics of the .774" lift cam are stable enough to be able to handle things with less pressures than usual.
JIM
My old 427 would *mysteriously* lose about a tenth and a mph at the track after 1-2 years of running with the solid flat tappet cams and beating on it regularly. After verifying everything else, a simple spring check showed they had lost some pressure. As soon as that was corrected it was instantly back in the game. Never felt it..or heard it...but since I was racing regularly it showed on the timeslips.
Interestingly...during a recent freshen up of my 540...I found the 6-7 year old springs had lost a LOT of pressure. They were fine a year or so back...but now were way down finally. Funny thing was that the car never slowed a bit even with 7500 rpm shifts and 9 sec 1/4 mile passes over 140 mph. Apparently the dynamics of the .774" lift cam are stable enough to be able to handle things with less pressures than usual.
JIM
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Thread Starter
Racer
Joined: Mar 2009
Posts: 331
Likes: 1
From: Brooklin Ontario
No reason to pull heads to verify spring pressure. All you need to do is pull valve covers and use one of the tools that checks them by leveraging the rocker arms. If they are weak...just replace them or shim them possibly right on the car. Not hard to do.
My old 427 would *mysteriously* lose about a tenth and a mph at the track after 1-2 years of running with the solid flat tappet cams and beating on it regularly. After verifying everything else, a simple spring check showed they had lost some pressure. As soon as that was corrected it was instantly back in the game. Never felt it..or heard it...but since I was racing regularly it showed on the timeslips.
Interestingly...during a recent freshen up of my 540...I found the 6-7 year old springs had lost a LOT of pressure. They were fine a year or so back...but now were way down finally. Funny thing was that the car never slowed a bit even with 7500 rpm shifts and 9 sec 1/4 mile passes over 140 mph. Apparently the dynamics of the .774" lift cam are stable enough to be able to handle things with less pressures than usual.
JIM
My old 427 would *mysteriously* lose about a tenth and a mph at the track after 1-2 years of running with the solid flat tappet cams and beating on it regularly. After verifying everything else, a simple spring check showed they had lost some pressure. As soon as that was corrected it was instantly back in the game. Never felt it..or heard it...but since I was racing regularly it showed on the timeslips.
Interestingly...during a recent freshen up of my 540...I found the 6-7 year old springs had lost a LOT of pressure. They were fine a year or so back...but now were way down finally. Funny thing was that the car never slowed a bit even with 7500 rpm shifts and 9 sec 1/4 mile passes over 140 mph. Apparently the dynamics of the .774" lift cam are stable enough to be able to handle things with less pressures than usual.
JIM
Later, Rog.
