My first post here. I would like to go to an assembled Edelbrock Performer Aluminum head on my 492 bbc (.040 over, .250 longer arm) for the "out of the box" experience without getting in line at the machine shop. However, I run a comp cams (11-404-4) cam with matching #924 springs with dampners. The Eddy heads come with single springs (no dampners) and closed spring pressure of 125 lbs at 1.975 installed height and differ from the #924 comp cams at 112 lbs at 1.900, so a little tighter on the Edelbrock.

The open pressures are 310 lbs at 1.415 for the Eddy's and 335 lbs at 1.2 inches installed height for the comp cams springs.
The '70 chevelle also a Vortech supercharger and runs through the traps (3.90 gear, 28" tire) at 6700-6800 RPM.

I hate to have any surprises on the big end of the track. Am I just overthinking this, or should I get back in line at the machine shop to have comp cam #924 springs installed? The people at Comp Cams and Edelbrock seem to think the springs pressures are close enough. Don't see any reason to go to a 2.25 intake or bigger valve with a blower, or the smaller bore (4.290). The Edelbrock heads are #60559 rectangular ports. Fire away.

Spring heights were all over the place, not enough seat pressure b/c the heights were all over, springs lost pressure fast. They come with dual springs AFAIK - mine did. I actually have the GMPP version of the heads (have the 2.25 valves).

The worst part about them though was the factory valve job - piss poor. Everyone but a couple leaked...these were new heads. But them bare and let your shop go through them. Better yet, go with AFR or Brodix b/c they have higher quality control.

Hi Vince.
I'm going through this today as well.
Pulled the stock GM spring /retainer... and found the spring heights almost perfect at 1.945 (.060 shim under spring) These are new heads/never run.

Checked the heights with the new retainer/lock and find them at 2.045" or .100" long.
I'm told that GM used a -.050 lock and this makes sense as there is a lot of valve stem protruding with the GM retainers/locks. Almost zip with the new ones.

I am checking with the lock/retainer mfg. to see if they shipped a +.050 lock and also see if there is a -.050 one to get the right heights.

Anybody else have a similar issue with these GMPP big block heads???

My first post here. I would like to go to an assembled Edelbrock Performer Aluminum head on my 492 bbc (.040 over, .250 longer arm) for the "out of the box" experience without getting in line at the machine shop. However, I run a comp cams (11-404-4) cam with matching #924 springs with dampners. The Eddy heads come with single springs (no dampners) and closed spring pressure of 125 lbs at 1.975 installed height and differ from the #924 comp cams at 112 lbs at 1.900, so a little tighter on the Edelbrock.

The open pressures are 310 lbs at 1.415 for the Eddy's and 335 lbs at 1.2 inches installed height for the comp cams springs.
The '70 chevelle also a Vortech supercharger and runs through the traps (3.90 gear, 28" tire) at 6700-6800 RPM.

I hate to have any surprises on the big end of the track. Am I just overthinking this, or should I get back in line at the machine shop to have comp cam #924 springs installed? The people at Comp Cams and Edelbrock seem to think the springs pressures are close enough. Don't see any reason to go to a 2.25 intake or bigger valve with a blower, or the smaller bore (4.290). The Edelbrock heads are #60559 rectangular ports. Fire away.

First thing you need to do is get that cam broken in successfully, and that involves running a lighter break in spring. You should be able to remove the inner springs for the break in. Once it's broken in, I like to add seat pressure to counteract the positive pressure created by the supercharger. I would like to see 130# seated which should result in about 320# open which will still give you good cam and lifter life. I always groove the lifter bores on the big blocks with performance cams since they have the smallest lifters and highest rocker ratio. If your block is together you can buy the Crower hydraulic lifters with the coolface option. http://store.summitracing.com/egnsearch.asp?N=400401+307616+115&autoview=sku

ttt

My first post here. I would like to go to an assembled Edelbrock Performer Aluminum head on my 492 bbc (.040 over, .250 longer arm) for the "out of the box" experience without getting in line at the machine shop. However, I run a comp cams (11-404-4) cam with matching #924 springs with dampners. The Eddy heads come with single springs (no dampners) and closed spring pressure of 125 lbs at 1.975 installed height and differ from the #924 comp cams at 112 lbs at 1.900, so a little tighter on the Edelbrock.

The open pressures are 310 lbs at 1.415 for the Eddy's and 335 lbs at 1.2 inches installed height for the comp cams springs.
The '70 chevelle also a Vortech supercharger and runs through the traps (3.90 gear, 28" tire) at 6700-6800 RPM.

I hate to have any surprises on the big end of the track. Am I just overthinking this, or should I get back in line at the machine shop to have comp cam #924 springs installed? The people at Comp Cams and Edelbrock seem to think the springs pressures are close enough. Don't see any reason to go to a 2.25 intake or bigger valve with a blower, or the smaller bore (4.290). The Edelbrock heads are #60559 rectangular ports. Fire away.

The 924 spring is a poor choice and you will get valve float by 5800 rpm's.

Hi Vince.
I'm going through this today as well.
Pulled the stock GM spring /retainer... and found the spring heights almost perfect at 1.945 (.060 shim under spring) These are new heads/never run.

Checked the heights with the new retainer/lock and find them at 2.045" or .100" long.
I'm told that GM used a -.050 lock and this makes sense as there is a lot of valve stem protruding with the GM retainers/locks. Almost zip with the new ones.

I am checking with the lock/retainer mfg. to see if they shipped a +.050 lock and also see if there is a -.050 one to get the right heights.

Anybody else have a similar issue with these GMPP big block heads???


Looks like Eddy has better QC than does GMPP. I wonder if Eddy does the assembly work to for GMPP? One set of valve heights was about .030 higher than the other heads, so I had to shim them accordingly.

Mine only cam with a .015 under each spring. I used a .060 locator, and -.050 locks in addition to the misc shims needed to bring my installed height to 1.900 for these springs.

Hi Vince.
I am reading your other post at the moment.
I am tempted just to sell these and use some Brodix heads ;)

http://www.chevelles.com/forums/showthread.php?t=187089&highlight=retainer+height

Levon,
Don't do that because that cam is designed for those heads. I sent you an e-mail but your locks you have from me should have a recess in the top which means they are std locks. In your case we can do the following:

Go a -.050" valve lock which will give you more stem protrusion and use some .060/.070 spring locators and shims to get us exact.

Use the locks you have and go with a spring cup and a .060" shim.

Either of which will work just fine.

Hi Chris.
I replied to your Email.
The note above was just a vent ;). I would not do that.
The heads I have are fine. I want to do the -.050 locks and the spring locators.

Measure the spring pockets and I will get you some locators. No point in sending the locks back, I will send you a set of -50's at no charge....just send me a pic of the car in the winners circle this year....

Now thisis why we have such a GREAT circle of friends. You cannot do business with better people!!!!!
You'll get the second picture :-)

Levon,
Measure the ID on the springs I sent, it should be around .705". Give me the OD of the valve guide on that head and I will get the locators ordered and sent. USPS has a new envelope for international so I will send them that way. Hopefully quicker then the rest of the stuff took....

Spring ID = .728"
OD Valve guide = .563"

Can we do anything else via EMail? Its not adding to the post... unless others want to see the great job you do ;-)

Levon,
Yeah no problem, I just caught you on the site so I thought it may be quicker. I have everything I need, will get you some locators....

As said earlier.
A gentleman!!!!!!!!!!!!!