Here's the basic run down of my combo:

Mark IV 454 14015445 casting ('77 truck block, 4-bolt main)
bored to 468CID
stock GM cast crank
GM 7/16 rods, externally balanced
ARP bolts/studs ETC
Brodix Race Rites, 115cc with CNC chamber, assembled (springs to match cam, comes with competition valve job, valve bowl blend)
Lunati 402A3LUN cut on a 112 LSA (276/284 at .020, 243/251 at .050, .586/.600 valve lift)
Standard stamped rocker arms
Carter 172-gph mech. pump with 1/2'' fuel line
SRP 139515 (23cc dome, should achieve 10.2:1 SCR running 93 octane)
Holley 850 CFM double-pumper
K&N air filter
Accel HEI distributor
TKO 600=2.87/1.89/1.28/1.00/.64OD
4.10 rear with posi (12-bolt)
True dual exhaust with 1 7/8'' headers and Hooker Aerochambers, 3'' piping, 2.5'' tail pipes.


I already have an Edelbrock Performer RPM intake. I am just curious though on if there would be any better intake for my set-up? Someone here already suggested the RPM Air-Gap. I was wondering if there would be any other dual-plane intakes that would work especially well with the combo that would possibly be worth me looking into. I may decide to put it on before I build the engine, or wait because not now, but later I plan to maybe change rocker arms to some rollers or something, and I would maybe do an intake then too. Anyway...just curious if anyone had any input, thanks.

P.S. are the headers the right size? Thanks.

I think the air-gap is a bit taller than the standard performer RPM and you may lose hood to aircleaner space. Nothing wrong with that manifold you have now for that combo. You also mentioned changing the rockers to rollers later? You are not running stock rockers with a .600 lift cam are you? I thought "long slots" at least were needed for that.
....you actually have that Tremec installed??

I don't think there is any difference between the standard RPM and the RPM AirGap, other than the looks of the AirGap. :cool:

I have always wanted to try the Weiand Stealth for a big block. Looks like a real nice piece.

I have heard that the Stealth has a little bigger runner volume and with the fact that the plenum divider has been milled down would help higher rpm's (6000+) at the cost of a little low-mid range power. The Stealth might work a little better on a larger engine (496+)

Since you already have the RPM, I would probably just run that and save the $$$. ;)

If you want the benefits of the Air Gap with a "regular" RPM,block off the exhaust crossovers and the use the GM valley splash tray.

If you didn't have yours I would go with the Weiand Stealth or Air Gap. ;)
I really doubt you will see much if any gain from what you have though & it is a lot less expensive :D

The headers should be fine.

Thanks all for the tips. I'll stick with what I have.

Originally posted by Epistuff:
You also mentioned changing the rockers to rollers later? You are not running stock rockers with a .600 lift cam are you? I thought "long slots" at least were needed for that.
....you actually have that Tremec installed?? Yes, I just bought some replacement stamped rockers from Summit for that cam. What do you mean long slots though? I didn't know there would be any problem so if I'm going to run into mechanical problems that would be bad.

Nope, don't have the Tremec installed yet. Probably will be a spring break sort of project.

Thanks all.

Mike,

Is Holley still selling their BB version of the 300-36, SB high-rise?? (I think it was called a Street Avenger or maybe a Street Dom.??)...

I don't know if Holley sold both large oval and rect. ones or not, but I always wondered how it stacked up against the RPM/RPM-A/G and Stealth??

AND is there any decent OFFY intakes out there anymore for this use??

pdq67

Right now there is no good reason for you to change your intake manifold. Until something else new is designed the RPM manifold is the best dual-plane for that application. The Air-Gap runners are exactly the same as the the RPM runners. The Air-Gap is worth 3-5 hp from cooler charge air if all the conditions are right, sometimes no power gain. Blocking off both sides of the heat riser is usually worth 5-8 hp, blocking off one side will usually give 3-5 hp. Most of the gain from blocking the heat riser results from eliminating the communication betweeen the two exhaust ports. The rest from elimination of the heat.

Can anyone clarify the thing about the rocker arms? I'm curious now..thanks.

You just need to make sure the slot in the rocker arm has adequate clearance between the stud and the rocker at full lift. If it doesn't, the rocker arm will contact the rocker stud, and then bad things happen......like bent pushrod and broken studs.
Roller rockers are a good way to go. Harland Sharp has decent parts at a reasonable price.

Ron

Is there a way I can test this, maybe during assembly? Maybe once I have cam and stuff installed and I can turn it over by hand to see if there is any binding or anything? Don't get me wrong, I'm not about to try to jerry-rig anything with this engine, but already have the parts so you know how it goes, I'd at least like to try.

Thanks..

Originally posted by pdq67:
Mike,

Is Holley still selling their BB version of the 300-36, SB high-rise?? (I think it was called a Street Avenger or maybe a Street Dom.??)...

I don't know if Holley sold both large oval and rect. ones or not, but I always wondered how it stacked up against the RPM/RPM-A/G and Stealth??

AND is there any decent OFFY intakes out there anymore for this use??

pdq67 =
Don't have a clue on the Holley, or the Offy as I don't use em.
The Stealth is a better intake on larger & or higher RPM engines as it has more plenum & slightly larger runners than the EDE intakes.

Taylor,
One of the best "old school" flat tappet cams was the 3143 or 425/435HP GM cam & it was only .500 lift.
GM had never had factory cams over .600 lift in rats except for the "off road" or ZL1 deal & the "Can Am or fuel injection" cam.
GM also had a factory "long slot" rocker. to go with these so it is a good idea to check for rocker to stud interference at full lift with a .600 lift cam.

You can easily check this with a very expensive & hard to use tool called a paper clip. :D
Just straighten it & see that it will slip between the stud & rocker slot at full lift.

For info, in my opinion, the biggest problem with GM rockers & most copies is you have no clue what the damn ratio is until you install & measure the lift.

Thanks Mike..

Can anybody else fill me in on what I asked about the Holley and Offy intakes??

Bttt, And He, He!! About the "paper-clip"!!

He, He!!

"Shade-tree" all the way and works great!!

pdq67