What do I want for my 350 buildup? The Edelbrock performer, performer RPM, or airgap....is there any major difference? I'm using the XE268H Comp cam at around 10.25-10.6:1 CR (funny guy at summit "you can't run over 10:1 on pump gas")....I don't know which intake would compliment that...if it doesn't really matter I'm just gonna get the cheapest one.

 

use the rpm. the air gap will show around 6-8 more hp but the cost is far out! in all honesty you shouldn't go over 9.7:1 with iron heads unless you really know what your doing with timming, cam timming, squish, sharp edges, fuel atomization, and fuel curve. you'll probably have to run you ignition more retarded than normal to stay away from detonation and spark knock. the air gap would be better if you were using a speed demon carb or holley HP carb, because they have a better booster design for more uniform atomization of the fuel.

 

THe Vortec heads will take more than 9.7 CR. I started with 11.07:1 and never had nock unless I matted the gas in 5th gear at under 2300 rpm. THis is using 93. I rebuilt it with 10.7 CR and it doesn't knock at all in any gear, at any rpm. Timing is set at 34* in by 2500rpm.

 

you seldom hear detonation,ping you can hear though. detonation can tear a motor apart in seconds, ping wont. sometimes you can get away with high comp. if your cooling system is up to par and the heads dont have excess casting flash in the water jackets. 9.5 is safe for most people who just bolt stuff on and go. 10.5 "usually" requires more tuning. altitude also plays a large part in how high you can go in CR. the lower your altitude the lower you have to go because the air is more dense and the cylinders get packed with a better charge and because of this the cylinder pressure rises more. i live in MAINE, and for the most part we are at sea level so our engines run happy at 9.5 :1. tkae us up 3000' and they become slugish or noticably slower.

 

I'll have to run a 160 stat and keep the engine as cool as possible, i dont' do alot of highway driving, im real close to school/work....if i have to retard the timing a little in summer so be it...the way i figure, the summit kit says 10.7, but you ALWAYS loose a little compression from what they advertise, i figure if im 10.25-10.5 ill be making plenty of power without to much ignition trouble...if not, mill a little out of the heads or pistons...i have access to a mill/lathe it's not a problem...im leaning towards the RPM right now...i have heard quite a few people using it with good results

 

the RPM is an excellent manifold, the only problem you may encounter would be hood clearance, they sit higher then other dual plains, thats why the stealth manifold sometimes gets used. i've used teh stealth and its ok, i feel that the bottom end is a little soft with this manifold but has a strong top end because of the larger runners(and shorter). im using a RPM air gap this time, and when i get the 3.73 or 4.10 ill be using a Victor jr on my 408.

 

Make sure to consider the fact that the RPM Air-gap has water outlets in the rear (making heater core hookup a little easier) and two distributor clamp-down locations...

My standard RPM vortec manifold with 800cfm edelbrock and a 14x3" triangular air cleaner did require the use of an aftermarket cowl hood.. (3" harwood)

 

Performer RPM, and a 1" spacer. with that cam. and the compression your running low end won't be a problem, that should feed ya to 6000-6100rpm.

I'm running that intake stuff, on mine. with a 274 cam and running around on 93 octane with appox 10.7 compression., race it on pump gas, 36* not a ping to be found.

lil misnomer about "compression ratio" and what hte pistons say, if you put them in a standard block the compression will be one way. probalby a smidge lower than they advertise.

you put them in a Zero deck block it'll end up slightly higher most of the time. run flattop pistons with a standard .039 headgasket, and vortecs that have been just decked flat, your looking at around 10.25:1 if the pistons have the standard valve reliefs.

 

i completely forgot about hood clearance....of the 3 which sits the lowest? i don't plan on running a carbed setup for long, a year at most....i eventually want to use the TPI from the 305 and get EFI back once i can afford to go miniram or something like that......a 500$ cowl hood is most definately not in the budget....does the miniram require more clearance? if that doesn't clear a stock hood them maybe ill have to consider it.

thanks for the feedback

 

Miniram is about as low as you can go.

I see they list one for "GM Fast Burn Heads". I didn't realize they had a Vortec-style.

 

Vortec and Fast burn have the exact same intake port heights and use the same intake, fast burns are aluminun, vortecs are cast iron...other then that they are basically the same as far as i know...well and the fact that aluminum ones cost more then cast iron ones.

 

The Fast Burns have 210 intake ports, and bigger, hollow valves. THe Vortecs have 170 ports, and 194/150 valves.

 

well what are you runnign for heads? if they are not vortech get a WIEAND 8004, if your running vortech go to the junk yard and get an intake off a truck, seeing how your only running it for awhile theres no sence in wasting all that money. besides the RPM theres not much difference in HP. the other option is a STEALTH intake which sits pretty low. stock intakes make more power up to 3500 rpm anyway, most people dont know that or wont accept it.

 

The Performer RPm intake is the one to use.

It will fit fine under the hood with the right aircleaner.
The right aircleaner and best available is the Aircleaner origionally used on 67 to 72 Camaros Corvettes and Chevelles.

Actually all you need is the aircleaner base as the top is the saame as most aftermarket ones.
You can still buy this aircleaner base from Restoration sources
like Noal Performance.

www.noahperformance.com

Much cheaper than a new hood.

I ran my vortec motor on 93/94 octane gas with mild cam timing and a true measured 10:1 cr. No problems.