Camrs89

Ok, me and HrdRockA4305 tested my camaro the other day on a back road and it wouldnt pull after 5000 rpms when it should be able to go up to 8500 rpms without any problems. I asked him about it and he said a couple things are hurting me

1. Intake manifold- I have a performer rpm which he says I should switch to a victor jr. intake so I can take advantage of my rpm range (2500-8500)

2. Carb-I have a Vac. secondary Holley 750. He says those are crap and he has a Dominator 800 double pumper that I can "have"

3. Headers- I have the $99 Heddmen headers and 2 1/2 inch exhaust. I know thats choking me so I think I may try to run true dual exhaust with 3-inch pipes.

4. Gears-Current are the weak 2.73 gears. He says that I should put 4.10's in or go with a 9-inch w/ 4.11's.

Then after all of this he wants me to run a nitrous setup with about 200 shot.

What's everyone's thoughts on this.

Vader

RS89,

What are your cam specs? The Victor and 800 are going to suck below 2,000 RPM with any cam. If your cam has a lot of overlap, the Victor induction may be right for high RPM operation. However, it certainly doesn't match your gearing for street operation, but if you were testing it correctly, that shouldn't matter. The engine should eventually be able to make RPM unless aerodynamic drag is excessive.

NASCAR typically uses 2.10 gearing and runs their cars at 8,500 RPM regularly - along with under 600 CFM carburetors. If you want to get that kind of RPM in quarter mile runs, you're way off the mark on gearing. If you want to run around the back roads at 185 MPH, you're just about right.

And it wouldn't hurt to list the other mods as well.

Camrs89

Vadar-My cam is a solid lifter with a little over .500 lift. I really dont want to tell the cam I am using but its power band is from 2500-8500. My engine builder, who also builds circle track cars, says that 4.56 gears would be ideal, but I think thats a little too much. What do you recommend?

My mods...Ummm. 350 4 bolt main .30 over and decked, Eagle rods, ARP bolts, Keith black flattops, solid lifter cam, 305 heads that have 3-angle valve job, large valves, ported and polished, 1.5 aluminum roller rockers and edelbrock valve springs, MSD HEI ignition, Holley electric fuel pump, Taylor wires, TH350 with TCI saturday night covertor (I know I am forgetting some minor stuff) and planning on the stuff I mentioned above.

This car is pretty much going to be a car driven locally on nice sunny days and I want it to be a car no one wants to mess with.

Any suggestions would be appreciated.

Also, The guy has a set of Brodix aluminum heads for a good price thats got me thinking...

cfabe

I'm not nearly an expert in engines, but i'd think the 305 heads would be a huge limit on this motor.

84 Z-28 350

yeah the heads are a huge reducer in RPM's they have 1.84/1.50 valves and that just kills you above 4500 RPM or so get a set of good aftermarket heads like trick flow or dart and do some research before you buy them, you want somthing with really high flow ratings and 2.0x/1.60 or if possable even larger valves and look into getting 18* degree heads to help you breath better I have trick flow 23* heads W/CNC combuston chambers and I had the runners enlarged and polished and the area around the bace of each valve polished.

RB83L69

Without cam specs, specifically the .050" duration, it's impossible to even guess what sort of RPM characteristics the engine should have.

What are your goals for this car? ET, HP, class, etc.?

With 305 heads your motor will be lucky to make its peak HP anywhere beyond 5000 RPM no matter what else is in it. In other words, if you hold it in low gear and rev it past that peak HP point whatever it happens to be, your car will go slower.

8500 RPM is unrealistic for your bottom end. I doubt it would do that even once, let alone on a regular basis. IMHO the Perf RPM is a perfectly good intake for a mild cam like yours appears to be. There's nothing necessarily wrong with a 750 vac sec carb. A "free" $500 carb as a gift from someone who would probably be running it if it was any good is kind of scary no matter what size, brand or model it is.

Fix the exhaust, put a set of real heads on it, and come back and let us know how it does.

spartyon

i know 305 heads are worse than 350s in the flow area but dont 305s on a 350 boost compression? isnt higher compression good for racing? i dont know i am just stumped on this all my buddies who are big car freaks are tellin me to rebuild the 305 head and put them on my 350 for compression but my machinist says no because of the flow. which is worse the flow or compression. in other words what do i want for more power flow or compression?

Camrs89

My heads are on there for compression (11.5:1) but I am thinking about the Brodix aluminum heads for it. Those would be nice!

The carb is my engine builder's. He has a whole garage full of race parts, just because thats what he does. I said free b/c after trade in on my carb I will only have to pay like $100.

My goal for this car is to run low 12's on motor, 11's on the bottle.

RB83L69

Drop compression ratio from 11.5:1 to 10.5:1 = -5% HP; gain from flow improvement 305 heads to good heads = +50% HP

Which side of the tradeoff seems better to you?

High compression + big nitrous shot = scatter bottom end all over the track

A properly designed racing motor is set up either for N/A, or for nitrous. Numerous things are different: compression, cam profile, ignition setup, etc. If you want a nitrous motor, you should build one, and forget about what it does N/A. Or, if you want a top-notch N/A motor, build it that way, and use a small nitrous shot at most.

What kind of cam are you running?