jchaussee

350 bored .030 over.
Pro topline srt heads
167cc 67cc 1.94/1.50
Cam is 236 /244 .520 in .535 ex at .050 duration
Performer RPM intake
QJET CARB
3.23 rear i believe. Out of a 99 trans am

Pistons are just plain rebuilders pistons
Stock rods
Havent got rocker arms or pushrods yet
No lifters yet
700r4 trans

So suggestions on stall, if i should get different pistons and what type of power thereoretacilly should i get.
And any other sugegestions on parts such as mechanical fuel pump or electric, etc

jchaussee

Oh and be easy on me. My first build. I want to only do it one time. And i want everything to work well together.

sofakingdom

iTrader: (1)

That cam/carb combo will test your tuning skillz to the absolute limit. In this day and time, probably also your Q-Jet parts tracking-down skillz, as lots of the tuning parts you're likely to need are going to be REAL tough to find.

Too much cam for the compression; it'll come out somewhere around 9 flat, maybe a bit less. Also it has too much exh duration for the int, unless you're planning on about 250 HP of nitrous, in which case, it's set up just about perfect.

That cam/compression/gear combo will have essentially no bottom-end torque at all. It won't really start making power until 3000 or so. You'll want a stall somewhere in that range; maybe 3000 - 3200 or thereabouts.

Best things you could do is get decent pistons, and zero-deck the block. "Rebuilder" pistons (ANY cast, MOST hypers such as SpeedPro, and MANY forged such as TRW) will add .020" to the already excessive stock .025 - .035", for a total deck clearance in the .045 - .055" range. Just getting that down to zero will bump the compression up to where it needs to be for the cam, in the high 9s to almost 10. Look at Mahle, Probe, SRP, etc. Stock rods won't help the situation, as they're almost always shorter than "spec", which adds to the deck clearance problem, and inconsistent besides.

The head specs look like they have smaller runners than some stock ones. Look in fact like they're designed to be legal in classes that require stock heads, as being an acceptable "stock replacement", similar to World S/R Torquer for example ("S/R" = "Stock Replacement"). I'd re-think those if possible.

86LG4Bird

iTrader: (1)

Sofa covered it all.
Even if this weren't your first build, I'd shoot for more compression AND LESS CAM.

jchaussee

Unfortunately i have lready invested the money in the heads so i am stuck with them. I still have to take my block to machine shop so i will have them do thier work. What intake and pistons would you suggest. I would like to get compression as high as i can while still using 92 octane. And if i get my compression upnwill that help out botton end power?

sofakingdom

iTrader: (1)

Intake you posted should work fine. No problem there.

True actual 1.56" pistons, not "designed to fit engines with 1.56" nominal deck height", plus zero-decking the block to them AFTER making sure ALL your rods are REALLY 5.700" long, will bring your compression up to right close to 10:1. Should be fine with that HUUUUUUJJJJJJJJE cam.

The thing about compression and cams is, the larger the cam is, the longer it holds the intake valve open. (duh) And of course all of that "longer", is while the piston is already HEADED BACK UP after it has already passed BDC. Which of course is GREAT for high-RPM horsepower, since it allows the inertia of the mixture rushing down the runners, to continue filling the cyl before the sound wave from the piston reaches the valve, as is the case at high RPMs; but at low RPMs, that just looks to the overall system, like a GIANT compression leak. Mixture gets pumped back OUT OF the cyl, BACKWARDS back into the intake for a significant amount of the compression stroke. End result is, very poor cyl fill at low RPMs, meaning, no power output under those conditions, meaning, no low RPM torque.

Getting good "leave" is going to be an uphill battle. Even with proper machine work and the right pistons, to get the compression up to somewhere near almost the absolute bare minimum that would be appropriate to that cam, it's still going to get 60'-ed by stock 2-bbl cars.

If you don't already have that cam also, I'd re-think that. While it may be "custom", it's clearly "custom" designed for some completely other combo than the one you have. It's a total mismatch to everything else in YOUR combo and thus clearly not "custom" for YOUR setup. If I had the heads you have and the compression you have and the gears you have and all that, I'd be looking at cams w about 10° less duration than that one, and less int/exh split. Something more nearly like this http://www.summitracing.com/parts/lu...03lk/overview/ which incidentally, solves your lifter dilemma at the same time. As cheeeeeeeeeeeeeeeeeeeeeeeeeep as cams are in the overall "big picture", I'd drop the one you posted like a prom dress, and get a RIGHT one to match the rest of what you've got. Starting with, the heads, that don't have large enough runners to ever reach high enough RPM for that HUUUUUUJJJJJJJJE cam to ever do what it's designed to do. Those kinda put you in a box as far as your possibilities; working WITH what they give you instead of mismatching to them, will give the ONLY acceptable results.

A stock 305 carb fuel pump (mech) will work fine. They're entirely adequate for well over 400 HP. Just, make sure the fuel system behind it, is unobstructed; like, drop the tank, and rod out the pickup tube to get rid of the crusties from sitting up, and put a new "sock" filter on it. Use a lightweight pump drive rod, as that extends the upper RPM limit a couple thou RPMs, and increases the pump capacity by about half besides. http://www.summitracing.com/parts/mor-65750/overview/ or http://www.summitracing.com/parts/hrs-94475/overview/ for example.

You don't mention exhaust. Don't skimp there either. A GOOD QUALITY set of headers, not just the cheeeeeepest thing you can find that it's still legal to print the word "headers" on the box, ceramic coated; a good cat; and your choice of high-quality cat-back exhaust. (I heartily recommend this one http://www.summitracing.com/parts/ho...t/model/camaro )

jchaussee

I have some cheap shorty headers to get by but i will do a higher quality exhaust later down the road. I may go with a new cam now and run with heads i have or use cam and switch out heads later. I do want something lumpy but want the lower end rpm power. What ratio rocker arms should i go with amd in your opinion if i switch out cam do you think ill make the 300hp mark.?

sofakingdom

iTrader: (1)

You'll make 300 HP with what you posted, easy. That's not the problem.

Problem is, you won't have squat until you're doing about 50 mph in 1st gear. It'll take you about 12 seconds to get from 0 to 50, then about 3 to get to 100. Then it'll be time to shift to 2nd. Meanwhile, that Kia minivan with the dippy housewife jabbering on the phone that you were trying to beat out of a place in traffic so you could turn left, will be like 500 yards ahead of you.

Fundamental rule is, "lumpy" is the direct opposite of "low end power". Can't have both, at least, not without ALOT of cubic inches. (which you don't have) You give up the one to get the other. The trick obviously is finding the right compromise: give up the least you have to of what matters less, to get the most possible of what matters more. With the gear you've got, you need to err on the side of LESS "lumpy", otherwise you'll be real disappointed at traffic lights.

Rocker ratio opens the valves farther, for the same length of time. Higher ratio ones can help BIG TIME if the valves are The Bottleneck in your particular combo. That won't really be the case in your setup, intake runners will, so more lift by itself really won't do a whole lot of good. I'd recommend steel roller ones, 1.5 ratio, NOT aluminum. As always, good quality (Comp or Crower for example), not just, the cheeeeeeeeeepest thing eBay will allow somebody to title "steel roller rockers". (yes, there's ALOT of cheeeeeeep chineeeze knockoffs on there; CAT for example... how many rockers per thousand miles do you want to have to replace?)

jchaussee

So if i replace my cam with one younsuggested i should be ok?

DeltaElite121

My take on it: Don't change parts to cater towards a gimped build. Not saying you need $2,000 pistons with billet rods and crank, but I am saying to build it the way you want it the first time, and do it right. It will cost you more money that way, but it will make up for it in a better running engine and less headaches in the long run.

Like I mentioned in your other thread, you need to figure out what you have first. Then, do accordingly:

1. figure out what your budget is. Yes, you NEED a budget.
2. figure out what you want out of your build.
3. figure out which parts will still apply to steps #2 & 3.
4. Sell the parts that will not apply to your decided goals.
5. Do the SAFETY modifications first. Making power is easy; doing it to handle power so you don't hurt others is where things get expensive.
6. Build the rest slowly, and take your time doing it.

sofakingdom

iTrader: (1)

Good advice: especially steps 2 - 4. It doesn't work to start out with a cam and then try to build a motor around it.

The order of designing an engine goes something like:

Establish a power level. Bear in mind that ANY motor, when properly optimized, will have a peak torque of about 1.25 x CID on pump gas, at whatever its peak torque RPM is; you can't raise that, only lower it by screwing up. => you have a 350, your peak torque will be as high as about 435 - 440 ft-lbs, at SOME unknown RPM. Odds are it will be slightly lower; call it 400 ish.

Establish the "optimum" RPM range for the motor to run in. This extends from converter stall to some reasonable upper limit, based on usage, gearing, etc. Be realistic; avoid pie-in-the-sky. With a 3.23 gear, that's probably something around 5000 RPM.

Design the motor for peak HP at that conservatively estimated RPM. If you had no heads, this is where you'd choose them. CID and RPM are the main factors that you'd take into account. Since you already have heads, all you can do here is, accept what those heads give you, and move on. Given that, about 5000 RPM is all your heads will support anyway, even a little optimistically. A cam that goes to 7200 RPM or something, is a mismatch.

Choose your cam so that your peak torque RPM is about 65% of peak HP RPM; that being, approximately how far the RPMs drop when you shift. If you shift at peak HP (which is more or less the optimum shift point for making the car go the fastest), then immediately after the shift, you'll be at peak torque, and the RPM will climb through gently decreasing torque to the peak HP RPM again, and you'll shift again. Look at a dyno graph of an engine with an ascending torque curve (NOT for example, LG4 or L03) to get a feel for an engine's output through that range. If peak HP is at 5000, then you want peak torque at about 3300 - 3500 or so. Select a cam that gives peak torque at 3500 and peak HP at 5000. (clearly that will NOT be the cam you posted) Peak HP will then be, whatever the torque is at that RPM, times that RPM, divided by 5252.11. Nothing you can do to change that. Obviously since your peak HP is at some RPM BELOW 5252, and you're at some torque LESS THAN your peak torque of 400-ish ft-lbs at that RPM, your HP will be LESS THAN 400. How much less, remains to be seen; that will ultimately depend on FLOW i.e. exhaust for the most part.

Select a converter that stalls at an RPM with no less than about 80% of peak torque. IOW, if peak torque is 400 ft-lbs @ 3500 and the RPM at which torque reaches 320 ft-lbs is 2300, then you need about a 2300 RPM stall.

Once you have all this worked out, price parts that provide this level of performance with high reliability. Don't overkill anything, and don't skimp on anything. Use parts appropriate to this goal. Include EVERYTHING: converter, drive train upgrades, cooling system, and so on. Include machine work and other outside services. Multiply by some factor to handle the unforeseeable: 1.25 to 1.33 is probably good, ONCE you have BEEN HONEST about including all the things that you will REALLY need. Going into ostrich mode now about something that isn't going to cut it, will only lead to nasty surprises on down the road. Don't try to delude yourself with rose-colored glasses.

Not so tough, eh? It's really all about logic and matching and common sense and making all the parts work together toward the same goal without any one part crippling any other part.

I would add to his step 5, DURABILITY and RELIABILITY. You not only don't want to hurt other people or yourself, you don't want the car to hurt ITSELF any more than it has to. That means, all the running gear (suspension, brakes, tires, etc.) in good shape; drive train all in good working order; electrical system functional; cooling system capable of keeping the engine in equilibrium under any conceivable operating conditions; transmission working right; and so on.