brodysZ28

the results are 209 hp at 4000 rpm and 314 lb/ft torque at 3000 rpm.

the setup is a eagle 383 stroker, lunati cam (468, 489 lift), ported and polished 416 heads, edelbrock performer eps intake, holley 750 carb vacuum sec.

I am very dissapointed with this, i was told i would make closer to 300 whp, the guy there told me that the heads werent flowing enough and to look for different ones. i will also be putting my edelbrock 650 back on b/c the holley was giving it way too much gas.

IROCtheThird

iTrader: (15)

Do those 416's still have the stock 1.85" valves in them? If so I would have to agree on heads being a restriction, throw a set of 1.94"s or even a set of 2.02"s on it. Have you tuned it since you have put this combo together? Thats pretty much a good running LB9 with a good tune and exhaust. Just keep playing with everything and let us know how it goes.

chevymec

iTrader: (5)

Your choking it with those heads. I would setup up to an RPM or Air Gap intake also.

Confuzed1

iTrader: (4)

I'd agree that the heads are restricting you. Get a pair of nice heads, maybe a more aggressive cam (you only mentioned the lift though) and keep the 750 Holley - you'll need it. You didn't mention the exhaust you were running, but if it's still 305 stuff, it's gotta go...your 383 needs to breathe...takes a few peanuts to feed an elephant!

But I also agree with IrocZ30589 - I think you should be getting more HP/Tq than that as is. Something's not right.

rhit_rs

iTrader: (1)

What were the air fuel ratio numbers during the pulls? Was the engine on a dyno, or was it a chassis dyno? Even with those heads, I would expect more. Double check the timing and the valve lash. Both of those gave me problems when I was running my engine on a dyno. Another thing to check is the spark strength. If you aren't getting enough voltage to the coil, power will be down significantly. Also, what is the duration at 0.050" for your cam? Regardless of what heads you have, I would expect a performance cam to deliver peak hp at higher than 4k...

F-BIRD'88

You have a serious issue holding the motor back, that is unrealated to the heads being 416's.
A 350 with stock junk yard 416's will make more power and torque than what you made with your 383 and "ported 416's"

a 750cfm 3310-2 is very close right out the box. It will not give "too much gas".
should have 72 pri jet and a #21 metering plate.
Something seriously is not right. possible blown power valve diaphram. (over rich idle)
Start with a compression test and a ignition system trouble shoot. (starting with verifying true TDC on the timing tab/balancer using a piston stop.)
next, fuel flow capacity then inspect the valvetrain.
You make no mention of the exhaust system at all. Must not matter to you.
Try sucking (or blowing) thru a straw.

5678TA

my old 383 setup made 316rwhp @5500rpm and 359rwtq @ 4000rpm..

383
10:1
ported/polished camel backs
EPS manifold
650 thunder AVS edelbrock carb
comp cams solid flat tappet cam .525/.525 lift, 248/248 duration
1 3/4" long tube headers
2.5" true duals

Damon

I agree the heads are costing you SOME power, but that number is way low for that.

What kind of dyno was it run on?

I'm thinking ignition, valvetrain problem or restricted exhaust.

SuperRamFormula

iTrader: (1)

Think of your engine as a air pump, the more air it can pump the more power it will make. A restriction in any part of your system will cause you to lose power. Also try to match up your parts to your cars purpuse as best you can. I would definitly look at your heads and exhaust system. You will need a good set of headers and free flowing exhasut system. What is the duration of you cam? I would look at getting a good set of heads maybe AFR 190cc, with your cam and intake I would stay below 200cc intake ports. Maybe add 1.6:1 rockers (make sure to check for valve spring bind). If you have the exhaust manifolds on it right now and a restrictive exhaust, I would change those first and try the dyno again.

brodysZ28

the exhaust has hooker headers with a single in dual out flowmaster, no cats, it was on a dyno jet, oh ya and it was chassis dyno.

i know its not the carb because i had a edelbrock 650 on it and it was acting the same way. we tuned the timing and carb on the dyno, ended up gaining 20 hp and 25 tq, the heads are stock valves, so 1.85/ 1.5 or 1.6?

the duration on the cam is 219/227. and the timing ended up being 16 initial and 36 total. does that sound right?

the valves dont chatter or anything, the only thing i can think of is change the oil and check for metal dust from the cam...

also air fuel was way rich, 12 between 3 and 3.5 grand and drops right to 10 between 3700 and 4000.

327_TPI_77_Maro

iTrader: (8)

1.84 valves on a 383 is just bad. As was said, those heads have to come off! Also, running that rich will cost you a lot of HP. You need to lean that thing out. Your carb is way off.

brodysZ28

yea im putting the edel 650 back on, we adjusted it as much as we could but it didnt have a metering block on the secondaries, ok what should i look for for heads, im probably going to have to get them used because i dont have a lot of money to work with...

F-BIRD'88

So in other words there is nothing or not much of anything really done to those 305 heads in terms of real porting other than putting a spit shine on them.

You have the right, cheap, low buck head, you probabily just didn't finish (or start) the job. Depending on how you look at it. Don't mean to be so critical, but
others are running very respectable with these heads in ported form.
MW66NOVA runs low 12's @ over 108mph with these heads on a 305 with the stock size valves yet.

These heads need a full effort port and larger 1.94x 1.60" valves for a 383.

Even so, that all aside, should have made more power with even stock untouched 305 heads.
Something else is really killing the power. Like you're missing a whole cylinder.
The jetting on the 3310 should have not been too rich if it had the stock metering in it. Thats weird. Possible leaking accelerator shooter nozzle at WOT.
("pull over") This can really mess out the metering at WOT. But you say the Eddy 650 was the same?

the exhaust has hooker headers with a single in dual out flowmaster

What size are the pipes? ( main pipe) Did you try uncapping the headers?
Have you ever run this down the 1/4 mile? ET? MPH?

http://store.summitracing.com/partde...5&autoview=sku

A nice power full bolt on head for your 383

http://store.summitracing.com/partde...5&autoview=sku
another good choice.

brodysZ28

well i gasket matched them, and got around the valve stem, i mean i didnt start reshaping the runners or anything like that in fear of going too deep, but i didnt just run a piece of sandpaper over it and call it good. they are stock valves though.

thats what i thought about power too, thats why i was extremely dissapointed.

but ya the edelbrock 650 was acting the same way, nosing over at 4k, the pipe is 3" the only thing about that, which might make a little difference, is when it bottoms out, it hits the cross pipe and is caved a quarter to half way in. it is not pinched by any means though. prolly like running a 2" pipe...

no never ran it at the track. i am going to an airstrip sat. though but its just 1/4 mile mph only.

yea i have nowhere near that much money to spend, i will prolly go used.
what about these?

https://www.thirdgen.org/forums/engi...eads-sale.html

BASSETT IROC 85

iTrader: (2)

I have seen these heads and they are ok. I would buy GM vortec heads, Check out summit racing. You will have to change the intake.

Sonix

iTrader: (1)

Geez, you almost made me cry a bit there Brody!

Well i'll be strapping my car up to a dyno in the next month or so to give you some REAL results! (better not speak too soon )

I have a 350 with fully ported 416 heads, 1.94/1.5 valves, 1.6 rockers, BIG 240/240 cam with .512" lift on a 108 LSA.
Just gotta hook up my AFR gauge and do some ballpark tuning, then rent the dyno. Out of town all this month so....

Brody - you're down in the 10:1 ratio up where the engine would be making some power (above 3700RPM). I think that's probably the first thing to check eh?!? That's an easy one, ignition or carb, but don't tear open the engine until you have that running like a swiss watch!

Damon

Your final timing looks about perfect- that's right in the usual range. So I doubt that's the problem.

Goes super-fat at 3500, eh? Certainly sounds like something's wrong with the secondaries becuase that's about where they would begin having a significant effect on the mixture (and is definitely costing you power). But you say the Eddy carb did the same thing...... huh, that's a stumper.

Is there any chance you made a run with the air cleaner removed? I'm starting to think of off stuff like the air cleaner lid being too close to the top of the carb (acting like the choke is partially closed when airflow demand gets high).

Have you run a compression test on all 8 cylinders? A compression test can lay things bare if something's hurt inside the motor.

FYI- I have a spreadsheet that cross-references Holley secondary metering plate numbers with their equivalent jet size. If you want it, just shoot me an email. Might be handy if you've got some other plates laying around and want to try tuning that 750 without converting to a secondary metering block.

jwscab

what do you have for ignition?

since you say both carbs react the same, I'm thinking maybe you have a weak coil or ignition module. I also would check your float levels.

brodysZ28

yea i am surprised because i havnt heard anything bad about these heads... vortec would be an option...

sonix, what do you mean about the compression, i know its pretty high and that will add power right? but whats the first thing to check?

as for carbs, i never ran the edel on the dyno but when i had it on it acted about the same way, nosing over at 4 grand...

i havnt run it with the cleaner off, but i had the same cleaner and edel carb on the 305 and it seemed fine, until it started losing compression...

damon thanks for the info but im going to go ahead and put the edel back on tom.

ignition is a stock replacement hei, it only has prolly 3000 miles on it. and the float bowls were adjusted.

Sonix

iTrader: (1)

I didn't say anything about compression...? Quote me to clarify eh?

Ok, if both carbs nosed over at 4k, i'd say ignition, OR both carbs have the same problem. Tune one! Pick one and tweak it. You're running rich at the higher RPM, that an obvious source of lack of power. Fix that! You have a wideband? If not, you have to do it by seat of the pants. Something is wrong in carb or ignition. You can check the strength of your spark, there is a tool for that. Maybe your ignition doesn't have enough juice to jump a large gap at high compression ? What's your gap? What plugs?
Lots of little factors to play with. Air cleaner? What style? Perhaps it's not allowing enough air to get through, hence it goes rich.
Let those brain juices flow Brody, you know what's wrong, play with what could cause it eh?

brodysZ28

[quote=Sonix;3891704]
Brody - you're down in the 10:1 ratio up where the engine would be making some power (above 3700RPM). I think that's probably the first thing to check eh?!? That's an easy one, ignition or carbquote]

by 10:1 ratio do you mean compression? then why do you say thats the first thing to check?

well we tuned the holley as much as we could, still rich though. and would a stock replacement hei not be able to put out enough spark?

idk the gap... they are the split fire ones from autozone...

my air cleaner is just a 14" k&n its lk 3 in tall with the edel cover,

idk wat the deal is, the only thing i could think of is that it ate away the cam a little...

Sonix

iTrader: (1)

OH ! I gotcha! No, I meant air fuel ratio. 10:1. You'd be down on power running that rich.

Yes a stock HEI should be good enough, as long as its working right. Electronics are prone to being DOA (dead on arrival) more so then a mechanical part. Or, weak on arrival I guess.
OH SNAP! Throw those POS plugs out the window!!! Get yourself some delco R43T's and put those in. Those split fires are NOTORIOUS for causing weird troubles with cars. Search the forums about spark plugs. Gap your new plugs to .035".

No, cams don't really get eaten. If it was, it'd be rattling under the valve covers.

brodysZ28

oh, yea that other carb should help the air fuel ratio. ok i will check into the plugs, yea thats true about the cam...

well, my tranny is about to blow up so i think im done with driving it until i get the money to get one able to handle the power that it will be putting down, that means save up for what is priority, right now that is tranny...

Saabster

iTrader: (2)

Here's your problem, tiny valves and a small cam. You either need to go way bigger on the cam, like 240-250 duration (a Comp N 30-30S might do the trick) and/or go bigger with the valves.

I plugged most of what you've told us into desktop dyno and that virtual motor fell flat on its face at 4000. It made a max of 290 hp at 4000, which is 230 at the wheels with 20% loss. According to the simulation, you'll really need better flowing heads. So either port the crap out of what you have or bolt some vortecs on there. A bigger cam and RPM intake will help this too.

brodysZ28

ok so what would the hp be if i put some vortecs on there? i cant really go much higher lift if i ran stock vortecs could I? i think they are maxed at .5.

Saabster

iTrader: (2)

You'd pickup about 50 hp with vortecs. 240 duration cam and high flow intake will pickup the other 50, leaving somewhere around 400 @ 5500. This is all assuming that you have a good exhaust system, which I see little to no info.

However, before you go buying things, get the motor you got running right.

327_TPI_77_Maro

iTrader: (8)

Are you serious? This is not something to overlook either. It sounds like you have a bunch of problems with this combo. A 3" pipe is borderline too small anyway, and your is crushed halfway shut? You realize you can't push a 383 through a single 2" pipe...............................

Saabster

iTrader: (2)

I missed that, yeah, that needs fixing. You'll probably need at least a single 3.5" pipe. Doesn't sound like a big difference, but it's 35%+ bigger. If 3.5" won't fit, break it into two 2.5" pipes.

Think of the engine like an air pump, what goes in has to come out. And there's more gasses coming out cause you're burning gasoline.

Tell us the whole exhaust setup, from the headers all the way to the exhaust tip.

brodysZ28

oh, i didnt realize it would make that much of a difference, its about a 2 and a 1/2 section thats caved.

its got hooker shorty headers then they cross to the passenger side (where it bottoms out) then runs to the rearend with one pipe (no cat), over the axel then to a horizontally opposed flowmaster, then out to 3 and 1/2 tips.

whats usually run in these cars to get good exhaust flow?

irocz28boy

iTrader: (2)

Which hookers? And what is the size of the y-pipe?

LMSkyliner

iTrader: (1)

Feel free to correct me if i'm wrong,

but as far as exhaust goes, the flowmasters are also killing you. I think a good magnaflow or hooker muffler will pick up some power as well. I've heard bad things about the "performance" of flowmasters.

brodysZ28

i didnt buy the headers but i am pretty sure they are these, except silver.
http://store.summitracing.com/partde...5&autoview=sku

and the y pipe is 3 inches before being dented in...

how much of a difference hp wise would a full 3.5 inch setup with a better muffler if the flowmaster isnt flowing enough?

LMSkyliner

iTrader: (1)

It's not the main problem, but you should pick up a good 10-15 HP if you get the engine running right. At least i think so.

brodysZ28

yea, i agree, should help some...

AC

iTrader: (3)

Not trying to pimp my for sale ad, but if you're interested in heads I'm selling the Dart Iron Eagle heads from my 383. 1200 miles on them. I'm going aluminum heads now and don't need these. Nothing wrong with them. 215cc/72cc, centerbolt & parimeter style valve cover compatible.

F-BIRD'88

Those lil shorty headers can make good hp but they give up a lot lot of torque to a long tube header. The torque makes you accelerate. (ET)

One way you can fool those short tube headers into thinking they are longer and make more torque is a 2 into 1 scaveging merge collector.
say Flowmaster #flo-Y250350 2.5" into single 3.5" main pipe.
Custom pipe fabrication is required.
I would use a FLO-Y250300 2.5 into 3" Y pipe at minimum.
Now you got some real scavedging action in the exhaust.
http://store.summitracing.com/partde...5&autoview=sku

I prefer a big magnaflow muffler at the back.

brodysZ28

so is the scavanger used as a y pipe basically?

LMSkyliner

iTrader: (1)

not my area of expertise, but i think it's the other way around.


and i like magnaflow mufflers also. Though i have hooker.

F-BIRD'88

ya it becomes your 2 into 1 transistion. Compnaies cannot sell a system like this in a box cause the cat would not be in the stock posistion. All exhaust "kits" must retain the as factoryOEM cat position. "Cat Back."
YOu need to build your own exhaust system to get best performance.

Something like what MW66nova did except have it go over the axle with the muffler at the rear.
You could run the right side (pass) primary pipe in its present path over to the fender and run the left (drivers) along the transmission as in the pic.
have them joint using the 2 into 1 collector behind the transmission as in the pic.
Althou it would be tight, I believe small body high flow twin cats could be fit in there too.

vette9190

iTrader: (2)

A stock HEI will not power that combo up high.
The GM Coil on cap HEI suffers from coil saturation at around 4500 rpm and power nosedives after this. A stock replacement might even be worse then that depending on the components used to manufacture it. The guy I learned engines from used to specialize in dizzy rebuilding in the 70's and 80's and use to pound the stock hei for this problem all the time.
You need an aftermarket ignition for it, or at least a coil and module fome someone like MSD or Accel.
Just thought I'd throw
Although I do agree about the heads and crushed exhaust pipe not helping either.

brodysZ28

ya, that exhaust system looks lk it would flow much better than mine...

as for ignition... what does everyone run? nobody uses stock stuff for a high performance setup???

F-BIRD'88

I use a stock GM HEI distributor with a MSD in cap coil. Runs 11's. 6600rpm.
Doesn't miss a beat. The advance curve is modified from stock. The stock GM coil center post has to be changed for a low resistance steel one (MSD) when you change the coil.
The early 1975ish first gen HEI's were dogs. GM redesigned the stock internal module some years ago. I use a stock OEM GM AC delco ignition module.
Good to 7000rpm ith the simple addition of the MSD hi perf coil.
You need a decent set of wires (MSD, taylor) and a quality cap and rotor.

The undeserved old reputation the HEI got was from the short comings of the old early ones. Old wives tales die hard.

Everything you have "heard" about the GM HEI is not true.
Here is the truth. You only need x amountof ignition spark power to ionize the spark plug gap and create a good spark to like the air/fuel mixture in the combustion chamber.
Up to about 4800-5000 the stock GM HEI has over 300% extra spark power output than what is nessessary to ignite the fuel. Even thou at around 4800-5000 rpm the amount of spark power output starts to taper off with increased rpm, it still has over 100% (double) the amount of spark power output nesssessary to run your motor. (when used with the stock GM module and the MSD coil and a .035" spark plug gap)
Any more power than whats required to do the job is not used.
You do not need or want a .060" spark plug gap.
You want to use (and GM recomends) a .035" spark plug gap.
Any more just creates more headaches than it's potentially worth.
large spark plug gaps require more ignition system power (than you need) and the extra voltage shortens the usefull life of the distributor cap and rotor.
The old 70-80's era GM cars used to use a large spark plug gap cause they were trying to lite off a less than idea (read crappy) airfuel mixture at idle and low speeds in a old 70-80's carbed smog motor. This excessive gap shortens the life of the cap and rotor. This is why people used to wine about the old HEI on the old cars.
On a car that is tuned properly (or even decently) (jetting/timing etc) only needs X amount of spark power and a .035" spark plug gap. Which the stock GM hei has more than enough spark power capacity to fire at rpms up and over 6000rpm with a stock GM coil and over 7000rpm with the MSD coil all with the stock GM module.

brodysZ28

wow thats a little more reassuring... i didnt want to go out and blow 500 bucks on a whole new ignition. i though the hei's were good setups, im glad thats true... but even with the stock coil, that wouldnt have anything to do with the problem right?

ok as for the heads, say u have a 350 and 383 built the same with 416 heads, would they make the same power BECAUSE of the restrictive valves?

i mean i know more cc's = more power but if the heads were holding both engines back the same (flowing the same amount of air) would they have about the same amount of power??