tjtaylor

for the past summer ive been running around with my freshly build 383. somethings has to be wrong with it, ive ran it at the track and best i got was a 13.9 at 107 mph, stock tpi cars are doing better than that! now it is carb'd, i recently picked up an 87 tpi system complete with harness and ecm and fans and sensors blah blah blah. i wanted to convert my 91 383 carb'd to tpi. my question is should i invest in making this tpi unit (stock one) flow enough for the 383 or should i buy an aftermarket kit that has a standalone ecm like the FIRST intake or a HSR i cant really imagine spending 3k for a fuel injection system.. any input guys??

Orr89RocZ

iTrader: (20)

Whats done to the 383? Stock TPI system wont feed a 383 very well and you may end up going slower. An aftermarket TPI will help but depending on the heads/cam you currently have, it may not help enough. If the motor wants more rpm, then an HSR or miniram will be the best bet.

You can still use the TPI harness and ECM, just tune it for the intake manifold of your choice. No need to spend 2K on an aftermarket ECM unless 1) you cant tune stock ECM or 2) dont know anyone that can tune one for you locally

A nice intake you can get that looks like a carbed manifold is the Victor E EFI single plane. It will work fine on a 383, and you can use a MPFI type throttle body and a carb style air cleaner. Also work with the TPI ecm, just need to tune and possibly splice in new TPS/IAC sensors for the TB.

tjtaylor

well its a reman block from summit 98-02 355 or 383 4 bolt. has an eagle forged rotating assembly hbeams forged pistons at 9.86 compression. comp xr288hr full roller. pro comp aluminum 200cc heads soon to be trickflow 195 fast as cast?? 1.5 full roller rockers. summit stage 2 intake. 650 edelbrock carb. no porting on anything.

lol at going slower thats the last thing i want. i figured when i built this car it sould be in the 12s easy i was pretty dissapointed at the track that summer day. so a first system may not be enough either?? good to know i can use the stock ecm and harness. but i dont know how i would start to tune that kinda of thing and the closest thing to reputable tuning arounf here is big shot dyno and thats about it. maybe ohio horsepower.

Orr89RocZ

iTrader: (20)

Why so low on compression? If you can have the heads shaved a bit, it will wake up alot! Getting closer to 10.5-11 to 1 with aluminum heads will help.

Nice cam and head combination...definately a 12 second combo and to be honest, i dont see why it shouldnt go high 11's if everything else is right. Cam is big enough for near 500hp, although I'd like to see abit more lift with that. 1.6 rockers would help some but even with the current setup, it should make alot more power to push a thirdgen faster than 107 mph

FIRST TPI can work on that setup and it will likely be a 12 second ride. That cam and heads wants to go to 6000+ rpm, so I think a shorter runner intake would suit you much better. But a FIRST TPI can work... it will peak likely in the lower 5000 rpm range and hold that peak to 6000 just about due to the cam being big enough.

Holley stealth ram you can buy just base and plenum with fuel rails for ~550-600 bucks. very nice option IMO. I ran one with a different cam on my 383 and it was a 11.4's car in summer air.

Victor EFI single plane you can get for 420 bucks with rails, but then you need to setup the fuel lines for it with external regulator, and a MPFI throttle body or convert to LS1 throttle body with intake elbow. Edelbrock has a few elbows to choose from or you can have intakeelbows.com make one. Actually I see they are 6061.com now.

edelbrock pro-flo xt intake could work too. LSx style throttle body.

Miniram is nice but expensive unless find used. ~1200 ish new with rails.

You definately have some options, just need to figure out how to get it tuned. Where in ohio are you?


You probably have a lot of potential in the carb setup, just need to look at the carb and intake. I dont know how a summit stage 2 intake compares to a performer RPM type dual plane but a good ported dual plane should be more than enough for that setup. Carb is abit small, i'd go for a 750 double pumper of some sort. I'm not a carb guy tho, but i've had friends run bigger carbs on 350's with good success and they had milder motors than what you have.

vetteoz

iTrader: (13)

My thoughts also
My 383 w/similar spec GM847 cam ,TFS 195's, Vic Jnr single plane and 750DP dynoed 410RWHP but I have over 11:1 CR

(Dynoed with carb to get baseline for future tuning with Vic E and Accufab 4bbl TB)
May be needing your advice on that matter

tjtaylor

well when i had built the motor i was thinking about future plans where i would boost the motor, but those plans since then have failed with me buying a full suspension for the car and soon to be in a paint booth.. at the moment the chambers on the heads are 64cc. TFS has a 64 a 62 and i think a 56cc.

thats what i thought in the beginning when i built the motor is that it should have been able to faster than that. granted that 107 was on my 3.08 gear. havent been out with the moser set up yet.

thanks for the options ORR! glad to have experience talk instead of thoughts. definatly have some investigating to do. i am in stow ohio, ten minutes from summit racing where are you finding all these intakes so cheap??

the only real reason im going to be fuel injected is that i want better mialge and reliability and i want it to look a little cleaner under the hood as well.

Orr89RocZ

iTrader: (20)

Well perhaps keep playing with the current combination to see if it improves unless you really want to go EFI. EFI is very nice but again, the tuning makes the difference. A MAF sensor system will likely be abit easier to tune than the 91-92 speed density systems.

I've used the Stealth ram alot. On mild 350, on my 383, and my friends 360. I've helped tune a few other cars using modded TPI systems and stealth rams. I now use Victor E on my turbo car and its been great for normal driving.

Summit sells the intakes, just need to locate the right part numbers.

Victor E EFI intake
http://www.summitracing.com/parts/EDL-29785/
Rails
http://www.summitracing.com/parts/EDL-3630/

On my mild 401, with mild cam and low compression, it drove around fine even tho the intake says 4500-8500 rpm range. Its great for the street IMO.


Stealth ram is now under Weiand.
http://www.summitracing.com/parts/WND-7540/
Rails which are kinda pricey and to be honest, the regulators have been known to fail. Mine never did however, but a better regulator is the Kirban billet unit for Grand nationals which fit these rails. they run about 120 bucks
http://www.summitracing.com/parts/HLY-534-186/

Pro Flo XT. havent seen many use this yet but its comparable to the stealth ram.
http://www.summitracing.com/parts/EDL-7137/
rails
http://www.summitracing.com/parts/EDL-3627/
Will need external regulator for this like the victor E.

305sbc

iTrader: (3)

IMO your cam is too big for the rest of your combo.
Your actual static compression ratio is probably even less than you have figured, and your dynamic compression is probably abysmal. Do you have a photo of the top of your pistons? Did you measure your deck height? What is the compressed height of your head gaskets?

You also didn't say anything about your ignition, - exactly what distributor are you running? and how did you set up the spark curve?

Please don't take offense, but another big question that comes to mind for me is how you are going to manage to properly tune a port injection system after not figuring out a simple carbureted system? I see a LOT of people post on here that can't figure out how to tune with a carburetor, yet want to swap to EFI. Unless you bite the bullet and figure out how to tune what you've got, then neither system is going to work well or be reliable for you.
That really needed to be said because it is reality.

For tuning you will need a dial-back style timing light, a wide-band O2 installed into your exhaust, probably a tuning kit for both your distributor and carburetor, and an accelerometer would also be helpful - though you might be able to borrow one.

Without at least previous experience tuning, you aren't going to bolt together some parts and run low twelves in the quarter mile.
First you need to take care of your low dynamic cylinder pressure by swapping to a much milder cam, - something like the LPE cam listed in my signature. The cam swap will be the easiest and cheapest route for you to fix most of your problem with engine output. Then you need to do some tuning after that.

tjtaylor

"Your actual static compression ratio is probably even less than you have figured, and your dynamic compression is probably abysmal. Do you have a photo of the top of your pistons? Did you measure your deck height? What is the compressed height of your head gaskets?"

hmmm never checked my static or dynamic, may have to find out how to do that. and no i dont have a photo but there a D-dish type if it helps, nope didnt measure the deck height either when i put it together, its almost all out of the car now because itll be sent to the paint booth for a while and ill work on it then. and hmmm .041? idk on that either, not much help.

You also didn't say anything about your ignition, - exactly what distributor are you running? and how did you set up the spark curve?

"Please don't take offense, but another big question that comes to mind for me is how you are going to manage to properly tune a port injection system after not figuring out a simple carbureted system? I see a LOT of people post on here that can't figure out how to tune with a carburetor, yet want to swap to EFI. Unless you bite the bullet and figure out how to tune what you've got, then neither system is going to work well or be reliable for you."

my distributor is an msd street fire distributor HEI. spark curve is by vacuumm advance. and i wont take any offense to that. all opinions help. to bad i love the sound of the idle my cam makes. idk if i could go smaller. i had a 504 524 and i went bigger ha. but i believe my edelbrock carb we have fine tuned pretty well. i have used a dial back timing light for tuning, a wideband already installed, and tuned the carb multiple times..never the distributor though, didnt even know that was possible.

ORR what are you spinning your 401 to may i ask? does that 4500-8500 ever come into play?? i more or less like the stealth ram "weiand" look. But ive heard the air doesnt wanna make the first 90* bend to well and it leans on the front cylinders more than the rear.. ever happen to you?

"FIRST TPI can work on that setup and it will likely be a 12 second ride. That cam and heads wants to go to 6000+ rpm, so I think a shorter runner intake would suit you much better. But a FIRST TPI can work... it will peak likely in the lower 5000 rpm range and hold that peak to 6000 just about due to the cam being big enough."

Are you saying that (with the right tuning obviously) the FIRST TPI system would only make it a 12 second ride and that i could go even quicker with such as a stealth ram or single plane? and that 11.4 you ran in the 383 was that on spray or n/a. just curious, oh and i dont think ive ever gotten the motor above that 6500 mark even at the drag strip, i felt like that rpm range was about right for the power curve..never dynoed it so idk but i dont think i could imagine running that motor over 7k itd take forever to spin that high.

305sbc

iTrader: (3)

Dished pistons

Look up your exact piston to find your dish volume.
Factory block deck height is usually around 0.025"
Typical compression height for Fel-Pro gaskets is around 0.038"

Now take your information and plug into a compression calculator like this one:
http://www.race-cars.net/calculators...alculator.html

Most typical "street" type long duration cams like yours like static compression to be closer to 11:1 for best power under the curve (low-end).

FYI, there are short duration roller cams (like the one in my sig) that also have a very healthy lift number over 0.500" at the valve, - especially with higher ratio rockers. They are great for power under the curve, fuel mileage, ease of tuning, and work well with highway gears.

The distributor is tuned with springs and/or bushings, - or travel-limiters on the mechanical advance plate inside the distributor. You decide where you want your initial timing to be set for easy cranking, - generally a low number of 10* or less. Next you use your dial-back light to measure how much centrifugal advance your distributor adds, and how soon in the RPM range the advance is added.
For example a typical distributor will add around 22* of mechanical advance, - giving you a total of 32* advance if your initial was set at 10*.
Using the thicker (stronger) springs on the advance plate may bring in all 22* of mechanical advance by 4000 RPM or so.
Using lighter springs will make the advance all come in at a lower RPM - (desired). Too much too soon can result in knock. That's why the distributor tuning kit (comes with most aftermarket performance distributors) has a mixture of springs to choose from.

You use either bushings or travel limiters on the advance plate to limit or increase the amount of spark advance added by the centrifugal mechanism. Limiting the travel of the advance mechanism can lower the advance from 22* to around 18* (typical). You could also increase the amount of centrifugal to 30* if you wanted to run a very low initial advance of around 4*.

You should have an adjustable vacuum advance mechanism and connect it to full manifold vacuum. It is used for very low load cruise & idle conditions. Typically you add as much vacuum advance as the engine will tolerate without knocking. It is typical to add 15* - 20* of vacuum advance depending on two factors: what your initial advance is, and how much vacuum your engine produces.

Engines with large cams produce weak vacuum at idle, and often cannot achieve your maximum amount of vacuum advance at idle. Most engines produce maximum vacuum during engine deceleration.

If you make your vacuum source switched or valved for your vacuum advance mechanism, then you can cut the vacuum at idle when you feel like hearing your camshaft loping. Even a very mild cam will lope at a low idle with only 4* of initial advance. Apply vacuum once again to the vacuum advance mechanism and the idle will smooth back out.
You often need to switch the advance side of the vacuum line to an "open" to relieve whatever vacuum was already present in that part of the line or your vacuum applied advance will remain active at the mechanism.

HTH
There is a link in my sig for more info about setting up a distributor.

vetteoz

iTrader: (13)

I have your Dynamic CR at 7.60 w/288HR cam using the CR calc at bottom of this link

http://members.uia.net/pkelley2/DynamicCR.html

tjtaylor

wow i didnt know there was so much you could do to a distributor! definatly something to read about.

still confused on dynamic and static compression. i assume 7.6 is very crappy?

midias

Saw this on ebay a little bit ago. I don't know if it is a good deal but I am sure someone will

http://www.ebay.com/itm/FULLY-PORTED...item2c6204e26c

305sbc

iTrader: (3)

There is some information about dial-back timing lights here:
http://www.chevelles.com/forums/arch.../t-214136.html

Supposedly the MSD and Craftsman lights are most accurate.
I have the Craftsman from Sears.

I've never bought an HEI style distributor from MSD, so I don't know what all it came with, or if a normal HEI re-curve kit will work on it. You'll need to look into that. MSD often includes the tuning parts in the box with new distributors though.

midias

I do not know if it is still true but I remember for a while actron made the craftsman lights. I like my actron dial back CP7528 but would love to check it vs a few others as a science experiment.

Orr89RocZ

iTrader: (20)

That rpm range on the intake is kinda misleading. Maybe for a carb application it would be a high rpm intake but for EFI, it doesnt really make a difference. Its a dry flow application where fuel is precisely injected.... no longer relying off vacuum signal to carb to meter the fuel. My 401 only went to 6000 rpm Now I have cammed up a good bit and should be shifting at 7K or close to it, and the manifold is extensively ported to match the new heads but I'm still not using the full potential of the intake.

Stealth ram is an interesting intake. I did have a small air fuel distribution issue but I couldnt really tell if it was during nitrous use or WOT or just part throttle. The back cylinders appeared much richer than the fronts. Pistons were more carbonized/black and so were the spark plugs on average. Wasnt a huge difference as the motor ran fine/strong but you could tell the motor was seeing different air amounts front to rear. It actually seemed to be the opposite of what I expected to see. The rear being richer indicates less air made it to the rear. Air will make that 90 bend even tho it doesnt like to. I think a larger TB helps here to slow air velocity thru the intake opening to allow it to make that bend alittle easier. I ran a big 58MM twin setup on my 383. I spun that motor to 6800 ALOT. It does NOT take along time to spin that high. I've been off the limiter at 7K a bunch of times because it flys thru gear so fast i couldnt manually shift the automatic fast enough

Dont be discouraged by the HSR tho. Its a great intake. Alot of front fed intakes do the same thing. Miniram does it too. Just be aware of it and when tuning, look at your front plugs and rear plugs and compare. Tune to the leanest cylinder, and you will be fine. I tuned my car with a single wideband o2 sensor in the header collector and never looked at my plugs and still was ok. I only checked my plugs a few times just to get an idea what my cruise and idle air fuels were doing. They were in line with the wideband o2, so I never bothered to check again.

The single plane with my intake elbow on top did not show distribution problems. I'm sure there is a minor one due to the runner shapes and air entry angles, but the pistons all looked the same and the spark plugs all looked the same. So its much more even IMO and with boost using a batch fire EFI system, that was important to me.

Naw, the FIRST likely can be an 11 second ride too but you will have an easier time getting to the 11's with that cam using a miniram or stealth ram or single plane efi. The cam will rev to higher rpms than what the FIRST will support. This will limit HP. Theres a chance the HSR or short runner intake will pull more hp from 5500-6000+ rpm giving you much more area under the curve....more average power = faster ET at the track most of the time, assuming everything else from gearing to suspension is optimized.

My 11.4 was all motor. 10.6 on a 150 shot. Peak power was at 6250 but held that to 6500 and didnt fall off much maybe 5-8 hp by 6600 where the dyno stopped. I shifted 6800 most of the time. It was a blast. Your cam in a 383 should be about same power band as my 383... 6500 wouldnt be a bad point to shift.

It wants compression tho. 7.6 dynamic is abit low. I was at 8.3 dynamic, 11 to 1 static. Generally you want to be between 8-8.5 to 1 dynamic. 10.5-11 to 1 static with aluminum heads is always a good idea for a street strip build.

Steve Mack

iTrader: (5)

Keep your carb intake and buy the Fast EZ EFI system it will run better than all the other systems.It is self tuning.And you will find your missing horse power

tjtaylor

wow, there is alot of knowledge here to soak up. i read the article on dynamic and static compression and understand the concept alot better now, thanks vetteoz.

so to get my dynamic compression up higher without changing my cam just because its very new and dont wanna buy another 300 dollar cam, could i actually advance my cam timing? i know they say i can but without the proper tools to tell how far the valve is from the piston top .035-.045 spec is it safe to try? obviously turn motor over a couple times by hand but is there a calculator for that oo if i advance the time?

"I think a larger TB helps here to slow air velocity thru the intake opening to allow it to make that bend alittle easier. I ran a big 58MM twin setup on my 383. I spun that motor to 6800 ALOT. It does NOT take along time to spin that high. I've been off the limiter at 7K a bunch of times because it flys thru gear so fast i couldnt manually shift the automatic fast enough "

so are you implying that a 58 mm TB was to small and a bigger one would suffice? do they even sell something over that hah, soo i think i realized how you got your rpms up faster than i may have been doing. when i was running the times at the track i forgot to mention what i was leaving at... it was a 3.08 gear open rear with no good street tires and a slight misfire from dropping manifold onto the spark plug earlier that day to install the wideband i was leaving at idle. its a 5 speed and if i did anything higher it just sat there and burned them till i feathered the pedal out. that may be part of why i couldnt get the 383 to spin that fast? oops

Orr89RocZ

iTrader: (20)

If you had a timing chain/sprocket setup with some advance marks in it, you can advance the cam. You would then measure piston to valve clearance using clay and turning motor over with rocker/pushrod/solid lifter assembled. But with heads on, its impossible to do that. Another way is to check valve lift manually with dial indicator as piston approaches and leaves top dead center. You'd have to take the spring out, and move crank til the piston is roughly 20 deg from TDC. (I think I read that its typical to see valve closest to piston around 12 deg BTDC but I could be wrong here. If I am, just do this process from when lifter just starts to move (intake valve opening event on the cam card))
Then lower valve off the seat til it contacts the piston. Measure the lifter lift at this point as well to calculate the actual valve lift the cam would have. Subtract the difference from contact point number and actual cam lift the valve would see. That gives you clearance. Keep iterating this process til after TDC about 10-20 deg or so. Should get you an idea where you are at.
Advance would help bring back some low end but in the end, you still need more static compression to really get the most out of that cam. Smaller head chambers is the only way now but I wouldnt sweat it too much right now. I'd try the injection swap now and see where it gets you, then worry about the cam placement and/or head chambers for compression.

twin 58 is not too small. It actually may be abit large for my power level, but I'll never know now. I know guys running bigger monoblades with great success and no lack of throttle response so its hard to say what size is "optimal". If you go by flow capability in cfm, a twin 52mm will handle most builds and a stock 48mm twin setup wont hurt power that much on alot of builds.

tjtaylor

yeah my timing chain and sprockets are optioned for advancing or retarding, but oh forgot i need more static. thanks guys you have been a great help on my quest for more power. ORR the reason i said 58 wasnt big enough? was because i thought you said a bigger TB would help the air distribution better and you had problems on yours so i assumed you meant 58 wasnt big enough to solve that problem, no bigge i understand all i really need is the 52 mm

tjtaylor

piston dish is +16.00 cc by the way. never got a carb with my block telling me what the specs are on it like how much it was shaved..

305sbc

iTrader: (3)

I ran your numbers in the compression calculator, which doesn't take into account ring-land area or the area between the bore and inside edge of the gasket. I used 0.058" for deck-height + gasket, and it says you have:
9.516:1 static compression.

That's probably very close to what you actually have. If your top ring land is moved down lower on the piston for boost, then the compression will be a little less.
You're not going to fix that by advancing the cam, so I wouldn't even bother with the attempt. That kind of move is only good for fine tuning for track conditions.

About 20 years ago I found myself in a similar situation as you.
In an effort to band-aid the problem I advanced my cam 7*, installed variable duration lifters, put in a 3000- RPM stall and 3.73:1 gears.
The car got faster but it didn't fix the problem.
Eventually I broke down and put in a smaller cam, and the problem was immediately fixed. The car gained a full second E.T. and the torque started bending the frame & body.
I'm trying to save you some time & trouble.
Either way you go it will eventually be a good learning experience.

Orr89RocZ

iTrader: (20)

Alittle smaller cam definately will pick up torque with that low compression but even then, that combo needs boost or new pistons...but you can shave those heads down to 58cc likely and get SOME compression back. May need to shave the intake too since alot of material needs taken off the heads with an angle mill. May beable to flat mill it tho.

Cam needs 11 to 1 with aluminum if you ever want it to perform like it should all motor Else enjoy it as is until you get funds to do a boosted project.

tjtaylor

ook, so let me understand this. my compression is around 9.5 to 1. dynamic is like 7.4, that is only because of the fact that my cam has a large duration 234 242. now that is how long the valve is open correct? now i figured with the 383 the motor wanted to breathe well allowing substantial air in and out of the motor. ect big lift big duration. now this thought crossed my mind. if i go down in duration how much should i go to.. and wont the motor have a harder time breatheing since there isnt as much air going into the cylinders anymore?

but my main problem would be the pistons having such a low dish. thats really were i messed up if i was to keep the motor N/A. But less just say for the sake of the thread since i began asking why i was running horrible times, if i was to keep my cam in it now and eventually go boosted with efi that i would then be fine with my dynamic and static compressions? or is a cam change still in order. but i am not gonna change the pistons though.

Orr89RocZ

iTrader: (20)

9.5 using a .058" deck height plus gasket is abit high. Was the block decked when it was rebuilt?

IF it was decked and hopefully zero decked so that the piston tops are flush with the block surface, you can run a normal .041 gasket. This will get you better squish height and bring comp to 9.8 to 1. getting better.

Bring the heads down from 64cc chambers to 58 cc which should be doable and that will get you back to 10.5 to 1. Now your in business!

Now if the block was not decked and the pistons are in the hole, i'd measure them to see just how far. Typically rotating assemblies are 9" long and the block deck is 9.025". Zero deck would be 9" obviously but it can vary because you can have different height rotating assemblies. My 401 uses 9.020" setup so the deck was only decked .005. My zero is now 9.020". So assuming you used a standard 9" assembly the pistons would be .025" down in the hole.

Once you find out how far they are down below deck height, get a gasket in a thickness that will give you around .040-.050" in piston to head deck clearance. This will be best for combustion and power...typically. So a .025 in the hole should try to use a .015-.020 gasket if possible. May need to go custom for that or run a shelf .028" gasket and get .053 clearance. Not great but it will do if thats the only option. A good MLS gasket in .020" could be made and work great if the deck is flat and the heads are milled flat.

Now with that .050" piston to head deck clearance compression would drop from 10.5 to 10.25. Not a big deal. Alittle bit of power gone but still should work.

Cam swap down to a 230 deg with some advance in the cam would help pick up some low end power and mid range. Duration change may not let the valve stay open and thus not pass as much air, but what happens is you close the valve earlier, trapping more gas in the cylinder while its burning, thus trapping more cylinder pressure! Theres a time period where the exhaust valve and intake valve are open at the same time! This is overlap. Your cam has higher overlap than a smaller cam so during that phase when both valves are open, theres more of a chance that cylinder pressure will bleed out the exhaust!

So thats a reason why smaller cam (smaller duration) can make more power in a low compression type motor. Then again, theres lobe seperation angle where the intake valve is offset from the exhaust a certain angle. Widen that valve from say 110 lsa to 114 and you dropped overlap alot. So you can have a shorter duration cam on a tiny 105 lsa that will have more overlap than a larger duration cam thats on a wider 114 lsa! So theres lots of variables in cam design.

Mainly you want to increase your trapped cylinder pressure so close the intake valve earlier.

If you are serious about upgrading heads, I'd keep your cam and just have the heads shaved down to 58cc. Maybe advance your cam another 4 deg with the new heads during install and that combination will pick up alot of power

305sbc

iTrader: (3)

The mechanisms that let your engine breath are cylinder head flow, and the time (duration) that the valves are open. Obviously for max power you WANT both, but realistically that's not very streetable, and performance in a street type car will suffer when you try to do this.

Basically, stretching out the duration of the camshaft was/is a band-aid for poor flowing cylinder heads. The better your heads flow, the less duration you need from your camshaft to make X-amount of power, or to feed X-amount of cubic inches.

Right now you have low cylinder pressure, partly due to lack of static compression, and partly due to low velocity in your intake ports.

Carburetors (for the street) need higher velocity in the intake port than a port-injected induction needs. The velocity provides steady metering signal to the carb's boosters, and keeps fuel suspended in the air for better combustion quality (more power). A 180cc intake port close to ideal with a carbureted 383 that is street driven. You have a 200cc port, and so velocity is poor.

With low velocity in the port, your high intake duration hurts you even more because you will get bad reversion in your intake port until the engine speed (RPM) gets up pretty high, - to the point where you are finally getting some velocity in the port to keep the reversion down. Reversion costs you a lot of power in the lower RPM ranges, especially with a carburetor.

With your relatively good flowing heads, and large 200cc intake ports, you will need to lower your intake duration to something between 215* and 220* @0.050" (hydraulic roller type cam) in order to bring your cylinder pressure up to an acceptable level for best performance. You still want a high valve lift to take advantage of your head flow capability, but you don't need the long duration.

The long duration camshafts with significant overlap period are meant to be run at high RPM, and with an open exhaust system, so that reversion in the intake port isn't really an issue. When you try to use this tactic in a street car, especially with a carburetor, it often creates multiple headaches.

Right now, since your cylinder pressure is so low, if you are set on keeping your camshaft, then your best bet is to adjust the tune of your engine to better match your low cylinder pressure. In this case you would switch to 87 octane fuel (if you haven't already), and readjust your timing curve to increase low RPM power output.

Since you have a manual trans, and may not be consistent with your ETs, then you want to watch your trap speed as an indicator of power output increases during the tuning process.

tjtaylor

okay guys bringing this one back. i have now aquired the funds to do lots more with this motor. im selling my pro comp 64 cc chamber heads 200 cc intake 68 cc exhaust and my comp 288 hr cam as well. im looking to get this cylinder head combo from trickflow specialties. http://www.summitracing.com/parts/TFS-K314-500-450/

now i have a few questions on how to do this. before i had very low compression and it was due to partly my dished pistons and the overlap of the camshaft. Is this cam going to fix my problems above?? And what is my static and dynamic comp going to be now??

i also am trying to get my buddies p1sc and throw on my system. yesterday i bought a hsr from a guy on here in missouri. fully assembled. Will the heads and cam above fix my problem of low power i had before? dont take into account the p1sc just yet though.

midias

Those heads are gonna lower you compression about 1 point over the 64cc heads

tjtaylor

yes i do realize that and the purpose was partly for more boost. Or should i find a combo with 64cc heads, or less like 58 or 62 and just run less boost?

tjtaylor

anybody?? or should i just run my heads that i have on it and figure out my oil burning problem..

tjtaylor

please give me some pointers?

Orr89RocZ

iTrader: (20)

Heads may lower your compression and that cam is gonna make things much much worse...its much bigger than your current 288 cam.

tjtaylor

so are you telling me not to get this combo kit? i would like high lift, i love the sound of the lope. but what set up would you recommend then? i do intend on installign the procharger and the stealth ram. but i was burning oil on these heads again when i pulled the intake last fall due to a exploded lifter. the head port of the valve that blew was completely full of oil. cant figure out what it could be. so i just was goning to buy new heads..

Orr89RocZ

iTrader: (20)

valve stem seals and a loose guide? Maybe intake leak...engines will pull oil from lifter valley when intake gaskets dont seal up right.


As far as recommendations, no I wouldnt run that Trickflow setup. heads are ok but i wouldnt match that cam to it, and I'd prefer to see more compression...

What exactly do you want this motor to do? Are you definately getting the P1sc blower? Your current pro comps if aluminum will be ok with mild levels of boost from that blower.

But now you are greatly complicating things here. you dont have an efi based car yet and now you want to throw a blower on it. First need to get it running 100% with HSR installed and then worry about the blower...that in itself is gonna be tricky and expensive. You can try a FMU setup but its not gonna be optimal. Next bet is code $59 on factory ECM or perhaps EBL flash but neither are optimal for beginners...I cant speak for EBL flash as much since I never used it but tuning factory ecm's does take some time to learn, as with any system. Problem is no body out there really messes with the stuff anymore. LS1 is where its at. You can do that ecm and conversion but now your in the 1500 buck range for EFI and alot of work converting things. At this point might as well get a well known aftermarket plug and play setup like FAST/Holley/etc that has TPI based harnesses to make it easy. Find a shop that can tune.

Either way, aluminum heads and 9.5 to 1 with that cam isnt quite gonna get it done. 11 to 1 is better and should give a good bit of power back. But if you want that blower, then keep it where its at...9-9.8 to 1 is fine for some boost.

tjtaylor

okay so it might be the intake gasket.. i was told the other day that the old blue style felpro intake gaskets are meant for iron head to iron intakes. they crush better iguess. and the aluminum to aluminum doesnt crush it so i need a softer gasket?? sound right to you or is he blowing smoke??

okay so looks like im going to keep these heads then, yes they are aluminu heads. and should i ultimaly find a camshaft that is more blower friendly?? my goals with this motor are striclty nice driving days, car shows, and then run atleast 11s at the track.

yes for sure i am getting the p1sc, as a matter of fact its laying at my bedside right now all polished up haha.

and yeah i am making it more complicated with the tuning but i have a few key plays here. i stripped my buddies complete engine bay off his 88 formula. i have everything to install a factory tpi setup on my motor. unfortunatly the guys down at big3racing told me that the obd1 comp is to primitive to run the type of mods i have done on my 383 and boost. he recommended me the holley hp tuning system. the 1500 dollar engine management system that is self tuning. you just set your octane and runs off the wide band? opinions on that set up?

Either way, aluminum heads and 9.5 to 1 with that cam isnt quite gonna get it done. 11 to 1 is better and should give a good bit of power back.

yes im doing boost for sure no doubt. so which cam are you refering to when you say "that cam".

But if you want that blower, then keep it where its at...9-9.8 to 1 is fine for some boost.
keep same heads and the comp 288 cam and run the blower? or change the cam..

thank you so much for your patience

Orr89RocZ

iTrader: (20)

For boost I'd try the comp blower grind 224/236 or some other brands similar cam for your block. Anything with 10-12 deg split would be nice on a 112-114 lsa.

Your current cam could work but its not necessary to have. The setup would be better with a more blower oriented cam. Alittle less duration to make it drive nicer and keep rpms down.

Holley HP is a nice system which does have a self tuning feature but I'd still use manual tuning with the boost. Self tuning can only do so much.

tjtaylor

soo a grind around a 224/236? or does the 10/12 degree split not matter how low or high the duration is..
http://www.summitracing.com/parts/CCA-08-301-8/ opinion? they say its a nitrous camshaft? same purpose right? or is it completely different..
Orr how about something with a lift like this http://www.summitracing.com/parts/CCA-08-303-8/ still has the 12 degree split on 113 lsa

tjtaylor

anybody? TTT

Orr89RocZ

iTrader: (20)

I wouldnt go too big on the cam. mid high 220's deg on the intake is nice. The comp nitrous cams double as a supercharger cam. They can work well in both applications.

08-303-8 cam you listed is too big.

tjtaylor

Sweet looks like ill be going with the 8-301-8

tjtaylor

"Do you have a photo of the top of your pistons? Did you measure your deck height? What is the compressed height of your head gaskets?"


is this considered zero deck? how do the pistons look condition wise?

conlinj

iTrader: (3)

Before I tore the motor apart I would look into the drivetrain a bit. With a 3.08 open rear you said you had to leave at idle to avoid burning the tire up. Before I added more power I would get a better gear ratio, posi/locker/spool and some tires. No sense in making more power if you can't put it to the ground. After doing that I'm sure you would see some better times than 13.9. Can you post a pic of your timeslip from the track?

tjtaylor

hah no need to worry about that. I have the drivetrain covered. In the rear i have a Moser 9" with a detroit trutrac locker 3.55 gear. stock t-5, tubular everythign upfront from bmr with coilovers. this alone on the carbed setup should have been high twleves if not better.. and yes i can postthem but not till tomorrow. and everything mentioned above is going in after i get it back from paint. everything is being dropped in from the bottom as to not scratch the new bay

midias

I would at minimum add a cluster support cover to your t5

tjtaylor

Would a Lakewood bell housing be considered a cluster support? I have one of those. And can I reuse my rings? Or do I have to get new ones. All I'm gunna do is adjust the gap

midias

They run between 30 and 60 bucks and go behind the 5tgh gear cluster

tjtaylor

ohis that like inside of the transmisson itself? i assume yes.. lol

midias

Yup

tjtaylor

humfph ive never taken a trans apart befor.. couldnbt be too hard i would assume, what exactly does a cluster support do?

tjtaylor

here is my timeslip. i cant find the one i can a 13.9 on though. best time i found was 14.3, this one though i was racing my buddies built 5.0 he was so upset. some reason photo wont upload
*reaction- +.1328
60ft-2.4177
330ft-6.5260
et@594ft-9.0856
1/8et-9.63
1/8mph-81.37
1000'et-12.2149
1/4 et 14.3933
1/4mph-105.64