305RSlc

Well I am extremely close to having the $$ to finally build my engine, the only thing is...I wanna save a little. So far I have decided to go with a 87-newer roller 383 with ProTopline iron heads. My cam selection was based on the intake I wanted to run, which was the HSR, but the whole system is really pricey so I was gonna go carb just to get her running until I saved up for the entire system. The cam is a GMPP 350-High Performance cam with specs coming in at 234/242 degrees duration @.050" 112 degree lobe seperation, and .539/.558 lift with 1.5 rockers. Is this a good cam to run with a carb? If so, what kind of carb would anyone recommend? I want to make excellent power from about 1K-6k rpm, decent idle, and for a daily driver backed by a T56 and 4:10's out back. I'm gonna run the Air Gap for the intake. Also, should I go with a cc carb, what cfm? I'm not too knowledgable about carbs but hope to learn in order to get this engine running. I'm looking to get at least 400rwhp. And, what type of distributor should I run to compliment the carb? Any help suggestions would be appreciated...hope to have it built and running by the end of the summer. Thanks!

Damon

You're beyond what a computer controlled carb setup can handle- and they require a specific ECM and a bunch of sensors which are sometimes different than equivalent later EFI sensors. Way too much trouble. You just want a plain old Holley non-computer controlled carb of about 750-850 CFM airflow capacity for that combo. Vacuum secondary or double pumper will both worth fine. Vacuum secondary for better street manners, double pumper for a little more on-track performance.

You'll also need a non-computer controlled distributor. Any ECM is going to freak out if it doesn't see the EFI system or computer controlled carb attached to it.

It'll run like a raped ape. You'll be wondering if the EFI system is really necessary once you get this combo really tuned right.

Specific brands and manufacturers of carb and distributor is up to you. A solid choice is a standard Holley brand carb and an MSD distributor, if you're looking to buy new. Junkyard stuff can actually be mande to work jsut as well if you know what you're doing, but it takes time, knowlege and experience to make them work. And home-tweaked junkyard stuff has little resale value. A new Holley carb and an MSD distributor (both in good condition with few miles) can always be unloaded for decent money when it comes time to finance your EFI upgrade.

ramrod85

Damn, that's a whole lotta cam. I'm using a Crane Cam (109841) with those specs in my 396 LT1 w/11-1 compression,3:73s. and a 3500 vigilante. I agree with Damon on the new Holley and MSD setup.

305RSlc

Damon, thanks a whole lot for the reply, I greatly appreciate it. What kind of distributor should I get, I'm not too sure if HEI is totally computer controlled or not...I'm used to the computer stuff so what would be a good choice to go with w/o worrying about any electronics for now? Thanks again for the reply.

ramrod, that engine just LOOKS sick...I bet it's gonna be a beast on the road....man, a 396 LT1:hail:

fb305svs

agree with damon, and i think you'll like that cam... (my cam is 236/242 @050, 520/540 lift)

www.ss-perf.com/steves91.htm

thats my car, dyno charts and such are all there, check it out

what heads are you running? roller or flat tappet? if its roller your DEFINATELY going to to want a rev kit, OR go solid lifter... thats a big cam for a factory roller setup and you'll float the valves before ya hit peak hp...

Chickenman35

Don't go larger than a 750 DP if you run a Holley and drive it on the street.. 750's have a 1.4" venturi. 800's and larger have a 1.5" venturi and this absolutely kills booster signal.

Booster signal is the single most important criteria in a carb. A 750 can easily be modified to flow over 800 cfm without decreasing booster signal. 830 cfm from a 750DP not uncommon and you will have crisper throttle response and driveability to boot.

305RSlc

I'm gonna be running Pro Topline iron heads, with the 180cc intake runner and 64cc combustion chamber. I was hoping to run just a regular hyd. roller valve train w/o the rev kit. From what I have heard, the rev kit is like 70's technology and just adds weight to the valve train components. Would just adding solid roller lifters be save insurance from floating the valves?

so I should just stick with 700-750 cfm if I go with DP right? I was gonna go with a dp just for the added performance, but do they cost any more than a vacuum secondary one?

Chickenman35

A Rev kit does not add weight to valve train components. But if you do not exceed 6,000 to 6,500....TOP quality springs will do the job. Once you're over about .500" lift and 230 duration at .050" you're talking serious springs and valve train components. ARP makes an excellant kit called Hydra-Rev if you want to go that route.

IMHO you're a tad big on the cam for street use. If it's a weekend only Strip car then fine. But if you want to go cruisin' I think you'd be better off with a bit shorter duration. Next step down should be good. Around 230\236 @ .050". This will give you monster torque and pull hard tp 6,000. Hydraulic roller would be my recommendation...but if you afford the extra cash for a solid roller go with that.

Valve train must haves:

1: Excellant springs. I'm an Isky fan. Hard to beat IMHO. 8005A's should do the trick. use Isky's steel retainers and Super Locks. Titanium also available if you're feeling flush.

2: 7\16" ARP rocker studs. With the spring pressures you need, don't even think about 3\8" studs.

3: .080" wall Chrome Moly pushrods. A lot of people buy Chrome Moly pushrods but only get .060" or .065" wall thickness. Won't do the job with a big cam ( They will flex ). Comp Cams, Isky or Crane.

4: Comp cams Pro-Magnum Stainless Steel Rockers..or Hi-Tech Stainless steel rockers. Virtually indestructable. Well worth the money. 1.52 ratio Intakes and 1.6 Exhausts would be my choice.

fb305svs

The rev kit is made by AFR, i think chicken man had a brain fart :P

anyways, it does not add weight- it places spring in lifter valley and uses springs to push down on the body of the lifter, thus taking the pressure off the plunger in the hydrolic lifter to help keep th elifter seated on the cam. if you spin over 6k this will become quite apparently necesary. trust me, i installed one on my motor and a, DAMN glad i did.

To address other issues brought up, i would go no further than a 750 - im running a 670 street avenger holley and it loss very few hp over a worked over 800 cfm holley...

As for the heads - consider, if you dont already have them, there 190's or 195's. they will better suit a cam like what you mentioned - otherwise if you have the 180cc heads, i would choose soemthing with less lift and something more along the line of duration asd what chickenman mentioned - as a general rule of thumb, much over 236 lift just pushs the peak numbers up in rpm...

Steve

fb305svs

Just wanted to note on chickenmans points

first off- don't be scared with the duration you're thinking about- i'm running a xr288 comp cams cam, and altho it barely produces ebnough vacum for brakes and such, a vacum pump would be easy to work into the equation. As for street manners, its GREAT, very responsive. I'm running a victor jr intake.

Springs- 130-140lbs of seat pressure, and about 330lbs of open pressure is about all you can get away with on hydro rollers lifters- they will collapse. this narrows ur choice of springs down consdierably. i prefer comps's springs, but iskys are good too. make sure to get a double spring valve spring- they are far more reliable and will be good longer.

Studs- 7/26th studs would be the way to go- purely insurance, even tho for the cam you specified, 3/8 arp studs would be fine. make sure you get th eproper rockers accordingly.

Pushrods - do make sure you get good pushrods, but until u get into the upper 500's, i wouldnt worry too much about pushrod deflection- albeit, it is a good investment.

Can't argue with those rockers, they are great rockers for the cost. instead of staggering the ratios, get a cam thats more appropriate- comp cams would be more than happy to grind you a custom grind for only 30 bucks more than a normal cam. Its not worth buying two diff sets of rockers for that purpose....

Chickenman35

Yes...I did fart...and it was smelly...... Air Flow Research makes the Hydra-Rev kit of course, not ARP.

You don't have to buy two different sets of rockers. Comp cams offers all of their sets in mixed ratios. You just have to order the correct Part number suffix.

EG: for Pro Magnum's 1.52 ratio 7\16" stud you would normally order 1304-16. For Pro Magnums 1.6 ratio 7\16" stud you would order 1305-16. You can also order half sets or even individual rockers...but they don't list this in their catalogs. They will tell you this if you phone their Tech lines.

To order a mixed ratio set you can change the suffix. 1304-8 and 1305-8 will give you (8) 1.52 ratio 7\16" rockers and (8) 1.6 ratio 7\16" rockers. I believe they also have a kit with one Part# if you phone them.

Running a single pattern cam is the other option.

fb305svs

cool- good stuff, did not know that

305RSlc

Well based on chickenman's recommendation, I guess i'll go one step down since I don't want to worry about floating the valves or anything. how does the comp cams XR282HR sound for this? It gives a little lower duration with 230/236 @ .050" and some smaller lift with only .510 and .520 with a 110 degree lsa. sound like it'd work better for running with say a 700cfm holley dp, and the airgap? I don't want it to go crazy on the street so I'll just save up for the cam as well as the induction later on when I convert to HSR. Would this combo, on a well built 383 with the Pro (195cc.....mistyped when I said 180cc) heads sound like it'd get me solidly into the 400-450hp range? Thanks for all your suggestions guys!

Chickenman35

Yep I'd say that would work fine. With the 383 don't be afraid to go with a 750DP...but no bigger.

A suggestion on Cam mfg's. Comp Cams goes with a lot of " Generic " profiles. Most of their "off the shelf" units are all ground on a 110 deg lobe center...whether the cam is for a Chevy, Ford,Mopar, Pontiac or AMC. Now don't you find it curious that all of these vastly different engines should like the same LCA. Answer is of course is that they don't . It's just cheaper for them to mfg this way. Now you can of course get a custom grind, but that costs you more money.

The other big issue with Comp cams is that they tend to be hard on valve trains. They have very aggressive ramps, more so than other mfgs. This is one of the main reasons I don't like them. I've seen far too many valve train issues that have been caused by this. When you have half a dozen friends, with different vehicles, all having valve train issues that disappear when they switch to a different mfg....well, that tells you something if you're listening.

IMHO you'll be much better off with a Crane or Isky cam of similiar durations. Lunati also makes good stuff.

Damon

Please do yourself a favor- stay away from "rev kits" and extensive carburetor modifications. For what you're doing they're totally unnecessary. Your motor is going to make power in the 2500-6500 range. You don't need way out trick parts to do that. Any set of standard valvesprings that are designed to work with that cam will do just peachy.

A 750 double pumper will do just fine on that combo. Personally, I would go bigger (and have) but somewhere around there is going to do just fine. You won't be able to tell the difference between a 700 and an 850 CFM carb by the seat of your pants, I guarnatee you. Maybe a tenth at the strip- that's it. Don't over-think it.

Any of the MSD Pro-Billet distributors will work. The HEI one will plug right into your factory power/tach wiring, assuming your car originally came with a large cap computer controlled HEI distributor (up to about 1986). None of the MSD distributors are computer controlled, so power and tach connections around about all you have to worry about.

305RSlc

Well thanks for the help guys. I guess I should think this out just a little while longer...no biggie, give me more time to save money. I am definitely going to go in the 230 duration for the cam with at least .500 lift, just gotta do a little more shopping around for the right choice. If I get a cc HEI distributer, could I just hook it up to the computer and that be it...not have teh carb or anything else hooked up? I'm just kinda curious how this would work cuz all I have dealt with is cc stuff so far. Also along the lines of cc and wiring junk, could I install an electric fan on the car without a computer, or would I have to use a V-belt system for cooling?Also wondering how that would work since there would be sensors but no "brain" to tell the fans to kick on. Again, thanks for the suggestions.

Damon

Running a computer controlled distributor with a non-computer controlled carb is a big no-no. The ECM freaks when it doesn't see the computer controlled carb, throws the check engine penalty flag, and gives you a very weak advance curve. Get a non-computer controlled distributor for this combo if you want to get power out of it without pulling your hair out.

ljnowell

comp cams are the way to go man. I've known a lot of great engine builders that swear by them, and I've never had a problem with em

Chickenman35

Well you'd have a hard time convincing my Buddy...who had three Comp Cams fail on him with his 462CI Poncho. Switched to a Crane cam ( nearly identical cam specs ) with no other changes to the engine and no problems whatsoever.

I'm also going by my Engine builder who's been building Drag and Marine Jet Boat motors for over 25 years and he has told me enough horror stories to convince me.

To each his own though....

ljnowell

Thats probably why comp cams has been in business so long, they make crappy products. Everyone has a bad product come every once in a while. Three cams fail on one engine?? I think that could be chalked up to user error.

RB83L69

I'll toss in an opinion here...

I used to live in Memphis and build motors for people. Comp, Lunati, Cam Dynamics, Ultradyne, and Bullet are a few of the cam companies located in and around Memphis that I've either known people who worked at including my own brothers, did engineering work for, walked into their buildings and bought parts either off-the-shelf or special ordered for motors I was building, etc. etc. I think I've used every one of them's parts (except maybe Bullet), as well as Crane (Daytona FL), Crower (CA), and a few others. I don't claim to have any special cam expertise or anything though, I'm no Harold Brookshire or any such expert, all I have is a small amount of first-hand BTDT along with personal acquaintance with the companies.

They were or are all run by people with a keen sense of upholding their reputation in the marketplace, and customer service. Every one of those companies makes (or made, as the case may be) very good products. Every one of them can also be made to fail. Every one can (or could) grind you a cam that you could stick in a motor and exceed what the rest of the parts in the motor could tolerate, and something would get destroyed as a result.

The Comp Xtreme grinds are very aggressive by design. They are meant for people who are willing to step up their whole motor program to toughen up the things that the cam will stress out. Where you get into trouble, is the typical "can I use my stock 120,000 mile L03 springs on my XE274" type of people. Basically they push the envelope of survival of the parts around them. You want the most cam you can get at a given .050" duration, you better be prepared for it. You'll also find that you can get a cam with specs that, on paper, look identical; that is, same .050" and peak lift; but compare the .200" and .300" and .400" duration. The Xtreme grinds have ALOT more than most. They get the valves open as far as possible as fast as possible, hold them there as long as possible, and snap them back shut as fast as possible. That's why they beat valve trains to death, not because they're "bad".

Personally I think Comp's recommendations for peripheral parts to go around those cams are not stringent enough. For springs especially, I would not think it wise to put a XE268 or larger under any 1.25" springs, regardless of the "peak lift" number; and when using a larger diameter spring, I prefer to use the next step more spring than the one they recommend.

Go look at Crower's recommendations for their most aggressive street cams, for a good example of more conservative spring choices.

Given the state of the art in springs, I'd prefer a solid roller for any lift over .550" or so. A hydraulic system just can't stand up very well to the acceleration and pressures that you get from that much cam, at least not for very long.

/rant mode off

305RSlc

Very enlightening...

MrDude_1

i agree.

you're building a simple motor.

just continue your route.. get a nice cheap single plane carb intake, a holley or edelbrock carb and a HEI distrib.

im keeping in mind what you said... moneys getting close, you just want this to run, and the carb setup is temp...

for the intake i would reccomend either a used brand name single plane, or one of the new pro-products ones off ebay.

for the carb
if you choose holley, id go with a electric choke, Vac secondary 750. choke might not be needed now, but if you end up going thru next winter with it, it would be nice to have a electric choke and not have to make a choke cable hole.
vac secondary for street economy (without costing power)
anything between 600 and 750 will work, so dont throw away a good deal...
if you go edelbrock, performer non emissions, elec choke would be my choice.

for the distrib, i would run a regular GM one wire HEI from any SBC car or truck.. if you want rebuilt, theres the proform and summit ones.. if you want new (read $$$) then the MSD one.


you arnt building a all out tweeked race motor... you dont need a rev kit.. you dont need a solid roller valvetrain.. just build a good strong simple motor, and you'll be happy with it for a long time.

Chickenman35

Never said they made crappy products...just that they have very aggressive profiles that can cause problems and WILL cause problems....moeso than other brands. This shows up much more in Road Racing and Circle Track motors than in Drag Racing.

Read RB83L69's post. He's got it bang on.

ISKY, Crane and Lunati have been around for a long time as well...in fact longer that Comp Cams. And I'm not referring to just one motor.......

Chickenman35

Very good...agree 100% . A more detailed explanation of what I was trying to say.

Comp Cams Xtreme series is well known for it's aggressive profile...and as you say that can reveal any weakness in the valve train. It is very hard on valve springs. Interesting that you should say that Comp Cams underspecs their spring packages and that you usually go one step higher than the Comp Cams recommendation for a particular cam. That is precisley how my engine builder feels about their lineup as well.

Chevy High Performance ( I believe it was them ) also did a buildup with " Danger Mouse ". One of their tests was using the XR288HR cam. They ran into a valve float issue at relatively low RPM's . ( I don't have the article in front of me to quote at what speed but it was below 6.000 RPM's ). The recommended spring by Comp was a 986-16. Changing springs to a stiffer 987-16 not only stopped the valve float issue...but also picked up some power and torque at 4,500 RPM. Only explanation that the Dyno Operator could figure was a harmonics in the valve train caused by inadequate spring pressure.

With a custom ground, fairly mild Hyd Roller my motor made good pwer to 6,500. If I had to, I could " run it out the back door " to 7,000. Engine still pulled hard but past peak power point of cam. Comp Pro-Magnum 1.6 rockers, Isky 6105 springs and ARP 7\16 studs.

Changed to a Comp Cams XR288HR ( on my 355 ) to gain some upper RPM power for Hillclimbs. Isky 6105 springs would not be enough for this combo...so switched to 8005A springs. Engine made HUGE power from 4,500 to 6,400...and then fell flat on it's face. Couldn't pull over 6,500...whereas with the smaller cam it would merrily buzz to 7,0000 ( The limit of the Hydraulic valve train ). Turns out the problem was the pushrods. I had Chrome Moly pushrods...but they were only .065" wall thickness. I was getting a hrmonic in the valve train caused by the extreme ramp accelerations. Changed to .080" wall pushrods ( Comp Hi-Tech serioes ) and problem was eliminated.

Just an illustration of how you must have all of the components matched when going with big cams. And some MFG's profiles are more aggressive that others...Comp being one of the mfg's going this route. IE: their Xtreme Energy series.

Does this mean that all the other mfg's such as Isky, Crane, Lunati and Crower are bad...or make less power...No...of course not. They've just gone about it in a different way. IMHO...a better way... Ramp profiles that beat the valve train to death are not MY idea of a good design. But I'm a Road Racer...so my values may be different to that of a Drag Racer. I'm perfectly willing to give away 5hp...for more longevity, IE: Not breaking springs or rockers etc, etc.

Hope that cleared things up.....

305RSlc

Excuse my incessant ignorance, but with an electric choke, wouldn't I have to run a computer to control the choke? Or am I just not seeing something here? The reason I ask is because my friend has an 85 t/a with a cc carb, and an electric choke so I am assuming that the only part that is cc is the choke...is this a correct assumption? It wouldn't be a problem, I'd just have to know which computer to find to run it for the time I need. Thanks again guys, this is becoming a bit more easy by the day!

five7kid

iTrader: (14)

Wrong assumption. Electric chokes have been around a lot longer than computers.

The "electric" part is just 12 volts to heat up the choke thermostat coil. It isn't "electrically controlled", just electricly heated.

305RSlc

SWEET! Thanks for clarifying that for me. That gives me a whole new realm of carb choices cuz I was considering "electric choke" carbs unfit for what I am gonna run. So basically you just wire it so a 12V source, with a ground, and it just heats the thermostat coil in the choke? It's that simple?

What on the carb exactly is cc? Could someone shed light on this one for me?

THEGENERAL

dont just hook up a 12 volt sorce to that coil make sure it is a sorce that turns on and off with the ignition .......

Chickenman35

But...don't hook it up to the ignition circuit itself. Hook it up to a separate 12 volt Circuit that goes turns on and off with Ignition.

THEGENERAL

hopefully he would know better than to do that ..LOL

305RSlc

MrDude_1

yup, you got it.
basicly when you start the car it goes like this:
1.key on
2.push pedal to the floor once
3.start.

its natural once you get used to it, and the car should start up FASTER then a fuel injected one.... no choke to pull or anything.


ive never had a computer controled Qjet, but ive worked on other computer controled carb motors.
usually theres a needle valve that richens or leans the mix... the computer just moves this needle valve in or out to get the desired mix...

ljnowell

honestly as far as reliabilty and driving, a CC carb is great. They work like a charm. I've only had one on one car, and it ran great. But, they just dont do a lot for performance.

305RSlc

This is awesome!! LOL, I honestly never knew it was so simple to hook up and run a carb....should've figured since A LOT of guys are running them. It makes me want to go out and build it right this very second!!! Just gotta find the right cam and it'll be on it's way....what kind of single plane would ya'll recommend? The air gap is less than $200 plus about another $300 for a carb, maybe, and $100-150 for distributor so for about $600 I would have a complete intake system as opposed to 2300....this is gonna be fun!

THEGENERAL

yeah using a carb is one of the easiest ways to build that engine ..i hope you keep us posted once you start sounds like your enthusiastic about it and i like to see people build what they want how they want ...so good luck and keep us posted man

305RSlc

hey guys, I've come up with another question. It involves wiring of the electric choke. Well I was wiring my amp up the other day, and of course it runs directly off a power wire from the battery. and of course, with the ignition on it has power, with it off, it doesn't. Could i wire the electric choke this way too?Just run a small wire from the battery neg. and pos. to the choke and be done with it?

THEGENERAL

you want the power to be ran to a power that is on with the key in the on postition and off with it in the off position ...then it would work just fine you dont want it to have full power all the time "like if you ran strait from the battery" you would burn it up

305RSlc

any recommended places? I really dont' know all the systems that are on with ignition in the "on" position but turn off afterwards. If you could throw some choices to run it off of out I could figure it out from there I"m sure.

THEGENERAL

well the best thing to do is look in the fuse box and there should be a acc outlet on it with nothing in it you can buy a spade clip and plug it in right there but other than that you need to get a voltmeter or test light and turn the key on and test and then turn the key on and test but the best thing to tap into is the fuse box by running a new wire to it

ljnowell

Ok let me try to describe this without confusing you. On most of these cars, if you bend down and look at the fuse panel there are some accesorry spots open. What you need is a spade connector that will plug in to the fuse panel (found in any hardware store) and you can crimp the wire into. When you look at the fusepanel, on the bottom right as you look at it , or if you want the corner closest to the steering column and the floor there should be some accessory spots open. Best way to do it.

THEGENERAL

yep

305RSlc

K, I'm just gonna stop thinking now. Every time I do, I make things more complicated than they really are....But thanks for the info, lol, sounds like a cinch to do.

ljnowell

Sorry to make it sound so difficult, sometimes its just hard to explain. Also, the best place to run throught the firewall is through the rubber grommet on the firewall to the bottom right of the brake booster.