602 GM Crate vs. Built Engine

[rick7343]

excellent thread guys! Care to get into what cams work with these 2 bbl built engines?

[Brian W]

I looked in my pile of heads today and did not find any 487x's. I did however find a set of 993's and one 441. All virgin 1.94 castings. I did not get a chance to flow test any though. Its been a while since I have had one of these stock heads on the bench but if I remember correctly the 487's were the best and the 441's were a close 2nd. I also seem to remember that the 487's might have been 10 or so CC'c larger on the intake runner... but not for sure about that. The 993's flow close to the same as well, not a bunch of difference. Will get actual numbers another day. I do alot of the EQ heads as thats what most of my customers want. They flow better, unless you do some work to the OEM's port and are brand new... but if your going to spend the time on the port its better to do the EQ, wayyy less core shift and more uniform ports and alot less work. It is possible though to make the 487 flow more air though because of the bigger valve but your gonna have to work on the port a bit to get the gain thats worth the trouble. I have did some full port jobs on the 041 heads (for a Modified) which have basicly the same port as the 487, 441's and had them flowing 250 and they could be a little better then that with more time spent on them. However with that kind of work done your not gonna "hide" it.

[MidgetMotorsports07]

I don't know for sure about the 487 but I am pretty sure the 487X has a slightly bigger runner Brian. IMO if you are going to run the stock head, that would be the one I would look for. They are getting a little harder to find though.

[MidgetMotorsports07]

excellent thread guys! Care to get into what cams work with these 2 bbl built engines?

Depends on the driver... and the track of course. I usually run on the smaller side compared to most. If you tell me the track size and what you want I could probably give you a rage to try. Or you could ask MIke/CamKing. He definitely knows what he is talking about.

[IMCADW]

If you get a good combo and have a driver that can get up on the wheel and take advantage of the claim engine gearing, you're golden.

[1997bird]

I don't know for sure about the 487 but I am pretty sure the 487X has a slightly bigger runner Brian. IMO if you are going to run the stock head, that would be the one I would look for. They are getting a little harder to find though.

The 487 casting was for a 1970 LT-1 and the 487x was a 1971 LT-1, to my knowledge they are the same intake runner which is roughly 171cc intake runners and had a 65cc exhaust runner.

The 441 castings are your next best castings to use and were roughly 165cc intake runners and had a 65cc exhaust port.

Your 882 or 993 castings were roughly 152-159cc intake ports and had a 59cc exhaust runner.

This was from memory from when I was looking into head castings for my IMCA Southern Sport Mod class builds.

[raceman14]

Per the post on leaning out a rich looking engine making more power;

Sometimes I get an idea to go in a certain direction by looking at the physical paramenters like fuel burn on the plugs, and header temperatures about 3" back of the flange. Usually I can get a real good impression of what the engine wants. In the case of the new "Green Fuel" VP 98 it showed to be a little fat in both cases. When I dropped the jet 2 ( I normally skip 2 sizes in the 70's ) the torque curve suffered from 3500up. Just for fun, I jumped 4 bigger to get back to original setting and jump 2 jets and the curve picked up 11# and about 7rwhp. I went up another 2 and it went back the other way so I dropped back to +2 sizes over baseline 70-77. I did the same thing with power valves and ended up going from 3.5f/3.5r to 6.5f/4.5 r and picked up another 17ft# /9rwhp.

I had already timing swept the distributor and dropped from 38* to 34*( +7rwhp ). I also swapped to a "treated" spark marine plug I sell for crates (+4rwhp ).

The 602 steel head likes things a little different than the 604 because of the increased bottom end that it shows, so in turn it like fuel coming in a little early. At the same time I discovered a little double whammy in the VP98 as it likes to come in early partly I guess cause it has a slower boil curve in the intake and also lower octane levels than Unleaded 100 they used last year.

BrianW,
What is the port volume of the Spec head? Did I miss it? Depending on how the ports sound I like to go up in manometer pressure to see if the port can handle the extra air speed without degrading. Many times you will see stock heads outperform aftermarket heads in this testing because the designers of the newer port take the easy way out in port design as they increase volume and pushrod choke, without considering the changes needed in the short side to accommodate the extra air and fuel...in that case more is not always better, and I see folks say it all the time, this engine with all the new stuff does not pull as good as my old motor in the corner of the shop. Why, because it does not have the proper ability to present the combustion chamber with a good air/fuel emulsion. All the air in the world don't matter if it can't carry its own fuel to the fire...

DW & Midget
As far as cams go I have a couple engine builders using my stuff in their engines for the past couple years and they have sent me dyno sheets showing +30-40# TQ accross the board. My program addresses a more complete change in the program including dizzy, timing, spark plugs, cam and carb. It is hard to affect big changes without making big changes in the fuel and spark system of the engine. I have a different idea on making power with stock stuff than most as I have been working with the engines for 25+ years. I prefer to feed the engines early in the rpm curve and slow the timing to accommodate slow burning lower octane race fuels, at the same time I like to lean out the fuel curve in the metering blocks to allow the vacuum of the engine compensate thru the opening and closing off of the Power Valves. As far as cam timing goes I like to open the intake as early as possible to charge the air off the seat and then close the exhaust early as possible to trap all the cylinder pressure that I can. My stuff is way wierd and does not just go into an engine and make more power, there is multiple steps to be done to make it happen, like I said earlier I retard timing, slow the advance curve, retract the spark plug, rich bottom end leaning to the top end etc.

In stock style engines & Crate engines there is 30-40HP just hanging around in getting things right with the fuel you are burning and then you can start on the engine development part of making power. Even though you are not supposed to change things on crate engines I have built them for Road Racing and "Outlaw" Pavement and Dirt series, I have made close to 500RWHP GM Legal, 550RWHP with slight variations in cam timing and seat positioning ( ASA Legal thru full tech ), and almost 600HP engine for Road Race application ( Lift rule cam, better springs, LS or Economy Steel rod, Road Race wet oil pan, new seats and GM stock valves cut to match port ).

After 25 years of flow testing accompanied by engine and chassis DYno testing I have come accross what I consider standardized numbers to estimate possible power output on a given combination and there is still way more in both 602 and 604's to make power. I feel the same way about most stock heads as the "chinese copies" have lost a couple key factors in the translation.

I catch a lot of flack about posting numbers cause folks freak out, and most folks think dyno numbers are for show. In this case I have a long list of folks that are winning National events on a weekly basis as the best support of what I have been doing.

[MidgetMotorsports07]

Raceman14


I can see what you are saying.... I know some engine builders that have the same theory as you do. I agree with the slowing of the ignition curve, and I have tried opening the valve as early as possible and closing it early to build cylinder pressure. If you have the piston to valve clearence for it you can do that with almost any cam. Just install it on a 98 or 99 centerline and you will be right in that wheel house. I try to run as tight on quench as I can so i usually don't take anything below a 100 or 102 centerline. I don't run split duration cams very often on anything with a 2 barrel. I think it was you that had a post on the Choke Flow thread and we were all talking about how the intake charge was rushing to till the cylinder even after BDC. Where do we draw the line on when to close the valve so we don't lose inlet charge?

[raceman14]

Midget,
It might have been me on the other thread, but I am not the guru engineer to tell you what is the max you can go. I know I have gone way past you on 2bbl and opens and I have not hit a wall yet.

I don't think you can physically get the valve open too soon as the peak piston velocity is usually in the 80*'s range for most SBC's. I also prefer as small as I can go on the bore and as big as I can with stroke and as short a rod as possible. I know this is contrary to most folks out there but I have worked the combination for 20+ years with good success. Most of that theory on long rods are back from the 60's when pistons were 4" tall, now they are 2" tall. Big bore & small stroke is better with heads that require an unshrouded intake to flow properly. I am of the opinion that the smaller the cylinder the more vacuum it can pull with bigger stroke, given equal flow from the cylinder head the velocity should increase proportionally. Big pull on the port makes better off the seat flow numbers and I am all about getting the intake port excited and working as soon as possible because that is the engines 60' time. The faster you can accelerate the first .050" flow numbers the more the rest will follow along and that is where most head porters miss the boat. All you have to do is listen to a vortec port -vs- standard 23* the sound will tell the story.

I also run the bench pressure up as high as possible even at the cost of bubbling the red fluid so I can listen to the port. What you are hearing is the Helmholtz tuning of the port especially when you hook the intake and header to the head. I have conducted FFT ( speaker testing pulses ) to verify tuning lengths and harmonic frequencies and they are pretty close ( the FFT and Formulae for calculation considers laminar flow and constant size ), intakes, heads and headers are not constant but they are pretty close like 5% of what you would estimate. So when I build stuff with a budget, my manifolds are big as well as my headers. That stuff about too big is bad for power is only when you follow all the other myths that support that theory.

Ain't nothing gonna change if you are doing the same thing over and over !!!

I have been as low as 94 ICL, on a 100lobe spread cam, with the advance ground into the shaft. Advancing the cam at the chain still improved torque and HP, so I guess I will go more next time. I use lower lift numbers and big duration at .050 with very high intesity ( small advertised minus big .050" Duration = hi intensity ), usually called fat lobe. Can be rough on the valvetrain but decent springs will handle almost any cam you can put in the engine. I am talking in general with oval or road race engines below about 8500rpms. Above that and you have a wayyyy different animal, and bad things happen in a hurry.

[MidgetMotorsports07]

Raceman


I have no doubt you have pushed the limits much farther than I have. You said you have been at it for 25 years.... I'm 24.

I do ok camshaft wise I know more than most people my age about Minor,Major intensity. Ramp speeds and the other fun stuff like that. Actually I had no idea of any of that until I read a big article written by Harvey Crane. That opened my eyes to all the possibilities of the various combinations of lobe intensity overlap and lobe seperations.


I also agree on the big stroke and small bore in a restricted engine. I think it could potentially pull more vacuum as well.


I will be honest, I didn't know what to think about you for a little while. You say things that just seem off the wall sometimes and you say a lot of names of people I have never heard of. As I said I'm 24 so I definitely don't think I know more than the next guy on this Forum.
The last 2 posts you have had have been the most reasonable I have seen so far. Keep it up and they guys might not be so hard on you lol. I will learn from whomever is willing to teach.

[raceman14]

Midget,

I built my first engine at 14 and my first real race engine at 16 and I am now 52 so it is more like 35 years. I had about 10 years of practical experience before I purchased my Flow Bench when I was 25. A couple years later I purchased a used Serdi and I started working on it. At 30 I met the man who designed the Serdi and decided he was pretty sharp but the machine still had a lot of room for improvement. In the next 10 years I probably sold 50 of my modificated machines.
At 40 I went to work and ran Serdi North America for a couple years. I got fired for making unapproved adjustments to faulty machines that were in about 15 race engine shops in Charlotte. I took care of friends of mine that spent close to $100K to get a machine I begged them not to buy.

After about 2 years, a million dollars in returned equipment and a couple law suits Serdi decided to install my hydraulic repair system to make their new design hydraulic locking machines operate. It was really pretty simple and cost a couple hundred dollars from Parker Pneumatics. It was a couple double swedged high pressure lines run to a vented pressure switch that relieved the high pressure when machine was at rest. It only needed about 200psi to lock and hold and not 2000psi. You ever see a 2000psi oil leak, it will put out an eyeball or just about cut thru metal. Only takes about 10 seconds to empty the oil reservoir in a new-style Serdi and 10 hours of dis-assembly and cleaning, cause air float don't like oil everywhere.

Oh well, I just a dumb Canadian as some of my race friends call me.

You will come to see that I really don't care what folks think as I have got way greater concerns. As long as the folks paying the bills are happy and my family is happy that is about all that matters. I post stuff on the internet in hopes of finding 1 in a million racers that has a brain, knows how to think for himself and understands original thought.

Folks that think my statements are far fetched, have not tested or tried what I have or they are not aware that there is another way of doing things that might not follow the standard recipe.

The folks you might have seen me refer to are the people I grew up racing with. As off the wall as it may seem, Dale Earnhardt opened a lot of doors for me because I sold his original engine builder Jack Tant as Serdi machine 10 years before anybody in Charlotte had one. It was not uncommon to see him at the engine shop or at the track and just shoot the $hot on the pit wall about his kids, hunting, fishing, and whatever. Racing was what we did for a living and talking about that was only when practice or testing started. Believe it or not Dale Jrs' sister Kelly could drive him into the ground. A buddy of mine Jon taught them both to drive at Hickory and Carraway. Jon drove for me at a couple ARCA events and is by far the most talented driver I have ever known, and I have seen hundreds of them. If someone wanted to know about me I just directed them to some key folks and
my machines started selling like hotcakes.

If you can read or if you understand basic physics and have a grasp on the physical sciences you will come to find that my posting are based in Fact and Upon personal things I have done in my shop or at the track.

So if you think my ideas would work on a restricted application, why then would they not be better for an open engine application??? Doesn't increased vacuum help the engine work no matter the type.

You have to think of an engine as an air pump right...Anything you do to increase vacuum below the throttle blades is like creating positive pressure above the throttle blades...I don't know of any engine that does not like pressurized air into the carb.

Air in an engine travels in big chunks and the faster it turns the quicker it has to get that next chunk of air in the engine, so anything that creates pressure on top of the blades or vacuum under the blades facilitates that process.

As you said, your eyes were opened on camshaft design by some papers by Harvey Crane, I used to talk to him regularly and order cams from him directly 25 years ago. I still talk to him on sometimes although it is easier to catch him via e-mail. Same thing with Harold Brookshire, Deema Elgin, Kip Fabre, Joe Hornick, Joe and Joey Lunati, Charlie in VA, and I worked for John Reed for a couple years. Each one of them is responsible for a certain area of advancement in my knowledge base and camshaft education.

You need to further your education on your own by learning what a camshaft does at the valve, and how that relates to engine air gulping. Once you run about 20 cams thru the wheel and graph out the lift and flow curves you will have a better understanding on how cams affect an engines output.

From that point if you can be lucky enough you might find someone with a Spintron so you can watch and see what happens to valve train in real life. From that point you might build some manifolds for CUP teams with marguard windows epoxied in them so you can watch what happens to fuel with an ultra-high speed camera.

That is pretty much how you figure out what valvetrain loft is, how to achieve it and how to make it work to your advantage. Everybody is raising hell about hydraulic lifters and how they won't work, last time I checked a lifter does not know what it is until you build it to do what you want it to.

If you can make a hydraulic lifter act like a solid lifter up to 7500 is it a hydraulic acting like a solid or is it solid up to 7500rpms? Or does it even matter as long as it does what you want it to?

Sooo, I still like the built engine -vs- Legal 602.

[Brian W]

BrianW,
What is the port volume of the Spec head? Did I miss it? Depending on how the ports sound I like to go up in manometer pressure to see if the port can handle the extra air speed without degrading. Many times you will see stock heads outperform aftermarket heads in this testing because the designers of the newer port take the easy way out in port design as they increase volume and pushrod choke, without considering the changes needed in the short side to accommodate the extra air and fuel...in that case more is not always better, and I see folks say it all the time, this engine with all the new stuff does not pull as good as my old motor in the corner of the shop. Why, because it does not have the proper ability to present the combustion chamber with a good air/fuel emulsion. All the air in the world don't matter if it can't carry its own fuel to the fire...

The intake runner volume on the spec head is around 169 give or take a few. Runs in the 174-175 after some "hidden" work. The spec head has a better SSR then the OEM out of the box. So depending on what way you want to go, I.E. cheat or run legal,... the spec head in my opinion is better legal and is also better then the OEM with some hidden porting... if you don't care about hiding your portwork then the OEM might be a better option because of valve size but if you don't care about hiding your portwork then what says you can't put a larger valve in the spec head. I have did both and the spec head runs better on the track according to one of my customers who has two engines built pretty much the same with the exception of the heads. One has OEM 487x's that have been "stealth" ported, done before they went to the spec head option, and another with the "stealth" ported spec heads. Both heads have the same size valves @ 2" X 1.6. Neither engine has been on the dyno though, so take that for what its worth.

[rick7343]

I am going thru the same scenario... the stock (?) 602's with 500 Holley seem to dominate the class I am joining this year... but I like built engines.... we are limited to an edelbrock 2101 with cast non vortec or bowtie heads....

SO why does the crate engine do so well? Have heard they dyno 320 stock to 370 "freshened'.... heads must be part of it, what about the intake? 2101 vs. the GM intake....

Any agreement on what flat tappet cam to run? 1/4 mile asphalt oval track... would like around 6500 rpm...

[dirtracr5]

i think the crate does so well possibly because of the powerband and the efficiency of the vortec head. we have guys around here than can afford to build the best "built" engine you can dream up but they all switched to crates? makes you wonder.

[MidgetMotorsports07]

I dont necessarily know if the crate is better or not. I know that it is far less tempermental and much easier to maintain. The guys that have all the money to build a good claim engine, probably don't want to be claimed anymore. They crate is highly competitive and you can't lose it.

That being said.... if there is a will, there is a way to beat them. I'm sure they won't be AS dominant this season. Too many guys have a hatred for them. We will figure out a combination that works and try to run with it.