Pushing the RPM limit

cometguy

Well-known member
This season we will be asking the 200 to spin a little higher...installing 5.43 gears and expecting 6000-6100 at the end of the track. Also plan to upgrade to 3/8" pushrods. Any suggestions to prevent disaster? I have no idea how much I can push the combination. Please keep in mind that we are drag racing in IHRA Stock and cannot use aftermarket pieces for the most part. I'm looking for areas where there is inherent weakness.
 
I regularly shift mine at 5800-6000 rpms.

The only thing done to mine was complete balance, ARP rod bolts, hardened pushrods, roller rockers, Clifford hardened locks & keepers & clifford double (triple maybe?) valve springs

I also switched the front rocker arm stand from the early "bleed off" style to the later style that didnt have the bleed off. All it amounts to is using one of the regular stands in place of the bleed off stand.

Thats how they did it on the later engines and its worth about an extra 5 lbs of oil pressure.

I am also running the fl 299 oil filter for extra capacity and a Aussie 7 quart deep sump oil pan.

I would at least switch to the bigger filter (if you can) for the extra oil capacity.

Oiling, valve float, and points bounce (if you have to run points & condenser) are the big problems I see. All easily overcome IMO! :D :D :D

Later,

Doug
 
All stock early hydraulic cam six cylinder engines (Valiant slants sixes, Ford 200's and Aussie GM Holden 186 -202 L6's) could drown the valve gear with high revs, while the main bearings went dry!.

The key is to over fill the sump, and add a windage tray, and use the old SpeedPro HT lifters which are a bit better than the stock Ford items. When you run better oil pumps, you have to adjust the sump capacity and deal with the windage of balls of oil cavitating in the crankcase above 5000 rpm.

The rest is just dealing with the risks, and doing a few periodic tear downs of the sump and rocker cover to check all is peachy.

I'd say that the idea is to make the engine work harder by rasing the compression first up.


Hp = Cubes times rpm
. all over an efficiency factor

So to run faster, you either up the cubes, up the revs, or up the efficiency.

You can't gain a usable higher rpm range unless you alter the cam phasing with the stock cam, or find a legal grind which suits the head cfm.

I'd be checking with APTFast or FSPP, and a cam which has maximum allowable duration and lift, with a bit more rise off the ramps with the hydraulic lifters operating as solids.
 
What I would try to do is upgrade the crankshaft for higher rev potential, one made out of a different material, i forgot exactly what kind. Then I would try to lighten up pretty much every moving part of the engine and get the parts with durability. You would definately need to be able to feed more oil to the parts too.
 
Mustang_Geezer":249edp4h said:
I regularly shift mine at 5800-6000 rpms.
Later,
Doug

:shock: :shock: :shock:

I run (ring) mine up to 5500 RPM, I guess the ballance job makes a BIG difference....BTW Doug, when you rev it that high, does it sound like it's gonna.....y'know.... :shock:

Alex
 
Some great tips, thanks guys. The rules prevent me from taking advantage of some of them but it helps to get the brain matter stimulated. The rods should be acceptable as long as the stroke is maintained and they are the same weight as the model year(72). ARP bolts are OK as well. I'm using the big filter and the oil pan has a scraper. The valve sizes must remain stock and head mods are not allowed in Stock Eliminator. I have the adjustable rockers and will be switching to the DSII distributor. We are allowed aftermarket valve springs of stock dia and configuration. The engine has the late model pulley, the head must be a casting from the 69-72 years and we are using a Hooker header for now. I would like to have a more exotic header built at some point.
 
My Grand father built me my first race car using old school tricks. He raced Hudsons in the Fourties and fifties. Shaved the piston skirts almost to the wrist pins and turned down the counter weights.
This was done about 22 years ago. Grand pa was a master machinist and mechanic for fifty plus years.

Stufed this package in a sprint car and just trashed the local boys in the 3/8 mile oval. It sounded like ripping fabric on steroids just a ear spliting whine.

dont know what I miss more the car or my grandpa.
 
Sounds like my Grandpa and my Dad.

Dad told me about a Car they used to have when they uh...."made whisky" togther. It was a 40 Ford Coupe with a Flathead V8. Useing redneck tricks and backwoods igenutity (combined with driving skills that will make you crap your pants) they we're out running cop cars well into the late 50's early 60's.

They got out of the business in the early 70's, but my dads still got that flathead engine....sitting in his barn. The car got wrecked (actually by my grandma on a trip to the grocery store) in 62, it was replaced by a 57 Plymouth sedan.....no work was done to the plymouth...but it still woulda had trouble even getting caught up with that old flathead.

Its funny what a little bit of time and alot of experince and igenuety will do.
 
Howdy Back All:

Hey Comet guy, I know that you specifically asked about points of weakness, but, this is a bigger mind-bender than just that. Fact is you have a good strong stock system. I'd focus on lightening, balancing and controlling oil to improve on it.

But would you mind sharing answers to a few detail questions? Is this on an 1/8 mile track? What carb are you using? What trans? You said a range of '69 to '72 for engine parts. How limited are you to modifying stock parts? Such as a performance valve job, back cutting valves, can you use a lighter, one piece stock 4.0 V6 retainer?

In general, it is a good plan to choose a cam profile that compliments the flow characteristics of your head. What are your cam specs? If these two components are coordinated you will increase your engines efficency in that range. The flow capacity of a stock one barrel may dictate the optimum rpm range. The other details are to tune your gearing, ignition and exhaust to that range too.

Keep the info coming.

Adios, David
 
I would also consider a "cheater" cam such as the stock one from a 250, same years. A factory cam with a little more lift and duration. Then I would "adjust" the cam timing to try and pick up the upper rpm curve a bit. A little judicious filing on the cam gear slot to retard it a couple of degrees. Practically undetectable. :twisted:

You probably can't add a port divider to the head, but there's probably nothing to disallow welding it to the header.
 
I can help out a bit here, for NHRA Stock Eliminator you must run specific "stock" parts. There have been some exemptions such as aftermarket con rods, electric waterpump drive,elec fuel pump, any ignition, stock lift but unlimited duration cam, etc.

The head is allowed a 3 angle valve job PERIOD! No porting, polishing, grinding, back cutting valves, etc, whatsoever. Same as intake, as cast, no grinding to even remove sand flashing. Must keep original carb for year of engine with no mods which will increase airflow.

With extremely tight rules, you must flow a bunch of stock heads to pick the best head. (flow differences due to casting or mold condition) Guys will have BOXES of new pushrods to get 12 (or 16) EXACT SAME LENGTH pushrods.

You can only lighten up the remainder of the rotating assy to the lightest. In other words, weigh all the pistons and rods, and balance the others to match the lightest. You must have at least one stock, unlightened piston. As far as skirt mods (or ring width,placement,number) the pistons must remain stock or an approved aftermarket replacement. (there is a approved piston list)

My 2 cents, run the strongest pushrod you can afford (due to the length) to minimize deflection and loss of lift. There is no approved rod or piston for a 71 so your stuck there, I would change to a shorter pin and spiro locks which would be a bit lighter then rebalance (yes this is legal)
The rocker stand trick is good, but I wouldn't get bent up about lots of oil pressure, any more than 7-10 pounds per 1000rpm is wasting hp. You have a scraper which is good, you want to cut down on windage. Are you running royal purple oil? Expensive but they pay contingency and more importantly they reduce drag. (and run a light grade, talk to them they will recommend what oil to run in your application)

Cam: I know your running a stocker cam now, talk to bullet or comp cams and see if there is a better one for the new parameters. Different duration/lobe spacing/centrelines. Are you running shubeck or Sherman lifters? Rpm potential there with the ability to run stupid high seat and nose pressures. What are you running for a damper? The stock cast ones can be dangerous above stock rpm, not only for the harmonics they don't cancel out, in comparison to a rattler/etc, but also due to them possibly exploding from centrifical forces. 6000-6200 would be all I would want to spin up any engine with a cast damper. (or dampner for some of you, Lol)

One last thing, I don't know what your running for headers, but a properly tuned (length and dia) set will certainly help get up there, and make more power at peak. Talk to Greg Fulk over at classracer.com on the tech board, he's the guru for inline sixes, fours or anything that's an oddball unknown combo. :wink:

Lotsa luck! (I knew you'd keep the six instead of a crate 302 :D )
 
Oh yeah, something else I just thought of.

A question for those more knowledgeable than me with the 200, would restricting oil flow to the top end help? Are they prone to oil starvation/spinning bearings at high rpm? If so, restricters could be installed to minimize that.
 
If you haven't already, I would buy a wide band A/F meter. You can't run it in competition, but you can use it at the local track to nail down tuning sessions.

I have sen cars with poorly fitting hoods. You know how the hinges don't quite close all the way down in the back? It's called poorman's cowl induction.

The oil pressure info is worth alot more than you would think. The first thing to consider is oil returning to the pan. The better you can control the oil the less, pressure and volum you can run. Check to see if you can enlarge and polish return passages. Concentrate on the passages at the rear the most, this will help reduce oil hitting the crank and robbing power.

There are lots of things you can do with lifters. Crower sells Chevy lifters that are hyd that you run at the botttom of their travel. When you look at it, it is a hyd with the spring but it functions as a solid. I would think they also sell fords. You have to run longer pushrods to keep the correct rocker geometry.

Once you get it running on a solid lifter, you can test with the lash tight and loose, then you can try tight int and loose exh and vise versa. Record results and talk to your cam guy.

Speaking of rocker geometry, at some point you should check it well. I have seen engines with poor geometry do crazy things. You should check it with lite weight springs and a good indicator. If the pushrods aren't the right length you will not get full lift and it will have more friction.
I would also check into having the rockers coated inside with some kind of dry film lubricant. Maybe even bushed (if allowed) with an extra wide oil groove in the center. Reduced contact area(less friction). A yearly rebuild should not be too costly.

I looked for info on the IHRA and NHRA websites and found no info for port volumes on log heads. 8) It might be possible to work on the log and leave the ports alone. If you can't see it you can't tech it. I personaly think that you can be competitive without actualy cheating tho.

There are lots of ares on the car that can be pushed to their limits. You aren't running terribly high speeds so you can experiment with added air pressure to the front tires for the least amount of traction (drag).

You can experiment with front end bushings and shocks. You have two things to consider. A lot of front end travel will let the car rock back and kind of get a running start before breaking the beams which usualy results in lower ETs. The flip side is, that will slow the cars reaction time. You need to be able to cut the best reaction time possible, if the cars reaction time isn't quick enough you will get beat by a slower car.

While we are on the topic of Ford front ends. Check the specs closely and think less rolling resistance. Also think about the ride heigth. (front end rared up coming out of the hole) Visualise the tie rods being level at static setting. When the front end raises the tires will toe out scrubbing off speed. Lower the front end and it would appear to do the same. This is not taking into account the unequal length control arms. I would consider the possibility of setting it up a little lower than centered. The theory being that when you launch, it will rare up about the same amount above centerline (back in spec) and then settle down to below centerline (back in spec) on the top in of the track. Actualy before the top in because air will be pushing down on the car. The unequal length control arms might blow this theory out of the water but I would check every possible source for improvement. You can take some videos and use a jack to explore this area. If it looks promising hook up with a good front end guy and explore it further. Also check to see that the rear end is aligned properly. You would be supprised how many are off. Your car is running slow enough for these things to be a huge benefit. You can also look at overall height of the car. If rules permit. Holman and Moody were known for lowered cars. In Nascar they would role the rockers to allow them to lower the cars more. Speaking of Nascar, a progressive rate spring will allow the car to run lower at speed and still pass tech's minimum height.
Again you don't want to make it unstable but you have room for improvement form the factory specs. These cars were setup to be stable for anybody to drive, not maximized for minimum friction.

Just apply Simtty's hundred puond rule to every part possible and it will get there.
 
Stubby, I agree with your post, but there are some area's of concern.

You wrote "I have sen cars with poorly fitting hoods. You know how the hinges don't quite close all the way down in the back? It's called poorman's cowl induction. " Quite true, this does indeed work....well enough that Nhra and Ihra tech watch for it.

"There are lots of things you can do with lifters. Crower sells Chevy lifters that are hyd that you run at the botttom of their travel. When you look at it, it is a hyd with the spring but it functions as a solid. I would think they also sell fords. You have to run longer pushrods to keep the correct rocker geometry."
Also true, this is exactly what I was refering to. With both Shubeck's (which are a mainstay in S and SS) and the less costly Sherman racing lifter do this only you can run stock length pushrods.(if that's what you need of course) The Shubeck's have a ceramic bottom and you can run over 600# over the nose in a SS engine as long as your running a billet cam.

"Speaking of rocker geometry, at some point you should check it well. I have seen engines with poor geometry do crazy things"
OH BABY ain't that the truth!! I've seen a motor run hard to 6300, drop 30hp then climb to 7600. Eventually it was discovered spring resonance caused by weak/wrong length pushrods was the culprit!

"It might be possible to work on the log and leave the ports alone"
UMMMM....NO! If caught blatently cheating you get at least a one year vacation. The amount you would gain would not be worth the risk. Remember, unless he is going for a record, the chance of a heads up run are fairly rare in that class. There are gray area's to exploit....but grinding isn't gray.(not to say there aren't questionable heads/intake/etc) :roll:

The rest on suspension is also dead on, I would think that as a class car already, he has done the majority, if not all of what you have said.
I think he is interested in just rpm potential and possible problems.

Class racing is so cool, how often to you get to see a 6 cyl pacer pull the wheels on the launch with stock parts??
 
I wanted to thank everyone for their insight and input. We will incorporate a number of the suggestions into the off-season overhaul.

In summary, the 2006 season was fairly satisfying. We ran a best of 15.30 at 86mph under ideal atmosheric conditions in October. That puts us 1/2 second under the NHRA/IHRA index for the class (22 lb/hp). The Maverick is still 100 lb over the minimum weight so another tenth of a second reduction could be assumed. The plan is to install a low first gear set in the C4 and improve the valve train(springs & pushrods), to survive higher rpm limits.

Hopefully next season will bring a 14 sec timeslip. :thanks:
 
All of my data is 1/4 mile. In my local race territory, there is one 1/8th mile track near Buffalo NY but it seems that every time we are scheduled there it rains, (or snows as it on Oct 14th)

A number of the IHRA divisional points meets are 1/8th mile but the majority of them are in the Southeast and just a little far for an Ontario, Canada lad to reach in a weekend.
 
goinbroke2":zbwpnhge said:
I can help out a bit here, for NHRA Stock Eliminator you must run specific "stock" parts. There have been some exemptions such as aftermarket con rods, electric waterpump drive,elec fuel pump, any ignition, stock lift but unlimited duration cam, etc.

The head is allowed a 3 angle valve job PERIOD! No porting, polishing, grinding, back cutting valves, etc, whatsoever. Same as intake, as cast, no grinding to even remove sand flashing. Must keep original carb for year of engine with no mods which will increase airflow.

A common trick (illegal of course) is to do most of the above being very careful to not to exceed the dimensions the tech guys check and then "shot peen" the head - chambers, ports to hide your work.
Stock Eliminator has some of the best kept secrets in drag racing.
 

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