This information is a sincere effort to impart a basic understanding of
automobile technology.
If, while attempting to apply any of the ideas,
procedures or suggestions herein, you should experience any kind of
automobile system failure, it will be as a result of your own
conscious decision and actions. All authors of text found here, or anywhere on
this site, disclaim responsibility for any reader's actions, and any damage,
injury, or death that occured or may occur based on information found
herein. Before proceeding, please read our
disclaimer.
Below are selected comments by engine builder Don Dulmage regarding B/RB engine build ups.
Rings are getting a lot of verbal abuse I notice so I will attempt to clear the air. first , these days rings are rarely the cause of oiling in an engine. Even motors with 200000 on them are still running with no trouble. 25 years ago that was unheard of.
Ring end gaps do not cause engine oiling BTW. hypereutetic pistons require huge ring gaps on the top ring otherwise they will butt at full throttle high load and pull the top off of the piston which is one of the reasons hypereutectics get a bad name. They require the huge end gaps because they trap more of the heat energy in the top of the piston rather than disapating it throughout. When set as the manufacturers specifies (.027 to .032 etc) for the top ring they will in fact under a full load position be almost butted but not quite.
The Ring end gap thing is very debatable even for file fit. Hastings ring company did some tests i read about in the late seventies with ring gaps and found no power increase from closing up ring gaps. they found no measurable power loss until gaps reached .052 in a 4 inch bore. Hastings are the OEM designer of most factory rings including imports . Mostly because of their technology on the flex a vet oil ring and if you are an experienced engine builder you can spot their unique design immediately so they are not dummies in this field. They have steadfastly refused to make a file fit ring set for racing.
Do I file fit my rings? Sure I do but i am telling you this just so you know it is rarely the rings or the ring gaps that cause oil use. PCV system can be a source of trouble . especially in a well sealed engine (i.e. total seals etc) They even used to warn about it in their early instruction sheets.
The black Mopar Performance valve covers are terrible for oil control. baffling is insufficient although Greg Bolt in Campellford came up with a new set of baffles that work much better. We also have welded a full length baffle in the valve covers to cure the problem in race engines with full rocker oiling. If you have a mopar book read the blurb on the unpainted covers in the MP catalog. That is a real eye opener.
Valve seals and valve guides are another source of trouble and #1 on the list. The intakes need to be the sealed type that press over the guide otherwise on some cars, on the passenger rear, will suck oil if it is slightly over-ed in some situations. Also guides in stock heads are too long for any cams over 500 lift and must be shortened to provide enough clearance for the valve seal at full lift. otherwise the retainer will smack them and split the seal and VOILA , instant oil burner. even just one split intake seal will turn a good sound engine into a plug fouling smoker.
The engine can suck oil under the intake of there is a mismatch or weak gasket seal. #1 culprit is when heads are planed the intake doesn't sit right. Often this is caused by the ends of the manifold sitting proud on the block end rail not allowing the manifold to sit down on the head properly. We always relieve the ends of the manifold with a grinder back about an inch underneath on all four corners .
As for the rings: The Oil ring controls oil and the second ring in some designs is said to scrap the walls clean but the top ring really does give a dang and has no affect on engine oiling. Another common cause is Chevy disease which is when a Chevy guy built a B mopar and fits the pistons to small block Chevy specs.
Also a tight pin falls into this category as well. These two conditions cause piston and cylinder wall scuffing and the combo of the two is worse. Why does a tight pin cause cylinder wall scuffing you ask? good question! because the tight pin causes the piston to get hotter than it was designed to be in the pin boss area. When a piece of aluminum heats it expands quickly and if there is not enough room for it to grow it squeezes the oil film off of the cylinder wall and proceeds to try and fuse itself to the wall. Very quickly. In less than an hour there will be two long grooves worn in both the cylinder wall and the pistons which are very distinct. The machine shop guy will have some wonderful explanation that is designed to confuse ending with how mopars are junk etc etc but in reality pins were too tight and clearance too small. An engine in this condition will still run but will eventually become noisy and a severe oil user. I see this at least two or there times a year as we are called on often to do there pair or to consult on the problem or cause. We alway check and correct pin fit in all motors although i must say Sealed Power (FM or TRW) have really done a great job cleaning up their act in this area. Obviously they care. Pins should not have any perceptible tightness when properly installed. BTW A race engine on the street with race rings and clearances will always use a bit of oil . It will be hard on tires too but somehow it doesn't seem to be important.
Well thermo quads were great in their day and were a huge improvement over the AVS BUT a good Holley will hammer the doors of them matter what. They are a very complicated carb . I believe they have something like 131 parts inside, plus the floats are prone to sinking, so always replace them . Last time I looked no strip kits were available. I used to do a lot of them and once had a fellow drive from Florida to have me fix one he couldn't get repaired properly there so i am very familiar. Wager is a great fan of them and always tries them on every motor but the old Holley will beat them every time.
Why? well because they are an emissions oriented carb. That is why they were made and despite the huge CFM that design and fuel curve inherit to each other. That is not to say they are bad. because they aren't and they do make a nice working carb on a 340 etc but my experience at least has been that a good Holley well set up will always be fast at the track no matter what you try. We even have a carter competition thermo-quad we have used but results are always the same.
Duration controls RPM, lift doesn't really enter into it. For a hydraulic in a typical BB Mopar every degree of duration at .050" gives 25.34 RPM. If you have 231 @ .050" you should expect 5853 RPM. I would change that to around 5800 RPM but it gives you a way to predict it that works.
For a solid with 231 @ .050 you can expect a bit less as a solid gives 23.54 rpm for every degree at .050" so it would be 5437.74 or 5400rpm. Yes friends, a solid gives less rpm for the same duration than hydraulic but it can run higher rpm so once you approach 7000 area it becomes the cam of choice. below that you are just kidding yourself however sometimes until recently we had no choice because really serious grinds were not out there other than my old friend Racer brown and of course cheater stocker hyd grinds. Nowadays there are many real good choices.
First, more lift in an iron headed engine does not produce more power. In fact, it usually produces less. "What makes you so sure, Don?" You ask (I can hear what your thinking). Well if you have been to my website or read my book, you know that I've tested everything first so it is not opinion. I have run 23 cams in these motors. I bought an Ultradyne 613 cam after I had Old Reliable running strong. Our head flow was in the mid 280 for CFM at 540 lift. We knew that head flow did not improve above that and in fact would go backwards above those figures We knew we could port the heads so they would sustain lifts to 600 but they still wouldn't flow as much air as the real good heads did at 540. (Dvorak did a real good "honest" test of all heads in the 90s in Chrysler Power Magazine and it is one of the best i have seen. Our own tests agree with his, exactly! ).
Still not sure? I ordered the 613 cam as it was advertised as the most powerful solid racing cam currently available for the BB mopar (Muscle Motors ad from the early days. ) I replaced the Racer brown which was running 11.50s at the time in a 4150 lb car. (I am not kidding that is fact! it weighs that much) The car immediately slowed down. I ran shift loops at a different track so know one would bother me for two days , tried jetting, tried 1/2 inch fuel line and bigger pump. Different timing setting, moved the cam etc etc. Could just get the car into the 11s with 11.76 being the best on an extremely good run with awesome hook. MPH was also down so I took the engine apart to see if all was well. It was. I retest-ed the heads on my flow bench and came again up against the limited lift ability of the heads. I took another head and ported each intake port different including one bronzed up and holding a 2.3 inch valve made from a reworked BB Chevy valve.Still was unable to get flow above what my heads flowed (I still have this test piece by the way).
So i contacted cam manufacturers and asked for a cam with similar opening and closing durations as the Ultradyne but reduced lift. Lunati was able to supply a cam that had exactly the same specs except it was 520 lift. This will be the perfect test i thought to see if my tests were correct or if I was just dreaming. I installed the cam and immediately the car ran 11.51 and the higher MPH returned . The Lunati was an excellent cam but hard on valve springs. It ran exactly to the tenth of a second what the STX 20 Racer Brown ran and the racer brown was very easy on parts so I eventually reinstalled it.
Mr Dvorak by the way draws the line at 530 lift while I stretch it to 540. Even if I am an idiot he is no fool when it comes to these motors. So bottom line is would a car with a high lift ultradyne or Hughs cam and ported iron heads run faster with a STX 20 racer brown or the 520 Lunati listed in my book? The answer is YES. Because the cam more suits the design of the iron cyl heads.
I believe however with after market heads the ultradyne would do the job if the heads support flow above say 615 to 629 lift.
As for the rocker ratios. I would like so see a controlled test back to back runs with 1.5s 1.6s and 1.7 on an iron head engine. I suspect the actual results would be "disappointing" to say the least however me and Wagar are going to try that this summer. to find out for sure because there is nothing like actually testing the stuff. I asked my cam grinders what they thought and they both said "sometimes it works, sometimes it doesn't. There are many factors involved " We made a set of 1.7s in the seventies and tried them on my 440 dart. there was ZERO difference but times have a changed and i want to try it again. Having said all that if you love your cam just enjoy it and dont worry about t what i think.. You car is running real strong and that is all that matters
Guides in stock heads are too long for any cams over 500 lift and must be shortened to provide enough clearance for the valve seal at full lift. otherwise the retainer will smack them and split the seal and VOILA , instant oil burner. even just one split intake seal will turn a good sound engine into a plug fouling smoker.
Nowadays the hole or cylinder is finished to the 030 size and the piston is actually smaller than that allowing the manufacturer to control the piston clearance automatically. It was not always so but manufacturers had so much trouble with people fitting pistons too tight that this method which is a no brainer was adopted.
If the engine is to be abused (driven hard) then we still add a bit of extra clearance for safety. I remember when i was training at a TRW engine clinic. The instructor said, and I quote: "When we say a piston need .003" clearance , that means that is the MINIMUM clearance that piston can survive with. The same is true for bearing clearances. If the spec is 0015" to 0025" if you fit is less than .0015" then IT WILL FAIL. That low figure is not the ideal spec. It is the absolute MINIMUM that will survive. The same applies to Piston Skirts."
For the most part the change in making the clearance on the piston and using a standard bore size (ie +.030" or +.060") has reduced the problems greatly however we still see every year someone trying to build a big 440 engine with small block Chevy clearances. They are always done in a Chevy shop and they always fail within a week or so of firing the motor.
Regarding Summit cams, If you just want a rough idle they will do the job as will sealed power, federal mogul, and many other generic cams. You will get little if any power from these cams .My favorite is racer brown because these cams were specifically developed for theses motors, however Comp cams has recently put in an admiral effort and developed their extreme energy series which so far appears to be excellent and Mopar specific. Ultradyne has mopar specific but for me the lifts are too high for the duration which is to say they do not match the reality of the iron head engines.
They would be fine for aftermarket headed engines though and Hughes is similar. Erson in the 70s had some excellent Mopar B/RB cams but they are not in the in the catalog anymore since they became all things to all people.
Lunati has some Mopar cams as well , one is their version of the 426 max we degreed cam and I suspect it would be a good cam although I have not run that particular one.
Dual planes are essentially two four cyl manifolds grouped together on a V*. They each feed from one side of the carb or carbs and make a effort to separate the cylinders by firing sequence as much as practical. This is good for torque and bottom end performance. Single planes draw all from the same plenum and use runner length and the availability of all four barrels of the carb to make extra power. They typically are not as torquey down low and midrange strong as a dual plane.
However, the Edelbrock Performer RPM is a serious piece of manifold that has huge port runners at the proper length with a generous plenum. It is the best of both worlds and a cut above most other manifolds. It is particularity well suited to our engines in traditional tune . It does not belong in the category of "just dual planes" but is a cut above (make that a thick slice above.)
If we could get Vic and his Daughters to make us a 2X4 set up with a Performer RPM design then we would really have some fun. Food for thought though, many 273s and 318 were single plane from the factory in the early years of the LA motors so a single plane can be made to work down low with small runners to speed up velocity. (Port velocity helps torque. ) The Max Wedge single 4bbl (Yes Virginia they really did make them and I have e one) was originally built in a single plane then came the rev2 manifold that is a dual plane and a very well designed manifold. It was said at the time to be 14 HP over the single plane design.
The single plane is not always the best set up. It depends on what you want the engine to do. Our engines have strong midrange and bottom end with a respectable top end . The competition has very little bottom end grunt and a so so midrange, They are more of a top end motor so when you are building a B wedge to compete it is wise to concentrate on what makes these engine es great. and to build your combo around these unusual characteristics. Otherwise it is like trying to make Merle Haggard an opera singer. (Like Why ruin a good thing?) Build on strengths is my motto. A well set up Mopar wedge can have the race won long before the bowtie begins its charge. Then all you need is enough HP to hold him off up top. I am talking about stock based iron headed stuff here by the way not the megabuck superflow 300cfm plus hi-dollar setups.
the perforated side of the manifold gasket goes into the garbage can with t he other side. Do not use them, The engine is not supposed to have gaskets there and the usually blowout sh ortly. Clean both surfaces well and skim a light smear of Hi temp ultra co pper silicon on the manifold surface and install. That will last forever
Don's law: Double the cubes. for the street go to the nearest below and for strip the nearest above, For a 440 440 X 2 = 880cfm so a 850cfm (or 870cfm Street Avenger would be good.) For a strip car, a bit bigger wont hurt. For a 400 we use a 800cfm for street and an 850cfm for strip. A 383 we use a 750cfm/780cfm for street and a 750cfm/780cfm with full mods (no choke , top +cut off etc ) for strip. A 340 needs/360 needs a 700cfm although a 750cfm works well if vacuum secondaries. A 318 likes a 600cfm. If you use the other formula the results when you match it will still give the +same carb size. A 440 is almost impossible to overcarbeurate
The article though v can say whatever it wants. The flow bench and the engine dont give a darn. A 452 or 346 will outperform a set of 906s hands down when modified and all will leave a set of 915s in the dust. Smog by the way doesn't mean no performance. The heads are redesigned to burn better and flow better. I am currently doing two motors , one and old reliable for the street and the other a B series for Le-mans race in France. Both have the last issue 452s with the small plugs and extra spark plug cooling. I am impressed to say the least. There are little nuances in these heads that the others dont have. Best ever flow bench test was Dan Dvoraks in the 90s that appeared in Chrysler Power. When we tested heads here we found almost identical results.
So if you guys want to chuck all those smog heads chuck them at my door please. They make serious HP when ported and 214/191 s are installed. I saw the same test as Bob. It was by my favorite writer but because of the way he did it. (lumps all together) I found as someone very familiar with these heads it was meaningless. Started with one premise to test all heads and ended up with another ignoring the ones more or less we are talking about.
We were able best ever to get 286 CFM out of a 452. That was unusual but high 270s to just into the 280 cfms are possible. (906 cant make that) the 346 is not far behind the 452 , just minor. That much flow would be capable under ideal conditions to produce 629 hp That would be in a perfect world but in our down to earth "life's like that" world high 500 and even 600 HP would be possible. That is HP way above street requirements for most of us and even bracket race requirements. I am thinking it ain't too bad myself.
Our rule for header size which never gets us in trouble is the dia of the primary pipe should be as close to the diameter of the exhaust valve as possible. then all the calculations work. Bigger (oversize) headers must be longer to work at the same RPM and smaller (undersized)headers , well anything smaller than the exhaust valve diameter is too small in my thought. For instance with a 1 .74 exhaust we use a hooker 1 3/4 (We often lengthen the primary anyway because they are tuned above our engines sweet spot. ) for 1.81 we use 1 7/8 for 1.88 we use 2 inch. Like everything else we have discovered HUGE power comes when the combo is matched. "Bigger is better" thinking is always a power hurting decision. Like Earl says though too small will kill ya, every time.
Every motor I build is pre-oiled (leaves with enough oil to start it in it. ). I now often use my intervenes method though as it works perfectly and is less hassle. I also use high pressure grease on every cam and lifters. and have for many many years (30 plus) It has served me well. I DO NOT use white assembly grease (except on the cars door latches. ) On top of that I use the supplier's moly as well. I am fanatical about this because I have seen so many cams go south from friends and even competing shops that I take absolutely no chances . The time may be approaching though especially for full race engines that it is just not worth the risk running a flat tappet cam and we may become roller-ized. Once you get over 300 # spring pressure you are rolling the dice. you can get cams coated or even nitrided I have heard but the extra dough would almost buy the roller. It is too bad but I think the days of the flat tappet may be numbered. I am much more comfortable with a early core as in well used. I also recommend and used Diesel truck oil (aka gasoline severe service) as i believe it gives much more protection but even it isn't what it was 10 years ago as far as cam or scuff protection goes.