Starter/electrical question:

[BillyGman]

Okay my fellow enthusiasts, I must admit to all of you who don't already know, that electrical tech stuff intimidates me, and is my absolute weak point amongst automotive topics. So it's for that reason that I need to ask you the following, which I suspect will be easy stuff for some of you guys. If you don't care to read all of the details nor the reasons for my question, then just scroll down and read the rest of the words in this post of mine that are in blue, and if you're curious about some of the reasons and details, then feel free to read the words in black also.....


I want to turn over the BBC crate engine I've purchased using the starter motor that I've already mounted on it. I want to do this before installing the engine in the car, in order to satisfy this carnut curiosity I have concerning exactly what PSI reading a compression test will yield for this engine.

In case you're curious about my reasons, let me explain that although a compression tester is most commonly used to detect the possibility of worn piston rings, or valve seals, that isn't the reason for my desire to perform this test on this engine since it's a brand new motor.

I've just read an extremely informative and intriguing article written by David Vizard (this guy knows his stuff!!!) which among other things, explains how and why a compression test reading can be used for evaluating if the compression ratio of an engine is ideal for the camshaft and valve timing that's used therein. Before anyone argues, please note that I'm very aware of the fact that a compression tester cannot be used to determine the static compression ratio of an engine, and that isn't what David Vizard is stating in the article. But since I'm not intending for this thread to be about David Vizards article, if you wish to hear more about my choice to use a compression tester for this evaluation, then click on this link to read his article, and it will explain. http://popularhotrodding.com/enginemasters/articles/hardcore/0311em_power_squeeze/

If you don't want to read the whole article, then just scroll down to the part that's titled "Dynamic CR" since that's what can be determined by the use of a compression tester, and also read the short section titled "Compression Pressure" which is right after that. It speaks of the ideal PSI readings being between 180 and 210 for the best combination of power and avoiding detonation/pinging for an engine that's run on 93 octane pump gasoline alone (which will be what my BBC engine will be run on).

Anyway, I need to know exactly how to jump the starter and solenoid in order to turn the engine over with the starter, in order to perform a compression test, before I put the engine in the car. I did this once before with a Cadillac engine, but it was so long ago, that I don't remember which of the starter terminals to use.

Obviously the positive battery cable get's hooked to the big terminal which is located on the starter motor itself, but that leaves the two small terminals on the solenoid sarter solenoid, one of them being the "S" terminal (short for "switch") which I know is for merely kicking out the pinion gear to mesh it with the teeth on the ring gear of the flex plate/flywheel. But how do I run a jump in order to turn the starter , and therefore turn the engine over for the compression test that I wish to do?? I know that I can simply use a screwdriver for this, or I can use a handheld button that has terminal clips that's made specially for bumping the engine with the starter, but which terminals do I need to run the jump from, and to ????

[BillyGman]

Ya know, someone just reminded me of the fact that this test might not be accurate with a cold engine, and I honestly was completely overlooking that. So maybe I'll have to wait until I get the engine in the car, and I'm then able to run it in order to get it to operating temperature before performing a compression test. That's the usual precedure anyway, but I completely forgot about that. False alarm....nevermind....if anyone is interested, let me know, and I'll tell you what the compression readings are once I perform this test on the engine after it's already in the car. (good article though).

[Zack]

Jump the positive terminal to the S terminal and the motor will crank.
Negative cable to the engine block.

[BillyGman]

Jump the positive terminal to the S terminal and the motor will crank.
Negative cable to the engine block. Okay Zack. Thanks very much!!

[shakes_26]

What Zack said.

I used to have a push button switch I attached to a 6ft cable with 2 conductors, they each had a clip on the end, for doing just what your thinking about.

They sell them at Napa, etc..

[Smokie]

Billy see if you like this product easy to use, inexpensive:CLICK (http://store.summitracing.com/egnsearch.asp?Ntt=starter+swit ch&N=115+314319&D=314319&Ntk=KeywordSearch)

[BillyGman]

Yes, I already have one of those, and they work great. It's just that it's been so long since I used it, that I had forgotten which terminals to hook the clips to, and I was concerned about damaging the starter if I hooked it up wrong.

[Smokie]

Yes, I already have one of those, and they work great. It's just that it's been so long since I used it, that I had forgotten which terminals to hook the clips to, and I was concerned about damaging the starter if I hooked it up wrong.

Billy the two wire switch I am familiar with connects one side to the battery POSITIVE, the other clip goes to the starter solenoid small terminal S. when you press the button, you are hitting the SOLENOID with 12v bypasssing the ignition switch. Engine turns over but you have no ignition.

[BillyGman]

Billy the two wire switch I am familiar with connects one side to the battery POSITIVE, the other clip goes to the starter solenoid small terminal S. when you press the button, you are hitting the SOLENOID with 12v bypasssing the ignition switch. Engine turns over but you have no ignition.Okay Javier. Got it. Thanks my friend. I used to use that trigger switch for bumping the engine on my 73 Vette when I adjusted the valves, but since I sold the Vette 2 years ago, I didn't even remember which terminal on the solenoid to hook it to.

So both Zack and you have been of help. When I get this behemoth of an engine into my Chevelle later on this month, that hand held trigger switch will once again be put to use from then on, since this engine has a solid roller lifter cam in it, and even with the poly-Locks and the stud girdles in place, I'll probably need to adjust the valve Lash as often as I change the oil (or at the very least check it that often anyway).

[David Morton]

Redo the lash after the first sub-average ET pass or when you notice a difference in the power band.

More often is overkill and a PITA.

[BillyGman]

Redo the lash after the first sub-average ET pass or when you notice a difference in the power band.

More often is overkill and a PITA.Dave, I'm open to opinions and insight on that, since this will be the first engine I've ever owned with solid lifters, as well as one with camshaft specs that are as radical as the ones this has (duration @ .050" is 268/271 int./exh. and lift is .705"/.708" int./exh.). Although Lunati states in their catalog that this cam is "easy on valve train parts" I think it's safe to say that this cam is on the edge of streetability.

I'll be driving the car on the street every week in the spring, summer and early fall months. So it will see considerably more street time than race time on the drag strip. So I won't usually be able to tell that the valve lash is out of adjustment by ET's being higher, and I would think that with the power level this thing is at, I won't be able to hook-up well enough on the street to use enough of it's power potential below 60 MPH to notice a difference in the power band (although the latter remains to be seen I guess).

One thing that I learned from an article I recently read that was written by the owner of Shaffiroff racing engines, is that having a regular routine of checking the valve lash on a solid roller cam engine can prevent bad things from happening to the valve train. The example he gave in that article was that if one of the lifters is beginning to go ( which as I'm sure that you know usually is caused by the bearings collapsing in a roller lifter due to the extreme pressure of the valvesprings that have to be used with solid roller cams) routinely checking the lash adjustment can uncover an early warning sign in the form of a lash setting on one particular valve being significantly further out of spec than the rest of them are, as well as being further out of spec than it usually is when an adjustment is needed. That can only be noticed through routine lash adjustment checks.

Only regular routine checking of the lash settings will enable you to recognize the early onset of such a warning sign. In which case, once it's discovered, it would be wise to at least remove the lifter in question to inspect it, and rebuild or replace it before it collapses completely, and thereby causes more extensive damage to other valve train parts such as the camshaft, and perhaps even damage to the lifter valley of the block.

It's for those reasons why I've been planning on valvelash checks and possible adjustments at every oil change. And since I'll probably only be driving this car once per week, and puting only about 5,000 miles on it per year, that will only equate to about two valvelash adjustments per year. So that isn't too bad. That's what my thinking is. If you believe that I'm overlooking something, then please let me know. ;)

[Joe Walsh]

Billy, I'm running a pretty stout solid lifter cam in the Cobra (although it is not a solid roller cam.).
I've found that it is pretty easy to tell when it is time to check/adjust the valve lash as the lifters get much noisier at certain rpms.
Also the engine will 'feel a little soft', and the exhaust note is not the usual crisp staccato blasts out of the side pipes.
I always keep a log book of how far each valve's lash is out whenever I readjust them.

[BillyGman]

Billy, I'm running a pretty stout solid lifter cam in the Cobra (although it is not a solid roller cam.).
I've found that it is pretty easy to tell when it is time to check/adjust the valve lash as the lifters get much noisier at certain rpms.
Also the engine will 'feel a little soft', and the exhaust note is not the usual crisp staccato blasts out of the side pipes. AAAAAAHHH, thankyou Joe. Sounds like good info to me, and info that's based on experience too. I aprreciate that bud.
I always keep a log book of how far each valve's lash is out whenever I readjust them. A Logbook? I like that idea. I'm gonna use that one. A small effort that might be worth a whole lot later on down the road. :up:

BTW Joe, the carnut in me is intrigued.....do you remember what the cam specs are of your Cobra cam?? I LUV that kinda stuff. I don't care if it's greater nor lesser than the cam in my engine. That really doesn't matter. It's still cool info to digest!! I rather look at a cam card than a news paper any day!!!

[Joe Walsh]

A Logbook? I like that idea. I'm gonna use that one. A small effort that might be worth a whole lot later on down the road. :up:

BTW Joe, the carnut in me is intrigued.....do you remember what the cam specs are of your Cobra cam?? I LUV that kinda stuff. I don't care if it's greater nor lesser than the cam in my engine. That really doesn't matter. It's still cool info to digest!! I rather look at a cam card than a news paper any day!!!

If memory serves it is @.600 lift and just under 300 degrees....I'll dig out the Cam spec card when I have a chance.
The cam is pretty wild, but it is 468 cubes in a manual transmission car that is very light.

[BillyGman]

If memory serves it is @.600 lift and just under 300 degrees....I'll dig out the Cam spec card when I have a chance.
The cam is pretty wild, but it is 468 cubes in a manual transmission car that is very light.Yep, that is pretty stout for a 468 engine. I'm told that in general, the bigger you go with the displacement, the bigger you can go with the duration and lift w/out sacrificing low-end power.

And I know those cobras are super light. I believe they're only 2500-2600 LBS. It's too bad that they don't allow people to race them at the dragstrips, because I'd LUV to see the times some of those things will turn. I know they don't let them race because of safety issues though.

BTW, if you do dig up the cam card, it's the duration figure @ .050" that I'm curious about, and not the "advertised" duration. The advertised duration on my camshaft is 304/309 (int./exh.) but since all the cam companies take those advertised duration readins at different lifts (some @ .006", and some @ .009" ) then it's worthless for comparisant purposes. And that's why they came up with the standard of the duration figures @ .050" lift.

[David Morton]

Sounds like you're gonna do alright with that motor Billy, I was just passing along third person hearsay from a guy I once knew that did a bit of dragging in his 340 "shorty" '73 Dart. It had a 1 gallon coolant reserve tank (no radiator) electric W/P, etc.

I myself don't get the logic of having a street-car with solid lifters. Unless 9000+ rpm is the target and weight is a major concern, there's lots of ways to get hydraulic lifters to work without pumping them up and causing valve float. Restricting the flow of oil to the lifter gallery is a popular method and also there are (or used to be) hi-perf lifters that have high bleed-off rates to allow for higher rpm operation without the pumping-up action of normal lifters although they do sacrifice some duration and lift at the lower rpms.

Still, (getting back on hi-jacked topic) there seems to be a bit of myth that cam failures are caused by too much lash on a solid lifter setup. This comes from a misunderstanding of the events that occur when too much lash is present. When the cam lobe returns to it's base circle, if there's excessive lash, it will simply let things loosen up until the lobe starts it's rise event loading things up again, things that happen even when the lash is on target. A good cam grind shouldn't be so drastic in it's rise event that lash becomes a critical concern, although I admit such a grind could be possible. I just don't see a good cam manufacturer like Crane doing something like that. Remember, the need for lash has to do with having the engine run when it's cold (which is why you have to adjust the lash on a cold engine) and then allowing for the thermal expansion of the pushrod (mostly) when it gets hot. No lash cold means valves that never completely close when the pushrod gets hot. So all solid lifter setups have to have a lash adjustment, so it will let the valves close when it gets hot.

Needle bearings break and cam lobes get hammered by the lifter only when the lobe recedes faster than the valve springs' ability to overcome the inertia of the valve, rocker arm, pushrod and lifter is exceeded and is unable to keep the lifter on the lobe when it receeds. When that happens, whether it be caused by a weakening spring or by overrevving, the inertia does get overcome eventually, but the lifter has already separated from the cam lobe, and that's when the lifter slams into the base lobe and things break.

The only thing that happens when there's too much lash is that the torque curve changes because of the decreased duration and lift. In fact many racers have used this knowledge to "tune' the torque curve of thier camshafts, ususally in dirt track or off-road racing applications.

Don't buy the myth that a bit too much lash is gonna hurt something mechanical. That's simply untrue. Until it's outrageously noisey(er), you're Ok.

[BillyGman]

David,
as always, I do appreciate your input. I think you've misunderstood what i was saying, so apparently, I've failed to make my points clear in one of my previous posts. Allow me to try and clear this up.....

I wasn't suggesting that excessive valve lash would be, or can be the cause of a lifter failure, but rather it's the other way around. A lifter that's beginning to collapse, will cause the valve lash to be further out of adjustment spec than usual, and periodic checks can catch such an early warning sign before the lifter collapses completely, and then causes other valve train damage.

If whenever you go to adjust the valve lash periodically, you'll get use to seeing how many thousandths of an inch they're usually out of adjustment. And if you find one day that one of them is much further out of spec than the rest are, the cause of that might very well be the bearings of one of the solid roller lifters beginning to bite the dust. These early warning signs can be used to catch a lifter failure before it occurs.

Now let's move onto your comment about it not making any sense for me to run a solid cam on the street....

there's something you're either overlooking here, or something you're not aware of concerning roller camshafts....

and that is the fact that solid roller cams have much more aggressive lobe profiles than any hydraulic roller cams ever can. Because if you ever tried to use hydraulic roller lifters on a cam lobe profile that's as aggressive as most solid roller cam lobes are, it would fail very quickly, and/or would never follow the steeper ramps of the solid roller cam lobes.

In order for any lifter to follow the profile of the more extreme solid roller cams, very high open spring pressures have to be used (my camshaft uses 550 LBS of open spring pressure ) and there isn't a hydraulic roller lifter on the planet that can hold up very long to that level of spring pressure.

The point being, that higher RPM potential is NOT the only advantage of a solid ROLLER camshaft. Even if the engine red line is only 6,000 RPM like mine is, it will still have more power if fitted with a solid roller cam than it would with any hydraulic roller cam. And of course that's due to the valves opening up wider and staying open longer with the solid roller camshafts. So this engine I have will churn out more power from 2500 RPM right up to red line having the solid roller camshaft that it does, than if it were fitted with any hydraulic camshaft in existence. So that's the reason for running solid roller camshafts on the street, and on street/strip cars like the one I'm building.

[Joe Walsh]

Not to mention that wicked solid lifter sound that lets everyone know you are serious!!!:D

BTW: My engine builder, who is known for his 'FE' big block engines, did not want to even CONSIDER a hydraulic cam for my 427.
He said: "It just isn't right building a 427 without a soild lifter cam."

[BillyGman]

Not to mention that wicked solid lifter sound that lets everyone know you are serious!!!:D

BTW: My engine builder, who is known for his 'FE' big block engines, did not want to even CONSIDER a hydraulic cam for my 427.
He said: "It just isn't right building a 427 without a soild lifter cam."Solid cams are thought of by some to be "old school" for street cars, but that's simply NOT true IF you want maximum power. Higher RPM potentials are NOT the only advantage of using solid cams. There's also more power potential with them even in the midrange RPM's due to bigger lift cam lobes, which also have steeper opening and closing ramps with more area under the curve. That equates to greater volume of air/fuel charges entering the cylinders (more power).

[mtnh]

Billy, I hope that you'll be able to post a sound clip of that bad boy at idle...

[David Morton]

Good point Billy. You will do well with this motor.

Guess I'm still too much old school in some areas.

I remember the days of "Mushroom" tappets, when they were the hot setup.

[BillyGman]

Good point Billy. You will do well with this motor.

Guess I'm still too much old school in some areas.

I remember the days of "Mushroom" tappets, when they were the hot setup.That's okay Dave. You still are very helpful to me very often. There's also something to be said for years of experience in this hi-perf car game. I'm finding that it helps to have a balance of experience w/old school knowledge, while at the same time being a little bit studied on the newer and more up to date stuff. Some newer stuff is all gimicks and is worthless, while some of it is plain superior. Having a little bit of old school knowledge helps me recognize that at times. But nobody knows it all, and eveyone has their strong points as well as weak points in the different areas of car knowledge. There's no way that anyone can s[ecialize in every single facet of this game.