Just to give you an example.... (before performing the test I removed all of the rocker arms and spark plugs). Five out of the eight cylinders took from 37-45 seconds to leak down from 100psi to 50psi. #1 cylinder only took 15 seconds, #2 took 21 seconds, and #7 took 24 seconds. You could actually hear the air escaping the cylinders from the intake manifold that had the lower readings....I then turned the motor over just a bit, tapped on the valve/valve springs with a rubber mallet, and tried it again with the same results.

I spoke with Indy Cylinder Head this morning... They are ready to go back through it as soon as I can get it to them. Now where did I put my checkbook...?


[Modified by TONYDEE64, 10:25 AM 7/7/2004]

 

hmmmm...a leak down test is a touchy subject due to many different variables. Including a penchant for TDC or BDC testing. Personally, I believe it should be done at different points along the bore, or by moving the crank if possible....If you're really picky.

Check this link out. From what I've always heard, is that a leak down is based on a percentage difference between each of the two gauges when the cylinder is pressurized....Not the amount of time it takes for the cylinder to empty.
http://www.racerpartswholesale.com/long29a.htm

Here's another guy's opinion. See the bottom based on "ring seating"
http://www.type2.com/library/engineg/leaktst.htm

What I do know (learning from the pros who built some friends 10 second mustangs) is that on a new motor, Vaccum readings (or blowby + or - thereof) should always be taken with a grain of salt until rings have had enough heat cycles to cause proper seating.

I'm only trying to put you at ease. I seriously wouldn't do anything to the internals until you run it a while, but if you're worried I don't blame you for worrying about the valves being a possible culprit if you are in fact have leaks due to what you've stated before.




[Modified by vvv90, 10:20 AM 7/6/2004]

 

Thanks for the input. I will also check out the links. I did also find a small piece of what could be a bearing in my lifter valley so I still think I should yank it. I also heard a faint "tink" sound when the motor quit. If you were me, wouldn't you just pull it out and go through it just to put your mind at ease. I have big money in the motor (the block has thousands of $$ in it due to ... clearancing, machining, lifter bushings, o-ring, 4.6 bore. I have not totalled up the cost to replace this motor, but I'm guessing it's around $15-20k for the long block... I really don't want this thing to go "boom" at 20 psi.

Besides... I really miss those $2,000+ a month parts bills...

 

Ummmm.....Ok.....Damn good point.

Especially if you're finding pieces of bearings.


[Modified by vvv90, 10:35 AM 7/6/2004]

 

Believe me, I've thought of every excuse there is to not have to pull this motor.... I can guarantee you it won't be the last time that engine gets pulled.

Of course I was hoping to actually get some road time before pulling it... but that's just the way it goes...

 

Tore the motor down last night and found that my no-name gear drive (yep, this was the one place I did not ante up the big money for a name brand such a Pete Jackson, Jesel, etc.) and it simply let go. Beware, you get what you pay for!!!!... One of the snap rings of one of the idler gears came off and let that gear slide off its shaft and go bye-bye. This allowed the other idler gear to slam/wedge into the cam gear shearing off the dowel pin of the cam, two of the cam bolts, leaving the remaining cam bolt partially stripped and loose. There were a lot of shavings from the gears in the oil pan. The good news is the pistons looked perfect as did two rod bearings I looked at. I also didn't readily notice any bent valves.

I delivered the motor to the engine builder today and he immediately said that my cam was shot from sliding back and forth in the cam bearings (I thought it looked ok). I spoke with Crane and they are going to trade me for another one for a reduced price ($250 vs. $325). I'm going to try and take the next step to the next largest roller this time around and get a little bit rougher of an idle if they think it will still pull a reasonable vacuum.

I am having them dissassemble the entire motor and go back through it. He also said that you should NEVER leave the Dart heads valve job alone out of the box. So, I'm getting a valve job as well.

He will tear into it next week and I'll learn more, but for the time being I think I might get out of this for somewhere in the $2,000 range... and of course countless hours of my time. Stay tuned!

 

That whole situation really sucks. But at least you're going to have peace of mind. Especially considering what he said about the valves. What in perticular did he say was the reason for Dart assemblies to be redone? Just bad machining?

 

Hey Tony! Glad to hear that the damage was minimal. At least you may get a bigger cam with more lump to it! I doubt with the blower and the cubic inches that you would loose much bottom end. In fact with all that you may just want to loose a little on the bottom end

 

That's kind of what I was thinking... I don't think I'm going to have a hard time spinning the tires.

Matt, my machinest simply said that Dart mass produces their heads and they never send a set out the door before doing a valve job. In my case it's almost got to be the valves because I have total seal gapless rings, and there is no way there could be that much difference in leakage with those rings.

 

Tony, it would be very easy for your machinist to check them heads out. The machine shop I use takes a jig which attaches to the individual intake and exhaust runners. Vacuum is applied to the jig and the operator observes the gauge for signs of leakage. Any mis-ground valve or leaking seat would show up at that point like a sore thumb I always check my heads no matter who built them or from what ever manufacturer. Keep us posted on your progress I can't wait to see a video of that beast running and boiling the tires

 

Good point...Now that they're off, have you had your heads bench flowed yet?

 

I should have mentioned that they will test them with vacuum first before doing the valve job.

If you look at the pictures of my roll bar you will notice a tang mounted in the middle of the cross bar...that is for a video camera.

 

No, I haven't flowed them yet.. Maybe I will have them CNC'd and flowed during my next tear down. It's just a matter of time. So far they have been gasket matched, pocket ported, smoothed and blended. Much work was spent on smoothing the exhaust tracts and transitions (the blower will help the intakes). Of course the intake tracts were cleaned of casting slag, etc.

Here is a picture of my cam gear. I guess I was wrong, I didn't shear two bolts, but the other two were stripped in places.

http://f2.pg.photos.yahoo.com/ph/ton...&.dnm=3019.jpg

 

Cool engine,**** can the gear drive and start cruising.

 

You got that straight!!! BTW, I must honestly say that you have one of the most awesome Vettes I've ever seen... That thing looks almost like a Hot Wheel it is so unreal. I can't even imagine anyone ever trying you at a stoplight.... Any video?

 

big632

Holy sh|t ***** batman! That car of yours is sorta quick

I had to do some searching to find your link. You should add it to your sig.

 

Update..... I just got back from picking up my motor from the engine builder...I decided not to go back to Indy Cylinder Head this time and instead go with a small shop that is highly regarded around here. For the first time ever in my life I actually walked out of a machine shop and felt good about what I paid versus what I got in return. Their work looks top notch!!! I even gave them a good tip.

They did say that some of my valves in my new Dart heads were almost 3 degrees off from being concentric in relation to the valve seats...They said that they see this not only in Dart heads but also others from time to time.. Hey, when you mass produce I guess you sacrifice quality at least to some extent. Anyway, I couldn't be happier.. I had all new bearings put in (not that it necessarily needed them.. just cheap insurance). I am now more than ever a true believer of Mobil 1 synthetic oil!!!! No doubt it saved my motor from extensive damage.

This time I am going with a larger cam that has more lift and lope to it.(I already installed a vacuum can). I think the other cam was too small for my motor and really didn't lope all that much... wasn't obvious anyway.. This time I'll put ARP head studs in the blind lifter valley head bolt bosses (left them out before). I'll also take this opp. to take care of a few odds and ends.

I highly recommend Jim Stewart at Stewart Racing Engines.. His number is (317) 244-9129. I asked Jim if he has a punch card program in place like at Subway (buy four get one free)... cause you know I'll be back there.... just a matter of time....

Hopefully I will get it fired next week sometime.....

 

Awesome news. Anything else you're waiting on until you can drive it? Cryo treatment perhaps? Or is all you have to do is bolt it up?

 

I am adding the high flow Meziere so I have to reconfigure my blower brackets as well as alter the water pump inlet. So, that means I have to pick up some 1.75" alum. tubing and Tig up a long cross over pipe from the water pump.. I never did get around to cryoing anything... I'll probably be sorry about that.... Maybe next time... I just REALLY want to drive this thing.. I'm tired of waiting!!! The motor is not totally together and ready to go back in.. I'm shooting for starting this pig on or before this next weekend.. Did I mention that it's HOT out there in that garage??!!!!

 

As long as you don't plan on running super sticky tires, loss of traction will end up saving your driveline.