dukvet76

Okay, so spent a ton of money on getting my engine rebuilt this summer. Know what ... now that the guy has my money, and I have my engine, he won't spend any time tuning the damn thing.

My normal mechanic who R&Red the engine doesn't even know where to go with the damn thing. So now I am left with an engine I'm disappointed in!! To top it off, oil is leaking from the valve covers all over the freshly painted engine. :mad

I brought it to a recommended place to tune it, and they wouldn't even spend time on it! I'm getting very frustrated and at my wits end.

I would like to find someone that knows what they are doing to tune my car properly so I can get out what I put into it. It can get up and go on the highway, but I think it's still lacking in the take-off area. Could it be the carb, timing, jets?? I have no idea, that's why I need a guru.

Here's the specs on what's been done: http://forums.corvetteforum.com/zerothread?id=526826

He also rebuilt the Q-Jet that's on it now. I'm willing to pay someone to get it right!! Thanks in advance.

Fevre

Wish I knew more about Q-jets and I would give ya hand for free. Nothing worse than having a sweet car that runs like crap. You are welcome to come over to my place for lunch and a tune session if you like. I am not a guru but not a hack either.


[Modified by Fevre, 1:51 PM 7/8/2003]


[Modified by Fevre, 1:51 PM 7/8/2003]

Jvette73

i looked at yur cam specs on the other page. Looks like you got the XE268. That cam is not gonna be real peppy down low. When you describe it will run good from a roll but seems to lack from a dead stop. That sounds like a classic case of cam to big for stall speed, or stall speed not high enough for the cam. Do you have an automatic trans? If so is it a stock tq convertor. If so, the symptoms you describe match how the XE268 would function in a heavy car like yur vette with a auto trans and stock convertor. That cam wont start making good power untill about 3000rpm. When you leave from a dead stop your rpms are well below the beginning of the power range for that cam. so it will move out sort of sluggish untill the rpms get up higher, then it starts to kick in better. Sound familiar?

dukvet76

Sounds right on the nose :thumbs: I am running an automatic transmission. It was rebuilt last summer, but we are still not sure if it's a stock convertor. My assumption would be yes, it is stock. What can I do to pick up the take off on the car? Right now, for me to get any decent acceleration off the start, I have to hold down the brake and raise the RPM just before I take off. Is this the hand I was dealt on the rebuild? Is there anything I can do to help it? Thanks!

Fevre

Sounds like John pretty much nailed it and you didn't have to drive to Ann Arbor. :) You could play with the timing some but a new convertor sounds in order since you are unsure what you have now. I have a 2800 stall in my Formula and it blips right up to 2000 with little effort but of course the car hardly moves.

dukvet76

Any ideas on what the R&R time on this job would be? Also, what convertor should I buy?

bb69

One thing I can tell you, is to get rid of that high volume oil pump. I rebuilt my engine last year, and just installed a standard volume pump after having the high volume. The amount of wear on the distributor drive gear was amazing (high). Also, the extra oil pressure just caused oil to spit out my breather and onto my exhaust. I strongly recommend a standard volume pump. You should be able to get a new one for $20, and if you're going to pull the trans, pulling the pan shouldn't be a big deal. Just something to think about, but this is coming from my direct experience.

Good luck with the convertor.

Jvette73

Ive not had any problems with high volume pumps in either of my sB chevy engines. One thing you dont need is heavy weight oil like 20w/50. Heavy weight oil used with high volume pumps can cause extra stress that bb69 mentions. 10w/30 is better and will flow at a higher rate although the pressure might be a little lower. Protection is not about pressure though, protection is about volume. More oil circulating past a wear point provides better protection. I say the high volume pumps are good and would recomend Mobil1 10w/30 oil.

On the convertor recomendation. when I still had my TH400 I was using the TCI Breakaway 11" convertor. Its stall speed was 23-2500rpm. I was using it with the XE268 and 3.08 gears. It helped the launch alot.

bb69

Jvette73,
I have to disagree with you on the volume issue. Shoving more oil at let's say the crank bearing does very little. The actual protection is provided by the physical separation of metal. This is dictated by shaft speed, oil viscosity, surface finish, and oil pressure. You cannot increase this film thickness just by increasing the oil volume. The other problem with high volume pumps is they have the possibility, and I stress possibility, of sucking the sump dry in cornering or acceleration.

I will say that the higher volume could carry away more debris, but that shouldn't be a problem. The higher pressure can also have the affect of pumping up your lifters more than they were designed for.

After saying this, everyone is probably wondering why I used one. Well, I bought it before I attended some very informative bearing training classes, and also because I saw others were using it. Also, I must say that I have a freshly rebuilt stock engine with basic street clearances. If you build a race engine and open up the clearances, everything changes. I do agree with the Mobil 1 recommendation; that's exactly what I use.

Jvette73

bb69, the idea of high volume pump helping with bearing protection is that it circulates more oil thru the areas in a given amount of time. More oil passing thru helps keep the surfaces cooler which helps reduce wear. Yur definatly right about the gaps which oil fills between the bearing and crank surfaces. A high volume pump just replaces the oil in that gap more often. You can have all the pressure in the world, but if you dont have volume and circulation, yur gonna have problems. You also mentioned a couple of problems that could arise and your points are well taken. However, a sump running dry would take a combination of errors. Things like, running with low oil level, sludge in motor clogging drain back holes, and running at high rpms for extended periods of time. These things combined with a higher volume pump could make it happen sooner. But to blame the pan running dry solely as a fault of a high volume pump is an exageration in my opinion. Think about how low the pickup is in the pan. Its almost smack on the bottom. Some serious things would have to be wrong to run it dry. When it comes to hydraylic lifters "pumping up" as you described it, there would have to be other problems there too. Im talkin high volume, when a lifter problem might be caused by high pressure. Im sure you know that hydraulic lifters are designed to simply keep the valve train at 0 lash. If any oil pump would cause a lifter to push a valve into negitive lash, I would suggest the lifter preload is too tight or the valve springs are too weak.

So im not nessisarily dis-agreeing with you, but rather trying to be more complete in describing problems that could occur in any engine, regardless of what oil pump was run. And yes, if other conditions in the engine were not right, then a higher volume pump could add to the problem. But provided other things are as they should be, I can only see how a high volume pump would provide increased engine protection.

So again, I dont regard this discussion as a dis-agreement, but more of a means to fully explain and understand the full spectrum of the topic at hand. Good debate is a great way to learn. I dont think either one of us is flat out wrong.
:)


[Modified by Jvette73, 2:59 PM 7/10/2003]

dukvet76

It's kind of funny how things slide a bit off topic, but would anyone help in letting me know what kind of convertor I need to purchase to help the situation?

bb69

Sorry dukvet76, we just saw something that I thought needed attention. I can't help you with a convertor, because all my experience is with a manual.

Jvette73,
You make good points. I think the choice really needs to be made by the individual, but they should take both of our points into consideration. No one can argue with me that my gear shows significant wear, and no one can argue with your real world experience. I think our conversation will at least make people think.

I'm glad you're not p!ssed. This is what a forum is about. :cheers:

MikeC

Rob a torque convertor swap should take around 2 hours to do. fairly easy and straight forward.

I' d personaly put around a 2000-2400 stall convertor. This should let you get off the line much quicker when you want but won't be that bad for a cruiser. Much higher than that and you'll start noticing more slippage and cruising speeds.

Also since you convertor is now looser..... get and auxilliary oil cooler for it. This looseness in the convertor creates a lot more heat..... the cooler the oil the better in a auto transmission.

vettenoir

Have you tried Chuck & Kenny at Performance Parts Plus / Kenny's Performance Plus? They have a lot of experience between the two of them. I have the black '77 with the 80 ducktail that you may have seen cruising around LaSalle.

dukvet76

Thanks for the info, that should help out alot. Sorry vettenoir, haven't seen you yet, but you should see my vette at the Town Hall every once and awhile. After September, you should be able to see it all the time in LaSalle as I will be getting my new house then. We should meet up some time!