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Well, after more than a year in complete overhaul/restoration, I finally got my beloved Pantera (#5253) back today. It's bittersweet, however, and after the more than a few deliveries followed by immediate returns due to problems, I'm sort of at my limit considering the six figures I've put into the car chasing the dreams of my childhood.

Part of the project included a new engine. A Ford Boss 427F engine ( with Ford Z2 heads ( was built for the car, using a Jesel valve train. I've got a 750CFM carb on it. All of the work was done locally at a shop here in Las Vegas, NV. I haven't done anything to the car yet.

One would expect that with a 7.0L engine, the car would be devastatingly fast. At least as fast as the 2014 Shelby GT500 she shares the garage with. However, the car still has issues and I'd like to get some advice from folks on the forum.

1. The car runs way too rich. The exhaust is, literally not joking, eyewatering. If you're in the garage with this thing idling, it's going to be just like you were when they shot Ol' Yeller.

2. The car reeks of gasoline, but there are no leaks in the fuel system or the tank.

3. The car is gutless. With a 7 liter stroker, it's got practically no cajones. Not that I'm looking to do burnouts at highway speed or have to be put in traction due to the insane acceleration, but I feel like it should be a lot more...responsive when you dig into it a little.

4. There is a tremendous vibration through the car at around 2200RPM that only goes away if you're above 3000 or below 2000 RPM. It's so bad that the rear view mirror is largely useless. The engine is supposedly internally balanced from Ford and, as with the rest of this car, everything is quite literally new.

I get the feeling that a lot of the issues with the car are stemming from most shops nowadays not really knowing what to do with a car unless it's got the cookie cutter LS swap with a self-learning EFI system slapped onto it. It doesn't feel like it's been tuned at all, it's just been set to dump buckets of gasoline into the cylinders to keep it running. I loathe to return it to the same shop again because it's been dropped off three times now and returned twice. I get the feeling I'm going to have to end up learning how to tune carbs.

So, if anyone has any pointers on where to start addressing these problems and any advice to share, I'd really appreciate it. Also, apologies if this was also part rant...because it kinda is.

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Sorry to hear about your disappointing experience. I would think any decent mechanic that has experience with carbs should be able to tune your engine assuming all the mechanicals are in good order. Is the exhaust actually visible, gray or whitish/gray or black during idle? Is the engine rough, at the mentioned RPM range, during acceleration and deceleration? Is the vibration consistent? Is the distributor set up correctly? My experience tells me that moderately rich doesn’t cause vibration as you described. If you think it’s the carb tuning I would contact the carb manufacturer for a recommendation on jetting for your engine configuration. They should be able to get you close or at least drivable. Is the damper new?
Being accustomed to modern engines with EFI and cats, old school engine exhaust is a real eye burner.


@forestg The local shop was paid to do everything. And I mean everything. The car spent more than a year in restoration/overhaul. The car was stripped, media blasted, body worked (including installation of steel Group 4 flares), and repainted. The original wiring was completely replaced as the original harness had been chopped into quite a bit by previous owners. All new engine, new suspension, new interior...The list is very very very very long and very very very expensive. The fuel pump is an in-tank unit, I'm not sure exactly which one. I need to get all that information from the shop when I go down this weekend to collect the remaining parts.

@racecarmike The engine lopes at idle but is otherwise smooth. I'm told this is the result of the cam that was installed. I don't know what cam that is, but will need to find out. The vibration appears only on acceleration under load, and only within the 2000-2400-ish RPM range. I am concerned that the car smells of raw, uncooked gasoline, and when I went to turn it off today it dieseled a bit, leading me to believe that excess fuel is in the cylinders and is igniting after shutoff. Timing issue?

Agreed, fuel pressure should be checked. That can be done easily with a temporary hook up. If the pressure is too high a pressure regulator can be added. There should be a pressure spec for that carb.

Lopey idle is likely caused by the cam choice.

Along with carb tuning the ignition timing curve should be checked. Does the distributor have vacuum advance?

Holly is known to over-jet their carburetors out of the box. I believe this is because too rich doesn’t generally harm a motor like a lean fuel condition will.

I also endorse Bob Oliver for tuning your Holley That is all he does. I had him blue print a new 670 avenger for my 404 Cleveland stroker. He had all of the engine specs and when I had the engine dynoed on a stand the operator was quite pleased with how the carburetor responded to mild jetting changes. He said he generally finds holly carburetors to be nearly impossible to tune.

your vibration could very well be coming from your half shafts. There are 16 sets of nuts and bolts that need to be totally tight or you will get a vibration just like you are describing.

insist on getting a full list of the components used to build your engine, suspension, wiring and any other work you had them do.

I think Forest may be onto something as most shops now do LS installations with in tank fuel pumps. They may have just done the same to you without thinking things through

good luck


@davidnunn I'll find out but I know we used a steel flywheel.

@lf-tp2511 I'll reach out to Bob Oliver. I also have a QuickFuel 735CFM carb coming back to me and I'm not opposed to putting something more friendly on the car, either. The car, at one point, did have an EFI system on the old 383 engine that was removed and the driver's side exhaust pipe does have an O2 sensor bung welded on, with a plug at the moment. I may just go back to EFI...

As far as the vibration goes, I'm actually using Scott's (SACC Restorations) CV joint half shafts on the car, but I did retain all of the original parts, including the U-joint based half shafts. I'll find out from the shop what they did and I'll be dropping by there for a surprise visit tomorrow to discuss further.

I probably shouldn't have started digging around in the car. The "in-tank fuel pump" I was told that was installed in the car is actually a mechanical fuel pump. There is no in-tank fuel pump.

They also reused the harmonic balancer off of the old 383 stroker that came out of the car. Ford's part number on that is M-6316-C351. I wonder if they removed the 28oz counterweight from the balancer before they installed it?

Last edited by Ceseuron

In listening here to this discussion, it sounds most likely that you have an engine assembled out of individual parts "uncoordinated" by the builder and that reeks of an un-knowledgeable builder.

Internally balanced engine rotating assemblies often use Mallory metal to achieve that objective. It doesn't happen often but on occasion those slugs of Mallory come loose. It shouldn't be but this is one of the reasons that who is in charge of the project does need to have enough hands on knowledge to recognize an issue on the spot.

An average enthusiast with a fat wallet is not necessarily the person that should be in charge of the project.

Dieseling after shut down is most likely an indication of wrong initial ignition timing as well as no power response.

The Holley mechanical secondary carburetors, i.e., "double-pumpers" are set with race car idling fuel mixtures to, in Holley's words, keep the header scavenging from leaning the mixture immediately off of idle.

That generally can be EASILY fixed by adjusting the idle air restriction. That carb that you have should have removable "air jets". That's where one would start and it will be helpful to have an air/fuel gauge installed with an oxygen sensor in the exhaust.

In MY experience, ALL Holley "double-pumpers" out of the box will have your eyes smarting at idle. That is to be expected of them. That can be corrected without NASA knowledge and equipment.

The "vibration" could be caused by several factors and may be a combination of different issues occurring simultaneously.

The first thing that can cause this is the ignition timing set wrong.

The second thing, which is less likely but possible, is that you have an external balancer and flywheel installed with an internally balanced rotating assembly.

The other thing on a Pantera is that the half shafts need to be sequenced with the differential. You would have to be experienced specifically with Panteras to initially know that and how to do that.

I would suspect that there is no serious damage done to your car at this point. All of these issues are very correctable but will take some time to do by both a competent engine shop and a Pantera expert.

The largest shame here is that the folks you trusted and paid to do this, at least were unsuccessful and likely COMPLETELY ignorant buffoons?

I suspect that you are going to wind up with the right shop eventually and some here can help with that depending on where you are in the country? I can think of a few already and a few are right here on this Forum.

You are going to be the one who determines if you paid for this already with the current "shop" or if this is beyond what they offered? Keep a tab on what this all costs to get right and then consult with a lawyer that has experience with these types of situations. You don't need a legal buffoon involved to complicate things more.

Although it seems like a mountain right now in front of you, you are mostly frustrated and you just need time to dial this car in.

This is all you did to the car right? You didn't touch the suspension, brakes and tires too, did you?

I'm thinking that your "project" created what I would describe as a "brand new virgin race car" much like the initial GT40's were when they were delivered to the first "customers" like Shelby American in LA. They got the first three.

Wanna' discuss what was wrong with them at that point? How about...everything?

It took about three YEARS for two race shops, Holman-Moody AND Shelby American to make those cars competitive. How much time you got?

Last edited by panteradoug

@panteradoug A lot of the car has been changed, including suspension. It sits on Ridetech coil-overs, but still use the original control arms. Brakes are Wilwood 4 piston calipers on two piece, outboard mounted rotors on all four corners, but that was actually done to the car about a year before it went into restoration and there were no issues then. The car was fitted with Group 4 fender flares and a set of wheels from PI Motorsports.

What is the process of sequencing the half shafts with the differential? Would it be recommended to go back to the original half shafts? The kit I have from SACC is a direct bolt-on replacement and the CV shafts bolt directly to the flanges on both sides.

In giving the whole thing some additional thought, I think I the biggest issue is probably one of my own making, in that I was operating under the impression that the car would come out the other side of this project as a turn-key build, given the amount of money that's already gone into it. But these things ultimately never wind up that way, do they? I talked to the shop this morning and he wants to put the car on a dyno now, hook it up to to gauges, and fine tune it that way. What are your thoughts on dyno tuning the car at this point?

Last edited by Ceseuron

When you re-assemble the shafts, the flanges need to be at 90° to each other. If you don't it will cause harmonics, i.e., "bad" vibration in the shafts themselves.

You mean the engine WASN'T dyno tuned and the shop HAS a dyno. That's where you run it in, setting the valves, the timing, the carb jetting, carb float level, checking for leaks, etc.

Was that an "extra" that you said no to? By all means, put the thing on the dyno. That's your chance to fix what needs to be and build confidence that it is set up correctly and ready to run.

That's the most scientific you can be with the engine.

Last edited by panteradoug

Was the engine purchased as a crate (all assembled) engine or was it assembled by an engine shop? Most crate engines are quite good these days. If the engine runs with no vibration outside of the 2000 ~ 2500 RPM range then it's likely mechanically OK. The old damper is of some concern. I would look into the damper/flywheel comb for peace of mind. Not vibrating on deceleration suggests that it's not an engine balance issue but that's not conclusive.

CV joints are typically much smoother than U-joints and tolerate higher shaft angles much better. CV joints are superior to U-joints. Practically every car today with axle joints uses CV joints, certainly every high end sports car and every race car does. A half shaft issue/vibration would most likely be related to vehicle speed not engine speed.  I don't know your setup but I know Scott does nice work. Personally, I would not go back to U-joints. Most likely not your problem if they are installed correctly.

Can you better describe the vibration. An engine imbalance can feel different than a fuel-ignition induced rapid misfire kind of vibration.

@panteradoug The shop doesn't have the dyno at their location. The engine builder has the dyno. I most certainly have not said "no" to any part of this project. I am into this well over what the car is likely even worth, and I'm not really keen on cutting corners on it. I've insisted on the dyno and we're trying to get a date for that now.

When you say the flanges need to be 90 degrees in relation to each other, do you mean the flanges on either side of the gearbox? Or do you mean the flanges need to be 90 degrees in relation to each other from the gearbox flange to the axle hub flange?

@racecarmike I've asked for exact part numbers for the flywheel and harmonic balancer that was installed, but the shop did tell me the flywheel didn't have weights on it. The harmonic balancer, I'm told, also doesn't have any weights on it. The engine is the Ford Boss 427F short block with a complete rotating assembly and internals already installed.

Short Block:

Ford wouldn't provide an assembled motor entirely, I'm told, due to liability. I did go with a Jesel valve train on those Z2 heads, but I can't imagine that would cause the vibrations we have now.

The vibration that I get feels like a harmonic, rather rough hum that goes through the car between 2000-2500RPM. I just tested the car a moment ago in the garage and it does this in neutral, parked, when you run through the 2000-3000RPM range. It starts at 2000, gets progressively worse until 2500 or so, and then starts to go away the closer you get to 3000RPM. As it gets closer to the worse spot, the rear view mirror is basically reduced to worthlessness.

I don't think I'll focus much on the transmission side of things yet, as this appears to be more related to the engine. I think I'll spend my lunch break verifying we actually have the correct firing order just in case someone's crossed a plug wire that shouldn't be crossed.

I know Ford did sell complete engines. Let me check.....

They still do. I would initiate a live chat with a Ford tech on there Ford Performance website. When I bought my aluminum Ford block they where very helpful answering a few questions we had. They should be able to tell you what you have and which flywheel and damper you need. Your vibration description does suggest a harmonic caused by something not balanced correctly.

You can cross the transaxle and half-shafts off your list.

Since you purchased a Ford factory crate short block that part should be good to go. I suggest researching and confirming the damper and flywheel are both correct for that application before any dyno work. You need to get that behind you before you get to tuning.

@Ceseuron posted:


When you say the flanges need to be 90 degrees in relation to each other, do you mean the flanges on either side of the gearbox? Or do you mean the flanges need to be 90 degrees in relation to each other from the gearbox flange to the axle hub flange?

The flanges on the axle assembly.

Since the axle is in two parts, a male and a female, the two parts slide in and out to compensate for the change in length as the suspension moves up and down.

In servicing the axle it can be disassembled and reassembled with the axle flanges in a different location.

Those flanges need to be kept at 90° to each other. That would be in phase.

Being out of phase would create an unbalance when the axle was rotating at some rpm.

Last edited by panteradoug

Just to be clear, that applies to U-joint half-shafts. With CV joints axle plunge occurs at the CV joint spline. Some people argue that clocking CV (constant velocity) joints is only necessary with high axle angles. It's probably wise to clock your CV half shafts anyway. Easy to do. Basically the mounting holes from the inner should line up with the outer mounting holes. Some disassembly will be required. 

Disregard everything that was said about the axle phasing, you have clearly stated you have modern CV axles!

After the first couple posts my head was already saying get it on a dyno and a tune, a competent dyno guy will know where to adjust. At this point you want that to be chassis dyno running through the full drivetrain and not just an engine dyno which would require removal of the engine once again.


Well, we just got word back from the engine builder and we may have found the problem. It looks like the wrong flywheel did get installed and the one that's in there has a 28oz weight on it for an externally balanced application. So back the car goes, trans comes out, and the correct neutral balance flywheel goes in the car. From there, we're off to full chassis dyno for final tuning.

@racecarmike posted:

Just to be clear, that applies to U-joint half-shafts. With CV joints axle plunge occurs at the CV joint spline. Some people argue that clocking CV (constant velocity) joints is only necessary with high axle angles. It's probably wise to clock your CV half shafts anyway. Easy to do. Basically the mounting holes from the inner should line up with the outer mounting holes. Some disassembly will be required.

Yes, u-joints not CV's. I was answering his question Julian.

Last edited by panteradoug
@Ceseuron posted:

Well, we just got word back from the engine builder and we may have found the problem. It looks like the wrong flywheel did get installed and the one that's in there has a 28oz weight on it for an externally balanced application. So back the car goes, trans comes out, and the correct neutral balance flywheel goes in the car. From there, we're off to full chassis dyno for final tuning.

When you find something like this, that is evidence of incompetence, you need to check everything. Assume nothing is correct. You likely have more than one problem. Start with the crank damper. Rick’s suggestion is important too. Check that the motor mounts are installed in their correct locations, assembled correctly and that they’re tight. Move on to the ZF mounts and make sure they are shimmed properly, etc., etc., etc. It might be easier to ship the car to someone like Don Byars in Los Angeles and let him go through it.

795BC1B7-49D7-4A8E-A701-404281D83F1ADavid’s advice may seem extreme, but speaking from experience not necessarily a waste of time to perform

building my 404 Cleveland stroker was far from the smooth endeavor I had hoped for, with a very experienced local engine builder I had dealt with previously. Luckily I pulled a valve cover to inspect the push rod guide plates, an area I had cautioned the builder to pay special attention to.


Long story short I took the engine to my second choice local builder who did a complete tear down, check and recheck and proper reassembly.




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  • 795BC1B7-49D7-4A8E-A701-404281D83F1A
Last edited by lf-tp2511

My thought, when I suggested Don Byars was, sure, you have to ship the car there but Don can do in an hour what a non-Pantera specialist needs a day (or perhaps longer) to do. Don can tell at a glance whether something like engine and trans mounts are installed correctly. He also knows exactly how it should drive and “feel”. A non-Pantera specialist has no idea. You’ve invested a lot of $ in your Pantera and deserve to reap the benefit of that investment. Don’t let unqualified people ruin the experience for you.

Hey, Vegas to Lake Elsinore isn’t even that far!

Last edited by davidnunn

Unfortunately I'm on a time crunch. I'm moving on a set date that cannot be changed and I have auto transport for the cars showing up to pick them up. We have 14 days to solve this and get the dyno tune done. After that, I'll just have to find someone local to the midwest that can handle the car going forward.

I'm also hoping no significant issues come up with things like main bearings or anything else that could be damaged by excessive harmonics through the crank.

It will take as long as it takes to sort out your Pantera. A deadline won’t make someone incompetent, competent. Quite the opposite! You’ve heard the expression: “fool me once, shame on you . . .” Only someone competent can sort out your car. Why not get your transporter to go a bit further and leave it with Ron McCall? There are others too.

Frustration is usually an avoidable condition.

@davidnunn I suppose I should rephrase that. Either the car will be returned with the vibration issue resolved and the engine properly tuned, or the car will be picked up non-op by the carrier and shipped to my house. What follows then will be finding someone that can work on the car that is a Pantera expert, hopefully not terribly far away from me.

I'm hoping for the former situation, but should the latter one occur, then I'll be getting the cost of the work done to correct the car back one way or another. I would have used Don Byars for the whole project, and he did actually see the car not long after I bought it. But it wasn't too long after that I learned that he became a one man shop with cars on every lift and a backlog that would still have my car waiting to go in today. The car, in its pre-project state, was equally undrivable due to the badly built 383 that was in the car before.

At the end of the day, I believe the problem has been isolated and I intend to get what I paid for out of the current shop in the time I have remaining. However, given the cost of the project to date, if the issues still aren't resolved by the time I depart, then things will get a lot less civil going forward.

@jmardy The transmission was removed from the Pantera and, as we surmised, the wrong flywheel was installed. The miscommunication came about when the engine builder contacted Centerforce for the flywheel. As I understand it, Centerforce was told what exact engine was in the car, but also was told what the car was and the fine folks at Centerforce sent part number 700250-48, which has a 28-oz imbalance. In short, Centerforce provided a flywheel for a Pantera, not for the Ford Boss 427F engine that's actually in the car and this detail was missed during assembly.

To correct the problem, the flywheel and the entire McLeod RXT clutch have been sent over to Kroyer Racing Engines here in Las Vegas where they are going to balance the entire assembly to neutral. I'm not being charged for this, obviously. Once it's back, we'll reassemble the drivetrain and inspect everything again, change the oil and inspect what comes out for anything out of the ordinary, test the car and then we're off to chassis dyno for final tuning and adjustments.

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