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Buford T Justice Update: A Very Frustrating Day On The Dyno And How We’re Planning To Fix It


Buford T Justice Update: A Very Frustrating Day On The Dyno And How We’re Planning To Fix It

So first, I’ll lead with an apology. This update was supposed to run last week but a blizzard and a bunch of other stuff jumped up and caused the delay. With the amount of email, text, forum, and other messages I got from fans of  the Buford T Justice 1987 9C1 Caprice I knew that I couldn’t delay in getting this latest story posted. Like Chad and I have promised from the earliest days of BangShift, we’re here to tell you the truth, give you the whole story, and not shy away from looking dumb, especially when we do it to ourselves. Consider this one of those situations.

As you’ll read below, we didn’t make near the power we should have with the car during our last visit to Performance Auto and Dyno in Plymouth, Massachusetts and we missed some big signs and reasons why. Fear not. We’ll give you the specifics and we’ll also tell you our plan to fix those issues on our next visit, which should be really soon.

AS ALWAYS, THE LINKS TO EVERY PREVIOUS BUFORD T JUSTICE STORY WILL BE POSTED AT THE BOTTOM OF THIS PAGE – CATCH UP ON YOUR READING TODAY!

Before we launch into our normal litany of photos and stuff, we’ll give you a spoiler alert and tell you that nothing blew up or broke, we just sucked out loud on the day we visited the dyno and missed what should have been some obvious, basic signs that the car was trying to give us with regard to its failure to make the power we thought it would with our nicely cleaned up 083 cylinder heads by Custom Auto Machine and the nice new lumpy bump stick from COMP Cams. We’re not blaming the parts, they are finer than fine. This one is complete operator error.

….and away we go. 

Before we actually drove to the dyno we needed some type of exhaust on the car. Remember, a couple of updates back we bolted the heads on and installed our Flowtech headers, too. I cruised the car with open headers for a short time before an officer of the law advised me that such behavior would result in monetary penalty. A quick solution was had after making a call to our friends at Holley where we ordered a set of Purple Horny header mufflers. This was the entirety of the exhaust system. Bolting these to the headers resulted in a noise reduction of perhaps 1%. Had I run an entire set of tail pipes aft of these guys, things would have been quieter, but I was in a rush. Technically I had exhaust. Thankfully I didn't have to plead my case to a cop...yet.

At the dyno shop with the newly touched up heads, newly installed headers, and wildly obnoxious exhaust anticipation was running high that we'd see big gains right out of the box. We strapped the car down, fired it up, spun the rollers and made.....7hp more. HUH? Yep, that's right. SEVEN FREAKING HP. The air/fuel ratios were lean to the tune of 14:1 though most of the pull, so we knew it was time to jet up. That had to at least start to fix things.

I wasn't paying a whole lot of attention when I winged the rear float bowl off and had that awesome sinking feeling of, "Whoops...that's a metering plate." Proper planning prevents poor performance. I should have known that this carb had a plate and not a block in it. For those of you who don't speak Holley, a metering plate does not have the swappable jets a metering block has. Instead it uses orifices in the plate to meter the fuel as opposed to the block and jets. Eff. Some quick Google magic confirmed that the #54 on this plate equated to roughly an 82-jet in the carb.

Here's what the business side of the metering plate looks like. Those slots and passages are where the fuel travels through before feeding the engine.

Thankfully Travis and Ben had an old 750 parts carb under the bench and we were able to steal the metering block off of that carb along with the bowl screws, and jam it back on our engine. We decided to move to an #88 jet in the rear of the carb to try and work the air fuel ratio down into the high 12 range.

Again, for those of your playing at home, the two round deals with slots in them at the base of this block are the jets. Our Holley jet kit has a myriad of sizes in it and we went with the #88. (Bigger the number bigger the jet and more fuel flows through it)

As this is not a double pumper carb (on the engine) it uses a cross over tube to move fuel from the front to the rear of the carb. Adding the width of that metering block that wasn't there before in the rear rendered this thing useless. Why?

Here's why. Since the metal tube stretcher at the shop was recently stolen, we went with another method to fix this.

A little length of brake line, a pipe cutter, and the little nipples from the original crossover tube fixed us up in a jiffy. We fired the car up quick and made sure there were no leaks. Rather than make another pull and check the results with the new jets, we decided to dive right into the cam swap. This was a big mistake. Why? As you'll learn below we saw no improvement of the air/fuel ratios even after going up the six jet sizes. How is that possible? It hit us on the way home, but we don't think the secondaries are opening up and perhaps they haven't been opening up for the entire time we've had this carb on the car. How can we say that? We'll go into more depth below, but that's what we're feeling like even today. We've got a mechanical secondaries carb ready and willing to go.

Here’s a quick video of a pull being made with the stock cam and our current carb on top of the engine. Think the secondaries are opening?

We forged ahead with our cam swap, not giving the carb another thought we tore the front of the engine down. With help from my father in law Tom (who is well over 6', so working on the chin scraping Caprice is a chore!) this was about 20 minutes in.

This poor little engine has been apart and together more in the last couple months than most engines are in a life time. Sorry lab rat, the future will see you coming apart again pretty soon!

Now was going to be the moment of truth for our LS lifter guides that were installed when the heads were plunked back on a couple of updates ago. With the rocker arms backed off, I spun the engine over with a bar two times.

After the engine was turned the advised two revolutions, we pulled the harmonic balancer, and yanked off the timing cover, which was another major fail that caused us recent headaches. The car had a one piece oil pan gasket and it snapped like a twig when we pried the cover back. More on that coming soon.

The first thing we discovered was a timing chain with a massive amount of slack. This thing was loosy goosey to the max.

After lifting the distributor out of the engine and running a couple of small bolts into the cam as a makeshift handle, took a deep breath and gave a tug. Low and behold, the cam slid out no problem. Those little guide deals worked great and saved us a ton of time!

There was enough room to slide the cam straight out after pulling the radiator and removing a couple of small braces. The cam grind, as per the factory marks is the same as used in L98 350 engines of this era.

Our new COMP lumper bumper was ready to head into the engine and free us from this lack-o-horsepower hell we'd been living in. The first step for the hydraulic roller was to completely sauce it up with the COMP supplied lube.

For those of you playing at home, this is a COMP XR276HR-10 cam. Duration is 276/282, lift is .502/510, LSA is 110, and the intake centerline is 106 degrees.

Re-installing the cam had a couple of moments that left us holding our breath. The first was when we began sliding the new cam in and heard a metallic TINK! The cam would move no further into the engine. We gingerly removed it, shined a light into the cam tunnel and saw one of the lifters hanging dangerously low. Thankfully it was one of the number four lifters so we reached in with a long screw driver, pushed it up, and went back to it.

This scene had a couple of guys who visited the shop clearly confused. We got one of two, "How the hell do your make that work with the intake on?"

Once the cam was in, we installed the cam plate and then the new COMP double roller timing chain, making sure to line up our marks as the directions told us with both dots in the up position.

With the chain installed, the timing cover bolted on, and a bunch of silicone gobbed on to the areas where the gasket broke we filled the engine with COMP 10W-30 oil and fired it off. The mill lit off instantly and we ran it for several minutes to allow the cam some time to familiarize itself with the lifters and get well oiled. Remember, it is a roller. Want to know what it sounds like at idle?

PRESS PLAY TO HEAD THE SNOTTY PISSED-OFF ATTITUDE THE CAR NOW HAS AT IDLE –

So it was at this point that we just knew all of our troubles were behind us and this cam was going to make it all right again. We fired up the car and made a pull. It picked up….2HP. Yep, two freaking HP. By this time it was getting late in the day and we’d been hauling ass for hours so we rechecked the valve lash, timing, and even the damned firing order. We pulled the car a few more times and picked up one here, two there, and then lost some when messing with the timing. So what in the bloody hell is the problem?

[divider]

We’ve got a couple of issues happening here that have cut the nuts off of the engine…we think. As we mentioned earlier, at this point it certainly seems that the secondaries are not opening up on the carb. The circumstantial evidence is the fact that we went up six jet sizes and our air fuel ratio did not change from the very lean 14:1 we saw on every pull we monitored. Secondly, watch that dyno video we posted above. Do you hear them open? It sounds all the world like a 2bbl running at wide open to us. How did we not know this? Plain and simple we should have. We’d taken for granted that the carb was cranking all the way open from the time we bolted it on and it probably hasn’t been. It explains why the car fell off some when the Holley was swapped in place of the grungy Q-Jet months back, and why the thing continues to run out of breath at 4200 RPM even today…even with the new cam and fixed up heads. We’ve got a Holley 750 double pumper to bolt onto the engine and try. It has mechanical secondaries. Too much carb? Maybe. We’ll test that, too. Yes, it is getting full throttle travel from the pedal.

Secondly there’s the ignition. This is another area that we should have been more on top of but just took stuff from granted that we shouldn’t have. We had the stock advance springs and stock advance bushing in our MSD distributor. While the advance springs are not going to make us more peak power, they’ll make the engine get to the happy place a lot quicker. The bigger issue is the advance bushing (in our opinion). The stock bushing in these distributors allows for a maximum of 21 degrees of centrifugal advance. There is no vacuum advance on this distributor so with our initial timing set at 10-degrees, this thing was only seeing 31-degrees of timing all in at full advance. That’s several degrees short of where it should be for this engine to be happy. Ideally we’ll be looking at 36-38 degrees all in with decent gas in the tank. We’ve since swapped the smaller bushing in, which allows for 28 degrees of advance.

In our opinion, these are the two most major factors hampering the engine and keeping our HP totals down in the 215 at the tire range. We expected 240-250 at the tire with this combo and we’re going to get there. We promise you that!

What’s next?  We’re going to get back on the dyno as soon as we bolt the new carb on and the snowbanks melt a little. Also, we have a Flowmaster exhaust system to bolt on and finally put a sock in this thing’s mouth. It has been very obnoxious with the Purple Hornies on it, especially because they are the ONLY things on it. After that we’ve got some more parts to throw at it and a mental goal of where we want to end up with power at the tire…before the nitrous.

So there it is, a realistic look at what happens when you make assumptions, get ahead of yourself, and fail to heed the warning signs the car is giving you. Lesson learned Caprice. You’ve won this round in the battle of public humiliation, but we’re not going away that easy. Stay tuned…

EPILOGUE – After the day we had on the dyno, both my father in law and I were tired and kind of dejected at the complete lack of power and seemingly fruitless effort. Matters got exponentially worse when I pulled into my driveway after the 30-mile drive to find the entire engine bay absolutely drowning in oil. The front seal piece for the oil pan gasket did not seal at all and the thing had been pumping oil out the front of it for the entire ride. Thankfully the pan was not dry (a couple quarts left in it), nothing appears to have been harmed, and we’ve been driving the car since. It was majorly depressing, though. I actually had to walk away from the car for a couple of weeks because I was so annoyed, embarrassed, etc. Last week we swapped the oil pan gasket and got the Exxon Valdez issue sorted out. I’m back in love with the white barge….time to get after it again.


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37 thoughts on “Buford T Justice Update: A Very Frustrating Day On The Dyno And How We’re Planning To Fix It

    1. TheSilverBuick

      Too soon Monk, too soon.

      For us non-Holley-ites (Q-jets rule!) what is keeping the secondaries from opening?

  1. Anthony

    Brian,dont get frustrated. If anything you make me feel like Im not the only one that F’s up sometimes so I dont feel so bad! Why not try more intial timing? I have 16 in my 350 then 20 in the distributor with some kinda light springs with a little vac adv. too.

  2. Jesse

    Thanks for the update. It is never enjoyable when a gearhead’s stuff does not work first time. Maybe TNT is a good idea. The only thing worse I can think of is to try and do TNT while participating in Drag Week while a few hundred see how underpowered a combo can be ……………….but then again, even a bad day turning wrenches is better than a great day at work.

  3. Tommy Lee Byrd

    This is why I hate dyno-ing anything haha. My first trip to the dyno ended with a long, sad drive home. The second trip wasn’t much better. By the third trip, I had grown accustomed to the disappointment. It’s sad that my wife’s daily driver puts down more horsepower than the car I consider to be my “hot rod”. Stupid dyno.

  4. bkb

    We swapped out the stock but badly corroded Carter carb on my Jensen FF’s 383 with a lightly used edelbrock carb from my Barracuda. Sadly after the swap the motor didnt feel like a 300hp 383. Turned out the secondary butterfly’s actuator was hitting the manifold and keeping the secondaries from opening at all. Sounded just like Buford. Weadded a thicker heat sheild style gasket and the problem went away!

  5. Scott Liggett

    That is not a loose timing chain. Loose is when it wears a hole in the cover and you can pull the chain off without removing the cam gear.

    I would find out why the secondaries aren’t opening before bothering with a double pumper.

  6. Dude

    Too bad they don’t have a “lifter Guide” similar that would allow that trick with hydraulic flat tappet lifters…

    Why don’t you just put the Q-jet back on?

  7. b3m

    Awesome update. I instantly saw #88 jet as that is exactly my own custom reaming recently.. I conclude modern fuel. that should be right on the money when you get it to scream. I have done th backyad cam swap..the gasket spewing just might have satisfied new metals getting cozy (it has to go somewhere on an old unsterilized engine) my own chooses the oil pump, external mounted, to make similar changes. looking forward to really hearing this run. It seems it is saving itself…good signs.

  8. Greenjunk

    I ALWAYS pull the cover and take out the spring on the secondaries. Rookie mistake. Also your jets should be in the low 70’s if you’re 4 cornering it. Theres nothing wrong with the vac carb, unless you have huge heads and a giant cam, that 750 will more than likely kill all your tq, and pick up very little high end power.

  9. Schtauffer

    The lack of horsepower is the result of the removal of the awesome custom exhaust hanger I made for you.

  10. floating doc

    Ahh, if it was easy everyone would do it!

    Hang in there; we’re all pulling for you. I know you’ll get this car sorted.

  11. Chuck Noble

    I would not recommend removing secondary spring …a lighter one yes. Also check that interlock choke lever is allowing secondaries to open once choke is warmed. Choke will not allow secondaries to operate if it thinks motor is too cool. Got to get AFR up to a more performance oriented 12:1.
    Purple hornies are quick and sound cool (for a while) but aren’t really flow masters (pun intended). They tend to bottle neck the exhaust and kill velocity.
    Get the timing curve and AFR up to NON-EPA standards …. drop the mufflers or add a more performance tuned exhaust….. and HP jump “should” reach dual digits. Don’t expect 1969 numbers….your still dealing with an emissions era compression ratio…….SOUNDS WAY COOL THOUGH….. 🙂

  12. Seppo

    Well, I had trouble with secondaries not responding, but it was a compete opposite what happened here. It was blowthrough 750 DP Holley with quick rebuild with correct gaskets. No difference in a/f ratio, weather it had the smallest jets –> no jets at all! Fuel pressure and level ok, direct line from jets to boosters, tried with compressed air. I fought with it for few weeks and finally gave up and drove the rest of the summer with primary barrels only (secondaries wired shut and link removed). For next summer I built carb enclosure and stabbed in 600 cfm vacuum Holley (with sec. metering block). Works like a dream now! Go figure.. If you find out the problem with Caprice secondaries, let us know!

  13. Christian

    Ok, I still want to know why you have no secondaries, is it a mechanic interference issue or is the carb locking them out? Just wondering, and why the jump to another new carb even before you get this one working correctly, will the new one work any better, seems like a poor way of going about things.

  14. Jim Rockford

    Also ditch those shit ass nonflowing glasspacks, that shit sucks for flow,. You guys are really starting to piss me off picking shit parts….

  15. Mr. Safety

    Please GO easy on the guy, the glass packs were just to have an “exhaust” to avoid issues with local law enforcement. The holley needs a little tuning tweeking to work right. The emissions area Q Jet’s aren’t the greatest and the already have the Holley in place.

    I’m jonesing for updates too but this isn’t the guy’s main gig.

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