Shaved some tenths off

[6667fan]

Got a late start to track this year due to repairs/improvements on car and a very rainy summer. Eventually got down to an 11.20 ET.  Biggest difference maker was switching to a taller, wider slick. I went from a 28 x 9 to a 29 x 10.5. Started getting consistent high 1.5 60’ times. MPH in the 121-124 range. That mph seems high to me for going that ET. I see lots of guys going low 11s with mph in the 115 range. What is up with my combo and/or technique?

[Stangman]

Can’t remember your whole combo but everything looks right until the end. Your 11.20 is great and I know you can’t compare car to car but my 11.20 was like 119. I think your 124 means your really pumping out some HP at the top end. What was your 60 ft times with the 28 inch tires. Maybe you need more gear with the taller tire. What is your trap RPMs. Does It match your motors HP rpm or are you going through at a lower RPM.

[6667fan]

The 60’ with the 28” slick was 1.8. Trap rpm is right around peak hp, (6500), so I don’t feel like I need more gear. Gonna have to get a better 60’ number I assume. Perhaps the mph will be similar?
Thanks

[cjshaker]

I think Dale or Rory could be of much greater help here, but I'll throw in my .02 cents.

First, congrats on the drop in ET. I have the same issue as you. My fastest ET so far is 11.51 @ 119 (2 years ago, the last time I made it to the track). But I see many cars in the very low 11's with my trap speed.

Typically, dedicated race cars will go beyond peak HP rpm in the traps. As it is, you're shutting off right at the moment when you're making the most power. That's leaving some good power on the table. I'm no pro, and I'm still figuring out a lot of things, but I think typically guys will run at least 500-700 rpm past peak, maybe more. So more gear will help on the line, where your greatest ET drops will be had, and you'll be getting the full use out of your peak "band" on the top end. HP numbers usually taper off slowly at peak, unless the valvetrain can't handle it. That means you're still making good power past peak. That's good usable power.

The problem is, of course, with more gear, it makes the car that less streetable. So now you're looking at a decision of do you want to squeeze every last bit of ET out of the car, or keep it somewhat streetable? This is why I bought a Gear Vendors overdrive, so that I can add some more gear and still keep it streetable. I just haven't gotten it installed yet. I'm waiting to make that change once I put the new engine in.

[6667fan]

Thanks much for weighing in Doug.
The rear has been making some noise on deceleration on the street after the strip abuse. So I might be getting into it anyways. I have no problem trying a deeper ratio. I’ll be taking a look at the Wallace Racing calculator.

[Towd56]

Jim - I have a nice newer set up with spool and 4.70 gears. Welcome to try it.

[6667fan]

Thanks Dennis,
I’ll be in touch. Going to the Valley on Sunday for the swap meet.

[Posi67]

Since my name is Dale I might as well comment. Many many years ago I ran an 11.81 @ 116 MPH. Once some online calculators like Wallace came along both those numbers seem legit. I have no idea how a Moroso slide rule works but is also very accurate at predicting numbers. That said.......

Picking up some tenths is a huge improvement and you can't MPH without HP. Better 60' time will likely bring your ET in line with the MPH. Ignore what "other" cars are running. I also didn't review your Combo but if an auto then I'd be looking at a better Convertor for starters. More rear gear will also help lining up the numbers.

Something else that many will call BS but I know to be factual is if you are spinning hard at the start line then your MPH will tend to go up a little. Why you ask?? Because the car is basically taking a run at the 60' clocks and once it hooks the power will make MPH but your 60' time will look dismal. Been there many a time. My 390 will generally 60' around 1.42 and run a 10.20 over 132 MPH. Rory's Fairmont 60's way better which means a better ET but similar MPH. 

[6667fan]

Thanks Dale.
Transmission is a Jerico.
 My valvetrain was a little noisy coming down the return road after my last pass and it was late so car went on trailer. Inspection at home showed #7 intake adjuster nut had backed off. I’m mentioning it here because it’s an Erson set up and IIRC you run those. This is the second time this has happened with these, (different locations ). Have you found that the supplied adjuster nuts tend to loosen?

[Posi67]

Yes..  I have Ersons on my 390 but never had an adjuster problem The rockers seem to be the best part of that setup. Was the nut loose or you just ended up with extra lash? I'd take the adjuster and nut off and check for galling where it seats. Before that, make sure you don't have a bent pushrod. Keep us updated. Progress is always slow but worth it.

[6667fan]

The rocker was galled, enough that the pushrod wiped out some of the bottom threads. So I replaced that arm with a spare new one. The push rod looked so straight to the naked eye that I did not even roll it. What I don’t like now is that rocker’s adjuster is very high, as in several more threads showing above the nut than the other adjusting nuts. I tightened it until I could not spin the push rod and then went another 1/8 turn. (This is not my normal adjusting procedure with the short travel Morels).  I ran it a little above idle for under 5 minutes and it is noisy under that cover. I will be checking it tomorrow to see if it will lend itself to being adjusted like the others. Peering down through the intake the lifter does not look like it has a problem.

[blykins]

The rocker was galled, enough that the pushrod wiped out some of the bottom threads. So I replaced that arm with a spare new one. The push rod looked so straight to the naked eye that I did not even roll it. What I don’t like now is that rocker’s adjuster is very high, as in several more threads showing above the nut than the other adjusting nuts. I tightened it until I could not spin the push rod and then went another 1/8 turn. (This is not my normal adjusting procedure with the short travel Morels).  I ran it a little above idle for under 5 minutes and it is noisy under that cover. I will be checking it tomorrow to see if it will lend itself to being adjusted like the others. Peering down through the intake the lifter does not look like it has a problem.

One full turn on most adjusters is about .050".  If you just made an 1/8th turn, then you only have about .006" preload.  When the engine gets hot, that goes away, so you're pretty much at zero preload and could possibly even have some lash. 

I would run the short travels at 1/4 turn.  That would be about .015" preload on a lifter that has about .030" travel. 

I also wouldn't try to set them by spinning the pushrod.  If there's nothing pushing back up at you, you could potentially spin that pushrod with the piston bottomed all the way out in the lifter.  Try taking up the axial play by moving the pushrod up and down axially, then when you get to a point where it won't move anymore, call that zero.   Also, it may be helpful on a big cam like that to use the EVO method to run the valves.

[6667fan]

Brent, I normally use the axial movement method that you espouse. On this rocker I was being overly careful to, (hopefully), not go solid with that lifter. What seems weird is that even with that adjuster  backed WAY off I don’t have much axial movement. The threads on the adjuster are barely in the rocker before any axial movement develops. I’m concerned the lifter got out of shape from all the slop that was in the adjustment before I found it. Is that possible with the limited travel Morels? I can see the ball end in the lifter and the adjuster in the cup.
I put the cylinder that is firing on TDC, (utilizing my Innovators West balancer and the rotor), to run the valves.


Thanks much for responding. I appreciate it.

[blykins]

Brent, I normally use the axial movement method that you espouse. On this rocker I was being overly careful to, (hopefully), not go solid with that lifter. What seems weird is that even with that adjuster  backed WAY off I don’t have much axial movement. The threads on the adjuster are barely in the rocker before any axial movement develops. I’m concerned the lifter got out of shape from all the slop that was in the adjustment before I found it. Is that possible with the limited travel Morels? I can see the ball end in the lifter and the adjuster in the cup.
I put the cylinder that is firing on TDC, (utilizing my Innovators West balancer and the rotor), to run the valves.


Thanks much for responding. I appreciate it.

It could be the oil causing a "seal" on the pushrod end that you're feeling and making it harder to feel any play. 

I would urge you to switch to the EVO method with running the valves.  Hydraulic rollers tend to have a *lot* more overlap than a comparable solid roller camshaft and overlap is what causes valves to be open both at the same time. 

[6667fan]

I hear what you are saying about the overlap. I did not consider that.
Never cared for the subjectivity of “ when the exhaust rocker begins to move”. If I supply the cam card may the number of degrees of before and after TDC be calculated so that I could continue using my degreed balancer? Or is that just as subjective as EOIC ?

Thanks for humoring me.