B2 Motorsports - Mat Twiehaus 427SBF Build

[Clois Harlan]

Is that one of those spa's they advertise in the uban newspapers where most of the business's are upstairs in the alley?

[Clois Harlan]

Have you got the dates for London yet? Maybe Mat and I can trailer our cars up for that event. The Shelby show (which runs at the same time) has gotten too big for me to enjoy the track time.

Clois Harlan

[Sminor]

Originally Posted by Clois Harlan

Have you got the dates for London yet? Maybe Mat and I can trailer our cars up for that event. The Shelby show (which runs at the same time) has gotten too big for me to enjoy the track time.

Clois Harlan

Negative, however, we have a meeting in a couple of weeks and hopefully we'll have that discussion. I'll let you know what I find out.

[ERA Chas]

Clearances rods, mains, piston to wall? How deep in the hole?
Hey Brent, does Dart make a block with 4 bolts on all five mains?

[blykins]

I don't have the bearing clearances here in front of me, but I'll post them tomorrow. I usually aim for about .001"/in of journal, and after some half/half mixing, I got them there. So in this case, it would be around .0021" on the rods, .0027" on the mains.

Piston to wall clearance is a little looser than most with these Probes. They have a spec of .003-.007" and these fell right in the middle.

Pistons are about .007" in the hole if you measure over the wrist pin. If you measure on the quench pad with piston rock, they are within about .002" of the deck surface.

The Dart Iron Eagle block has 4 bolt caps all the way across.

[ERA Chas]

Thanks for the info pal. This bottom end should be bulletproof for the application.

[blykins]

Slight change in plans this weekend....

After a discussion with Mat over the intended use and expectations of the engine, I swapped cams to a Comp hydraulic roller cam.

Got it degreed, installed, and placed an order for a set of Comp short travel lifters and another set of valve springs.

[ERA Chas]

"short travel lifters"
May be a dumbass but never heard that term before Brent. Mind a short explanation?

[blykins]

The issues with a hydraulic roller lifter is that:

1. If you lose control of the valvetrain, the lifter will pump up and hang the valve open.
2. If you use a lot of spring pressure, it's possible to overcome the hydraulic pressure behind the plunger and you lose control.

A short travel lifter is not a typical hydraulic lifter. Instead of 1/2-3/4 turn of preload, they get 0 to 1/4 turn. The plunger stays up to the top of the lifter body and they are built/metered to take higher spring pressures.

These are basically "race-oriented" hydraulic roller lifters and will allow the engine to pull revs that a regular lifter wouldn't allow.

[ERA Chas]

Understood. So this build will run 6500-6800?

[blykins]

No, the cam isn't that wild. One of the things that Mat and I discussed is that this is not a 100% race car. It is predominantly a street car.....with A/C. Little less .050" duration than the flat tappet cam, but more lift....which is good.

[blykins]

Will post some more pics later, but got the springs sorted out, heads reassembled, head gaskets on, and heads bolted on/torqued.

New Comp lifters are in-house, as well as the new lifter spider. The Dart blocks are all cast taller in the lifter bore area to use the factory Ford roller cam setups. The short travel Comp lifters are only available in OEM style and I think they are a little lighter than the link bar stuff, so I went that route.

New cam specs are:

240/244 @ .050", 112 LSA, installed on a 108 ICL. Lift is .625/.634". Valve springs checked at a hair over 150 lbs seat, and 400 lbs open.

I've got a few engines that I'm working on concurrently, but my plan is to get Mat's engine supplied with lifters, the lifter spider, rocker geometry checked, guideplates sealed/torqued, and the intake fitment checked by tomorrow.

Waiting on Peterson's dry sump mandrel to show up and then I can take some measurements for the dry sump pump shaft for Mat and get the front end buttoned up.

[FUNFER2]

Brent- I don't want to change this thread, so just a short answer is fine.

What is your recommend max lift on the street, with either a Hydro or solid mechanical roller ? (all Isky valvetrain. EZ-Roll (no needles.etc)

Here's my cam choice so far.

298/305 duration
696/707 lift
110+4 lobe center

[blykins]

Originally Posted by FUNFER2

Brent- I don't want to change this thread, so just a short answer is fine.

What is your recommend max lift on the street, with either a Hydro or solid mechanical roller ? (all Isky valvetrain. EZ-Roll (no needles.etc)

Here's my cam choice so far.

298/305 duration
696/707 lift
110+4 lobe center

I wouldn't go any higher than that. When you start getting in the real high 600's and 700's, it starts working the spring really hard. If the cam lobes are aggressive, then it will be a "spring eater."

Even with good lifters, I would pull them periodically for inspection and also pull a couple valve springs for inspection. When they get worked hard, they will lose their "springiness."

Most of my hydraulic roller stuff falls around the mid 600's in lift. My street solid roller stuff is generally around .670-.680 gross lift.

[GBowman]

Brent

I sent you a PM, if you get a minute take a look thx again.

Gary

[blykins]

Gary, I didn't get anything from you....

[FUNFER2]

Brent- I agree on the spring psi and that's why I won't go much over 700, keeping the high lobes down. I really like the newer Isky springs and lifters for rollers.

The sprint car's cam is 780 (short track size) but we tear the motor down after every season and replace the springs no matter what, but these engines are a different animal than a street motor. I haven't had a mechanical cam on the street since my old Pro-Street days, and the technology has improved a great deal.

[blykins]

Your cam is going to be wild, so I'd keep a close eye on it. Most of these Edelbrock heads don't really do much more from .600 to .700 lift, so there's no real reason to run that big of a cam.

The Comp Xtreme Energy lobes work really well for most street solid roller applications. Any lobe with more than 38° MI will probably start to push the envelope, especially with FE rocker ratios.

[blykins]

[FUNFER2]

What gaskets are those ? The color looks different.