[PontiacMatt72]

(I posted in the street section earlier, but I plan on racing with this motor, after I get the car ready for it)



Pontiac 400 block, 6X-Heads, Eagle rotating assembly, Ross Flat-Tops, approx. 9.6 compression, Comp solid roller (custom grind), RPM intake.

A video of one of the runs (Not the best quality, but you can make out whats going on)
http://www.youtube.com/watch?v=c5_aaZ5RGCE




-Matt

[grandville455]

Your lucky u didnt melt something ! was pretty lean!.. the torque number is nice but it peaked and fell off immediately. Is this a stroker motor I take it? What is the cam specs etc, where installed

[Bill Meyer]

What Darby said X2. Scarry low oil pressure @ 5000+ RPM. I'd be checkin' the oil filter! - Bill

[PontiacMatt72]

Darby, yes it's a stroker=467 cid. The carb we ran was actually not mine- Ran a quickfuel, 650 i think. I had a vaccuum secondary carb that they thought wouldn't work correctly on the dyno. (thought probalby wouldn't open the secondary's correctly). Cam is solid roller, custom grind- 236/242 @ .050", net lift with 1.65 rockers is in .610-.630 range, 110 LSA, installed at 106 (or is supposed to be anyway.) I was really surprised at the torque figures it produced. it actualy touched 580.x in one run, but the printout was the best hp number.

Bill, ya looks like it dropped some... I'll cut into the filter before I get it in the car. This was an all new motor, broke in a tested in the same session.

Actually blew a head gasket the day before, but didn't do any damage to the rest of the engine.

[grandville455]

How many pulls did u make with that carb that lean? I would have stopped after the first pull, 650 is way to small for a 467...850 or bigger... Where was the timing at? The HP Peaked very early also. It did carry it out further,but man your torque fell like a rock. Was down over a 100 ft lbs at 5100... What size is your carb?

[ry57pont]

FWIW, i we tried a 1000cfm (dyno shops carb) and it made no more power than my 830 chokeless on my 462. i would bet an 850 would be perfect (but again i am speaking form absolutely no expierence other than my own)

[PontiacMatt72]

Darby, This printout was of the 6th and final pull. I definately agree, 650 is not enough. I have a q-jet that Cliff rebuilt a few months ago, I'm pretty sure is 800 cfm. That's what I'm planning on running on the engine, at least for a while. If I feel it isn't performing at the track, I'll get a holley dp, probably 850. Total timing was at 32 degrees, seemed to be where it ran best.

I too felt like the HP peak was pretty early -earlier than I expected. I thought it would peak in the 5000-5300 range somewhere, but obviously that was not the case. (I thought, overall, the powerband was fairly good and broad, at least within the dyno pull's rpm range.)

Honestly, I thought it would be normal for torque to start tapering off like that after it got up into the rpm range... I guess i was wrong?

[PontiacMatt72]

Where do you guys think hp should have peaked in RPM range?

What numbers do you think it should make with better a/f ratio and larger carb?

[ta man]

Dude I would not worry about your horsepower till you get a good carb and jetted properly.Like I said in the street section......Lean.

[BruceWilkie]

Unless heads were heavily ported that cam isnt going to peak power much higher rpm than where it did. Scary lean and scary oil pressure. Cliffs qjet should be a big improvement. You really dont need more than an 800-850 cfm carb with that combo anyway. Worry about your oil pressure and tune up. There is more power and tq to be found.

[PontiacMatt72]

Excuse my ignorance, just trying to learn here...

Why is this oil pressure scary? Lowest I see on the video is 44 psi. Held over 50 psi throughout the pull, then on deceleration dropped briefly to 44 then back up.

Pull acceleration:
3300 rpm = 63 psi
4000 = 64 psi
4500 = 56 psi
5000 = 53-54 psi
5500 = 53 psi

On deceleration:
5500-5400 = 47 psi
5300 = 45 psi
5200 = 44.8 psi
5100 = 45 psi
5000 = 46 psi
4800 = 50 psi
4600 = 53 psi
4000 = 53 psi
3500 = 53 psi
3200 = 54 psi


educate me!

[60man]

X3 on being LEAN & oil pressure.
A general rule of thumb is 10PSI per 1,000rpm. i.e. 5,000=50PSI. Was oil level correct?
I had trouble with lean situation my recent dyno session. Did you pull plugs ? Dyno sheet showed rich..plugs showed borderline LEAN. You can't play with timing much with a lean condition. when I got close on mixture we increased timing 2* (31 total) and found 18 more HP and moved HP band UP !!
I'm sure there is more in yours as well but watch OP & lean condition..
MY

[Bill Boyle]

Matt--once you get the carb calibrated for your engine and tuned, to include timing, you'll make a bit more power throughout the engine range. Troy's comment about finding more power is true--tuning will do that. Be patient, take one step at a time.