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 1320 (Pontiac Straightline Performance)
 Looking for thoughts about my build
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edbird
Tribal Scout

17 Posts

Posted - 05 Oct 2018 :  5:50:54 PM  Show Profile  Reply with Quote
Hello there,
I was just what impression people who were more experienced in the topic had about my overall build. Should I be making more power, going faster, etc?
455 + 0.040 (464)
Stock crank
Cast rods with arp bolts
Ported 6x-8s
Stock rockers
Cam xe284 (240/246@0.050 110 LSA) with matching springs and chain kit
Performer rpm intake
Holley 850 DP with 1? open spacer
Hooker competition headers (1 5/8? primaries)
3? system with chambered mufflers
Stock th350 with a shift kit
Stock 12? torque converter, though a stall is in the plans
3.36 posi 10 bolt

I supposed the car is making roughly 350-370 whp, as I ran a 12.5@110 with a 3385 race weight. Car was on 26x10.5 slicks and skinnies in the front.
Does this seem on track? Should I be making more power? With the MPH i was able to run, I would imagine I could run a 12 flat with a stall matched to my build. Just looking for overall thoughts. Thanks

Corncob2061
Cochise

USA
249 Posts

Posted - 05 Oct 2018 :  7:31:09 PM  Show Profile  Reply with Quote
Sounds in the ballpark to me, probably 415 to 425 at the flyweel. Maybe a little higher hp with the 3.36 gears. Compression was not mentioned, but those are common hp figures for that setup. As you said, adding a good converter should get you down a lot farther. What was your 60 foot? Jay
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edbird
Tribal Scout

17 Posts

Posted - 05 Oct 2018 :  7:36:33 PM  Show Profile  Reply with Quote
quote:
Originally posted by Corncob2061

Sounds in the ballpark to me, probably 415 to 425 at the flyweel. Maybe a little higher hp with the 3.36 gears. Compression was not mentioned, but those are common hp figures for that setup. As you said, adding a good converter should get you down a lot farther. What was your 60 foot? Jay



9.3:1 compression with forged flat tops
1.9x 60 foot launching at about 1500 rpm, just because that was as high as I could foot brake it.
Thanks for your input
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Steve C.
Chief PONTIAC

1866 Posts

Posted - 05 Oct 2018 :  8:48:08 PM  Show Profile  Reply with Quote
Were the valve springs supplied in the kit Comp 995? If not what part number on the springs? Was the actual installed height on the cylinder heads verified? If so was the spring pressure measured at that actual spring installed height? If so how much spring pressure was there at that installed height?

.
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edbird
Tribal Scout

17 Posts

Posted - 05 Oct 2018 :  10:20:54 PM  Show Profile  Reply with Quote
quote:
Originally posted by Steve C.

Were the valve springs supplied in the kit Comp 995? If not what part number on the springs? Was the actual installed height on the cylinder heads verified? If so was the spring pressure measured at that actual spring installed height? If so how much spring pressure was there at that installed height?

.



Yes, the springs are comp 995, as for the rest of that, I don?t really know. I sent the heads out to a fairly reputable machine shop for the work. I did get a 3 angle valve job as well.
Thanks
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Steve C.
Chief PONTIAC

1866 Posts

Posted - 06 Oct 2018 :  09:13:32 AM  Show Profile  Reply with Quote
Posted for entertainment and/or interest. And with potential here for the OP, currently or in the future. Just read between the lines within the attached thread....

"I built a 463 using that cam XE284. I was 9.25-1, RPM with 1" spacer, 850 Holley, clean up heads 220 cfm...dyno'd at 440hp / 532 tque. It went 11.98 @ 109 @ 3680 lbs. The valve springs in the heads were not adequate, so your combo has the potential for more power."

"Based on those comments....ponjohns engine was nosing over due to weak valvesprings. I have a hard time reading the dyno graph linked here for this engine in question. If it was not making peak power above 5000 rpm .... could there be a related issue here with the valve springs used ? As suggested, If the engine was pulled to a higher RPM could the results be different. This begs the question.... what valve springs are being used ? And how much spring pressure is in use here ?"

The engine in question was nosing over at about 4700 rpm.

Source:
http://forums.maxperformanceinc.com/forums/showthread.php?t=811943&highlight=XE284H


.

Edited by - Steve C. on 06 Oct 2018 09:15:27 AM
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Corncob2061
Cochise

USA
249 Posts

Posted - 06 Oct 2018 :  09:17:51 AM  Show Profile  Reply with Quote
1.9 is pretty quick for a launch with that cam from 1500. If you can keep it hooked up it should go into the 1.6s. Whatever time comes off the 60 ft you will take about double that off the et for the full pass. I would expect another mph too with a good converter. Work on mid range power,imo that is were most your improvement will come from. The xe 284 is very impressive for midrange. An 3 inch X pipe right after the headers, and a nice 3500 stall, something to help traction if you need something, and it should be knocking on the eleven second door.

What car are you running? Street car? Light race weight... Jay

Edited by - Corncob2061 on 06 Oct 2018 09:51:13 AM
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Corncob2061
Cochise

USA
249 Posts

Posted - 06 Oct 2018 :  09:21:19 AM  Show Profile  Reply with Quote
As Steve mentioned, the xe284 can be a tricky cam after 5000, especially in our d port pontiacs. Due to the 30 degree intake seats, they do not nestle into the seat like a 45. That cam slams the valve shut. Which is ok, but the valve bounces just enough to hurt the top end hp. That is IF the engine still has 30s. Some engine builders change the seat angle.

If the springs are an issue, could come with no audible problems, just hp loss on the top end. About 415 to 435hp is what is common with the xe284, and decent head flow in a 30 degree d port, 9:1, 455 pontiac. More there? Maybe, maybe not...

Where are you shifting at? Jay

Edited by - Corncob2061 on 06 Oct 2018 09:47:43 AM
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edbird
Tribal Scout

17 Posts

Posted - 06 Oct 2018 :  6:54:26 PM  Show Profile  Reply with Quote
Steve,
That was an interesting read. Is the implication here that the comp 995 springs supplied with their kit are insufficient for the cam? No one mentioned them specifically in the thread or that they had used the supplied springs. As far as nosing off at 5000 rpm, the amateur butt dyno cannot attest to that. The car seems to pull hard right up to 6000. A trip to an actual dyno may prove otherwise, I suppose. As for the car you linked to, 11.98 @ 3680 lbs is still impressive to me, nosing or not.

Jay,
I will look into an X pipe, and the car has cal-tracs.
I'm running a regularly street driven 67 Firebird with a fiberglass hood, I ditched the heater, carpet, and sound deadening as well. However, new carpet will be going in. The race weight actually surprised me, the car is 3160 plus my 225 lbs. I shift at 5500.

Edited by - edbird on 06 Oct 2018 7:02:21 PM
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Steve C.
Chief PONTIAC

1866 Posts

Posted - 06 Oct 2018 :  8:20:41 PM  Show Profile  Reply with Quote
"Is the implication here that the comp 995 springs supplied with their kit are insufficient for the cam?"

NO.

If set up with the appropriate spring pressure to control the valves they will be fine. Personally I want to know how much spring pressure I have.

" As for the car you linked to, 11.98 @ 3680 lbs is still impressive to me, nosing or not."

Fine, but later it started going away with loss of spring pressure. Once this happens there is the potential for problems in the valve train to come to light.

"Valve springs are among the most highly stressed components inside any high-winding racing engine."

Not suggesting you have a problem here, but this might be of interest....


https://www.motorstate.com/ValveSpringBasics.htm
.

Edited by - Steve C. on 06 Oct 2018 9:08:13 PM
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