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 17080272 /carb and 2157 Edelbrock cam kit
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bober
Sitting Bull

142 Posts

Posted - 10 Aug 2013 :  11:30:17 PM  Show Profile  Reply with Quote
I've just completed the 2 to4 brl swap with performer intake an all e/b cam kit,timing kit , springs. Had to rebuild the carb and so Finally got it running good . Don't know for sure what to set timing at , Set it at pontiac specs (16deg.) and it's to far adv. (starts hard when hot ) but seems to run good . I set it back to about 6-8 and seems good but a little rough . Any thoughts ? Thanks , 76 F/bird 350 auto with dual ex.

cortcomp
Coyote

USA
5335 Posts

Posted - 10 Aug 2013 :  11:55:25 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
13ish, try there.
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bober
Sitting Bull

142 Posts

Posted - 12 Aug 2013 :  08:50:06 AM  Show Profile  Reply with Quote
I set the timing to 16 and had to back it all the way back to 6-8 to get it to start rite . Should the original marks be diff after a mild cam swap as in 2157 edelbrock ? This cam as I've been told is not much more than stock .
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Blued and Painted
Chief PONTIAC

USA
3404 Posts

Posted - 12 Aug 2013 :  2:42:18 PM  Show Profile  Reply with Quote
http://www.summitracing.com/parts/edl-2157/overview/make/pontiac

Note the adv dur and lsa

Are the cylinder heads 6X-4


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.
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Bill Boyle
Horse Feathers (Charter Member)

USA
4793 Posts

Posted - 12 Aug 2013 :  3:30:05 PM  Show Profile  Visit Bill Boyle's Homepage  Reply with Quote
Timing marks on the crank won't change. Zero should be TDC on #1 no matter what cam is installed. What does change is the timing events of the camshaft in correlation with the piston movement. Many timing sets provided for multiple positions to either advance or retard the timing events of the camshaft. If you followed the cam card your events should be just fine; that won't effect the reading on the timing cover.

A false or inaccurate reading on the timing cover can occur in several ways but the most common with our Pontiac engines is the weakening of the bond between the rubber on the balancer. The outer ring will move or slip and that can give a wrong reading at the timing cover. That is why it's so very important, IMHO, to degree in a cam, and ascertain just where zero is on #1 when it's at TDC. A faulty balance can be detected during that procedure.

In your case, I'd bring the engine to zero on the timing cover and then remove and reinstall the distributor.

"Dedicated to keeping the classic Pontiac engine alive."

----
400 bored +.030, forged TRW pistons, ported 62 heads, Hedman headers, 2.5 SS dual exhaust X Pypes, Comp 276AH10 cam, Scorpion 1.65 RR, 850 Q-jet, stock intake & tuned HEI; original owner.
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bober
Sitting Bull

142 Posts

Posted - 12 Aug 2013 :  7:39:47 PM  Show Profile  Reply with Quote
The harmonic bal doesn't have the rubber just the solid one on this eng ( I got a new one but have to change timing pointer),The timing was as directions called for (straight up tdc) I have a new dist with adj adv that's going in it next . The problem was hard start when hot but it ran good . I set it back at small intervals til it started better and re adj. idle and so on. I've got it running good so I'm going to put some miles on it to help brk. things in more . The carb may still need more adj. as it hesitates under acceleration . All Cliff's parts in it and good carb rebuilder so I'm not going turn to many screws yet !!!
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bober
Sitting Bull

142 Posts

Posted - 12 Aug 2013 :  7:54:00 PM  Show Profile  Reply with Quote
Yes, I have 6x4 heads . I still have not got all these #'s figured out about the cam . A few has stated that this 2157 is not much diff than the stock ( U ) cam.
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Miles
Sitting Bull

Canada
138 Posts

Posted - 15 Aug 2013 :  4:06:09 PM  Show Profile  Reply with Quote
2175 has an advertised duration of 278/288 and at 50 204/214. LSA is 110.
The U - 9777254 has 269/277 and 195/203 with a 112.5 LSA
your up about 10 degrees intake and exhaust. Whether that is affecting the dynamic compression depends on the ICL, at what point the intake valve closes.
Your new cam is closer to the 67 and 86 Pontiac cams. All the Pontiac cams had wider LSA than your 2157. The ICL on the U cam is 112.5 so the valve closes later than the same cam with a smaller ICL.
I would say the timing should be 14-16 initial and should start easily.
Maybe the hard starting when hot is a starter/electrical issue not the cam?
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bober
Sitting Bull

142 Posts

Posted - 15 Aug 2013 :  8:32:07 PM  Show Profile  Reply with Quote
That's very possible but I did't have any issues before . Maybe there's more compression ,enough to cause a weak batt or starter to act up ? Must be a way to check The drag on the starter . I surely hope I don't need one of the high torque starters ,$$$'s .
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Blued and Painted
Chief PONTIAC

USA
3404 Posts

Posted - 16 Aug 2013 :  10:29:35 AM  Show Profile  Reply with Quote
I was parked on Daytona beach in my gto with a hot start issue. The tide was comming in and i had one chance to roll out and pop the clutch. It started.


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.
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Miles
Sitting Bull

Canada
138 Posts

Posted - 18 Aug 2013 :  6:58:28 PM  Show Profile  Reply with Quote
Your U cam closes the intake valve 25 degrees ABDC and the new cam closes it at 27 degrees ABDC.
If you didn't change the static compression ratio the dynamic C/R will be less than it was before the cam, intake,and carb change. The volumetric efficiency may be greater but the new cam wont make the starter work any more than it did before, most likely less.
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bober
Sitting Bull

142 Posts

Posted - 18 Aug 2013 :  11:33:54 PM  Show Profile  Reply with Quote
I did go back through the e/b 2157 instructions and it had 10 deg. at start point and adj. from there. I adj. the apt some and it responds better on acceleration . I went 1/2 turn cl/wise and again 1/4 . I have'nt drove it much since but I think it works better so far . Still makeing other adj. as I go . Need to adj. choke yet ,to lean . It's coming along .
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Phil
The Great White Buffalo

USA
7214 Posts

Posted - 19 Aug 2013 :  10:07:06 PM  Show Profile  Reply with Quote
What do you mean you have to change the timing pointer? Its cast into the timing cover, not a cheapo stamped steel add on one like a Chevy. And 350's in 76 came with the full size balancer, not the little hub style that was on some of the earlier entry level versions.

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.
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bober
Sitting Bull

142 Posts

Posted - 20 Aug 2013 :  08:43:41 AM  Show Profile  Reply with Quote
The one I have is a solid and the replacement I purchased is bigger around and the cast one won't work . The timing tab /pointer that's on it bolts on w.2 bolts for tim/cover.
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