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Making a Pontiac 350 more streetable.

  
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Making a Pontiac 350 more streetable.

 
btbob btbob
New User | Posts: 3 | Joined: 08/13
Posted: 08/06/13
03:32 PM

Pontiac 350 build, Running KRE heads at a 10.19:1 compression ratio. This engine is running FAST EZ-EFI through a Performer RPM Manifold, Hedman headers and Magnaflow dual exhaust. It sits in front of a 200R4 w/2800 converter and 10 bolt with highway gears.

Currently Running this CAM http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=6&sb=2. Would like to calm this engine down some as it's application is going to move to daily driver. Can I get away with re-degreeing the cam or is there a cam I need to be running that'll still give the performance I'm looking for but on 91+ octane.

Thanks in advance for any responses.  

70bird 70bird
Guru | Posts: 1064 | Joined: 02/13
Posted: 08/06/13
03:50 PM

Changing your existing cams installation timing will be insufficient in your case.

The xe274h cam below is a rockin cam with a moderate/nasty idle in a 350 ci block. I use them a lot.

You could try variable duration lifters, rhoads makes the old noisy ones and some new quieter adjustable ones. this will increase idle vacuum, smooth idle, increase bottom end and lower initial starting rpm by around 400. I wouldn't use them. I don't like variable things in my drivetrain unless it is in a z06 corvette, lol.


You should be on 91 octane now, are you not? IF NOT AND YOUR ADVANCE IS NOT EXCESSIVE YOU MIGHT HAVE A PROBLEM. THESE OTHER CAMS WILL GIVE YOU MORE COMPRESSION.

WALLLACE CALCULATOR SAYS YOU HAVE A CYLINDER CRANKING PRESSURE OF 134 PSI [ITS PROBABLY A BIT MORE] WITH YOUR CURRENT CAM WHICH IS LOW AND 165 WITH THE OTHERS.

What is your max ign timing and at what rpm does it max at?

How mild do you want it?

lower rpm range?

tire burner?

vacuum for power brakes?

mild, moderate or rough idle?

what is your gear ratio?

you might want to lower stall to around 2000-2200 for 268 or 275 cam or 2400 for 274.  


minimum recommended size 1600-5800 ivc = 60 bbdc

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1203&sb=0


in between size but does not hit as hard as the others, smoother power band. 1500-5800 rpm. ivc = 63 bbdc

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1209&sb=0


max recommended size 1800-6000. ivc = 63 bbdc

http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1204&sb=0


comp 041 cam ivc = a whopping 79 deg bbdc, lol.


Do not buy comp lifters, use cranes, howards etc.

A comparable lunati voodoo cam is also very good, a smaller cam with a 112 lsa instead of a 110 might be a bit smoother cam than the ones i listed also even though yours has a 112 now..  

btbob btbob
New User | Posts: 3 | Joined: 08/13
Posted: 08/06/13
04:32 PM

Wow, Thanks for the quick response.

Yes I'm running 91+ octane.

For timing, Im running 12 degrees initial with a 21 degree advance all in by 3000 rpm.

Rear end gears are currently 3.08:1.

No need for brake vacuum as I'm running hydroboost.


I'm not too concerned for Idle. My main concern for this engine is to squeeze as much performance as I can while keeping it capable of being a daily driver. I like to autocross it occasionally but this is also my ride to work and takes me on weekend trips pretty regularly.

So you're saying that these other cams will increase dynamic compression? I though I was pretty close to the threshold as is.  

Thanks for the help.  

70bird 70bird
Guru | Posts: 1064 | Joined: 02/13
Posted: 08/06/13
05:26 PM

Wow, Thanks for the quick response.

Yes I'm running 91+ octane.

ok


xxxxx


For timing, Im running 12 degrees initial with a 21 degree advance all in by 3000 rpm.


close enough for now but i would think you could get away with maybe 38 total imo.

does it ping by simply increasing it slightly by rotating dist to around 16 idle timing?

try that.


xxxxx


Rear end gears are currently 3.08:1.


Come on, be a man, at least run 323's, lol. You are trying have your cake and eat it to by cheating with that 2800 stall convertor, aren't ya, lol. It ain't gonna work for auto cross, just ask Mary Pozzi. Do you know who she is?


xxxxx


I'm not too concerned for Idle. My main concern for this engine is to squeeze as much performance as I can while keeping it capable of being a daily driver.


I don't understand this statement. your 041 cam is a daily driver so maybe you better explain exactly what you do not like about it so we can offer you better suggestions.


xxxxx


I like to autocross it


308's aint gonna cut it and neither will that high stall.


xxxxx


occasionally but this is also my ride to work and takes me on weekend trips pretty regularly.


geez, the speed limit is only 70, how fast do you need to get there, lol.


xxxxx


So you're saying that these other cams will increase dynamic compression?


oh, yes sirree bob they will.


xxxxx


I though I was pretty close to the threshold as is.


Why? The threshold is 170 - 180 for 93 according to Jim Hand so 155-158 is ok imo.

Can you do a compression test with a good gauge on just 1 cyl for our entertainment?



What is your rocker ratio?

Do your lifters make a ticking sound independent of your rockers?

What lash are they set at?

How old are they?

What model are they, magnum. full race or just the basic high energy ones?  

btbob btbob
New User | Posts: 3 | Joined: 08/13
Posted: 08/06/13
08:00 PM

OK, Ill adjust the timing tomorrow morning. Thanks for the tip.

And yeah, I guess I should have explained how this weird drivetrain combo came to be. Originally this thing just started as a daily driver. Thats why its got a 350 in it in the first place. Came in the car and the engine was in great shape, rebuilt it with a balanced butler crank. The 041 was a leftover from someone else's project. All of it looked and sounded fine at first, but then this car keeps evolving.

Haha.  Rear end was next on the list, and I figured out the stall was too high already. Mechanical engineering degree or not, this damn thing has taught me that I'm not as smart as I think I am. Thats why I hang out on here. Laugh

With the stall converter recommendations given I was thinking 3.55. Thoughts?

And once again, not as smart as I think I am. I plugged something wrong into the Wallace calculator. I was way off. Yeah, I'll do the compression test as soon as I can get around to it. This should be hilarious.

Rocker Ratio is 1.65.

No ticking sound that I can detect.

Using these: http://www.compperformancegroupstores.com/store/merchant.mvc?Store_Code=CC&Screen=PROD&Product_Code=852-16

The High energy hydraulic from Comp. Purchased in 2010, Installed this year with about 600 miles on the engine since the actual install.  

70bird 70bird
Guru | Posts: 1064 | Joined: 02/13
Posted: 08/06/13
09:45 PM

OK, Ill adjust the timing tomorrow morning. Thanks for the tip.


let us know what happens, unless it melts than simply loose the url, lol.


xxxxx


Haha.  Rear end was next on the list, and I figured out the stall was too high already. Mechanical engineering degree or not, this damn thing has taught me that I'm not as smart as I think I am. Thats why I hang out on here."


LOL, yeah them degree thingy's are just kinda wall hangars or kindling round here, lol.


xxxxx


"With the stall converter recommendations given I was thinking 3.55. Thoughts?"


Well, depends on what you want, 3.55 gears means 65 mph fwy speeds not 85, and it will increase your tire and fuel expense substantially, lol. Wallace has a mph/rpm calculator also.


xxxxx


And once again, not as smart as I think I am. I plugged something wrong into the Wallace calculator. I was way off. Yeah, I'll do the compression test as soon as I can get around to it. This should be hilarious."


LOL, LOL, LOL, I've NEEEEEEVER done anything dumb, lol.


xxxxx


Rocker Ratio is 1.65.


xxxxx


No ticking sound that I can detect.

ok, good.


xxxxx


Using these: http://www.compperformancegroupstores.com/store/merchant.mvc?Store_Code=CC&Screen=PROD&Product_Code=852-16

Ok, thanks, those are "high energy" lifters which are their base models.


xxxxx


The High energy hydraulic from Comp. Purchased in 2010, Installed this year with about 600 miles on the engine since the actual install.  



PS - You still haven't told me what you don't like about the 041 cam. Why don't you just leave it in and get your 355 gears or what ever gears you want first, you might be happy with it then. A 274 adv dur will still be a bit of a pig with 308's.  

barneyformula barneyformula
Addict | Posts: 3301 | Joined: 01/07
Posted: 08/07/13
06:29 PM

Just one little point to consider with the 200-4r and 3.08 gear, the first gear ratio of the 200-4r is 2.74:1 (maybe 2.75:1, not sure) compared to a TH350 at 2.52 or a TH400 at 2.48, he actually has deeper 1st gear total reduction of 8.44:1 than a TH350 with 3.23 (8.14:1) or a TH400 with 3.23 (8.01:1), infact, with a TH400 he'd need 3.42 to get 8.48:1. Just food for thought when making comparisons.
Steve  
A little help... 'cause we don't all have to learn the hard way!

70bird 70bird
Guru | Posts: 1064 | Joined: 02/13
Posted: 08/07/13
11:19 PM

hello


since 1st on the 200 trans is so low, with 355 gears, you will be able to roast the tires til the cows come home, lol.


ok thanks barneyformula

not a trans guy, did not know that, but i tend to go off the final drive anyway since they're going to end up there anyway.

i looked up 2nd also and it is 157. i guess it's up to him what rpm he wants to turn on the fwy.


27" tire + 4th gear @ 70 mph =

3.08 gear = 1798 rpm this is really lugging your eng

3.31 gear = 1932 rpm

3.43 gear = 2002 rpm this will roast the tires a little and set you back in your seat a little with your cam or the XE274.

3.55 gear = 2072 rpm this is not really spinning very fast.


A 235 x 60 - 15 tire is 26.6 diameter, a 245 x 60 - 15 is around 27.