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347 stroker tuning questions

Old 06-06-2010, 08:01 PM
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Default 347 stroker tuning questions

Hey guys, I've got a 95 gt I have recently started tinkering with again(couldn't afford it there for a while).

Here are my Mods:
347 stroker kit, AFR Heads, Trickflow track heat intake, 36lb injectors + fuel rail + Adjustable FPR and hi flow fuel pump, some other little goodies and a Comp Cams Extreme EFI stroker cam. Specs of cam are: Gross Valve lift .579 for both intake and exhaust. Duration @ .006 tappet lift is 286intake and 300 exhaust. Basically its a pretty healthy cam, they recommend no less than a 3000 stall converter on it.

My questions are this, #1 My car cant seem to figure out what speed to idle at, which i know is kinda normal with that healthy of a cam but sometimes it will actually die on me lol. It seems to be fine after it idles for a few seconds but then if you give it a little gas then let it return back to idle sometimes rpms will drop to low and it will die again. I think it may be running a little to rich too, I bought a MAF from brenspeed for it to compensate for the bigger injectors but the guy kept saying 30lb injectors and i kept correcting him that they were 36lb. He didn't seem to care though. Not sure if that makes that big of a deal or not. I thought Maybe a dyno tune would fix my idling issue but not sure. Any suggestions?

Question #2: Whats the best way to adjust timing on a "Race Motor" like this? Should I just unplug the spout connector and adjust it to like 12 degrees or so with it idling like a stock motor? I have heard of people adjusting timing on a race motor with it running at like 3000 rpms and setting it at max timing advance. Is this done with the spout connector plugged in? Also what would max advance be? Should i even bother with this?

All help is appreciated, if you need to know my mods in deeper detail just let me know.
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Old 06-06-2010, 09:41 PM
Join Date: Dec 2005
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its likely that they sent you an incorrect maf. I'd definitly check into that.

you NEED a dyno tune... end of story

and get a new intake manifold (sorry) but the one you have is going to choke out the top end on your motor (ask me how I know)
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Old 06-07-2010, 11:58 AM
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I have a friend with a 331 with the same xfi cam .579/.579 lift we put it together an got it running had small idling problems til we got the fuel right had 30lbs injectors with a stock meter until his calibrated meter came in ran fine just had to drop the fuel pressure to 32lbs, when he got the calibrated meter we went back to 40lbs. set tps voltage tp .998 idle. depending on the heads you have 165 185 etc the intake is ok, bigger than 185 u`d need to step it up! he has the vic jr heads and we opted for the r-series intake with your same camshaft.

your question about the timing: when you advance to say 35* like the (race engines) you mentioned you leave the spout out and thats that, 35 at idle 35 at wot! you dont want to ride the car that way the mpg will blow *****. and can be hard to start! not reccomended on efi!

the idle on your car can be corrected by the iac adj screw and the actual throttle screw! it takes time and is a headache but can be done!

the end result is you go to get a tune anyway or get and aftermarket engine management!

then you have to understand VE table and afr, and timing curves!
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Old 06-07-2010, 01:29 PM
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i have a mail order tune on my 347 and it runs perfect. only issue with my car is i had to up the fuel pressure to get the wot afr's dead on. no big deal imo it's been running great and beating on a lot of local guys. actually i got a dyno tune from livernois, which is a very reputable shop in michigan, and with my mail order it runs and idles way better. if you'd like more info on the tune pm me and i'll give you the guys info.

on the second issue, just pull your spout and adjust timing at idle like normal. 12* sounds right to me.
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Old 06-07-2010, 04:47 PM
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ctgreddy i sent you a pm, i would love some more info on the mail order tune. Wow I thought that intake would be sufficient.... What intake would you guys suggest?
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Old 11-25-2013, 10:03 AM
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heck yea ctgreddy would like to get some info from you as well , heck even if i have to trailer my car up there after im done with engine ...
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Old 12-01-2013, 04:51 AM
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yes a dyno tine is best but if you don't do that the best "guess" for your set up is 12 - 14 idle timing and 34 total at around 2700 rpm.

if your engine turns over mpre slowly when hot then retard the idle timing 3 degrees but keep the max timing of 34.
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