Re: 383 problems.
[Re: superbeedave]
#350859
06/20/09 04:08 PM
06/20/09 04:08 PM
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Anonymous
Unregistered
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Anonymous
Unregistered
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I have that cam in a 440 with a single plane intake and at 700 rpm idle it holds 14 inches of Hg. Your numbers seem low, meaning more initial timing is in order. The timing is jacked up too. The vacuum advance is limited to only 9 or 10 degrees advance, from manifold vacuum (not ported). My base timing is 20 initial and 33 total all in by 2100. This means that at idle, it has 30 degrees of advance. Also check out automotiveu.com.
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Re: 383 problems.
#350860
06/21/09 06:20 PM
06/21/09 06:20 PM
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Joined: May 2009
Posts: 508 Cincinnati, Ohio
superbeedave
OP
mopar
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OP
mopar
Joined: May 2009
Posts: 508
Cincinnati, Ohio
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The fan I have now is the stock 7 blade 18 inch and I am running the Mr. Gasket 160 degree thermastat. I have been running a 160 for probably 9 years now. Prior to the rebuild it never got past 190. I have read where some say it's best to run the 180 and some say 160 doesn't hurt anything. I will fix the timing later this week and see how it does at after that. I know I should try to get about 18-20 degrees at idle and 33-35 full advance. That is so far the plan. Joe M, what kind of dist. and advance springs are you running to get those numbers?
Last edited by superbeedave; 06/21/09 06:21 PM.
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Re: 383 problems.
[Re: superbeedave]
#350861
06/21/09 09:50 PM
06/21/09 09:50 PM
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Anonymous
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Anonymous
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The distributor is an old mopar one. The big slotted spring was removed. Kept the other spring. Shortened the mech adv slots. A 180 stat is really more suited for a street car. Better FE and emissions. The 160 at this point is doing nothing. You may find that more timing is needed at idle and less at cruising speed. Try hooking up a manifold vacuum gauge and advancing the base timing at idle for highest vacuum. I got to belive that with the xe268 and a dual plane intk, that 15 inHg is achieveable. And somewhere around 19 to 24 degrees for base timing. Then adjust the distributor so total mechanical is 34 to 35. To achieve the high amount of base timing, try using the vacuum advance connected from manifold vacuum. Once the idle timing is good (the motor will cool down), adjust the idle mixture screws for best vacuum. if backing out the screws does not over richen the mixture (you will know if over rich because the vacuum will drop), then open up the idle jet by about 2 thou (drill out). Not sure what carb your using. So, I have no advice for modifying the carb. Next thing to do, with veh in park, slowly increase the engine speed form idle (in about 100 rpm increments) to about 2500 rpm. If there is no sputtering, then you are good to go. If the engine skips or won't rev up smoothly, then it has too much timing and may be lean, especially if the exhasut manifolds get red hot. The vacuum advace may be adding 18 degrees, but with your quicker mech advance, 18 may be too much. the vacuum advance may need to be reduced to supply 10. Reduce the timing and try the rpm sweep again. You can move the distributor on the car before taking it out to modify anything. A good timing light (dial back) is also needed. If you think the timing is right, but still gets hot at cruise, then more fuel may be needed. Hope you had a chance to read some of the articles from automotiveu.com
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Re: 383 problems.
[Re: JG71B]
#350865
06/22/09 03:24 PM
06/22/09 03:24 PM
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Joined: Feb 2008
Posts: 992 Simi Valley, CA
MoparJ
super stock
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super stock
Joined: Feb 2008
Posts: 992
Simi Valley, CA
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Quote:
Quote:
Quote:
I got 120-140 psi (not bad according to FSM) and no leaks, but the car is slower than it should be with stock 383.
If you only have 120-140 cranking pressure you have a problem.
Should that not be around atleast 180-190lbs in each cylinder? I used to get 190lbs out of stock 400's.
If the stock or near stock compression pistons were kept it place and that higher lift and more aggressive duration cam were used, cylinder pressure will be somewhat diminished, which would read with lower compression readings, although not necessarily 120 psi low. Maybe 20-30 psi lower than stock.
2016 Ram 1500 Crew Cab: 5.7, 65RFE, 4.56 gears with locker, Hemifever tuned, AFE intake, 87mm throttle body, JBA headers, 3" Flowmaster exhaust, split to dual 2.5" exits. 13.57 best ET so far.
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Re: 383 problems.
[Re: 64Post]
#350867
06/22/09 10:19 PM
06/22/09 10:19 PM
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Joined: Feb 2003
Posts: 2,069 Renton, WA
GreenBlurr
super gas
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super gas
Joined: Feb 2003
Posts: 2,069
Renton, WA
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Yet another example of why even reading the question and answer forum makes my blood boil.
The main problem is a simple one. The fact that his timing was set a bit aggressive, and that he has a 160 degree thermostat and that the engine is undercarbed merely just aggravated it a little.
The engine has a MANIFOLD VACUUM LEAK. Plane and simple. You guys should have picked up on that in that the idle is inconsistent, and increases the more he drives and the engine is run longer while being so lean and the chambers get hotter and angrier, and also for the fact that he had the base timing pretty well up there, yet the vacuum was only 11 inches. That lift and duration of camshaft in a split pattern with that compression should pull at least 15-16 inches of vacuum, and that would be with not too terribly much timing and the idle set lean (i.e. a bit of a worst case scenario for idle conditions).
Those who replied to the post before me must be the same group that called me stupid for mentioning a vacuum guage as the thing to have if someone were to get only one tool period for timing and tuning a carbuerated engine.
The original poster even expressed a concern about his phenolic spacer possibly not having a uniform sealing surface, and you guys didnt pay attention.
Ok, so original poster: I would like to offer you some actual help here. Get rid of that phenolic spacer, or buy a new one if you are unsure about it. Remove and reseal the intake using ultra black RTV on every bit of sealing surface all around the bottom side of the valley pan gasket, and around every bit of port sealing surface on the top side of it. Also put RTV on the threads of all of your intake bolts, and torque the bolts properly at 35 ft lbs or there abouts. THEN you may retime your engine, and THEN you may redo the fuel mixture, and THEN check the manifold vacuum with a vacuum gauge and if it is still low and incosistent, ckeck anythign else that may be privy to said vacuum; whether it be the vacuum Tee on the intake, brake booster, nippled off ports on the intake or carb, PCV valve and hose, etc.
I hope the best for ya man. Get that top end resealed. I don't care if its a new motor. If you didn't build it, then why would you believe that the intake and valley pan weren't tossed on there more or less dry, etc?
Rant off, and guys, get your heads out of the clouds of complicated custom engine runability theory.
Last edited by 69DartGT; 06/24/09 04:09 PM.
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Re: 383 problems.
[Re: stumpy]
#350869
06/22/09 11:12 PM
06/22/09 11:12 PM
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Joined: Feb 2003
Posts: 2,069 Renton, WA
GreenBlurr
super gas
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super gas
Joined: Feb 2003
Posts: 2,069
Renton, WA
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Quote:
I am sure all of us are so glad you're around Greenblur. How would we ever survive without your condesending know it all posts. If you want to help then try doing it without all the comments.They aren't necessary and make you sound like the south end of a north bound horse.
You deffinitely make good points. But at least my outrageous post got your attention on top of being informative. You try reading the know it all drivel on the question and answer section for 8 years and see how you react after that. I wanted to get the poor guy headed in the right direction before yet another person had him field strip his distributor and possibly yank his camshaft.
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