I'm disassembling my 383 and need some feedback

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    Author Topic: I'm disassembling my 383 and need some feedback  (Read 9752 times)

    Offline dodge freak 2

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    Re: I'm disassembling my 383 and need some feedback
    « Reply #15 on: May 08, 2009 - 10:13:00 PM »
    No but next time keep a garden hose ready, I ran my little guy for 40 mins at 3000 down to 2200 rpms, took the water hose and hosed down the rad a few times, drove it then around town while shopping and then changed the oil and filter. All is good 1 year later.

    I use only "race oil" now of days...first that Valvoline "not street legal" motor oil but this year went with Pensoil GT race oil 25w/50 for like half the price.. I use only K/N oil filters...never use Fram!!
    « Last Edit: May 08, 2009 - 10:16:56 PM by dodge freak 2 »
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    Offline willard

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      • 1970 Challenger R/T
    Re: I'm disassembling my 383 and need some feedback
    « Reply #16 on: May 09, 2009 - 07:27:44 AM »
    That's a good idea but anyway I don't have water source in the garrage.
    Today was the test drive and in fact car performs worse than before the swap. I adjusted the carb and timing but it is still slower than before. The main reason is probably a very low stall (1800 before now 1700) torque converter while service manual says there should be some 2450-2650 behind a 383. So another purchase must be made  :(

    BTW I inspected the old cam once again and it has some purple paint residue so I assume it's a mopar camshaft. I don't know how to measure the lobes but the biggest diameter of the lobe (height?) measured w/a caliper is 1.602" -1.600" or close for both intake and exhaust.
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    1970 383 R/T SE

    Offline moper

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    Re: I'm disassembling my 383 and need some feedback
    « Reply #17 on: May 11, 2009 - 07:48:34 AM »
    Measure the width at the tallest point on each lobe, then measure the width where there is no lift on the lobe at all. The difference is cam lift. Take that and multiply times 1.5, and you have the advertised lift at the valve. What cam did you install? Can you do a cylinder pressure test and post the number?
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    Offline willard

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      • 1970 Challenger R/T
    Re: I'm disassembling my 383 and need some feedback
    « Reply #18 on: May 11, 2009 - 07:56:29 AM »
    I put lunati voodoo:
    Advertised Duration (Int/Exh): 262/268
    Duration @ .050 (Int/Exh): 220/226
    Gross Valve Lift (Int/Exh): .475/.494
    LSA/ICL: 112/108
    RPM Range: 1400-5800

    I did compression test last fall and all cylinders were 120 psi +/- 10 psi.
    Will measure the cam once again and post the results. With the old cam the car wasn't a killer to, it barely spun the tires at take off (235/60/R14). Now it obviously has less bottom end torque and power than before so the last thing to blame is the torque converter.
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    1970 383 R/T SE

    Offline moper

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    Re: I'm disassembling my 383 and need some feedback
    « Reply #19 on: May 11, 2009 - 08:04:09 AM »
    Well, changing parts does not lead to "the next thing to blame". That was why I'm curious... Convertors can make things better, but your butt dyno should tell you if it got better or not, even if it is not optomized witha  slippery convertor. Also, 383HPs should have had the high stall factory (Hemi) convertors.. a std 383 4bbl or 2bbl would not. Not sure what you're starting with there...
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    Offline willard

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      • 1970 Challenger R/T
    Re: I'm disassembling my 383 and need some feedback
    « Reply #20 on: May 11, 2009 - 08:22:07 AM »
    Thats a long story, I bought the car last summer and bring it to europe, the tranny and engine was said to be rebuild to factory specs but the low stall of 1800 vs approx 2400-2600 rpm as per service manual did not justify that. I verified one by one - filters, compression, timing, no blowby, changed carb to holley 770 street avenger, plugs, plug wires, set fuel mixture, finally changed the cam. As I did not know wat was the cam in the car (claimed to be "standard 383hp") switching to a modern grind lunati cam was anyway good idea.
    Everything apart the t/c is now checked, set and working well, so I decided to change the t/c.
    I was wondering if the person that rebuild it wanted a good gas mileage cruiser, with low stall converter and acceptable low end performance, not a dragstrip or performance car - just a cruiser. And in fact it was nice for cruising at 50 mph and 2000-2200 rpm.
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    1970 383 R/T SE

    Offline 73Chally

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    Re: I'm disassembling my 383 and need some feedback
    « Reply #21 on: May 11, 2009 - 08:54:56 AM »
    Have you checked your valve train?  Something might be off with the lash, lifters, etc that would be robbing power.  How recently was the engine rebuilt (miles?)?  If it is a relatively fresh rebuild, you might need to go back and double check everything to see if anything has changed.
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    Offline willard

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      • 1970 Challenger R/T
    Re: I'm disassembling my 383 and need some feedback
    « Reply #22 on: May 11, 2009 - 10:50:51 AM »
    Engine had about 1500 miles and the lifters, pushrods, rocker arms shafts, everything looks ok and works ok. New cam come with new lifters, properly primed them too. I know that it's hard to make a diagnose x thousands miles away  :sadwavey:
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    1970 383 R/T SE

    Offline moper

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    Re: I'm disassembling my 383 and need some feedback
    « Reply #23 on: May 11, 2009 - 12:20:27 PM »
    IMO, the 770 carb is too large for it, and that will keep it sluggish down low. Plus hurt gas milage at low throttle opening. It's the equivolent of an 850 4150 series Holley. The 670 would have been a wiser choice for what you have. ON the cam... the 335hp resto MP cam usually needs to be degreed. the last one I had (stock rebuild in #s matching engine, including the 9:1 real compression "10.5:1" pistons....) the cam was retarded by 10°. The worst ground MP cam I have ever seen. When it was put in correctly, the cylinder pressure went from 120psi to 175, adn the car was totally different. If the engine is down on power, the stall speed will be lower than it should be. What did it pump for pressure numbers? What does it pump now?
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    Offline willard

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    Re: I'm disassembling my 383 and need some feedback
    « Reply #24 on: May 11, 2009 - 03:01:17 PM »
    I went for 770 according to this site opinions and chryco's experience, erlier a 750 edelbrock performer was installed but was leaking and after the carb change the car feeld a little better. As I was installing a new cam+ new timing chain, the chances I assembled it retarded as before are minimum. I dont have the degree wheel and dial so I only lined the dots, checked it 3 times, rotated 2 full revolutions and all was ok.
     I had no chance to check the compresson after the swap.
    The converter I have has 10" flexplate so maybe it is from a SB tranny and has low stall?
    I know that the stall is also the effect of engine condition and torque - that's why I started with the engine checks/upgrades and not with the converter. I was eliminating the possible causes one by one.
    I measured the lift of the old mopar cam and it's about 0.42-0.43" lift at valve but it was measured with a simple digital caliper (1.6" at lobe, 1.322" across, difference multiplied by 1.5).
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    1970 383 R/T SE

    Offline 73Chally

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    Re: I'm disassembling my 383 and need some feedback
    « Reply #25 on: May 11, 2009 - 04:09:11 PM »
    IMHO you need to take the car to a reputable shop and have them look it over.  You're already nickle and diming yourself to death, not to mention the time you have put into it, trying to do it one part at a time, and by your own words you have gone backwards.  The cam/lifters/carb/intake all need to be matched to get the best performance, and if you keep changing things around, you're just going to keep chasing your tail.
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    Offline willard

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    Re: I'm disassembling my 383 and need some feedback
    « Reply #26 on: May 11, 2009 - 05:06:46 PM »
    it's not that easy in poland :walkaway: there's no reputable mopar workshop here, there's less than 10 mopars in the whole country and every owner has to rely on him/herself. If it were the states, I'd take it to any shop to have it checked byt here I'm on my own.
    However thanks to this board I have support and waste knowledge base.
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    1970 383 R/T SE

    Offline moper

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    Re: I'm disassembling my 383 and need some feedback
    « Reply #27 on: May 11, 2009 - 06:43:34 PM »
    you got the tools and the will, so I'm sure we can figure it out. Start with that cylinder pressure bit. In case you haven't got the info, the next question is your timing curve. What is initial, and total...
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    Offline 71chally416

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    Re: I'm disassembling my 383 and need some feedback
    « Reply #28 on: May 12, 2009 - 12:43:25 AM »
    I'd run a 383 like that with 38* total timing minimum. They really like lots of total timing. My race 383 ran best with over 40*. If you have 30 or 32* AND a tight vert AND numerically low rearend gearing like a 3.23 or worse it'll probably be a real turd off the line. :grinyes:
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    Offline willard

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    Re: I'm disassembling my 383 and need some feedback
    « Reply #29 on: May 12, 2009 - 03:55:05 AM »
    I have 14 deg of initial timing and was afraid of setting more. I have a simple strobe timing light but already ordered an adjustable one, maybe the distributor doesnt fully increase the timing above 3000rpm? I'll check it and the compression once again and post the results. As of now I'm postponing the purchse of a vert (shipping to poland is over 130usd  :scared: )

    Thanks for your input and patience.
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    1970 383 R/T SE
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