Fury1969WI
New Member
JE P/N 117200, Flat top, 4.350", Weight 636 grams. I was running 93 Octane (pump premium). Stock mopar electronic ignition (see posts above).
440 Rear-Wheel HP Numbers Seem Off 30-40%
- Thread starter Fury1969WI
- Start date
JE P/N 117200, Flat top, 4.350", Weight 636 grams. I was running 93 Octane (pump premium). Stock mopar electronic ignition (see posts above).
heyoldguy
Member
I use the Firecore50 distributors as my first choice. I use the Summit ignition box on all street type applications and have found it to be so reliable that I use one on my dyno.
http://www.summitracing.com/parts/sum-850610/overview/
heyoldguy
Member
Something is wrong in the ignition timing department and yes the RPM and the MP 5153525 dual plain are far superior to the old MP 4529118.
Landyacht
Active Member
From what I see your build seems to be fairly decent and you should get good results . I'm assuming that the cam you're using is the Magnum series 280H. Comp recommends using headers with this particular cam 2000 stall convertor and a 3.91 gear. Your total advance should be around 34 degrees BTC. I don't understand your detonation issue. A set of headers will help lower your combustion chamber temp which might reduce the chances for detonation to occur( although I think your problem is coming from somewhere else) . Comp recommends headers for that cam so ditch the cast iron manifolds . You will notice major power gains . That's guaranteed . . A slightly rich A/F ratio will also help cool the combustion chamber and help reduce spark knock. If your running 12.5:1 at WOT what is your idle and cruise A/F ratios? What are your A/F ratios under low vacuum conditions. Vacuum leaks can make your engine run lean and cause detonation.
Landyacht
Active Member
Did you block off the exhaust passages going through your intake manifold ?
Fury1969WI
New Member
Yes. Running the blocked valley pan.
If you (y'all) only had another few hundred bucks to sink into this drivetrain what would you do?
I got the Firecore distributor yesterday (Mancini Racing).
I despise headers since my 1970 Chevelle 30 years ago required weekly tightening and annual gaskets. I realize hardware is light years ahead by now. Good headers, TTI or Hooker Super-Competition? I'm guessing those are going to set me back $1,000 by the time i re-work the exhaust. Now is probably the time tho'...
What i don't understand is the 204 RWHP with this setup. This has to be at least as good as factory. Thinking timing and RPM intake as next steps. I think i'll leave the carb alone until i can get the other AF ratios you / somone inquired about.
Hoping for a test fire next month!
Thanks all.
70bigblockdodge
Old Man with a Hat
No bolts for headers on a big block use studs.
Landyacht
Active Member
B/RB Tri-Y Headers
If you do decide to go with TTIs order the optional O2 sensor bung and get a wide band air /fuel meter. They only cost around $200 and will take the guess work out of tuning your carb. You can monitor your A/F ratios in real time while you drive the car. I would also look into the Shumacher headers B/RB Tri-Y Headers before deciding on the TTIs.
Fury1969WI
New Member
70bigblockdodge
Old Man with a Hat
Yes I usually trim the studs to just be long enough when header is installed, I have also never used TTI headers as too rich for my blood.
moper
Well-Known Member
- Joined
- Nov 15, 2010
- Messages
- 813
- Reaction score
- 447
Which carburetor are you running? There are a few different "750 cfm" versions. Some are very lean by design.
Two other comments - you have basically a stock engine with a cam. The ignition will work with points. Not the best, but functional. Certainly not 80hp worth of gain. The results of ANY dyno, engine or chassis, should be taken with a grain of salt. It is VERY easy to manipulate the results. That being said - you should be able to spin the tires, and it shouldn't detonate. Ignition will not fix a detonation problem caused by being very lean, and whether very lean or very rich, with the large open chambers, they are both potential detonation causers.
Two other comments - you have basically a stock engine with a cam. The ignition will work with points. Not the best, but functional. Certainly not 80hp worth of gain. The results of ANY dyno, engine or chassis, should be taken with a grain of salt. It is VERY easy to manipulate the results. That being said - you should be able to spin the tires, and it shouldn't detonate. Ignition will not fix a detonation problem caused by being very lean, and whether very lean or very rich, with the large open chambers, they are both potential detonation causers.
440_Magnum
Member
I would guess that you are indeed missing a lot of power, but by your own first post you have a lot of suspects for where its going! Carb mixture off and not enough timing are definitely big problems just by themselves and should be fixed before you get back on a dyno. Also was the cam degreed in, or just slapped in wherever the peg went in the cam gear? That can cost a lot of power. Bent wheel? On a dyno? Why even bother? Granted a bent wheel won't cost you much real-world performance, but on a dyno where any slippage on the drum shows up as missing horsepower, I would definitely get that corrected (at least put the bent wheel on front!) before trying again. Also I wouldn't expect great things from "bone stock" 452 heads. They're OK, but without a little clean-up of the ports and bowls, you're counting on factory casting quality variations to NOT cost you some power, and that's a gamble I wouldn't take if I had an engine apart already.
Fury1969WI
New Member
Edelbrock 1407. Added the electronic choke the other day. Some asked if the carb was indeed wide open at WOT and i did notice that the secondaries are "sticky." I'll make sure next time it's running, hopefully later this month (fingers crossed).
Fury1969WI
New Member
Regarding the cam, i checked my notes and do not see info from the builder on cam install. I did pay for degreeing the cam and know talked about installing it other than straight-up (i want to say 3 degrees advanced). It has also been haunting me that the engine did not fire immediate upon rebuild - some say that will wipe a lobe in a few revolutions other say newer cam materials not so much.
I did not know about the bent rim until it got onto the dyno and at that point there was a line and it was too late.
Heads were fully assembled and i just slapped 'em on like Ma made 'em.
Still maintain i should hit 400 (corrected) HP with this set-up, 375 (Magnum) spec at least.
440_Magnum
Member
Good to know that they degreed the cam. I wouldn't worry too much about having wiped a lobe, especially if it was slathered up good with cam assembly lube. IMO the bigger risk of ruining a cam is if you fire it for a few minutes then have to shut it down for some reason and then restart it. That's long enough to wash the assembly lube off, but not long enough to fully break in the cam so you're in the danger zone. Besides, you'll FEEL a wiped lobe or two, its not like you just lose power. You get a dead miss, or at least a severe lope.
Landyacht
Active Member
Fury1969WI
New Member
Thanks for the post Land Yacht! I didn't have any rockers (though mine are the stamped steel, not the killer rollers like the video) with anywhere near that sort of movement and to 440_Magnum's point engine runs smooth and engine did not die when started ran through break-in period; 10-15 minutes maybe, something like that, and kept RPMs high., Dumped the oil and drove it like that until the restification disassembly started in early 2008.
moper
Well-Known Member
- Joined
- Nov 15, 2010
- Messages
- 813
- Reaction score
- 447
Ok - the 1407 is a performance carb. It normally is lean out of the box anyway so you will want to grab a strip kit for it, check the vacuum levels with a gage stuck to the windshield while you're driving around, and make sure the step up springs are matched well to the vacuum levels. Next step diagnostics-wise for me would be to take a cylinder pressure reading. That could indicate if the cam's in way wrong or not.
Fury1969WI
New Member
Strip kit? like the jets and spring kit? I have that, was assuming i'd try to lean this thing but am now planning to get the timing right before fiddling with the carb (other than i added an electric choke kit).
Regarding check on cylinder pressure; how 'xactly would i know that? Used to checking for variation cylinder to cylinder to spot problems but in this case if all are low, say below 110 cam is out of phase? (if that's the right word). Couldn't i still develop good cylinder pressure someone in the 720 degrees of rotation? I'm not understanding how this would tell me unless i know in relation to TDC and then "know" when lobes are working? I'm a hack mechanic in case y'all hadn't figured that out yet...
RemCharger
Active Member
A compression test is being suggested I believe, not a cylinder leak down test. Pull all plugs, hold throttle open and crank for 5 or 6 bumps on the gauge. Common would be 120~130psi.
Similar threads
