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  #1  
Old 07-13-2002, 02:40 PM
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dusterbd dusterbd is offline
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ok. i suck. ill fully admit to that, as well as the fact that my car is slow. but its a lot slower than i feel it should be, so im going to ask you guys your opinion:
the duster is a street car. 4 speed, 3.91 gears, 28 inch tall street tires, all steel. bench seat. 78 360 2barrel motor. has an offy divided single plane and a chevy 327 style carter AVS on it. 318 exhaust manifolds dumping into 2 inch exhaust with glasspacks. timing is set as high as it could go and still start easily and run without detonation. (did it by ear). im running 15.6 at 89 in rockingham NC right now. thats pathetic. i fell the car should be good for high 14's. still slow, but not quite as pathetic. anyt suggestions, or do i just have to face the fact that the motor is a worn out smogger job, and itys time to finally start the buildup i layed out a year ago?
the motor will hopefully come out next summer for the rebuild, and then its on to the rest of the car. hopefully.
thanks guys.
mike
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  #2  
Old 07-13-2002, 05:54 PM
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rumblefish360 rumblefish360 is offline
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The 360 engine has a few things wrong with it to run the numbers you want. 1st;

1) The 318 exhaust manifolds on it are choking it to death. I bet headers are part of you build up. So, go get them and run 2 1/4 inch pipe. Grab a crossover pipe if you can.

2) Try a bigger cam. The stock 2bbl. cam is very small. A stock 340 HP cam is good, or it's replacement with a tighter centerline.

IMO, the rear ratio / tire height combo is off. Ethier a smallr tire @ 26" or a ratio change would do. Say, 4.30's with the 28" tire.
Try a spacer on top of the intake. 1 inch should do.
Milling the heads to grab a little compresion would also be good. .050 mill and installation of 2.02's will help alot.
THE ENGINE MAY NOT BE WORN OUT. A COMPRESION CHECK SHOULD BE DONE FIRST BEFORE YOU DO ANYTHING!

My questions;

What car is it in? And the cars weight?
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Old 07-13-2002, 06:14 PM
mtrv8n mtrv8n is offline
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I agree, the tires are way too tall..and the cheapest way to fix , especially since you'll want more traction at 14 than at 15, is to go with wider tires in the next lower aspect ratio. BF goodrich has a great spread of choices in the t/a radial. If you got 70's on, go for 60's..you can get the spec online from the company. You want to top out at about 95-100 mph for a 14 sec trap, so your engine should be spinning at about 5500 rpm at that speed.

I don't know that changing the exhaust will help until you are flowing more from the ports, so a cam swap is the thing here. You can do a cheapo and swap just the cam, check out the mopar web site, it has suggestions for brackets.

mid 15's are not bad for a 78 360 smog motor, but don't go spending money on lotsa little things that don't match.

For example, the exhaust swap (a truck header from a dakota is a cheap way to upgrade, and hookers are not expensive either..) will cost in fabricating the pipes to match your header. It might not make the big difference without a cam swap, and careful carb tuning. Stick with smaller tires to start, you need the final ratio change even with all the other stuff, and might get into the 14's with that change alone
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Old 07-13-2002, 11:11 PM
451Mopar 451Mopar is offline
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You need headers and dual exhaust. I would run 2.5" dual exhaust with turbo mufflers (some glaspack mufflers really are more restrictive than full size mufflers.)

The carb may only be a 500 CFm 4-bbl? You may need a larger carb. Also you did not mention if you have tried jetting it for more power.

I'm not sure about the intake manifold? Is it a Port-O-sonic?
Since I don't know too much about the intake, I don't know if it would make much of a difference to change it at this point.

The stock 360 engines had very low compression ratios, mild cams and the nylon tooth cam sprocket / timming chain set (usually with the cam installed retarded too.)

You could install a mild performance cam of about 220 @ 0.050" duration (use at least 210 @ 0.050" duration, but your low compression really won't like cams with duration much over 220 @ 0.050") use a new double roller timming chain set and degree it in slightly advanced for more cylinder pressure. At the same time you could pull the heads, get a good multi-angle valve job (at a minimum) and mill them to increase the compresion ratio. Then re-assemble using the thin 0.020" steel shim head gaskets. If you use the composite fel-pro gaskets which are 0.040 to 0.050" (depends on the part number) you will reduce the compression ratio.

If you are looking for more power than that you could rebuilt the heads with the 2.02"/1.65" valves and port the heads, but that will run up the cost of the engine.

When your ready to rebuild the engine, there are many pistions avaliable to boost the compression ratio, and there is also the 4" stroker cranks that are reasonably priced to increase the displacement, and the option of better flowing aftermarket heads, but this is getting out of the scope of the original question.
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  #5  
Old 07-14-2002, 02:26 PM
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dusterbd dusterbd is offline
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thanks for the help guys. my origonal intention was just to see if i did something really wrong with the tune (other than the crappy exhaust. TTI step headers and 3 inch is in the works). it was just speculation to see if anyone had any ideas about the next direction to go before the 500 horse injection (hopefully a stroker crank. depends on how good the christmas bonus is). anyway, i was already thinking about the 26 inch tires as a good step up, so ill be trying that next time at the digs. also, the divided single plane goes under the offy 360 degree. its not a port-o-sonic, near as i can tell. its jut a toker with a milled divider plate simply put. do you guys think that an LD4B (friend has one to loan me) would be better? i realize the ports are smaller, but would the increase in velocity make up for it?im just trying simple, cheap things at this point, as all the money is going into the bank for the buildup. (if youre wondering what it is, search in the performance talkk archives under duster buildup plans)
anyway, thanks for the advice. i may just have to get brave and put on that old set of super shops headers that are collecting dust waiting to be posted on e-bay.)
again, thanks.
mike
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  #6  
Old 07-14-2002, 02:44 PM
Doug Wilson Doug Wilson is offline
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I think there is more to be had with the combo you've got. First, find out what your timing REALLY is - check to see if your timing mark is really at TDC - do you know how to do that? Second, make sure all the parts in your distributor are working right - advance plate, vacuum advance, etc. Third, have your distributor curved - I've got a guy here that will do it for about $40 plus parts, so there should be someone who can do it near you. I think you will find significant improvement in those steps.
Next, check your plugs for proper jetting - do you know how to do that? Re-jet as indicated.

All the stuff the other guys said is on the money, also.
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  #7  
Old 07-14-2002, 03:00 PM
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dusterbd dusterbd is offline
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yeah, the mark really is at TDC (at least it was 15,000 miles ago when i put the engine in). the distributor is in good working shape. just went through it not too long ago. ill agree that there is more to be found in the timing curve. as a cheap and temporary fix, could i remove one of the springs completely to let the timing in faster, or do i need to scrounge up an advance spring kit? anyway, messing with the timing is one of the things ill put that on the list of things to try.
also, about the jeting. i cant do a thing with it, as the carbs an AVS. no one makes rods. i think (correct me if im wrong) that the edelbrock rods will fit, but im not certain since its an AFBstyle. i know its running a little rich, so thats not a good thing. anyway, if the AFB rods will work, ill go with that.
also, to clarify the comment about being worn out: its pushing a bit of oil, and the oil pressure is low. so i know its on its way south, and its time to start amassing parts.
mike
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Old 07-14-2002, 04:15 PM
Doug Wilson Doug Wilson is offline
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I don't know for sure, but I think the AFB rods work. There is an outfit in Florida, I think that can tell you that stuff. I'll check and get back to you.
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  #9  
Old 07-14-2002, 04:20 PM
Doug Wilson Doug Wilson is offline
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Try daytonaparts.com - if they can't help, let me know, cause I've got another one somewhere.

I'm at ThunderboltRanch@msn.com
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