360 Magnum

[FredMcJoe]

I don't know where your vac is coming from.

Manifold vacuum at just below the throttle plates is the way cars were until the emission-minded 70s. The Carter on my 1977 Super Six slant 6 was ported to above the plates from a pipe on the upper right side of the carb. The benefit to having it at manifold vacuum is at idle, its at max vacuum advance. You want lots of advance to elongate the burn time of the relatively lean fuel mix (idle, closed throttle plates, lean mix of fuel being burned) which keeps the engine cooler.

This tended to increase emissions. The idea developed that using throttle vacuum, vacuum derived once the throttle plates opened, would reduce one of the emission particulates.. noxides comes to mind. Thus, the pipe out the right side of a Carter became the norm.

 

[Bruceynz]

MASSIVE UPDATE!!! MASSIVE UPDATE!!! MASSIVE UPDATE!!!

Ok tonight my buddy came over and we set the timing to 16 initial which gives me 36 total (Previously it was 10 initial) WOW!! what a difference it makes, dam thing got some got some balls now!!! 6 degrees kills a motor dead! Off line performance it will fry the tires! Gives a nice good push in the seat and winds up good, although I have not taken it over 5000rpm, maybe 4500, its working hard on bedding rings in, different RPMs but not taking to 5500rpm yet. My trans doesn't change into top gear and my vicious fan thingy growls, so just a couple more things to iron out and we are good to go! So some good progress, 600 holley seems to work nice as well! Any ideas why trans won't go into top? low oil or the kick down thing not adjusted right (I think the ratio is wrong)

 

[80mirada]

Probably you kickdown linkage keeping you.out of top gear.

 

[Bruceynz]

So what way does it need adjusting? My Buddy says they always take a bit of setting up, he thinks the ratio is wrong and I may need to change where the kickdown cable is mounted on throttle

 

[Bruceynz]

Ok, chatted to trans shop, he said the quickest way to work out if it is linkages or trans is to disconnect the kick down linkage and drive it down the road gently and see if it goes into top gear, he said do NOT give it any gas as it will fry the trans as the line pressure is only approx 70psi!!! He said it should change into top before 30mph. So thats the next thing to try.

 

[Bruceynz]

Ok I took some measurements tonight, the ratio is wrong by just over1/2", I need to move the accelerator up 1/2" I am lucky there is a hole just in the right place, from what I have been told this is a very critical part of the trans operation.

Secondly I fitted a shield on radiator. Cowling tonight. I need a new vicous fan clutch the one I have growls.

 

[Bruceynz]

I have adjusted my linkages, got to late to take out for a ride tonight. Will get to it in the weekend, played with the electric choke tonight, its a slow process but I think I have it sorted, just need 12v to it now.

 

[Bruceynz]

ok we are sorta getting there, we have top gear now but you take your foot off the gas then it drops into top. Ok looking at this pic with my red lines, the trans is the bottom one, if I shift that locking thing to the left its going to let the leaver return further, if I move it to the right its going to pull the on the leaver at the trans and push it further back, left will do what and right will do what?

Anyway here is some proof she is going, I didn't even try to do this out the front gate BTW its 90f today, hot for working on cars!

 

[Bruceynz]

Have a listen to the idle, its nice and deep and even

 

[AJ/FormS]

Hi Bruce
It runs! congrats.
I reread this entire thread, and I'm a little confused as to what the combo is ending up as.
Just to recap; are the cam and carb, the same ones you listed in the first post,namely 262/270/110 and the 770 Avenger?
And are you still running the 3.23s, and the A904?
Have you tested the TC stall yet?
And what are your driving impressions thus far?

 

[Bruceynz]

magnum engine, engine quest heads, air gap intake, 600 holley, 209/217 cam at .49" lift, headers, rebuilt 904 with transgo shift kit stage 1, 2000-2200rpm stall have not verified exact stall yet, 3.23 rear end, have not taken to 5000rpm yet but don't really need to for street use, got plenty of low down grunt!

 

[AJ/FormS]

OK thx.
Yeah I kindof know about that grunt; I had a similar combo.

 

[Bruceynz]

Yeah its brilliant! This is my combo of engine, I choose the whole package and I am very happy with it! Its not going to win any 1/4 mile races but it will give a few people at the stop lights an eye opener I like it its perfect and I am happy with the results!

The best thing about it is I know all the specs, I know whats been done!!! Smooth idle too, its basically the engine Chrysler should of built but never did, its better than the 360 RT engine but its not quickest thing in the world, but it will easily fry the tires! The cam I used is not a performance cam, its what I would call and RV cam, I had a RV cam in a 318 before and I was happy with that! I am 44 and lopey/lumpy idle not my thing! Love the nice smooth idle! One thing though my red holley fuel pump is noisy! it whirrs in the back

 

[AJ/FormS]

You have a very nice street combo, don't sell it short.
Those 3.23s will take her all the way to 55 and beyond. The 2200TC will get the engine close to where the torque is, and by 3600 she will be motoring pretty good. By 3900 the torque will be peaking and the nose will be up. Keep on it and by 5000 the power will be peaking, and you'll be doing close to 48 mph. But let her stretch out a bit another 400 rpm and she'll be doing about 52.Now she might be reaching the end of her lungs, but hang on with good valve springs, and a minimum lifter preload, she'll stretch out even more;( Mine went over 7000). At 60mph, she'll be doing about 6200 with 27s,let her buck.

My car went 12.9@106 with about the same pkg,3.55s and 3650 pounds......... so that translates to about 330hp. I remember that combo fondly.
It had a 270/276/110 cam. I tuned that combo to get hiway mileage like a modern-day EFI 4-banger. Allbeit I had help in the form of 10.9 Scr, double overdrive, and a stickshift. That engine had no problem pulling 2.76s.
I would still have it today,18 years later, if it had not dropped 2 lobes one day. It had a really awesome pull from idle to 6000. I played with all kinds of gearing on that combo; 2.76s,2.94s,3.23s,3.55,3.91, 4.10,4.30,4.88,5.13... And transmissions with low gears of; 2.66,and 3.09, and with top gears of 1.0, .73, .71. And with a GVOD used as a splitter.I'll tell you what, that engine didn't care what gears I fed her.
One of my favorites was this one;4.30s and the A833od,and the GVOD. This is what it looked like in terms of road gears;13.29-10.36-7.18-5.60-4.30-3.35-2.38; the splits were; .78-.69-.78-.77-.78-.71
The power peak was at about 5200, so I shifted it at 5800, and in most gears, the Rs fell to 4500, so the powerband requirement was 1300rpm, basically pulling max power all the way thru each gear.65mph was 1900rpm.
That engine was so much fun. I called it the little engine that could. It could do it all.I loved 3.23s with that engine; hammer down in first gear was instant tirespin at any speed below about 50 with 275/50-15s. I don't see why yours shouldn't do that too.
My final gear choice was 3.55s and an A833 with a 3.09 low, and still the GVOD.The current cam is a 276/286/110
I mostly drive it as a 5peed now, with road gears of
10.97-6.82-4.97-3.88-2.77, but this combo won't make gas-mileage,no how,heehee.

Keep the painted side up!

 

[jasperjacko]

I told you it would run!

 

[Bruceynz]

you did! all you guys in here are Awesome! You have all helped me out heaps with all my problems!!! Many thanks to all!!

Merry Xmas and a Happy New Year and a Mopar magnum for me in between the fenders for xmas, yipee

 

[Aspen500]

I was reading all your posts from when I kept missing staff meetings and, good deal on it all working out so good! Nice feeling, isn't it?

I noticed what you said about bumping your ignition timing ahead by 6 degrees and what a difference it made. Early last summer I bumped my initial ahead by 2 degrees from 10 btdc to 12 (brain fart on what my total is now) but wow! Like night and day. At highway speeds the exhaust was quieter, the engine didn't sound "labored", the throttle response was better, it starts with about 1/2 a turn of the crank, even on a cold engine, and added bonus, the mpg went from 10 up to 11.5. Only downside, have to run octane booster in warmer weather now but that's minor.

 

[Bruceynz]

Hahahaha someone told me to hurry up and get it going the suspense was killing them, may have been you anyway we have fuel issues here, we can get 91,85 and 98 and the Pump, but our fuel is RON rated, you guys get 87 and up but it is MON rated, our 95 is borderline your 87 and 98 is pretty close to your 87 so we are screwed for compression down under!

If I take my initial up to much more than 16 it might be a prick to start, I think the max I could go is 38 degrees but we may start pinging, when I have it all 100% nailed down I may fork out for a dyno tune and get some real numbers!

What I have is a drive train noise, when the car changes from 3rd to second and to 1st when you slow down, the trans is very quick on the changes now, it just goes pip and its in the next gear, its like you know when you goes from reverse to drive you can get a we clonk as everything takes up, its that kind of noise, any idea?

 

[AJ/FormS]

>Check your lugnuts
>Set the parking brake. Put it in neutral. Grab the driveshaft and turn it all the way over and back. How much play is in that rear end? Is it a limited slip? and what size?
>Now set the driveshaft to in the middle of the play. Then just jiggle it back and forth trying to feel just the pinion play. The backlash on that is usually in the range of .006 to .012, which is from just perceptible to a tiny ticka-ticka. The rest is in the side/spider gears and cross-pin. You wanna catch a failing cross-pin as soon as possible on account of they sometimes come out the back cover, Ziiiing.

Our gas here in Manitoba is (MON+RON)/2, and I'm set up to run 87E10 at 10.9 SCr.
I don't think you're screwed, but yeah, you are seriously challenged ; especially considering how expensive everything sounds to be.

 

[Bruceynz]

Diff is 8.25", No LSD, seems to be on with the old 360 in the car. Will look into soon, at work at the moment.