360 Magnum build questions

Posted By: mdwyer

360 Magnum build questions - 04/26/11 11:23 PM

Stock 360 magnum going into 72 satellite.

Stock 360 mag (1997)
Eddie RPM air gap
72 340/ 360 mainfolds
Air conditioning
4 speed (truck 833 o/d)
8 3/4 3.73
255/60/15 tire

Give me some ideas for cam (rerind) and carb.
looking for mileage and cruise. No drag racing.

thanks,
mike

Posted By: joedust451

Re: 360 Magnum build questions - 04/27/11 12:01 AM

Quote:

Stock 360 magnum going into 72 satellite.

Stock 360 mag (1997)
Eddie RPM air gap
72 340/ 360 mainfolds
Air conditioning
4 speed (truck 833 o/d)
8 3/4 3.73
255/60/15 tire

Give me some ideas for cam (rerind) and carb.
looking for mileage and cruise. No drag racing.

thanks,
mike

If your not looking for top perf., but more gas mileage, I would get the reg. perf. with the heat crossover over the RPM air gap, then run a TQ, I'm sure some are going to disagree, but i will tell you the magnum engine will have plenty of power, If you want a regrind, don't go crazy, You may just want to run the engine just the way it is with the stock cam & a set of 3.23s, this will make for better mileage & less hassle, I'm sure it'll still run good, just drop on the intake/carb & dist.

Posted By: Prince_Valiant

Re: 360 Magnum build questions - 04/27/11 01:08 AM

Probably just stick with the same cam...I used a stock magnum w/ eddy air-gap (same as performer rpm), MP ignition, 79 truck manifolds, eddy 600 carb...plenty strong as configured.

best mileage taking it easy was 17mpg in the little red truck. Best quarter was 15.1 @ 91mph...not too shabby for a 3.55 geared truck. The only thing was it sounded like a docile little 318 truck of course was really done at 4700rpm.

For a reground cam, I went with Hughes 218/228 @ .050 on a 106 LSA, installed on a 103 degree centerline...had a very nice (lumpy) idle, very strong mid range w/ a nice pull up to 5500rpm...mileage wasn't really much if any worse. I've got the cam lying around as I'm upgrading to an AL headed 408 magnum and it'd probably work well with the 3.73 gears. Never ran it at the track or got mileage numbers...but seat of the pants was dramatic (also did heads, carb, and headers at the same time...but it's safe to say it's mileage was similar and was perhaps a 13 second truck).

If I ever sell the truck, I'll probably swap in another magnum with this cam as it's really was a nice sounding/performing unit. Got 14 inches of vacuum.

If mileage is paramount, I mostly agree with joedust451...though I'd be open to keeping the intake if you've already got it, and invest in 3.23's...it's kind of nice to cruise at 65mph at only 2000 rpm

Posted By: mdwyer

Re: 360 Magnum build questions - 04/27/11 04:58 AM

thanks guys

I figured as much on the cam, will call Hughes and Bullet to see some basic profiles.

would like to run a thermoquad but this intake can't take it so a square bore carb is it.

The intake is the only one I have for a magnum.

3.73 gears and .73 od should put me about 2200 at 70 mph with a 255/60/15. This will be close to a daily driver.

Sounds like I'm in for a cheap build, that always scares me

Posted By: mopfried

Re: 360 Magnum build questions - 04/27/11 11:53 AM

you could always put an adaptor on it fot the thermoquad

Posted By: patrick

Re: 360 Magnum build questions - 04/27/11 12:20 PM

Quote:

Quote:

Stock 360 magnum going into 72 satellite.

Stock 360 mag (1997)
Eddie RPM air gap
72 340/ 360 mainfolds
Air conditioning
4 speed (truck 833 o/d)
8 3/4 3.73
255/60/15 tire

Give me some ideas for cam (rerind) and carb.
looking for mileage and cruise. No drag racing.

thanks,
mike

If your not looking for top perf., but more gas mileage, I would get the reg. perf. with the heat crossover over the RPM air gap, then run a TQ, I'm sure some are going to disagree, but i will tell you the magnum engine will have plenty of power, If you want a regrind, don't go crazy, You may just want to run the engine just the way it is with the stock cam & a set of 3.23s, this will make for better mileage & less hassle, I'm sure it'll still run good, just drop on the intake/carb & dist.

that would be an effort in futility, the performer flows way worse and is at best equal to a stock LA 4bbl intake as far as power, and a magnum doesn't have heat crossover passages in the heads anyway.

I'm very, very satisfied with my reground cam from bullet. I used their HR259/316 lobe for both intake and exhaust in my mag headed 318. I am running chrysler 2.2L/2.5L retainers from a junkyard, and hughes #1110 springs.

for mileage AND power, go for as little overlap, as much .050, .2 duration, and lift as possible....my cam is a reground LA roller on the stock (LA) LSA of 112, installed at 108. IIRC the magnum has a 2 degree wider LSA.

run headers, they'll be worth more than 20hp/20 lb-ft of torque

Posted By: mdwyer

Re: 360 Magnum build questions - 04/27/11 03:32 PM

Patrick,

I plan on running 1110 springs and have some 2.5 retainers.

trying to stay away from headers but it is an option. I have a pair.

looking for good power in the cruise rpm

car does have a/c and power brakes.

would a LA roller cam regrind give me anything more? or stick with bullets magnum regrinds?
I have both.

thanks,
mike

Posted By: HotRodDave

Re: 360 Magnum build questions - 04/27/11 03:32 PM

I would run a single pattern cam with around 208 or 210 duration @.050 and try to get around .480 lift and run about 110 or 112 LSA. Run some GM 3100 V6 springs and retainers. The air-gap intake will be just fine with an adapter and a t-quad.

Posted By: patrick

Re: 360 Magnum build questions - 04/27/11 06:55 PM

Quote:

Patrick,

I plan on running 1110 springs and have some 2.5 retainers.

trying to stay away from headers but it is an option. I have a pair.

looking for good power in the cruise rpm

car does have a/c and power brakes.

would a LA roller cam regrind give me anything more? or stick with bullets magnum regrinds?
I have both.

thanks,
mike

the LA cam, if from an M body will have a long snout for a fuel pump eccentric...that is about it's only real advantage.

my cam pulls 17 inches of vacuum at an 850 RPM idle, drops to ~700 and 13-14" in gear.

my 3950 lb 5th ave has been averaging 17-18.5mpg in mixed driving with my mag headed 318 with this cam, an A500 tranny, 3.55's and 27" tall tires.

engine combo is:
stock 86 short block
home ported magnum heads
aforementioned cam
1406 edelbrock 600cfm carb
eddie RPM air gap
summit 1 5/8" full length headers.

pulls real strong from ~1500-5500 RPM.

Posted By: 360view

Re: 360 Magnum build questions - 04/27/11 09:57 PM

For MPG
the stock factory 1994-1996 360 cam
is close to the best you can do,
aside from having a V8 cam custom ground with the cast iron 8L V10 engine cam lobe profiles.

The factory valve springs are very light
and the purpose was to have lower valve train friction, for slightly better fuel economy.

You can get about 6% better MPG
by raising the static compression ratio
as much as you dare.
Tight quench clearances will help accomplish this.
0.040 inches or better
0.026 may be getting near the edge

You can get about 10% better MPG
by running an air to fuel ratio
in the 18 to 20 range,
instead of the factory 14.7

Posted By: patrick

Re: 360 Magnum build questions - 04/28/11 02:45 PM

Quote:

For MPG
the stock factory 1994-1996 360 cam
is close to the best you can do,

really? it's got a lot of seat duration, and low lift...I'd think you'd do better to minimize seat duration and overlap, while maximizing lift and mid-lift duration...

http://bulletcams.com/Masters/HRlobes.htm

the stock 360's cam profile is similar to their HR258/250 lobe. I'd think you'd improve power and economy by going with say their HR252/320 lobe, which has 6 degrees less seat duration, but a whopping 22 degrees more .2" lobe lift duration.

Posted By: HotRodDave

Re: 360 Magnum build questions - 04/28/11 03:24 PM

If I was picking a cam strictly for mpg out of those bullet lobes I would make it a single pattern Hr231. Should make more MPG and TQ than the stock cam so it can pull a super high gear like a 2.45 or even 2.20 and that combo will really get good MPG. I bet if you built that motor with tight quench, that cam and that gear ratio you could get 30 mpg from a 318. I would use the stock magnum pistons and mill the block to zero deck them, that way you have no valve releifs like a KB167 that could interfere with flame travel or give a crevice volume that is useless.

Posted By: mdwyer

Re: 360 Magnum build questions - 04/28/11 03:38 PM

thanks guys

Patrick i will call John At bullet and see what he says. 259/316 or 259/326 or 252/320

My car weight and options are close to yours

current build
reringed 360 (deck trued)
home ported mag heads (gasketmatched cleaned up not hogged out) deck cut how much??

1110 hughes springs / 2.5 retainers
mp electronic kit
1406 eddie carb or 3310 holly carb
Eddie RPM airgap
Headers or ported mainfolds(71-73 340)????

3.73 8 3/4
833 o/d (.73 final)
255/60/15

looking like a good driver combo.

mike

Posted By: mdwyer

Re: 360 Magnum build questions - 04/28/11 04:14 PM

Rethinking gear ratios

3.23 27 inch tire 2250 rpm @ 75 mph
3.55 27 inch tire 2450 rpm @ 75 mph
3.73 27 inch tire 2575 rpm @ 75 mph
3.91 27 inch tire 2750 rpm @ 75 mph

what cam would you use for these? A/C & power brakes

Dave I will get as much quench as I can. Going to measure the 3 blocks for taper and deck height and go from there.

Patrick 1110 springs require NO machining correct? they are drop on?

thanks,
mike

Posted By: patrick

Re: 360 Magnum build questions - 04/28/11 04:57 PM

Quote:

thanks guys

Patrick i will call John At bullet and see what he says. 259/316 or 259/326 or 252/320

My car weight and options are close to yours

current build
reringed 360 (deck trued)
home ported mag heads (gasketmatched cleaned up not hogged out) deck cut how much??
1110 hughes springs / 2.5 retainers
mp electronic kit
1406 eddie carb or 3310 holly carb
Eddie RPM airgap
Headers or ported mainfolds(71-73 340)????

3.73 8 3/4
833 o/d (.73 final)
255/60/15

looking like a good driver combo.

mike

check your gross lift potential before the retainers and/or locks hit the seals. that's why I went with the 259/316 lobe. on my heads I wasn't comfortable going much above .520 lift.

Posted By: patrick

Re: 360 Magnum build questions - 04/28/11 05:00 PM

Quote:

Rethinking gear ratios

3.23 27 inch tire 2250 rpm @ 75 mph
3.55 27 inch tire 2450 rpm @ 75 mph
3.73 27 inch tire 2575 rpm @ 75 mph
3.91 27 inch tire 2750 rpm @ 75 mph

what cam would you use for these? A/C & power brakes

Dave I will get as much quench as I can. Going to measure the 3 blocks for taper and deck height and go from there.

Patrick 1110 springs require NO machining correct? they are drop on?

thanks,
mike

yes, a drop on.

which gears do you have currently? personally I'd go 3.23 or 3.55....all the regrinds we've discussed would work fine with any of these gears. don't forget, first in the A833OD is 3.09. 3.91's might make it too granny-ish to be usable on a day to day basis. first would be like a standard 4 speed with 4.56's

Posted By: mdwyer

Re: 360 Magnum build questions - 04/28/11 05:17 PM

Currently have a set of each.

I am currently thinking 3.55 or 2nd choice 3.23

259/316 profile 1110 springs
eddie RPM airgap
eddie 1406
340 mainfolds
zero deck block (stock pistons)
lightly ported heads

time to head off to the machine shop.

thanks,
mike

Posted By: 360view

Re: 360 Magnum build questions - 04/28/11 08:12 PM

Quote:

Stock 360 magnum going into 72 satellite.
Give me some ideas for cam (regrind) and carb.
looking for mileage and cruise. No drag racing.
thanks,
mike

If the 'No drag racing'
is true,
and MPG
and cruise performance
(higher potential torque at low rpm so that the engine 'feels so strong it doesn't need to downshift on the highway)
then we want:

Good gas velocity past the ring shaped valve annulus opening,
even at part-throttle when flow is way below maximum.
If the gas velocity is kept in the 230 to 290 mph range by being squeezed into the right area, then the 'momentum' of the gas will cause it to keep flowing into the cylinder even past bottom dead center.
This builds torque at low rpm
(Yes, near redline rpm it will be restricting flow)

We want good swirl at part throttle,
which is also enhanced by low lift
which 'shrouds' the valve opening more
and makes the air flow curve
as it enters the cylinder.
{this is also why the stock 'heart shaped' Magnum combustion chamber has that 'point' between the intake and exhaust valve seat... it guides the air flow into swirl)

We also want little reversion during overlap

These factors will help for part-throttle MPG
and as the vehicle hits hills
or wants to pull out and pass
this will also help create the most torque
in the 1700 to 2300 rpm range.

This calls for low intake valve lift
so that gas velocity stays high
and swirl helps create fast burn.

This can be confirmed by looking at
current year Chrysler practice
since the newest version 5.7 Hemi has
VVT (variable valve timing)
so a little searching will find out what
reduced durations, overlap and seat timing
are now set by the PCM
for part-throttle
and 1700 - 2300 rpm.

Soon we will be able to see what
valve lift reductions
the Fiat Multi-Air system
commands to be set for low rpm

If the engine was to be drag raced
the camshaft choices would be completely different.