Cam Question For Pro

[RamChgr318]

Given your obviously extensive knowledge, what cam would you use in an '87 318 (roller tappets) for towing at interstate speeds?
Thanks
Mike

[PRO]

Hey Mike,what is your approx. vehicle weight?and gear ratio?(include tire size) what mods on 318?and how much weight do you tow max? The pickins are slim for this cam anyhow but I know where you can get one ground to your desired spec's.Look forward to your reply....PRO...

[RamChgr318]

Thanks for the reply. The 318 is in a RamCharger, approx 4500lbs worth, stock height tires 28-29" and a 2.94 rear end. It has a mopar 4bbl maifold and thermoquad carb on it. The trailer I haul is 4000+. Right now its not bad off the line or in traffic but it takes forever to get to 65 or 70 mph. Its not what I really expected as it gets to 50 fine but 50 to 70 takes 2 or more miles. I would have thought the oposite i.e. once you finally got it rollin it would be ok but not so. The 4bbl, new ignition components, K&N filter, and new single turbo muffler all helped a BUNCH but its not quite there. And . . . there's always just that little bit more we can squeeze out of 'em, right? The sticking point is the durn roller tappets. There's tons of cams out there for up to 85-86s' but not many for the factory roller tappets. Do the new magnumcams work in these older 318s'? Hughes, Lunati, and Ma Mopar all list cams for these motors but will they fit/work in the pre Magnum roller engines. If you read Squads post re his 88 cop car he's in the same boat too. BTW is there a way to ditch the rollers and go with a hyd flat tappet in these motors. If I'd have done my homework before I bought my R/C I'd have looked for a slightly older one!!! ;-)
Thanks
Mike

[bandit340]

Mike
your asking alot out of your 318 with all that wieght and high axle ratio.Depending on your budget I would recommend at least a 3.23 ass end and instead of camming up your 318,try to find a longer stroke 360.You need torque.318 and 340 motors are for high reving HP,not for heavy trucks and towing

[Christopher]

I have a 86 Ramcharger with a 318 and 2.94 gears also.Mine is getting 15 mpg as it sits now.This is what I'm going to do ... 3.55 gears,a 340 replacement cam, lifters,timing chain set,Mopar valve springs,a true dual exhaust with the late Magnum exhaust manifolds(they are on the truck now)Edelbrock performer and a Holley 650 vac sec carb.I'm using the Holley as I've had it in the shop for a while now.If I didn't already have the Holley,I'd use either the Edelbrock 600 elec choke model,or a 600 cfm Holley.I've used this same setup on other Dodge trucks and cars,and it's always performed very well.You can change over to the non roller setup if you use the non roller pushrods,lifters and cam.My 86 block has the bosses for the retainer plate for the roller lifters,but never had them in it.It was a running change starting in 85 or 86.

[RamChgr318]

Thanks guys for all the suggestions. I am a Civil War re-enactor and haul a covered trailer with a cannon and all the attendant parts and tentage etc. We hauled this stuff with a Merc Sable wagon (3800 v6) for a couple of years with no trouble other than it was slower than molasses so it may not be as heavy as I said. I am getting the same kind of hwy milage (10-12) with the R/C that I got with the wgn so I'm not really unhappy with the R/C's performance I just want to hop her up a bit. :-) The R/C has an 8.25 rear end and MoPar performance only lists 3.55 and up for this axle, is that too low for freeway use or should I hunt the bone yards for one in between the 2.94 and 3.55? I do have the 999 trans with lockup so this helps with the revs at hwy speeds. I'm really happy to get a definitive answer re the factory roller tappets and this opens up a whole bunch of possibilities cam wise. This truck is my toy and warming it up will have to do till I find the "Right" A or B body MoPar. I was a "Hot Rodder & Street and Strip Racer" back in the 60's and like so many of us 50somethings, I've got some time and cash to play with FINALLY! Thanks for all the answers and suggestions they are taken to heart and I'll keep y'all posted. BTW thre's an 1/8 mile strip about 20miles from here and they run IHRA bracket racing Fri/Sat wouldn't it be fun run a relatively quick R/C out there and suprise a few folks?
Thanks again,
Mike

[Christopher]

I've looked at all the possibilities and my personal opinion is that the 3.55 gear is the way to go.

[RamChgr318]

Christopher,
I'm sure that is good advice and I do thank you. I'm interested in the magnum exhaust manifolds you are using, I too saw that suggestion in Mopar Muscle and was interested in trying that out also. What year truck did yours come off and what's your accessment, good, great, so so? How much did you have to give for them etc.?

[Christopher]

I used the Magnums as they are obviously quieter than headers.I got them from a guy who was putting Mopar headers on his 99 Ram.I paid $75.00 for them.I work for a major car rental company and we have all of the Dodge trucks(Durango,B-vans etc.)and the manifolds all look the same.My understanding they are about $60.00 each new from a Dodge dealer.I like them very much.What I'm doing is a "engineering evaluation" for a paper I'm doing for a college course I'm taking.So I am making one change at a time and recording results.I put the manifolds on and then went to a muffler shop owned by a good friend of mine and we installed new head pipes,but still using the factory single exhaust.Next phase is to install true duals and again,record the results.I can tell you that the truck has more power since the exhaust change.

[PRO]

RC sorry it took me so long to reply,I just bought a house and had to move,I just had to repo my other buisness,and my other one has been busy as all get out.Your best bet is also the least expensive as far as cams go,like Christopher said you can use a typical cam in place of your roller,just remember to change the pushrods too.A regrind is available but at $190 plus shipping its overpriced and your limited on lift and duration.My recommendation is more than just a cam though, keeping mileage and towing in mind

and using your 2.94s try the MP P4452755(.405/.410&240*/248*(overlap 24*,centerline 110*)you can use this w/no other mods but true duals(2 1/4")and magnum manifolds will really add to this combo.The next suggestion is my favorite,use MP P4452757(.410/.425&248*/256*(overlap 32* centerline 110)and run "shorty" truck headers w/true duals(2 1/4")and shop for a 3.21 gear,even just buy a complete rear axle if you have to and swap it out,be forewarned 100K is about all the longer the spider gears last in the 8 1/4 so shop for a lower mileage unit.The only specs I can find on the roller cam you have is .390/.390 duration is not stated and 26* overlap so these MP cams are a little bigger but not so much that it will hurt mileage in fact if you do exh and gears youll see a mpg increase,also what carb are you running? for this app. I like an edelbrock 600 or carter 625 they will definetly do better on mpg than a holley or thermoquad.Hope this helps let us know how it turns out........PRO....

[RamChgr318]

Well . . . .
Lots of GREAT tips and suggestions for which I thank you all muchly! So here's what I plan on doing.

I ran across a set of Doug Thorley 318 truck headers at a very reasonable price and made a deal for them so that's what I'll be using for headers. I'm going with the MP 2757 cam, Mopar performance valve springs, a double row timing chain, stock push rods and a Carter 625 carb. I've already got a stock 4bbl police manifold and tQuad on the truck but I can sell the tQuad to a friend. All that stuff is on order and I haven't made up my mind about the rear axle ratio yet but I'm leaning toward the 3.21/23 which can be had from Dodge or US Gear.

I do have a couple of other questions though if y'all don't mind helpin out an "OLD" man one more time? What do I do about catalytic converters and true duals, put another cat on it or toss the one that's there out and forget I ever heard of the things or . . .?

The second is what can I do with the ECU computer, can it be totally removed(disabled) or does it controll more than the spark advance and timing etc. I think I specifically am worried about the lockup converter and what controls that? I really have no problem moraly, doing away with the smog crap altogether as we have no inspections in our part of Florida yet but I'm concerned what mechanical implications it may have!

Thanks again for you help. BTW the major part of this project starts Feb 1, 2000. I've got a 60 day window between re-enactments that I plan on going to and that's probably enough time for someone as rusty as I am at this kind of stuff to get the job done. :-)

Mike

[Christopher]

Mike,I live in Florida also(Jacksonville)and this is what I'm doing about the cat converters,as we still have the smog inspections here.I'm going to use the ones that Discount Auto Parts sells,they are the cheapest ones price wise and is the exact same as what the muffler shops here are using.I'm using 2 1/4" tubing all the way back.As far as the "computer" type ignition,I'll be dumping that also and putting in the Mopar conversion kit.I've had the kit for about 4 months now,just haven't installed it yet.Removing the items you mentioned won't hurt the mechanicals of the vehicle.



[This message has been edited by Christopher (edited December 30, 1999).]