1988 Roller Cam 318 'entry-level' power potential?

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MopaR&D

MopaR&D

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I grabbed a super clean 1988 Chrysler 5th Avenue a couple months back as a back-up Mopar for my Duster while it's out of commission. Of course I can't leave it completely stock; I already gutted all the factory single exhaust from the manifolds back and made my own duals with side exits. Next step (more like project) is swapping out the atrocious 2.21:1 7 1/4" rear for an 8 1/4" rear with 3.07:1 gears out of a Jeep. After that I plan to "de-Lean Burn" the car and put in an old MSD box I got for free (yes I know it's overkill but I have it already) along with a ThermoQuad carb I put together with the best parts from a few cores I had lying around.

I know this subject has been beaten to death (upgrading stock 318s with 4-bbl, duals, etc.) but I'm wondering if anyone here has done this to one of the later roller-cam 318s like in my 5th Ave? Looking at the factory specs the torque rating jumped from 235 to 265 lb-ft just from the changeover to roller cam and 302 heads. 30 net lb-ft increase is pretty substantial IMO and I'm wondering if that additional torque would produce more HP than a similar stock-flat-tappet 318 after doing these "bolt-ons". One old article I read showed that a late '80s 318 with 4-bbl carb and 302 heads but factory flat-tappet cam (not roller) dyno'd at 186 HP; would it be a stretch to say the same setup but with the roller lifters might nudge the 200 HP mark? Not that it matters to me a whole lot, I'm still going to do the upgrades but it might be an interesting discussion...?

I know the cam profiles were the same for roller or flat tappet (teeny tiny) and I wouldn't expect this thing to pull much past 4500 RPM with that cam but still, I'm curious lol
 
I'd love to see some pics of that 5th! As far as the 318 your best bet is to do that rear end swap first and then see how you feel about the performance. With the lean burn removed and switched for the old style electronic ignition my 5th will spin that peg-leg all day long. I think it's a 2.76 but I haven't checked, I've got a 2.94 sure grip from a friend that is waiting to go in.

Personally I would do all your mods before going into the engine. At that point if you still want more I would get the EQ heads and leave the rest stock.
 
318 2bbl had 230 hp gross. Yes, it will respond well to the 4bbl. Keep in mind you most likely have a lock up converter, which from the factory are often "low stalls".
 
89.Fifth said:
I'd love to see some pics of that 5th! As far as the 318 your best bet is to do that rear end swap first and then see how you feel about the performance. With the lean burn removed and switched for the old style electronic ignition my 5th will spin that peg-leg all day long. I think it's a 2.76 but I haven't checked, I've got a 2.94 sure grip from a friend that is waiting to go in.

Personally I would do all your mods before going into the engine. At that point if you still want more I would get the EQ heads and leave the rest stock.
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Hey I remember you from FFMJBO lol... I'm "MoparKidD-4" on there. I have some pics on my phone I'll post some up here in a sec...
 
Torque, baby ...& more torque..... Better flown heads, with viscocity, and short time cams, so work well here... Your first cam choice, on the A body build, works well here... Add 302 casting, with bowl work, and a GOOD valve job.. Have fun.....
 
Here's my sled... got this baby for $700 (yes hundred)

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MOPE- I myself have not messed around with a roller 318. I have many times in the past fooled around with the regular Hyd. cam 318's starting in the same fashion.

I do not think the MSD is overkill. No way, no how. Just make sure that vacuum advance distributor is well tuned and timed.

3.07 gears? Are 3.21's to high?

I took a '74, 318 and gave it some bolt on parts and a cam. It went really well. The key for more rpm is cam and matching springs. (of course)

Do you have an intake yet?
 
That looks great, especially for the price! My old ride had Firehawks on it and I loved those tires, it's too bad they're discontinued.
 
Hey MOPE, I used to live in Wellington :D
One thing about your area, you are dealing with a lack of air, and your motors are feeling it. The engine doesn't increase red blood cells to accommodate... LOL, so whatever you can do to throw more air into the throat, the more that Fifth Ave will like it :) The 302 heads are perfect for a 318 of your type of build in Ft. Collins, and they'd be better if there were some home-porting. I personally don't know if I'd change the cam. You can increase top end power through the carb, intake, heads, and exhaust. that cam might be the ticket for maintaining low end torque
 
More HP? It all depends on where the torque peak moved to. I'd bet the torque peak moved lower with the roller cam (a good thing for the loooow rear gear) , and so peak HP may not have increased; that is really inconsequential though. If your torque increased through a significant part of the lower and mid RPM range, then the 'scoot' of the car HAS increased, regardless of where the peak HP number ended up at.

BTW, I like your car!
 
89.Fifth said:
That looks great, especially for the price! My old ride had Firehawks on it and I loved those tires, it's too bad they're discontinued.
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I've had these tires for about 6 years now, they really are great... WAYY better than BFG Radial T/As, they were on my Duster originally but since I had converted it to BBP these wheels were just a quick swap onto the 5th Ave. They do surprisingly well in the snow as well that's what really impressed me. It is a great car for the price, the guy I bought it from runs his own small mechanic shop in south Denver and has a few '60s Mopars outside of his shop so I knew he was legit lol. EVERYTHING works on this car it's amazing; A/C (with climate control), power windows, power seats, and best of all cruise control! And it's so comfortable to drive, I'd argue it's more comfy than my mom's 2014 300C but that's probably because I'm biased towards the old stuff LOL.

@rumblefish360 I considered a deeper ratio but I want this to stay a good highway cruiser, that's the main purpose I bought it for. Around here 8 1/4" rear ends out of Jeep Cherokees are a dime a dozen and they usually came with either 3.07 gears (M/T) or 3.55s (A/T). The rear end (which I got for $100 from an offroading buddy) has 3.55s in it but I got a 3.07 ring and pinion for $50 from a specialty Jeep salvage yard in Co. Springs. I haven't got one yet but I plan to use a regular Edelbrock Performer intake.

@318willrun That's cool, Wellington is quite close to me... Regarding upgrading the 318 my plan is to start with all the "bolt-ons" first and see how it runs. I'm really not inclined to change the cam because A) I don't want a flat-tappet cam and B) roller cams are expensive lol. Lunati just came out with a new line of street-oriented Voodoo Hydraulic Roller cams though they're calling me...

@nm9stheham I think the reason the HP rating didn't go up with the cam and heads upgrade is because the ultra-tiny carb (Holley 6280, smaller even than a Carter BBD) and single exhaust with three cats; the day after it passed emissions and I got it registered I ripped that garbage exhaust out faster than you can say "redneck sidepipes" lol

My Duster has "graduated" to being my full-on street machine/hot rod project so this old M-body is now my 'designated daily driver' (not including my '93 Jeep Cherokee which still runs like a champ but is really fatiguing on long trips). I just want it to not take 20 minutes to get up to speed off the line and be able to pass easily on the freeway; the way it is now it's useless to try the kickdown to 2nd, it pulls the same in 3rd as it does in 2nd at any speed above 65 MPH. Pathetic... lol
 
A rational post , with reality ...Khalid... The M bodies, are sweet in their own ways... The subtle, unknown mods, make the difference between a painful '80's daily driver, and a '80's stock turd....
 
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