Time for a rebuild - cam and engine selection help

[drhill]

Hello Gents,

Well,

The 302 I'm using in my HO swapped 84 wagon is burning a quart of oil to every 500-750 miles. I also can't seem to get the idle vacuum above 17.5 inches. If I remove the pcv system it puffs smoke when running. Still runs great and gets good mpg but it's getting to be time for a rebuild or replacement.

Here are my options:

1. Keep and rebuild the 5.0 HO I have. I want to use a smaller cam as the HO cam is not suited well for how I use my wagon. I have ported E7's with 1.7RR's, and the AOD from an 88 Mark VII with the factory higher stall converter and HO governor...and 3.08's in the rear. The converter helps, but this thing could use more low end torque...I rarely rev it out. I also have a trick flow intake on it that would get swapped for an explorer or cobra intake. What would be better - Explorer cam or Cobra/Thunderbird cam? Does anyone have the specs on these?

2. Buy a lower mileage 96 explorer long block. rebuild if needed - hopefully not. Upgrade the valve springs and use my 1.7RR's.


I like the added power and mpg of the HO conversion but it feels like I could use more power at lower RPMs.


Here's the curveball: I picked up a 80's era cartech mustang turbo kit for $100 from some kid who was parting out an old 5.0 mustang. Driver's side turbo manifold and a small turbo...excellent throttle response on this old kit that would be considered undersized today. It fits perfectly in the box engine bay. I got the turbo rebuilt and I'll custom make the cold side piping. I have all the parts to make it work with the stock ecu(cartech FMU & Blow off valve & Wastegate and MSD Boost Timing Retard box) but I may still get it professionally tuned if I feel like spending the dough.
I'll keep this kit at low boost as what I really want is good throttle response from the kit so I have added power when I want it - not outright max HP. Keep it to 8 psi max with a nice big wastegate. I've had really fast cars and the wagon just needs extra passing power while keeping the good MPG. Plus the 3.08 works better for the turbo than a 3.55 or 3.73 upgrade.

Thanks for the input guys!

[gadget73]

Honestly either cam would do well. The truck cam runs out about 4500 rpm though. I have one in my car. Given the choice to do it again, I'd probably put a Tbird/Cobra cam in there. Whenever I get motivated, I have a Comp XE258 for it, but thats somewhere after getting the non-cracked intake ported so I can put that on.

I kind of like the idea of rebuilding a motor out of the car, and then swapping it. Less downtime vs pulling and rebuilding the one you have. No clue what machine shop times are like in your neck of the woods but I've never gotten a block back in under a week, and 2 weeks is probably a more realistic guesstimate for the thing to be cleaned, bored, and the engine kit to arrive. Add to that a solid day of dissassembly before it goes to the shop, and a day or two of cleaning, painting, and re-assembly before its even ready to go back in. Then the day of actually dropping the motor in. If you can come up with a full set of engine brackets and all that, you could actually have your fresh engine completely drop-in ready. At that point you're looking at basically a weekend to pull, swap, and hook things back up.


The Mark VII trans doesn't have a higher stall converter. Its actually the same stupid low rpm one that the non-HO engines got, and the HO motor doesn't make power until about 2200 rpm. One thing that does help the low end throttle response is a better intake though. I have one of those old Holley SystemMax lowers on my otherwise bone stock Mark VII and it improved things. Its still an HO with a too-low stalling converter but it doesn't have as pronounced of a "kick in the pants" feel when it finally gets spun up enough to make some power. The stock intake is pretty horribly uneven in terms of airflow. The ported heads make those shortcomings even more obvious. An Explorer intake is an upgrade, but they're still not as even as would be ideal in stock form. A bit of port work will smooth that out. Mostly you aren't looking to maximize total airflow, but improve the poorly flowing cylinders so it matches the best flowing cylinders. I would expect a turbo would benefit from more even airflow too.

[drhill]

Honestly either cam would do well. The truck cam runs out about 4500 rpm though. I have one in my car. Given the choice to do it again, I'd probably put a Tbird/Cobra cam in there. Whenever I get motivated, I have a Comp XE258 for it, but thats somewhere after getting the non-cracked intake ported so I can put that on.

I kind of like the idea of rebuilding a motor out of the car, and then swapping it. Less downtime vs pulling and rebuilding the one you have. No clue what machine shop times are like in your neck of the woods but I've never gotten a block back in under a week, and 2 weeks is probably a more realistic guesstimate for the thing to be cleaned, bored, and the engine kit to arrive. Add to that a solid day of dissassembly before it goes to the shop, and a day or two of cleaning, painting, and re-assembly before its even ready to go back in. Then the day of actually dropping the motor in. If you can come up with a full set of engine brackets and all that, you could actually have your fresh engine completely drop-in ready. At that point you're looking at basically a weekend to pull, swap, and hook things back up.


The Mark VII trans doesn't have a higher stall converter. Its actually the same stupid low rpm one that the non-HO engines got, and the HO motor doesn't make power until about 2200 rpm. One thing that does help the low end throttle response is a better intake though. I have one of those old Holley SystemMax lowers on my otherwise bone stock Mark VII and it improved things. Its still an HO with a too-low stalling converter but it doesn't have as pronounced of a "kick in the pants" feel when it finally gets spun up enough to make some power. The stock intake is pretty horribly uneven in terms of airflow. The ported heads make those shortcomings even more obvious. An Explorer intake is an upgrade, but they're still not as even as would be ideal in stock form. A bit of port work will smooth that out. Mostly you aren't looking to maximize total airflow, but improve the poorly flowing cylinders so it matches the best flowing cylinders. I would expect a turbo would benefit from more even airflow too.

Thanks for the info! I was just unsure about the Cobra vs Explorer cam...don't want to give up HP unnecessarily but I know the HO cam is just not the right fit...with 3.55's maybe...

Are you sure on the AOD stall speeds? I've read for years that there were two different speeds...a low and a "high" stall. Low in the range of 1300 to 1500 and high in the range of 1700 to 1900 rpm. I've had several 5.0 Mark VII's and AOD 5.0 Mustangs...and tested the stall in all of them the Mark VII's definitely rev to just under 2k rpm before "grabbing" and the 5.0 mustangs were more like 1500 rpm...which sucks. In any case, the stall from the 88 Mark VII is higher than the stall from the 84 Colony Park and the 93 Mustang 5.0 I just sold

[gadget73]

The HO-equipped cars had a higher RPM governor but so far as I know they used the same torque converter. There is a Supercoupe converter thats supposed to be a little higher though. I get a bit shy of 1900 on my Towncar with it's rebuild trans and supposedly Supercoupe-sourced converter, and maybe about 1600 on the Mark VII. The Mark's trans is not original, and has a non-HO governor in it. Its a Ford Reman too, which makes the wrong governor more objectionable. The Mark is also a quarter million miles on a stock HO, the Towncar is a sub-30k mile motor with ported heads and an Explorer cam. Too many variables to really say with any certainty that one is actually lower than the other. Bolted to the same motor, I expect they would perform pretty closely.

[drhill]

The HO-equipped cars had a higher RPM governor but so far as I know they used the same torque converter. There is a Supercoupe converter thats supposed to be a little higher though. I get a bit shy of 1900 on my Towncar with it's rebuild trans and supposedly Supercoupe-sourced converter, and maybe about 1600 on the Mark VII. The Mark's trans is not original, and has a non-HO governor in it. Its a Ford Reman too, which makes the wrong governor more objectionable. The Mark is also a quarter million miles on a stock HO, the Towncar is a sub-30k mile motor with ported heads and an Explorer cam. Too many variables to really say with any certainty that one is actually lower than the other. Bolted to the same motor, I expect they would perform pretty closely.

Ah yes, I've heard the "supercoupe" moniker applied to the "high stall" factory converter as well. In any case, from what I've heard and felt in low mileage stock cars, you have the high stall in your town car, and a low stall in your Mark VII.

Doesn't really matter too much, I am curious if you think the explorer cam is too small at all in your town car...I've read that cam is like 187/196 at .050 duration vs a cobra cam at 208/208 at .050 and a stock HO at 211/211 at .050. I was feeling like 10 degrees smaller than the HO would be perfect but I don't think either one would fit that bill....

[sly]

2400 stall converter on an HO would roast tires nicely.

[gadget73]

The Explorer cam leaves me wanting more. It pulls good off the line but it just runs out of steam.

[johnunit]

IMO, unless you're doing all stop-and go city driving and really care about mileage, an HO cam or more aggressive and a 2300+rpm converter is what you want.

Doing modifications to make the car breathe better up top (intake, heads, exhaust) and then slapping something as mild as an Explorer cam on is not building a combination of parts that compliment each other. If you're hellbent on low end torque and stock driveability, save up for a stroker kit or 351W swap, crank up the compression, get a custom cam (not as expensive as you'd think) specced for as much torque as possible, and run premium.

If you're starting from a 302 block and wanting to just have a faster car in general, the answer to almost everything is more. More duration and lift, more exhaust flow, more header diameter (up until 1 3/4"), more head flow, etc. These engines are so mild with stock E5, E6, or E7 heads that I don't really buy that there's much you can do to kill 'bottom end torque." Slap in a converter to compliment the package and you're golden.

[merc91]

just posted in "new engine aquired for HO conversion" that would answer your question. Height of cam lift has nothing to do with rpm power range, height of lift just means more power everywhere. Rpm range is mainy determined by duration and overlap. Lumpy cams are lumpy because of overlap causing shatty running at low rpms... but accel in the real high range.

If you want more power than stock, don't buy stock cams.

Comp xe258 is a high .533/.544 lift but short durations with no overlap. That means stock idle and running, no loss in efficiency, flat curves and high tq and hp numbers all through 2000-6000rpm. Hands down the way to go. The ONLY downside is cost (not much) for the cam and valvesprings to handle the fast ramp rares (dual springs rated to .600 work great).

[88grandmarq]

Sorry guys.... there is NO "super coupe" torque converter for the AOD transmission.

AOD torque converters came in 2 flavors; ALL 302 engines = 1600-1800 rpm stall (sometimes called HI stall) .... ALL 351 engines = 1250-1500 rpm stall (sometimes called LOW stall).

3 governors were available for the AOD; low speed = 4200 rpm (used in non-HO applications) medium speed = 4500 rpm (used in ALL trucks) high speed = 4800 rpm (used in HO applications) - all 3 governors are now obsolete and very difficult to find.

[drhill]

just posted in "new engine aquired for HO conversion" that would answer your question. Height of cam lift has nothing to do with rpm power range, height of lift just means more power everywhere. Rpm range is mainy determined by duration and overlap. Lumpy cams are lumpy because of overlap causing shatty running at low rpms... but accel in the real high range.

If you want more power than stock, don't buy stock cams.

Comp xe258 is a high .533/.544 lift but short durations with no overlap. That means stock idle and running, no loss in efficiency, flat curves and high tq and hp numbers all through 2000-6000rpm. Hands down the way to go. The ONLY downside is cost (not much) for the cam and valvesprings to handle the fast ramp rares (dual springs rated to .600 work great).

I read your other post and...Yep, the more I look at this cam the better I like it. It looks like it would still work with the turbo kit I have if need be. Only worry would be that it probably builds more cylinder pressure than the HO cam...but 112 LSA is still mild. Gadget's opinion on the Explorer cam is what I expected. Sounds like the comp 258 is the best of both worlds...grunt off the line and some good upper RPM power.

The wagon is a daily driver: stoplights everyday, AC on, needs good mpg, heck...we took this thing on a 4500 mile roadtrip last month! These are all the things that prohibit a stall coverter and big cam for me. If I keep the car N/A, I would like to keep it to 87 octane - is that possible with the XE258 cam?

[merc91]

cylinder pressure is what makes power so yes it does do that better than stock cams, it doesn't up the pressure so much that you need to use higher octane though... you would need a few psi of boost to warrent that.
It's a great cam for power adders as it favours the exhaust side, I run nitrous through mine for a fw total of 450hp/600ftlbs on 91 octane in my daily driver at the strip without any issues at all. It's overlap that puts a damper on daily driving through low/mid rpm inefficiency which I assume is what you mean by big cam. Big lift without overlap keeps efficiency at all rpm.

[drhill]

Yes, big overlap cams are definately not for this car...good to hear of your success spraying with this cam...bodes well for what I want to do!

[drhill]

For any and all who care, I finally got started on installing a new short block, the cartech turbo kit and a 4r70w in my wagon. Here are some pics of the progress. I have an 11.25" "marauder" converter for the 4r70w which I'm told will stall in the 2500 rpm range behind my motor. I have the Baumann US Shift controller for it - which was just about the most expensive part of this build at $600 including the wiring harnesses.

I decided to keep the stock HO cam with 1.7 rockers as it has a great reputation as a mild turbo cam. I've had continual bad luck with tuners where I live so I'm just doing 24lb injectors an FMU with an assortment of discs and an MSD BTM. This method is tried and true for me but I know will not eek out the best HP. I picked up a wideband 02 to help out as well.

I'm not very good on updates but I'll try to keep some info flowing. That iron cartech manifold and small turbo fit perfectly in the box engine bay! It's a mess underhood right now but it'll clean up!

[gadget73]

awesome, looking forward to updates on this