[ronstory]

Yes, I know 400/461 combo for mileage is a cause for humor. I’m glad I can bring a smile to some faces. 

However, after searching, reading, searching even more the knowledgeable folks on this forum are great for sharing engine, cam, carb, gear combos plus HP/TQ and ETs, but seldom mention city and hiway mileage. I know that my 1964 Catalina at 4000+lbs and co-efficient of drag similar to a condominium will never challenge Prius for the mileage crown. However, I’m looking for a combo smiles per mile per gallon combo. I want a good level of performance at the 375-400HP & 450-500TQ range, and then how to get the best MPG after that performance level. I would prioritize hiway MPG over city.

My car now has a built 700R4 and 3.42 gears and 27” tires so I need enough power for the motor to turn 1800 rpm and keep moving at 60 mph. 70 rpm cruise will be 2200 rpm and I don’t really care about power past 5000+… since it’s a cruiser.

The engine will have 6x-8 heads CC’d at 100cc and 2.11/1.77” 5.1” valves and mild porting from Jim’s book, Crower 68405 springs and will be running the stock iron 4bbl manifold off a 1974 400 engine and Eldelbrock 1904 Qjet clone that I will rebuild with help from a Cliff kit… after I finish reading his book. ;^) I’m going to RARE long branch cast iron exhaust manifolds on 2.5” exhaust. I’ll have my HEI rebuilt by Sun Tuned for ‘all in’ by 3000-3200 rpm.

As for my driving style, I want to cruise with this car, have power brakes, good idle (indifferent about lope) and it will never get to ¼ mile track, so I don’t care about ET, 60ft time, etc. We have the ‘Race’ forum for that stuff. ;^)

Now the $1M question is what HFT cam to run? I’m thinking of a 0.050 Intake duration of 224-230 as entry point that should get close to the performance targets

I’m leaning toward Comp cams XE274H since there forum member Paul Westcott has similar combo (455/467 w/ 9.5CR) and gets 18mpg.
http://www.forums.maxperformanceinc....d.php?t=663187 post #6.

Here are some popular cams in the 224 to 230 Intake duration, so other ideas that may get better MPG than the XE274H are appreciated.

Brand Model AID AED ID050 ED050 IL1.5 EL1.5 LSA OL
Comp. Cams XE268H 268 280 224 230 0.48 0.48 110 50
Edelbrock 5057 298 304 224 234 0.47 0.49 114 73
Summit K2802 282 292 224 234 0.47 0.49 114 59
Crane H-288-2 288 296 226 234 0.46 0.47 114 64
Lunati 30702 285 300 228 235 0.47 0.47 110 72.5
Crower 60243 284 290 228 235 0.48 0.49 112 63
Comp. Cams 276AH-10 276 284 228 236 0.47 0.47 110 60
Crower 60210 278 288 229 239 0.48 0.5 108 68
Comp. Cams XE274H 274 268 230 236 0.49 0.49 110 59

[goatless]

The most important thing for out big old Pontiacs to get decent mileage is gearing. A 455- any 455 (or 461 in your case) is going to have enough torque to pull anything at any RPM. The more RPM, the more fuel used. With your overdrive trans you should have that pretty well covered. Well, okay actually the most important factor is to keep from getting into those huge secondaries on the Q-jet.

Years back I had a mostly stock 428 in my Lemans with the Summit 2801 cam in it. Idled like stock and managed 17-18 MPG while cruising at 80 MPH... with a 2.56 rear end.

Later I ran a mostly stock 455 in the same car with the Summit 2802 and a 3.08 rear. It ran 13.1s at the track and was very pleasant to drive on the street. I never really tracked the mileage but it did pretty well... at least compared to my current combo.

[ronstory]

Goatless--

Thanks, I was wondering in the summit 2802 would have enough duration to meet the performance goals. it's one of the smallest of the bunch I listed.

My engine builder has his dyno results from a recent 461/XE284 with 10CR ironheads, and managed 520HP and 560Tq. So the XE274 may be a more than I need. I really want this motor to be 'easy to live with', like the 389, but with a more grunt on the freeway.

[ronstory]

OH... and pump gas. Ideally 89 octane... so that leave me a bit of margin on those hot days or getting a tank of 'bad gas' to put 91 in it. There is no 93 in Oregon.

[77 TRASHCAN]

The 60243 and 2802 are very close. Another possible choice might be the factory 068 cam.
Steve Barcak (user name also) has a similar engine he's been running for a while w/ a 068 cam. Steve says he's been getting 20 MPG.
My T/A got 22 MPG (first 50,000 miles) before cam lobe starting going flat. 20-21 MPG was easy...had the 2.41 gear mind you, as Goatless stated about gearing.....

[ronstory]

77TC

Cool! The biggest seems to be 60243 has a bit more duration. Are their any differences between the lobs on 6024x cams and 6091x cams? I note the Crower 6021x has a LSA of only 108 so there something different there. Reminds me of Sesame Street skit "One of these are not like the other, one of these things are not quite the same".

Let see is Steve chimes in... otherwise I'll PM him.

[ronstory]

Interesting, after reading even more threads and posts on cams for a 455 or stoked 461 I'm almost more confused.

I got dump of the a bunch of aftermarket cams, loaded into a spreadsheet and started playing around. I did a simple calc of how many crank degrees does it take for the various manufactures to get to the 0.050” lift milestones. Basically, it’s the advertised duration minus the duration@0.050” divided by two. The results kinda make sense and how some of the cam profiles ramps vary by model series.

Comp Cams XE series 22 degs
Crower 60210 24.5 degs
Comp Cams Magnum 25 degs
Lunati 25-25.5 degs
Comp Cams DE series 26-27 degs
Ultradyne (small) 27.5 degs
Crower 60243 28 degs
Cranes (small) 28 degs
Ultradyne (large) 28.5 degs
Summit 280x 29 degs
Crower 6024[0124] 29-30 degs
Crane (large) 31 degs
Crower 60245 31.5 degs
Crower 60919 36.5 degs
Edelbrock 37-38.5 degs
Pontiac 068 38 degs
Pontiac 041 40 degs

No surprise, the Comp Cams XE were the fastest ramps and the Pontiac factory cams were the slowest… with the exception of the Lunati 10704 at 40.5 degs.

I’m sure their some specmanship in the numbers since they are all dependent on the numbers provide by the cam companies themselves. I wonder if a slower ramp is why Rhodes lifters seem to work so well 041 and 60919 cams? Oh well, just a thought.

I’m now starting to look at the Crower 60243 or the Summit 2802… and with the XE274 it’s a 3 cam race.

I can upload the spreadsheet for those that are naturally curious.

[PONTIAC LARRY]

With a bit more compression and the Summit 2802 should fit the bill , it will be much smoother and have better mpg than a XE cam and dont think you will see a high HP with an XE just good TQ numbers only IMO. I would really think you would need chambers down to 90 CC to get the HP mark and 240-250 / 180-190 cfm on the flow will bring it over the top.

[Blued and Painted]

You must be INN the small end of the advertized torque range plus 2 hundred RPM's for efficiency. You mentioned 1800 cruising rpm's. So you can throw out ALL the hot'ER street cams.
I'm leaning towards the crower 60240. Then have the heads set up for 1.65 rockers for some extra punch.
http://www.crower.com/camshafts/pont...m-270-hdp.html

Im running the 60243 and it's no fuel mizer. Another 2 cents.

[dmac]

I think if you use the rhoads lifters, you are effectively reducing the size of the cam at low rpms. But if you have heads that flow a lot of air, at lower rpm they are going to have a lower velocity if I read things right. That will hurt your mpg some- I don't know how much.

If you want 400+ hp, and good mpg, get the smallest cam, and smallest runner size you can to get you there. Then keep your foot off the gas. Remember that Steve Barcak gets his 20 mpg on the highway, and I bet he doesn't vary his speed at all.

I am planning a 350 stroker intending to get good mileage- I will likely end up with a two barrel throttle body EFi system, hiding under the original air cleaner. I should end up with over 400 lbs torque but not even 400 hp. I am seriously considering the 068 cam with rhoads, likely using the original small valve size the 350 came with or maybe upsizing to 2.02 intake valves with just minor cleanup of the runners..

The slower ramp is a lot easier on the entire valve train.

[ronstory]

B&P--

Great points! What useful RPM range do you get with the 60243? What kind of mileage have you got to date?

I was worried about that the 60210 cam would be too small for a 462. I'm reading Jim Hand's book now can he mentioned the 204/214 in a 350, 214/224 in a400 and 224/234 in a 455 would have similar idle and rpm range. The performance characteristics just increase with displacement.

[ronstory]

Dmac--

Yes, I've been reading the post from Steve Barcak and he is using a 068 cam and has reported 19mpg. I've also seen a posts from Paul Westcott who reported 18mpg with XE274H cam.

I'm clueless on the Rhodes. They seem like a solution for too big of cam at idle and with my cruise at 1800-2000 rpm, they will still be in 'leak-down' mode (until ~3000 rpm). So I'm trying to figure out if less lift (which looks like less duration) will improve the mpg... or not.

However, if I had to guess... since it make the cam think it's 'smaller', wouldn't it improve the mileage at lower RPMs?

[PONTIAC LARRY]

Considering the semi-low CR with 6x-8 heads a 2802 Summit with Rhoads lifters to tame it down to the off idle TQ a 068 would do but and heck of alot stronger mid range and upper plus consider 1.65 rockers if heads are ported would do very well on mpg and low end plus everything needed to give a strong power band that easily pulls up to and past 5000. I have difficulty seeing a XE274 pulling good MPG and I wouldnt run a cam with a 230 intake lobe in a big car cruiser that wont see over 5000 rpm

[ronstory]

Pontiac Larry--

Sorry, I missed your earlier post.

The summit 2802 is 224/234 with 0.050 ramp speed of 29 degs, which places it middle of the XE ramps and good old Pontiac 068 ramp. With the Rhodes lifters, hopefully it will be less noisy than the some of the complaints with the Rhodes on the XE cams.

Any guess on the ballpark idle speed and vacuum possible with decent intake and Q-jet? I'm, way into unchartered territory.

[ronstory]

drat. I need to learn to spell Rhoads correctly.

[dmac]

I don't find the rhoads lifters as noisy as some do. With headers, and a low restrictive exhaust, the exhaust is louder by a factor of at least five. You have to really be listening to hear the tapping. Unless you have your head under the hood, or maybe no firewall insulation, I don't see how anyone can hear them at all while actually driving, or even standing next to the car with the hood down.

[ronstory]

OK, so noise is just a minor issue. Looking that the Rhoads website, the have two versions for Pontiac, original and vmax. Also, they have 'lube' option for "better cam and lifter life".

What version do more folks use?

[pastry_chef]

Of your "shelf cams" I would go with Crower 60243


But more likely I would get a custom, say

ISKY on 114 LSA
-----------------
Intake Lobe H-438

274 Adv dur
226 dur @ .050
.326 lobe lift

Exhaust Lobe H-391

280 Adv dur
232 dur @ .050
.323 lobe lift


Or Lunati Voodoo on 114 LSA
------------------------------
Intake

268 Adv dur
227 dur @ .050
.326 lobe lift

Exhaust
276 Adv dur
233 dur @ .050
.336 lobe lift

As Harold advised the Voodoo lobes close at almost the same rate as standard GM, Rhoads lifters would be just fine. Isky's are also not know for crazy ramp rates.

[Blued and Painted]

The compression is a big factor. @ 9 to 1 you can kick back your numbers by 5 degrees intake duration.
On my scratch pad i also wrote 60915. {Close to the 60240}
Then it says 60918 Max
the 068 could be a smooth running sleeper.
All with 1.65 to make them act bigger.

the 60243 with more compression is running 12" vac on a good day. Border line for pwr brakes. Many of the cams with 228 and up duration will take more compression, some stall speed, and a good tuner.

[PONTIAC LARRY]

Originally Posted by ronstory

Pontiac Larry--

Sorry, I missed your earlier post.

The summit 2802 is 224/234 with 0.050 ramp speed of 29 degs, which places it middle of the XE ramps and good old Pontiac 068 ramp. With the Rhodes lifters, hopefully it will be less noisy than the some of the complaints with the Rhodes on the XE cams.

Any guess on the ballpark idle speed and vacuum possible with decent intake and Q-jet? I'm, way into unchartered territory.

Honestly I don't think you need the Rhoads lifters with the 2802 cam, it depends really if you have a stock converter or a slight 2200 or some such. The 2802 cam with its 109 ICl and 114 LSA give it a swell idle with slight lope at a steady 800-900 rpm idle with 16-17" vacuum. It is about the hottest cam you can squeak by with a stock converter but best results with a slight converter to get it over 2200 is preferred. You have way more than adequate gearing with a 3.42 and a 3.0 low gear 700 so it would be very responsive and snappy quick. It makes best power say from 2500-5500 +/- 300 rpm depending on other factors. A set of high quality regular lifters or some cam saver improved oiling ones would be a good investment , I don't think variable duration is needed unless you want more torque from 1500-2500 and insist on a stock converter. The gearing will help a bunch. Some people have a problem and wont buy the budget brand over more expensive brands hopefully your vision is clearer than that..lol The short answer is just about any 389-400 street car is suited damn good for a 2801 cam and just about every street 455 could benefit from a 2802 as far as real driver cars and mild gear with some performance improvements.