Questions about a mild build for a 350 in a Jeep

I would not recommend hypers with 7.2 DCR and regular grade fuel. Plus maybe, and that's a big maybe (after retarding the timing so bad it won't pull a greased string out of a cat's ass). Better compression would be 7.5-8:1 static for use with regular grade fuel (considering the inconsistencies we find from station to station) and the Crower level 2 cam.

This Crower level 2 cam uses the same 260* advertised duration you said earlier wasn't to your liking, same as the TA 112 (if the catalog is to be believed, which it apparently is, just like all the other myths floating around here).

Installing a Crower cam using a standard timing gear puts the cam at 4* advance by default, no further advancing required. But then, we can get into the need to buy extra tools and cam installation courses online to get it as close to perfect as we can, because that matters on every engine, right? Sure it won't be spot on (but then who gets it that close even with their degree wheel??), but as long as the compression is put in a safe zone, he won't have to bite his nails when breaking it in (or driving it, or pulling a load, or...).

To OP, pros and cons abound, but ask Steve about putting hypers close to borderline detonation in an iron engine. Even our beloved TA advises against them.

Oh, and don't forget to bore, stroke, deck, shave, sonic test, girdle, and get your quench just right too, like everyone says. And the studs. Can't forget those. Bolts are for wussies. But most of all, whatever you do, never ever use the OEM cam. We're building a racing chevy engine here afterall. Have your checkbook/mortgage note ready after I'm done. And don't forget to check your blinker fluid.

 

No more sensitive than the tolerances required to build these engines.

That chart is inaccurate. Just like half the advice given on this website.

If you want people to muck up their builds with 'veteran' knuckle-dragging advice, then I say to all who read: build at your own risk.

OR you can take it to the professionals. They'd like that.

Buick put variances in tolerances for a reason.

 

:grin::laugh:

 

Man, I just shelled out a ton for new moly coated harmonic muffler bearings. Now I have to go find blinker fluid?

That second mortgage may have to come sooner than I thought.

 

If you're looking to get even more torque out of your little sbb then you may want to consider doing a stroker build? Was just discussing a stroker build with the Federal Mogul stock replacement came with Gary that would be awesome in your Wagoneer!

Pistons would cost a bit more for the AutoTecs but they're the most modern piston for a sbb 350 that can be customized for no additional, in other words they're made to order for a reasonable cost for a made in USA piston. Here is a link for the Autotecs;

http://www.buyracingparts.com/pisto...totec-forged-350-buick-dished-piston-kit.html

The cool part of building a sbb 350 stroker is that the factory crank is offset ground to use with a set of nascar rods, to make the build in the realm of affordability the eBay nascar take out slightly used rods are pennies on the dollar and still have plenty of life left in them.

Here a sample of eBay rods that will work;

http://www.ebay.com/itm/151465658341?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT


Easy peasy, do a search and you should be able to find all the info to make your own stroker if that interests you. GL



Derek

 

Lets start from the beginning and take a closer look.

It is a 1969 Jeep Wagoneer with the 350 Dauntless (Buick) 350 with a TH400 tranny
SAE gross 230 hp @ 4400, 350 ft lbs @ 2400
9:1 compression ratio
Dana 20 transfer case with a 2.03 low range.

If a 700R is installed 1st gear drops from 2.48 to 3.06 and you add a .7 overdrive with a lock-up converter.
Don't forget there is a 2.03 low range for off road if needed.

If you use a 3.73 axle gear you can cruise at 2100 rpm @ 70 mph in overdrive.
If you drop out of overdrive to pull a hill the rpm is around 3000 depending on converter slip.

This a exactly the rpm where my truck operates at and it works OK.
2000 year ratings, HP 260 @ 4500, Torque 350 @ 2500
Do I wish for a turbocharger when trying to pull the 10 mile stretch on I-90 out of the Columbia River Gorge in central WA. You Bet!

There is always enough torque for off road including pulling a camper around.
Most of the time it only requires a slight touch on the gas pedal to get things rolling and traction is the real limitation.
Like the Roy said, he has a Wrangler if he wants to do any serious crawling.

IMO the biggest need for power is when trying to maintain highway speed up long grades with a load.
The focus becomes more towards mid range power rather than low end grunt.
You are also looking for a wide power band which calls for a split duration cam when considering the Buick 350 heads.

With fuel mileage as a requested consideration, a low compression ratio is not the direction that you want to go.
That eliminates cam lobe profiles with relatively short advertised duration if the decision is to use a 9:1 or greater static compression ratio.

I knew full well when I suggested it was OK to use a short duration cam it was after I said "I was not in favor of the TA 112".
I was hoping I would get nailed for it just to have someone else state that it would create problems unless the static compression ratio was very low.

A cam with a descent split duration and a relatively long advertised duration will fit the need.
Just need to figure out where the torque and power peaks need to be to get the job done.

More discussion needed.

Please correct if there is a discrepancy in vehicle info.

Paul

 

http://m.summitracing.com/parts/hrs-540011-12
Here is another cam that may work well for a lower rpm torque engine. Howards cams. Similar in design with around 260 duration with more exhaust emphasis.
Factory on your engine was a rating of 9 to 1 compression but actual was probably closer to 8.4 and once the steel shim head gasket is replaced its 8.1

 

Be careful Paul, you're starting to describe the characteristics of the Federal Mogul CS647 camshaft. :grin:

For ease of installation, precision geometry, and predicted results, one may wish to use it; however, for those diehards who wish to trade 10 ft. lbs. for 10 hp, we could devise a custom cam that mimics it, only with a bit more lobe intensity and concentrated power within a desired power range.

A bit more care would need to be taken during its install (as with any aftermarket custom cam), unless it was ground by a reputed and trusted purveyor, of which are are a few of course.

With stock manifolds and a 4 barrel carb, the CS647's torque will peak between 2800-3200 RPM, with a hp peak between 4600-4800, depending on exhaust used. With a good scavenging single exhaust, the lower RPM end can be expected, particularly with a large base 2g (or Holley 500).

With a freer flowing exhaust (such as small tube primary headers), torque peaks a bit higher (3750 RPM) and hp @ ~5000 RPM. A custom set of shorty headers would probably be somewhere between manifolds and the full length headers powerband wise, so figure 3000 RPM tq and 4700 RPM hp with this setup--OR polished manifolds and a scavenging "Y" or "X" pipe.

Not only does the torque peak in an ideal zone, but the torque band is incredibly wide and flat, ranging from 2000 RPM to 4000-4500 RPM where it trails off. A 500 CFM 2 barrel carb shows a peak torque between 2400-2800 RPM, where it is literally flat, showing the same torque numbers within that range, and only 15-20 ft. lbs. less outside of it from 1500-4000 RPM.

Using a compression ratio that doesn't necessarily require premium fuel all the time, but would benefit from it while under long-term loads (pulling up hill for extended periods of time), say around 7-7.25:1 DCR as was mentioned earlier, lower octane could be used under low-load driving conditions and reduced timing, although keeping premium in it all the time would ensure 'on the spot' detonation resistance when the need suddenly arised.

Keeping a 180* thermostat and very good cooling system to ensure adequate heat dissipation would also be a bonus for this application. A 160* thermostat is not recommended, and a 195* (factory) thermostat could still be retained as long as the cooling system was overly adequate.

There will no doubt be debates on which of these are best suited, but as long as the cooling system is more than enough and the engine doesn't run too cool (or too warm), is ideal.

With some 'backyard' massaging techniques that could be performed with relatively low-moderate skill, conservative power figures with a setup such as this could very well approach 400 ft. lbs. even with the stock cam, but don't let this number alone fool you. It exists within a very wide RPM range, making it even more valuable.

My 2c, for now.


Gary

 

OH NO!! Not the dreaded CS647 again. :eek2:

Actually to make this work the peak torque has to be less than the rpm you are trying to hold as the you pull a highway grade.
Let's say a 700R is used with 3.73 axle gears and high gear puts you at 70 mph at 3000 rpm while towing a load up a highway grade.
If the engine rpm is above the torque peak, as the grade/hill tries to drag the rpm down the torque increases which helps maintain speed.
If the engine rpm is below the peak, the torque decreases as rpm drops with no chance of recovery and speed is quickly lost requiring a down shift to second gear.

This puts the desired torque peak just under 3000 rpm. It would also be nice to have near 400 ft lbs of torque.
As Gary found, Improvements in exhaust system flow and scavenging make a big differences in torque.
A TBI system may be used with a TA dual plane intake manifold.
I also found decent gains going from 8:1 to 9:1 static compression ratio.

Because the .050" intake closing point is so close to BDC small changes in duration doesn't affect piston position very much at that point
however intake durations are still pretty much restricted to 200* without driving the torque peak beyond 3000 rpm.
So yes the Federal Mogul CS647 camshaft will do just fine.

One way to get torque beyond 400 ft lbs is to do head porting on the present heads or use the TA aluminum heads when they become available.
The TA heads will be closed chamber which will create decent quench velocity allowing a higher compression ratio.
Waiting for the first set to see what the port flow is compared to the iron heads.

The best way to get tons of torque is to bolt on a Burton Machine turbo system.
No problem getting 500+ ft lbs.

Paul

 

Gary

What is the difference in specs between the stock 350 2 bbl carb cam that is in the engine now and the CS647?

Thanks
Paul

 

To the best of my knowledge, the stock cams were the exact same for both 2v and 4v in '68 and '69, and got a little larger in '70-'74, then got considerably smaller in '75 with the introduction of the catalytic converters.

The CS647 cam is a little larger than the '68-'69 cams, a little smaller than the '70-'74 cams, and a lot larger than the '75+ cams.

I don't remember the exact specs offhand for all those cams, I just remember how they compared to the CS647, which I have memorized.

Conflicting information is reported too, since according to some parts catalogs, there is only one cam part number for the entire listing of Buick 350's, from '68 to '74 I think?

Regardless, the differences are pretty small, and I think GM measured the advertised specs at .002 back then, so they may appear 'larger' since they measure further down closer to the seat.

We're talking a couple of degrees here and there, and around .005 (or less) lift differences, which really wouldn't be very noticeable at all.

The difference between the Federal Mogul CS647 cam and the larger Melling cam on the dyno simulator is 1-2 numbers trade for tq and hp, both of which are the "GS" cam.

Either way, I would recommend replacement of any stock cam with the CS647 cam from Federal Mogul, along with Crower's camsaver lifters and a good (easy to compose) oiling recipe to ensure 10-12 lbs per 1,000 RPM (grooved cam bearings are a good idea too).

A couple reasons:

1) Wear

The old original iron cam is likely to be worn a bit, since you don't know who had it before you, how it was treated, any defects, etc. and because the hardening technology back then isn't what it is now.

2) Longevity

A fresh, modern OEM replica is just what the doctor ordered to ensure a long, happy life when used in conjunction with the aforementioned lifters and oiling techniques, and can all but guarantee a much longer lifespan than even the OEM cam it replaced.

3) Performance continuity

The Federal Mogul cam will behave much like the old (pre-1975) OEM cam it replaces, with improvements on performance both in numbers and in powerband.


As we know, all cams will have behavior based on a number of factors, mainly how well the rest of the engine flows. Choke one off, and not only do power numbers go down, but so does the powerband. This CS647 cam's design has the geometry to compensate for variances in air flow better than a standard symmetric cam (according to the dyno simulator's numbers) because of airflow dynamics that surround timing events and the lobe's ability to permit more (or less) air depending on how the air flows.

There is more time between .050 lift and seat to permit higher scavenging effect if such exists, for example, and so peak torque shows a leap of 500-700 RPM when using small tube primary headers vs the cast iron manifolds, but this peak is also accompanied with a higher overall torque across the entire powerband, even at lower RPM than the manifolds show.

Exhaust pulse scavenging (or any help pulling the exhaust out at all) is greatly rewarded with the geometry of this cam.

This means headers (small tube) or a good scavenging "Y" or "X" pipe with similar diameter pipe as the manifold exit port provides noticeable benefit.

One could easily change the powerband of the CS647 cam by the type of fuel delivery and exhaust used.

To gain 30-50 ft. lbs. within the low-mid RPM range using this same cam, a few things need to happen: injection or a large 2 barrel carb (intake runners on both intake and heads maintain velocity on a Buick 350, permitting it to use a larger carb), along with small tube primary headers and/or scavenging merger pipe(s), increased compression (and corresponding octane), smoothing/polishing of runners/manifolds to increase CFM quality and quantity, and of course tuning, will do the trick.


Gary

 

Gary,

Have you started your blueprinted 2 BBl engine yet? I have a 2bbl intake you can have it you need it.

 

Yeah sure, just stuff it in an envelope and send it down! :laugh:

I searched high and low and couldn't find the ultra rare 2 barrel intake manifold, and lo and behold, I can have one fo free???????

:grin:

 

CS647 is "a little smaller than the '70-'74 cams"

Hmmm, what is the Melling part number that is closer to those cams?

 

(As a note of interest, Melling shows the cam transition year as 1976, not 1975)

SBC-5 is the part number for the larger Melling cam. Here it is, listed under the 1970 Buick GS with a 350:

http://omnitek.co/mellingcatalog/#a...8Cyl%25205.7%2520350%2520Ohv&product-line=3/1

It's a little larger, but not by much, vs the Federal Mogul CS647 cam. The Federal Mogul cam has slightly more lift than the Melling cam, while having slightly less duration.

Main difference I think would be the 75* IVC point vs the CS647's 71*. The Melling cam needs around 10-10.5:1 comp for premium fuel, vs the Federal Mogul's 9.75-10.25:1.

As I said before, it trades a tiny amount of torque for hp; the differences are pretty negligible.

VS the Federal Mogul cam, the Melling cam has 2* more intake duration @.050 and 6* more @.006; same exhaust duration @.050 with 4* more @.006. These figures aside, the valve timing events are very similar. Basically it's 6 one way, half a dozen another. Two slightly different ways of creating similar results. The Melling cam can accommodate higher compression.

The Melling cam is slightly less intense than the Federal Mogul cam, having 4* more duration between .050 and .006 on both intake and exhaust lobes. Coupled with slightly less lift than the Federal Mogul cam, would make this cam even more gentle on the valvetrain, although the differences are so slight that I don't really see much of a noticeable difference would be detected on the user end.

So even though it's slightly larger, it really doesn't give much more power. It in fact trades tiny hp for tq, as mentioned earlier. You'd never really feel the difference and would only see it on a dyno. The other environmental variances are much more important than the differences between these two cams. As said before, main difference is the compression used, and even that's slight.

It would have maybe slightly more RPM potential, but not a lot vs the Federal Mogul cam.

This Melling cam trades about 2-3 hp for the same amount of torque vs the Federal Mogul cam on the dyno simulator with similar DCR's (see above). Powerband is moved about 50-100 RPM up.

Both cams are asymmetric, and both would work fine. Just need to build the engine around it.

The Melling sbc-11 cam is the smaller of the two Melling cams, and is strictly a low RPM grunt cam: http://omnitek.co/mellingcatalog/#a...2C8Cyl%25205.7%2520350%2520X&product-line=3/1

Very low compression for this cam. With an IVC point of 50* (!) it can turn an 8-8.25:1 engine into a premium fuel requiring stump puller. Asymmetric design also.

Heck, this might be the best cam for the Jeep...(and would suit a 350-500 CFM 2 barrel grunt engine to a T)


Gary

 

So reading between the lines you are saying the SBC-5 would be the cam to use with a sbb stroker build, right? The extra cubes should offset any extra duration making it seem like a smaller cam. :TU: Good catch Gary!


Derek

 

As I said before, the differences are so small there's really no reason to use one over the other unless your compression turned out as such that one would be better suited vs the other, or because of personal preference.

A stroker build would certainly offset any torque loss (2-3 ft. lbs.) the Melling cam has, and the tiny bit of extra duration (mostly at .006) would give a stroker slightly more breathing room vs the Federal Mogul cam.

The stock big block cam is sort of like this, in that it gives a lot of extra time between .050 and .006 with a much later IVC point @.006, so it makes more sense to use the larger Melling cam in a stroker engine following this same logic, although I'm not convinced you'd really see (or feel) a noticeable difference between the two if you compared them side-by-side in the same engine (with matching DCR's).

For the sake of max effort though, if you had to choose one for a stroker build, I'd go with the larger Melling SBC-5 cam.


Gary

 

A greater stroke short block will maintain driveability and easily "use up" a much bigger cam, being that it places a significantly greater demand on the intake tract, regardless of a "max effort" mindset.
The extra piston speed cures most of the evils associated with a little bit more cam.
It keeps velocity high.
Even if your trapped compression ratio drops a bit compared to the stock short block model being simulated, you will make more torque than stock.
Working on the intake tract via porting etc., only increases throttle response and in the case of pulling a load, usually offers mileage benefits.
Keep in mind that simulations don't show part throttle torque curves easily or even comparably.

 

I ran across some good luck this weekend. I found a set of axles I'm going to use for the swap. Dana 44's front and rear.

They came with 3.31 gears in them (the factory towing package gears). With the tires I'm planning on running and the TH400, that would put me around 2,700 RPM at 70.

I'm thinking that at my altitude, and the fact that I'll be running into the mountains, that should be a decent RPM range to have power to get up the grades while still being acceptable to drive around town (which will probably be a majority of how I use this Jeep).

I can maybe eke out a slightly larger tire to drop the RPMs a hair but I don't want to go too much bigger. Going up roughly an inch in tire size gives me 2600 RPM at 70 and that's as big as I want to go with the tires.

Is it fair to assume this is a decent RPM range to be in for the highway?