402 bbc, .030 bore
290 oval ports, 2.06/1.72 valves
XE274 cam
RPM intake
750 Holley v.s., 4150 series
Mallory HEI
TH350 trans
2500 stall converter
4.10 posi
Pushing all steel 71 Chevelle 2 dr ht, no a/c or heat, bucket seats, ps and pb

What do I win If I guess right ???

out of the box with traction 13.30's at 99 mph

If you're right I'll let you drive it. :D

I sure hope that guess is underestimated. Man that's slow. Sounds like I might as well keep the 350 in there......

I respect Tom's opinion..we've both been there and done that.
Just an FYI,I have Big Block Dave's old 396..this combo went a best of 12.45/105 MPH (1.72 60 ft)= .030 over 396,#215 heads with 2.06/1.72 valves
Crower solid flat tappet 240/246 @.050 .517/.530 114 LSA,RPM intake,BG 850,4.10's/TH400 and a 4000 flash stall.Dave did alot of tuning and had a lot of patience to run a 12.45 with that combo.
With 3.73's and a 10" TCI this was a low 13/high 12 second combo..so Tom's 13.30's is realistic..it might be better than that,but only a timeslip will tell.

Originally posted by Junkyard Dawg:
If you're right I'll let you drive it. :D

I sure hope that guess is underestimated. Man that's slow. Sounds like I might as well keep the 350 in there...... After extensive tuning to dial it in, optimizing your timing curve, adjust your suspension to not waste any motion and get it to really 60 ft you could just touch a 12.9x's or 13.0's.

Big part of my slower than you expected ET estimate is the tight converter you have listed. A 3600 converter will get you to the 12.90's with more ET to be found in the tuning. Keep in mind that tuning a combo can take a whole season to gain a tenth or two, been there a few times, but learned a lot along the way, an education well worth the effort.

Also, it's always better to expect a 13.30 and run a 13.10 than the other way around... :D

Thanks Chris...same back to you. Are we still on for the camp out during the two-day Hemmings Musclepalooza II in May. I have a bunch of buddies with their Chevelles and camaro's probably going to be there too hopefully hang out overnight. See if we can get BuffaloWill to come up too..

Wow, it's amazing that that lil 396 was pushing 12.45s with such a small cam. I know that Tom did a lot of tuning, but I'm still in the "wow" part. That pretty sweet!!! graemlins/thumbsup.gif

Originally posted by LXS:
Wow, it's amazing that that lil 396 was pushing 12.45s with such a small cam. I know that Tom did a lot of tuning, but I'm still in the "wow" part. That pretty sweet!!! graemlins/thumbsup.gif i dunno about all that. i'm running a half second faster with a small block and a hydraulic cam with same duration. :confused:

Originally posted by m71:
</font><blockquote>quote:</font><hr />Originally posted by LXS:
Wow, it's amazing that that lil 396 was pushing 12.45s with such a small cam. I know that Tom did a lot of tuning, but I'm still in the "wow" part. That pretty sweet!!! graemlins/thumbsup.gif i dunno about all that. i'm running a half second faster with a small block and a hydraulic cam with same duration. :confused: </font>[/QUOTE]M71,

Don't you run an 11.5:1, 406 CI SBC, with Dart Pro heads, 3700 pounds ? 4200 converter?

Last I heard you ran 7.86 @86 mph in the 1/8 thats 7.86 (x 1.57 conversion) = 12.34 ET ??

12.45 - 12.34 is not 0.5 seconds :confused:

I think Big Block Daves GM Iron headed 396 did pretty well as your car runs very well too.

Tom,I'll be there for the 2 day event-looking forward to it graemlins/thumbsup.gif

Dave's old 396 did well..and other then the cam,it was completely stock internally too..small valves,unported heads,stock .180 domes.
one of these days it'll find a home in something..maybe another Chevelle or G body.For now,it looks good parked next to the rest of the big blocks in my inventory :D

Hhhmm....well I originally wanted to run a XE284 cam with a 3000 stall converter but everyone advised me not to do it and to run an XE274 with a 2500 stall instead. I was hoping to put this car into the low-mid 12's. But with any of the info I've given does this sound out of reach?

I'd go with the XE284 cam and a 3600 converter if I had to choose between the two.

I'd say use the 3000 stall with the XE274. I changed from a 3000 stall to a 2500 stall behind a small block with the XE274 and went from 1.7-1.8 60's to solid 2.2's on slicks.

I've got a similar engine to yours,it goes 7.90s 1/8 right now with the wrong converter(too tight),1.95 60's due to converter.Not a 1/4 pass on this engine yet,and have swapped gears since last time out.

402,10.5:1
290 w/2.19-1.88-fully ported
Comp 294 solid
old crappy Torker
750 Speed Demon
Mallory Comp 9000-MSD 6a
TH400
TCI 2400
4.56 spool SSM QTP
'70 w/glass hood,full interior.

We're looking to go high 7.70s with the converter swap and current 3.73 locker.Have the NX Hitman on it also,haven't used it at the track yet.This car gets driven 70 miles a day also,to and from work.

Wow Tom you're the first that's actually recommended that cam! Everyone else says "Naw...that's too big for your application." Are there any other cams that can surpass that one?

Also on the stall converter...I was thinking of getting a Hughes 3000 stall....I would imagine it would stall right up toabout 3500-3600 behind a big block?

Originally posted by Junkyard Dawg:
Wow Tom you're the first that's actually recommended that cam! Everyone else says "Naw...that's too big for your application." Are there any other cams that can surpass that one?

Also on the stall converter...I was thinking of getting a Hughes 3000 stall....I would imagine it would stall right up toabout 3500-3600 behind a big block? Well I believe that there is no way to pick a perfect cam install it and run the fastest the combination will ever run the first time out unless you have the resources of Pro-Stock, Top Fuel, etc..

It is kind of a catch 22....

Let's say you car has a SET tuneup, gearing, engine parts, tires, traction, weather etc. that never changes..ever. You could find the perfect cam by reasonably trying maybe say 60 different cams with different combinations of duration, lift, LSA, advance, retard, dual pattern versus single pattern..etc.

Obviously that is not practical, so what we do is we try to come close by analyzing our knowns picking the cam that's in the range and then we vary the other items mentioned like tuneup, timing, carb, intake, etc. to make that cam work the best for us. This happens all the time to those of us that do a lot of tuning and tweaking.

Everyone drops the ball at one time or another, otherwise we would be racing Pro-Stock or at least building the engines so sometimes a cam swap is in order.

I would recommend the 284 cam with a 3600 converter that will likely flash at 3800 +/- assumming the rated 3600 is based on a 350 SB.

I would go with the 274 cam with the 3000 converter looking for 3200 +/-.

After you have maximized your power output and tweaked the components of your combo, only then will you know for sure if you were in the
ballpark with the cam.

I wish I had gone with a slightly different LSA with the cam that I have now, but now I know and I am not going to change it just for that.

Tom I may be mistaken but I think the reason why some recommended the XE274 over the XE284 is because they say the duration of the XE284 robs all of the vacuum needed to operate the power brakes and the trans vacuum modulator...that and I think they said something about 402's like lower end cams and not higher end cams.

But since this is a weekeend cruise/race car I'm after the most I can wring out of what I've got listed.

I wouldn't it robs all the vacuum, sure it will have less vacuum than the 274, but it is a balance. vaccum canisters work for a few inches of help. If this is a real issue than the 274 is better for your expectations and intended use to be on the safe side. To me, If the power brakes have trouble, I just make them manual..but that's me, and respectively opinions and desires vary.

Better driveability and respectable track times with the 274 and 3000 converter.

Less driveability, respectable track times with potential to be a bit quicker with the 3600 converter with the 284 cam. Quicker, but not enough to make a big difference if giving up some driveability is not desirable.

Another thing to consider is that with the 284 cam, upgrades to heads will be possible and would likely help, it kind of leaves the door open. You do have 4.10's so you will be in the RPM range.

If your project is to build it and street drive it, occasional fun time at the track, pop in the 274 3000 converter and have some fun and better street driveability.

Just honestly assess what your desire is. Also changing cams in the future is not such a big deal anyway if you decide to modify your combo.

I get the feeling, overall the 274 woukd be the better choice, but good luck with your decision and I look forward to hearing about your success at the track and that I was wrong in my ET prediction in that you went quicker ;)

They say that anything higher than 235 duration robs intake vacuum. This cam has I think a 240/246 duration.

For street use would the XE284 be unstreetable?

What kind of work to the heads would be needed for the XE284?

Also what kind of lope can I expect from either cam in a 408 bbc?

Of course if there is another cam like the XE284 that gives better street manners I'm all for it.

JD, I ran the 284. It was not too much for the street, but that's just my opinion. Others may say differently. It sounded pretty nasty though. Yes, the vacuum was way down, I had to keep that in mind, but it ran strong. Also, I sent you email. John

No, it wouldn't be too much for the street, but yes it will be low on vacuum, depends what you are willing to live with. I have 10-11" of vacuum with 254/262 duration at 900 RPM roller cam though they will have a little more vacuum so I am told.

You wouldn't NEED head work right away, but you would realize more of a gain from any head work you might do down the road such as pocket porting/bowl blend, multi-angle valve job. This really helps the smaller bore 396/402 motors.


Good real world experience fron John O...Thanks for chiming in. How are you doing? Are you going to make to Hemmings day on May 28 and May 29 ???

Hi Tom....Yes, I plan on going to LV in May. I've been good, hibernating all winter.But I spent a good part of today in the garage starting on heads for this years project, and I dropped the block off at the machine shop...sorry, dont wanna steal the string from JD....I'll drop you an email. JO

Well my two concerns are the power brakes and the vacuum modulator on the transmission. As long as they have what they need....hey...cool!

On the other hand I still want this car to perform like a raped ape. It needs to be able to keep up with the LS1 F bodies.