I'm getting ready to build a 406/408 that will run on 93 pump gas. It's going in a '79 El camino that weighs 3700-3800 with me. I plan to get the block zero decked & run a .039-.041 head gasket. This is a parts chaser that will get driven 1 day every week or two. I also want to keep my power brakes. :D Right now it has a 3.90 gear which will be too much for this combo (I think). I'm going to run a BFG or M/T 275/60-15 (28" tall tire) drag radial at the track. It's also got a 10" converter that'll go almost 3000 rpm behind a wore out 305 H.O. right now. I've got a brand new never used Comp Cams XE 268 Hyd Cam. This cams specs are: 224*/230* @ .050 with .477/.480 lift with 1.5 rockers on a 110*lobe separation. I've already purchased Scorpion 1.6 guided rockers so I'd consider using them. I read two similar buid-ups done in the past year where combo #1 uses a Lunati hyd 230/230* @ .050 with .455/.455 lift on a 114*lobe separation. combo #2 uses a Lunati hyd 230/230* @ .050 with .480/.480 lift on a 109* lobe separation. Both Lunati cams are using 1.5 rockers. I want to use a 3.23 or a 3.42 rearend gear. I'd also like to go 12.50s on drag radials. I am considering using either Lunati cam but the 268 XE is paid for & in my hands right now along with the Scorpion 1.6 self-guided rockers. I am thinking I might need a 11" 2400-2600 converter with this 406 combo.I'd appreciate any ideas/ thoughts on this future combo of mine.

Dave,
Our cars are setup very similiar. I have been happy with the xe-268 cam in my 70. It works well with the 11 inch TCI street fighter and my 3.73 gear. I have 1.6 rockers on mine also. The motor made 440hp@5300 and 500ft-lbs@4000 on an engine dyno. My car weighs 3625 with me in it and has run low 12s. I would think you could meet your goals with the parts you have listed. The cam is pretty mild, when I pull into a car show it sounds like a mellow 14 second cruiser. Which can be bad and good smile.gif .

I think you would be happy with either of the two gears you listed.
It didn't give my signature block.
70 chevelle
afr 190 heads
turbo 350
2.5 inch h-pipe
dart cool can intake(like a rpm)
12.06@111 on tires

Thanks for the reply 68chevelle533. I forgot to mention that I am running a turbo 350 also. I also have a 2.5 full exhaust system with H-pipe. It has flowmaster 50 series which are pretty quiet. The headers are hedman 1 1/2- 1 5/8 stepped headers though I wouldn't rule out changing over to a plain 1 5/8 header.I would like to use what I've already spent $$$ on though. I want to use it for chasing parts and mostly for annoying the h*ll out of the import guys on Fri nites at the track with maybe some occasional bracket racing. It's two tone with old,flat paint & 15x4/15x7 rallyes.Kinda junky/old school,slow,sleeper looking. :D

Forgot to mention I've got a brand new RPM vortec intake I bought a couple of years ago before the air-gap came out. I plan to remove 1/2"(vertical) of the center divider on this new intake. Any thoughts on this mod? I did the same thing to a Weiand Stealth on the 305H.O. I am now running. The mod killed torque right off the bottom but helped it rev out on top. i will run a 750 carb. Are you running vacuum or mech secondaries ? Any recommendations for the carb ? The 12.06 that your chevelle runs is awesome ! graemlins/thumbsup.gif Also the MPH shows some ball$ ! graemlins/hurray.gif

dave i suggest a 294s they make alot of power and enough vacume for power brakes especialy in a 406

I have had the best luck with a hp 950 on the car (bought it for the 533). I tried a 850double pumper and it was kind of soft off the line. The best street carb that I tried was a 3310 - 750 vac sec, it has really nice street manners but is quite a bit slower on the top end. I run a 1-3/4 inch header and it still 60's 1.74 with a 2500 stall. I think a 1-5/8 would be a better fit than your 1-1/2 but it is hard to argue against parts you all ready have. Taking the center out of the intake is a old trick, I think the big block steath intake allready has it done. You might try a spacer instead. I run a 1' open spacer on mine (needed it to clear the power brake vacumn port). I am a beliver in good heads first. I think the AFRs are why my engine works as well as it does. They are 100% CNC ported(from AFR) and flowed 280 intake and 195 exhaust. I would think the vortecs might like some port work. I would look for a shop that does a nice bowl job and general cleanup.

The Vortec heads have great intake flow (that's what "Vortec" is all about) but typical crappy stock exhaust flow. They therefore work best with a split pattern cam, with LOTS more exhaust lobe than intake. The XE cams, and ones from other mfrs with similar design approach, seem to work well. I'd bet an even bigger exhuast split might help some combos; especially big-inch motors with small headers.

For carb use, I'd keep the lobe separation at 110° (the off-the-shelf # for the XEs) or maybe a little less, depending on gears and converter. 114° is too wide; you'll end up with your peak torque lowered too muc and spread out too wide. In your combo the 110° is probably fine. With more gear and/or more stall, where the motor doesn't have to make power over as wide a RPM range, the tighter lobe sep might do better.

i wouldn't change the gears or the convertor either. i think for no more than you are going to be driving it you have a VERY nice sounding combo for very little cash. use what you have, IMO. graemlins/thumbsup.gif

Build the motor for right at 9.75 to 1 CR., b/c of todays poor gas that I bet WON'T ever get any better even after they pull the sulfur out of it.

Then, please consider a good old CC 270S solid cam and run it with the way your car is now and then see how it runs.

I say run a solid cam b/c they are known to make MORE power everywhere in the power curves over hy- cams b/c they can knock the lifters harder and thus accelerate the valvetrain faster which produces more torque.. Otherwise the XE268 cam you have is fine!!!

AND then start considering changing rearend gears and tires..

pdq67

PS., and I love my 12 bolt's stock, 3.31 gears!!!! They are at least to me, a great compromise between go and road!!!

Slightly roll her outta the hole and then nail her for go OR just rpm her for the road!!!

Thanks to all(junkyard dog,68chevelle533,RB69SS396Conv,m71, & pdq67) who have replied ! Since I last posted, I have picked up a used set of 1 5/8 long tube headers to replace the 1 1/2-1 5/8 stepped headers on the elky now. I have also found & purchased a used 3.73 gear to replace the 3.90. I went to a T & T last Thurs nite at a track a couple of hours away just to watch/hang out with friends. It's an 1/8th mile outlaw track. It helped me realize I was going too mild with the combo. I'm thinking forged pistons/Scat cast crank/good rods and still going with the vortec heads. There's someone local by the name of Kent Ford who I'm going to take the heads to for work on the exhaust port and possibly work on the rectangular ledge in the combustion chamber. The headwork won't happen for a few months. I definately want to go with a SOLID cam and I want my power brakes to work.I'm probably going to spray a 125-150 kit as well at times and try to use the 10" 3000rpm converter I have now. Can I get away with 11:1 or should I go lower? Help ! :confused: Any suggestions on cams ???? Me & a younger coworker have been talking trash and we each think we're gonna bust each others a$$.There's gonna be a 1/4 mile grudge race at an NHRA track once mines running.He's built a Ford Escort :eek: (older FWD) with a 4cyl motec fuel injection and nitrous weighs about 2200-2300 lbs I think. Mines at 3800 with me. He's 22 and I'm 47. Needless to say I don't want to look stupid. Plus I'm gonna push for a wager($$$). :D I appreciate any comments/ideas that any of you have. Thanks for all of the previous help. Dave H

how do you delete double posts?? :confused:

you sound like your about to build my engine (in profile)
I've only taken it to the track once so far and it ran a best of 12.41@108.7 with a slippery 1.86 60'.
let me know if want any more info

Hey Stangslayer, thanks for the offer on more info on your combo. I found out the other day, that a good friend is going to sell his ( 1 season old) fully CNC'd AFR 210's at the end of this season. :D I told him I wanted first dibs on them. So for the time being being, I'm just going to sit tight on doing anything with the 400 block until I figure out if I'm really going to get the AFR heads. I may just go ahead with the vortec heads on the 355 as that was the reason for the vortec heads/268 XE cam in the first place.The 355 is ready to go together now anyway. The pistons are Speed Pro H345NP. The block has never been decked and on inital trial assy, the pistons sit down in the block on average .025-.027. The block has been bored/new cam bearings/cleaned. Is it a good idea to go back & get the block zero decked with this mild combo? Or just a waste of time, money & effort? Any input from anyone is welcome ! Thanks. Dave

Dave,
At .025 down, just use the FelPro 1094 gasket & you will end up with the same quench without decking ;)

Hi Mike, thanks for the heads up on the quench situation ! Talked to you awhile back about the 496 I'm (still) going to build. Overtime is presently at zero, so everything for the most part is on hold until the fall. :rolleyes: But I haven't forgot about you. :D If the AFR heads become mine at the end of the season, then I'll need a rotating assy for the 400 that might (probably) get sprayed. The 496 will need a good crank ( just in case we get foolish with some N2o later on as well). Anyway, I regularly check out whats going on with this board & I'm glad to hear ideas/opinions of someone that builds engines for a living. Dave

Thanks Dave graemlins/beers.gif
Just hollar when you are ready,,,, always happy to help spend other peoples money :D