sbc 408 build
 

Looking for a couple of ideas. 77 4x4 th350 3:08 gear with 33's. Just dropped 406 off at machine shop going to have stock crank 5.7 rods and around 9:5 comp. Thinkn about at 2000 stall converter. Cant decide what heads vortec, afr 180,195 or profiler 195. Machine shop recommends profiler 195 for the price. Also trying to figure out a nice mild comp roller cam. Truck restored and i just want it to have a good power up to 5500-6000max. Somthing fun to drive with good street ,manners and vacuum for brakes and big smokey burnouts:metal:

Re: sbc 408 build
 

Not a lot of help here. Going to go with the profiler 195 heads not sure on cam yet.

Re: sbc 408 build
 

I think the lack help is stemming from the 3.08's with 33 inch tires. If that truck had 3.73's or so with 33 inch tires it would get some fingers typing.

Re: sbc 408 build
 

Even though a 406 will produce a bunch of torque, you would definitely benefit from a 3.73 gear with those 33" tires. You may get away with the 3.08's if you build the 406 for idle to about 4000 rpm power range. But those 195cc heads aren't going to work very well for an engine like that.

Re: sbc 408 build
 

Do you realize with 33's and a 3.08 gerar you will only be turning 2300 at 75mph? I predict a lot of trans failures in your future with even a mild stall. Your going to be driving around below stall all the time (= buttloads of heat and ineffeciency)
Unless your willing to get a more reasonable gear, I'd look for soething in a SMALL runner to get all you can out of the idle-2500rpm range and keep the cam near stock.

If it were me, I'd consider something like the Edelbrock 170cc E-tec to make as much low rpm torque as possible

Re: sbc 408 build
 

If you do not go with some lower gears with those tires. You are going to have to go with some 165-180 runners. Plus the bore an stroke on that engine is going to around 10.1 or higher comp. with anything smaller than 70cc chambers with flat tops pistons.

Re: sbc 408 build
 

I told comp my setup and they recommend a xr276hr cam. I'm thinking maybe just save little more money and put 700r4 with 3:73 gears in it. Its getting dished pistons. now at 75mph it spins about 2400-2500> Houghes torque converter recommended the 2000 stall.

Re: sbc 408 build
 

Some of the other guys can chime in, but I would do that an just install a Hydraulic camshaft in it.

Re: sbc 408 build
 

Like some of the fellas have said here, change your gear ratio. If you find a shop to do it for both axles with parts (ring&pinion+install kits) should be $1400 or less out the door. You could probably find a matching set of axles used for less than that in your neck of the woods, or at least buy matching used ring&pinions and then install using new install kits and seals. IMO 308 gears are for highway trucks only, and were meant for stock size tires. John

Re: sbc 408 build
 

This is EXACTLY why the ricer moron desk jockeys at Comp and Lunati are DESK JOCKEYS and not engine builders!!!

I can not find the exact one for retro fit kit for your block, but the cam timing is the same save the intake centline variation..

What's the description say??

http://www.compcams.com/Company/CC/c...?csid=188&sb=2

OK so Comp's spec sheet wants 2000+ stall,, and gears ...

What in that sounds like it matches your current combination of 3.08 gears and 33" tires... in a 4500+ pound 4WD truck. I am always astounded why industry puts minimum wage ricer or off-shore tech help morons on the desk to recomend parts.

With that tall of a tire you do not need the OD of a 700R. Your 75mph rpm w/ a R4 and 3.73 gears with the 33" tire would only be 1990rpm with the .7 final drive of a 700R. You'd be worse off than you are now except for the deep 3.06 first gear,,, but with 33's it will still be a wounded duck.

I run a 33" tall slick on the back of my 66,, with a 4.30 gear right now,, it's very 'street happy' there but I really don't care to burn the fuel to go play in the freeway (this motor is not intended for that). But when it was under 500HP I was running a 5.43 gear with those 33" tires.... roughly 2500rpm @ 45mph. I was BARELY into the power band of a Crane hydraulic roller that was only 8° more 0.050" timing than your looking at there with that XE274.

Sorry, [RANT OFF/]

http://www.small-block-chevy.com/ima...s/stir_pot.gif

Re: sbc 408 build
 

Hmmmm now i don't know what to do only more confused. i was hoping a 700r4 with 3:73 would run about 2100 at 75. I need figure the motor specs out soon so the machine shop can start building it. Maybe i do 4:10s but will they fit in my axles?

Re: sbc 408 build
 

Gears fit on to a center section, axles slide in to this center section. Gears do not go directly on to axles, so, my guess is you can probably find a steeper gear to run with your current axles and center section.

I called comp once to have them grind me a custom cam based on their lobes. I gave them the lobe numbers, told them where to put intake centerline, where to set the LSA at. They told me that it would not run in my combo. I told them to send it anyway, it was my money. It got ground and showed up at my door. It made a measly 521rwhp naturally aspirated through a 4l80e trans and idled fine and has pretty decent street manners to boot. There are only a couple of smart tech guys at comp. Good luck getting a hold of them.
Posted via Mobile Device

Re: sbc 408 build
 

I had a K5 that had a R4 in it. It did good in low gear. But, did not like the OD with 35" tires. It was a 350 an was fairly stout. Just the wrong combo. Really think it had stock gearing. That was about 15 years ago.

It would have been a totally different animal with a set of 3.73 or 4.10's in it with a different tranny.

Re: sbc 408 build
 

OK I'm going be picking up a 700r4 with np208 t-case tonight with shift linkage. Looking for just a little more help on my build. what rpm do you think 4.10s with 33s will be at at 70mph 2300? Do you think that xr274hr cam will be ok now that I'm going to regear and go with 700r4 or should i go with a smaller cam?

Re: sbc 408 build
 

Here is one of many speed/RPM calculators you can find online.......

http://www.csgnetwork.com/multirpmcalc.html

The cam manufacturers stated power range for small block cams is usually based on a 350 cu in engine. When installed in a larger cu in engine, a given cam will be a little milder and have a slightly lower power range.

Re: sbc 408 build
 

If your talking about making a whole bunch of power be careful with the 700r4. They have them living behind 500+hp I just don't see them lasting long. Make sure its built by a trusted builder. I'd be tempted to keep thm-350 and upgrade it or go with a thm-400 and change gears you need to change gears no matter what though. I like the 4.30-4.10 range for that build. My 408 bbc made almost 500hp and I went with 4L80e in a street truck.

Re: sbc 408 build
 

TCI has a new input shaft that they say will allow the 700R4 to handle 1000HP.

Re: sbc 408 build
 

I have a local shop that said he can build me a dependable 700r4 with converter for 1000$

Re: sbc 408 build
 

The input shaft isn't the problem. The 700 is basically a TH350 with a OD assembly hung in the already ill supported case. With stock components they were not designed to handle 350honest HP. To build one with premium components (input to output tolerant of 1000HP) will EASILY run over $4k

In fact the TCI superstreetfighter 700r is a $3200 with no converter, and only eclipsed in price by their 4L60 line

A 700r in a 4wd with big tires sounds like a receipie for DISASTER to me unless your going to spend the big bucks and do it with the big-buck trans.

A TH400 and a gear change is STILL the 'right' answer here IMO.... but you have a LONG ways to go....

Re: sbc 408 build
 

Drivetrain 3.73 or 4.11's
Heads 170cc an 68-70cc chambers. Depends on comp. with heads.
Camshaft idle to 5500 or 1800-5800
Converter stock to 2500 or so
Tranny wise 400 or 350 turbo.

Just my thoughts.