Hi:

I am a newbie to the chevy board and SBC's in general. I always thought that the cylinders should be in a straight line for an engine :flipoff2:

I just bought a smog exempt 75 3/4 ton for a tow rig. It has a stout, freshly rebuilt TH400 with an Allison 6 bolt converter, 14B, but the original 454 was replaced by a 350 of unknown vintage and source. PO said the engine was re-ringed and re bearinged and an RV cam added (again, no specs). It runs pretty good, but now I want to get it to tow well.

Exhaust is good, headers and duals (I am going to do an H pipe to balance the exhaust).

Does anybody have any tips on building this engine to about 330HP and 390 ft/lbs on a gotta-new-baby-at-home budget?

TBI?
Heads? (I think that it's important to track down the cam specs before I do anything with the heads, right?
Intake/carb

It's a 2 bolt main, so everything that I buy should be able to be swapped to a new 4 bolt main when $$ permits.

Thanks for any advice or links.

SeanP

let's just this out of the way: "fawk off newbie" "search"

if it was me ide put a 400 small block in it....they make alot of torque....heads are where all your power and torque is....same with compression...but one must compromise with compresssion...i would highly recommend balancing the motor,figuring out gear ratio,weight of the vehicle and cruise rpms.then u can decide on a camshaft.....my tow rig is a 72 gmc,with a 350 400turbo and 4.10s with a 235/75/16 tires.....i used a comp cams extreme dual pattern i think its like 268/272 duration....with 441 casting heads it pulls real well comes on good about 2000rpm and pulls hard to about 5700....my cruise on the freeway is right around 2800 or so..and the cam is happy there...as long as the whole package is matched i think ull be happy....u might wannna consider the edlebrock performer package...cam, intake i hear it works well ....

383 stroker (400 crank in 350 block). More stroke, more torque. You should be able to get a cast bottom end assembly for about the price of heads of less. Make sure your heads flow and have a nice cam.

Steve

i was messing around on desk top dyno and came up with this:
http://home.comcast.net/~virgilwalker1/dynoscreen.jpg

http://home.comcast.net/~virgilwalker1/dynoscreen2.jpg

vortec heads and just messing around with some cam specs i had on file.

I'd build a 383. the 400 has too many potential cooling problems, and good 4 bolt blocks are difficult to come by and pricey when you do. The you run the chance of the deck cracking out when you torque the heads(happened to me with 2 blocks).
Heads are important. The Vortech heads are nice, as are some mild World Products, etc. Stay with intake port size of 180cc or less for great bottom end and throttle response. As for the cam, like said above, get your rpms, etc together, and call a cam company like Comp or crane. Use a nice dual plane intake(I'd use a Edelbrock rpm) on the 383, but the Performer will work just fine. Have a good shop setup a Quadrajet for you and you be rollin'.
Check out ebay for deals on new cranks, rods, pistons. I build my last 383 with 85% ebay parts, and saved about 45% over Summit prices.

virgil, that combo looks great on paper, but in real world it wouldnt really work that well. the 8.1:1 dynamic compression ratio is on the verge of detonation problems. lower the static compression ratio to 9:1, which will give you a 7.7:1 DCR. it should run great on the cheap stuff while still retaining the power. just under 400 ft/lb across the board, and the curve is MUCH flatter than the one you posted.

also the 2 bolt vs 4 bolt argument, since this is a tow engine, not a high rpm race engine, you should be just fine with 2 bolts. make sure to replace the bolts with high quality bolts, such as ARP, and you should be good to go.

bored over .30, new pistons, gm performace cam, a pair of vortec heads and a good intake. thats what we usually build our 350's with in the shop if we got the stuff. makes for a good towing engine too. we've put a couple in place of the diesels.

thanks for all the replies, guys. I'll hang out on this board more and soak up some info. I am looking forward to building my low-dollar tow rig this year.

SeanP

k20, good point, i didn't realize i had the compresion ratio so high, must have forgotten to change it after my buddy was messin around with his camaro set up. also agree with you about the 4 bolt mains.

here is the result with 9.0 compression.
http://home.comcast.net/~virgilwalker1/9.jpg

you are lucky that you have a 350, there are so many more options that are available on a budget than with alot of other set ups.
i think last fall car craft had a contest to see who could build the best (most dyno power) small block with a budget of $2500.
here are links to the article
chevy (http://www.carcraft.com/techarticles/116_0311_clash/index2.html)
ford (http://www.carcraft.com/techarticles/116_0311_clash/index4.html)
mopar (http://www.carcraft.com/techarticles/116_0308_mope/index.html)
results (http://www.carcraft.com/techarticles/116_0311_clash/index.html)

not necisarily tow rig aplications but interesting reading none the less.

I was in the same place (mild 350 & Tow rig 88 1-ton 4dr 4wd). I purchased a Summit Cam & Performer Intake to liven up the 77k miles 350. Then ran across a deal on a low miles Cadillac 500 for $150. Now I have spent another $150 for the Caddy HEI distributor (mine was MIA), oil pan (need a rear sump), and motor mounts. Now if I can ever get the DD to stay in one piece long enoug for me to get the fab work completed on the engine mounts...

Anyway the torque #'s look impressive and the Caddy build quality is exceptional, + there is some performance stuff out there if need be, YES it's ^$$$, but you are already starting off with almost 500ft.# of torque at 2500 rpms...

Just wish I'd have headded down that road from the beginning as now I'm stuck with $500 worth of SBC 350 and parts that I don't need...

By comparison a 454 Chev in any useable condition was $1500...

Since we are on the subject..What also can be done to get more torque under 2000 RPMs?

here is what you do. put a towing- RV cam
Put on a set of vortec heads. if you can smooth the ports some do so. Put the edelbrock intake to go from vortec heads to a carb and then tow the piss out of it.
Also make sure you are running the correct gears for your aplication.
Vortec heads make a big difference.
the Gm ho crate motor uses a mild cam and vortec heads and they claim 330hp and 380torque

So is low end torque improved more by stroke ( longer stroke)
or by heads and cam?

Take II Low Performance heads mild port, 194/150 valves, 9.0 compression, Well built 750 cfm quadra trash, performer intake, 260HR cam and roller lifters. Match port your intake and exhaust and get another 10ft lbs.

Here is the same configuration in a 383 stroked block.

what rpm do you guys tow at?

I tow at about 3,000 myself.

"So is low end torque improved more by stroke ( longer stroke)
or by heads and cam?"

Both.

Torque will increase quite a bit with an increase in stroke. Think of this as using a 3' long breaker bar vs. a 1' long ratchet.

Heads and cam can increase volumetric efficiency which will seriously improve performance across the board, not just on the low end.

On the two bolt vs. four bolt arguement, not only is a four bolt not necessary in this instance, the desireable 400 small blocks are the two bolt main ones anyway.

I personally would build an engine with the longest stroke possible and a 4" bore minimum. That means 383 or 400.

To the guy above quoting numbers from DD2000 with a roller cam, keep in mind that while DD2000 is VERY accurate in most instances, it has been proven to overestimate the power/torque of roller cam engines. Also, you need to use a real headflow file to get accurate results, not just pick one of the ones that says something like "low performance mild port job" on it. Get a REAL headflow file, or make one from flow numbers.

DD2000 is garbage in, garbage out. Using the wrong heads will always screw up your numbers. If you input the right numbers, DD2000 is proven correct within a few percent.

Originally posted by Tim84K10
To the guy above quoting numbers from DD2000 with a roller cam, keep in mind that while DD2000 is VERY accurate in most instances, it has been proven to overestimate the power/torque of roller cam engines. Also, you need to use a real headflow file to get accurate results, not just pick one of the ones that says something like "low performance mild port job" on it. Get a REAL headflow file, or make one from flow numbers.

DD2000 is garbage in, garbage out. Using the wrong heads will always screw up your numbers. If you input the right numbers, DD2000 is proven correct within a few percent.

Why don't you bust out some numbers or post a link to a flow file that would be accurate in this case and I'll or maybe you can run it again. Mean whille don't bust my chops because I was just posting some examples. :flipoff2:

If you have AIM, contact me, my name is the same as my sn here, and I'll hook you up with a few dozen files.

I wasn't busting your chops....just saying that your numbers are a little optimistic there.

I have a ton of flw files as well
what casting number or model of heads would you like?

if you have played with flw files at all you would know that it makes a massive difference

using 2 different sources of stock 351C head flow numbers changes the output by 50-100hp

cruising at 3000rpm is one thing but the motor has to be able to get the load to that rpm

the motor gets incredibly hot under constant load
gearing and cooling
you will be better off with stock engine and a USgear splitter then a hp engine with stock tranny

Thanks guys. I installed a GM 882 casting 151cc flw spec and the readings did change much. I would love to have some extra flow files. Please send them to my email. I don't have AIM.

My motor never gets hot with 10,000 lbs behind it or less and it's a raggedy stock TBI 350 with a TH 400 and 4.10s and 31.5" tall tires.

A motor with a little more oomph in the top end is an outstanding way to get more acceleration.

If you think you need a gear splitter, you probably need lower gears in the back end first. I personally would like to have 4.56 or 4.88 in mine, or simply to have a 4 speed in my tow rig and then it wouldn't be an issue.

going back to the 2bolt vs. 4bolt main blocks... if you already have a 2bolt and aernt going to generate more than 500 ft/lb torque get splayed main caps.. its cheaper and just as strong as a 4bolt. also is anyone willing to share their nice dyno programs?!?

so what temperature does your engine oil hit while pulling that wieght up a steep hill?
gear spacing for hill climbs will not be found in any light truck tranny until recently
I live in extremely mountainous terrain so my opinion is slanted to the hill performance
the gear splits in a 465 are brutal

i've had real good luck with sb400's, but alot of guys don't want to get rid of them, so a 350 won'y give a big difference in power. the best i've seen for your baby budget would be go to northernautoparts.com to get your rebuild kit. a 350 complete kit runs 159.95. that even comes with pistons and cam. throw the cam away and while you have them on the phone order a crane 4X4 extreme energy cam. these cams produce phenominal torque. the boys at NAP can give you the number to crane's cam doctor. call them up and they will ask for all your specs, weight empty, loaded, tire size, gears, etc. and can give you the cam you need. get it balanced, buy good rod bolts and main bolts(2 bolt is fine) and a good double roller chain and your short block is done. top end wise, the vortecs are a good choice, but i am very impressed with the world products torker heads. the sportsmans are a good choice also, but for torque, the torkers will do fine. get a good dual plane manifold(performer or splurge for the air gap) and a good edelbrock 600. i know a lot of people bark about Q-jets, but Oreilly's carries Holley remans that have worked well in the past, just get one for an older(74-76) one ton. the one tons are a little bigger for the power you are wanting to produce. all in all, you could have anywhere from 700-2000 $$ depending on how far you want to go;)

Thanks all, Sean

Quick question: Which vortec heads will bolt to my mid 70s 350? I don't need any smog or egr stuff. Also, it was mentioned that there is an Edelbrock intake that will work with the Gen 1 blocks and vortec heads. Is this true?

Thanks

Xtreme Energy cams are made my COMP, not crane, and to do a sucessful engine build, you need to focus on more than just one line or one brand of cams. Every engine can sucessfully use a different cam, and focusing only on one brand name can seriously affect performance.

Vortec heads will bolt to any small block Chevy. You will need a special intake (expensive) and intake gaskets, and self aligning rocker arms.

If you don't have the Vortecs right now, get a set of World Producs S/R torquers instead.

vortex look like to much work when you can get better aftermarket that will bolt on and allow any intake to be used

THe edelbrock intake is not expensive to go from carb to vortec heads. it is about the same as their other intakes. the expensive ones that include egr. which he doesnt need.

vortec heads are also easy to do

No vortec head is going to include EGR. Vortec heads do not have an exhaust gas crossover.

Vortecs are really not that cost effective for most people. Even if you get them free, there are many hidden costs in them.

Springs only good for .450", intake pattern, different intake gaskets, valve covers if you dont use the centerbolt ones already, flow that doesn't compare to aftermarket heads similarly priced by the time you buy all the extras, rocker arms, small combustion chambers.....

Tim, they were referring to the intakes with EGR provisions, not the heads. the EGR on a Vortec engine has to be plumbed from the exhaust manifold. you're right though, Vortecs arent that cost effective for most people. a good way to get a set of heads cheap is to check your local GM Dealership. sometimes they have core engines that are from customer engine swaps. you can find alot of good stuff there. GM core on an L31 longblock is $100-150 this includes everything from the valve covers down, which eliminates all of the "expensive" little parts that everyone bitches about. although, as Tim said, they do have their disadvantages. low lift numbers are one. the increased flow however, is hard to beat in a 170cc head, and the combustion chamber is far superior to almost anything else on the market.

thanks beater that is what i was talking about.
I guess i feel that the vortec heads is a cheap head sway because i work at a chevy dealer and get the heads for next to nothing on occasion

that's exactly how i got mine. i was the parts counterman, and anything non warranty core that i wanted, or could use, i could get for the core charge.

Hey all, I know this is a really old thread. But I'm trying to be a good newbie and go through the FAQ's before I go making people answer the same questions numerous times.

Building a custom Jeep CJ-8 project ground up. Choosing my power plant. Looking for good torque as it's going to tow a small off-road pop up camper quite a bit. So other than that, it's going to be a daily driver so milage is of primary concern. I was leaning towards a GENIII 6.0L GM. And someone recently indicated that it's a gas guzzler. Cost, and speed of install, are also factors. I'd like to get a complete package out of a junkyard and spend my time fabbing it into the frame, adapting to the drive train, rather than building the engine.

Does any one have any advice?

I know I'll here a lot of negatives......but seriously, a set of TBI heads can do well in this application....TQ under 3500rpms. True, they are poor flowing heads for above 3500-4000rpms. They were designed by GM engineers for one purpose....TQ production and fuel economy. They have about 185cc on the intake runners and they do have good low (valve) lift numbers while keeping airflow velocity up<<<aids fuel atomization and cylinder filling....they're called swirlports for a reason. There have been a few here on this board who have used them successfully on 406 shortblocks with stock 5.7L injection on top.....resulting in very impressive TQ numbers. I too am looking to build a 406TBI motor for my DD/tow rig.

I will agree the Vortecs take over in the higher rpms (^3500rpms) but below that the TBI heads (#14102193 5.7L) can do just as well....a sleeper head if you will.


http://forums.chevyhiperformance.com/70/6484958/car-engine/combustion-chamber-size-of-swirl-port-tbi-heads/index.html

Read post #8 and #9...... http://www.thirdgen.org/techboard/tbi/336750-tbi-tpi-heads-headflow.html

Read post #8 and #11.....http://www.fullsizechevy.com/forums/general-discussion/performance/tbi-tuning-87-95-obd-i-ecm-pcm/275303-best-options-5-7-tbi.html

http://www.sallee-chevrolet.com/Discus/messages/3390/2930.html

ever heard of taking a 400 and putting a 350 crank in it. it does destroke it to like 378 but its all bottom end torque( towing, plowing etc)

ever heard of taking a 400 and putting a 350 crank in it. it does destroke it to like 378 but its all bottom end torque( towing, plowing etc)

Destroking a 400 doesn't give it more torque, if anything the reduction in cubes would lessen the torque. In fact, this is a popular mod for roundy-rounders. If you have a 377 that makes good torque, it isn't because of the 3.48" crank. It's because of the cam/head/intake/carb selection.


TEX

True...377's are hot in circle track ...they offer up mid range over a similar 350, allowing a car to come out of a corner with some good midrange and quick revs. You get a higher revving engine with a larger bore....large bore "short" stroke....maintaining displacement. The 377 has a 400s block/bore of 4.125+ and will accept bigger valves and induction which increases upper end breathing and tends to reduce the lower end due to lower VELOCITY through the ports at lower rpm. How many 377s have you seen with dual plane intakes???


For a torquey gas sbc the 400 is hard to beat for good low rpm grunt. Keep up on cooling sysytem maintainance and they'll generally be fine. Much of the bad rap the 400 got were form the earlier times when people swapped other sbc heads onto 400's and did not drill the steam holes or the maintainance was poor.....not changing out coolant, using straight water or tap water/coolant mix, not using a rust inhibitor.....etc etc...you guys get the picture. The 400's were IMO great truck engines....nice large bore, good stroke, ideal for a low rpm grunter. Some of those old boats (caprice etc) could actually return decent fuel mileage because of the good lowend TQ matched with highway gear ratios.

did not drill the steam holes

this is the most appropriate and most often missed part of the whole statement....

Hey guys, thanks for the replys. Apprecieate the input on the TBI Head option. But seriously, what I'm looking for is advice as to what is going to be the best engine to grab straight out of the junkyard (computer and all) and hook it up in the jeep. I really don't want to be buying parts and pieces and building an engine.

What is the best SB Chevy for priorities in this order:
1) MPG
2) Torque
3) Availability (whole thing in one purchase from a salvage yard)
4) Cost

thanks folks

But seriously, what I'm looking for is advice as to what is going to be the best engine to grab straight out of the junkyard (computer and all) and hook it up in the jeep. I really don't want to be buying parts and pieces and building an engine.

What is the best SB Chevy for priorities in this order:
1) MPG
2) Torque
3) Availability (whole thing in one purchase from a salvage yard)
4) Cost

thanks folks

WHAT???..... then why did you title your post "building a SBC for torque/towing"?

Maybe you should have asked..."What junkyard SBC to grab for torque/towing?"

To answer your new question I (two pages into your post) SBC TBI....good lowend TQ, mileage, and......simplicity and ease of diagnosis and repair.

WHAT???..... then why did you title your post "building a SBC for torque/towing"?

Maybe you should have asked..."What junkyard SBC to grab for torque/towing?"

To answer your new question I (two pages into your post) SBC TBI....good lowend TQ, mileage, and......simplicity and ease of diagnosis and repair.

If you would've read the whole post you would know that he didn't start this thread and that it was started back in 2004. He just added another question to it.

:shaking::shaking::shaking:

Actually I did read the entire post......just the not the start date.


....Oh, and lost track to who the OP was.......

well, its not an R

Thanks for the support....LOL. I look back at the post dates and really it flows right along as though it was a new post....I hate it when it does that! Sometimes I catch it and .......this time I didn't. Anyway, my answers are still the same.....LOL