oldchev

Well, here we go. It's time for a new motor in my '70. I've been kind of planning this for a long time but just nursing my old 350/350 along because I always had other projects going on. I've been driving this car for over 30 years. So now it's its time. I have some features I want to hit. But don't really know how to get there. I've restored many cars but I am not an engine builder. I'm not saying I can't put it together, but I don't know how to spec it out for a given result. I'm going to save this original motor. Put it on a stand in the coffee area and we can use it for a test lab on how bad an engine can get before you really have to rebuild or replace.
So here are some points I want to hit: I want a roller assembly, I want more power than the 350/350 had, I want a somewhat lopey idle but I want it to be a good cruiser. It will have A/C. I need to keep my cable tach drive distributor. I have a TH400 trans and 3:08:1 rear gears. I want low RPM driveable torq and power. Obviously, the hard things for me to pick out are the cam, heads, and intake. I have been reading about these specs for months till I'm counting flow numbers and lift/duration & LSA numbers in my sleep.
Here are a few ideas I have. Thinking a cast iron, small valve vortec head. Tech notes like in JEGS says to use the raised port Vortec style intake manifold. The heads have 170cc intake port, an 64cc chambers. i'm thinking the large valve vortec head won't flow enough till you are well into the 5000 + rpms to get its power.
I have been all over the map with the cam selections till i'm dizzy. I was looking at the Comps Xtreme Energy # 08-423-8. Suggested rpm range = 1900-5600. Duration at .050 = 224/230, Lift = 502/510. LSA = 110*. .... But the small valve vortec head says to limit the cam lift to .474" So I ruled this out. I looked at the Thumpr Cam with 227/241 duration, .513/.498 lift, LSA =107. But the lift is also too high for the head and I have been advised to stay away from a 107 LSA because I won't have enough vacuum to run the headlights, wiper door or ac/heat controls. I do not have power brakes.
So here is another cam I looked at. Comp Xtreme 4x4. #08-413-8. Suggested RPM range = 1500-5500. Duration = 220/224. Lift = .474/.474", LSA = 111*. Note says, needs headers and has noticeable idle. I have been running headers with 2.5" straight pipes with a chambered section and no mufflers for years. Pipes are hung in original under car location. So I have no idea what these parts will give me. My target power range is 400hp and 400 lbs-ft of torq. Any ideas. Thanks, Dave. Sorry to make this post so long.

Silvertone

Hi OldChev, you're going to start getting a ton of answers and ideas here. If it were mine I'd need to know about the budget, and I assume you've got stock rear tire height and torque converter? With your trans and rear gear, I'd be thinking about how to get more cubes and not go to crazy with the cam specs. Are you open to a 383 build?

learje

since ur going roller take time to give chris straub a call

http://www.straubtechnologies.com/

he spec'd the roller for my 402 and helped me along w head selection etc...gave me lots of advice on parts i didnt purchase from him

lear

oldchev

Yep, I am open to a 383. I do expect to change the Converter. i'm having the th400 worked over by a tranny shop that has an owner who races and uses a th400. the body of the car won't be modified, but I will sacrifice the hood to a LT1 or BB hood if I have to. But I really don't want to do that because I like the lines the way they are.

oldchev

Thanks Lear, I look into that. I took a quick look at his website. Looks good.

7t9l82

i think there are better choices than vortex heads for your build. the first cam you listed is slightly more lift than your stock cam with 1.6 rockers and the second has less lift. there are better choices there too. I'm sure many more will chime in and give you more ideas.

DABall

When I rebuilt the 454 in my 70 coupe I switched to a MSD electronic ignition that takes the mechanical cable tach drive. It is a great set up and maintains an original feel to the engine bay.

96 lt-4

I would go for a 383 with aluminum heads.180cc minimum and 195 better in most cases.Hyd roller cam(call a cam company and give them all your specs and tell them what YOU want it to do).Intake and carb of your choice and will affect power.Tell the cam grinder whether you are running headers or manifolds and what the rest of your exhaust consists of.Also what octane fuel is available that you plan to run.
I would build for torque with the 3.08 gears and don't go crazy on the stall converter.Make sure to run an auxillary tranny cooler.
You can easily build a 10.00-1 383 to run fine on pump gas and make 450 lb ft of torque with a broad flat torque curve.

Vortec heads are a good budget upgrade over stock heads and the bigger valve ones make good power.However there are better cheaper options.

There have been several short/long blocks for sale in the C4 parts section.Don't discount the idea of buying a running motor and making changes if necessary.Used parts are plentiful and I am not afraid to use them.

hugie82

I don't think I would ever build another 350 without making it a 383 nowadays. The kits are cheap and the machining is as common as a bore job. With the cam you chose a 383 would be much happier at low rpm than a 350. Just remember your compression goes up with your displacement. For which isn't a bad thing

oldchev

Thanks folks for the input. I think I will build a 383, but ya still have to pick the parts. I have gone to two engine shops that I know fairly well and I guess I picked the wrong time of year because they are so busy with engines coming in after the racing season that they can't tell me when they would get to mine. So I'm left with picking out the cam, heads and intake on my own. Any help is greatly appreciated. Dave.

REELAV8R

If it were me I think I'd look at an AFR 195 for heads for 383.
Cam I would be looking at a 239/243 @ .050' 290/294 combo. Maybe more split if your exhaust is more restrictive. Put it on 107 or 108 LSA.
Or for more grunt maybe a 282/292, 231/239 @.050 with a 107 LSA.

More displacement is more forgiving of low LSA for vacuum. What you are really looking at for vacuum in overlap in degrees. That first one would be 76* of overlap with a 108 LSA or 73* on the second one. Vacuum might be around 10 " or so at idle maybe.
The formula for overlap is; advertised durations added together then divided by 4 take that result subtract the LSA and multiply that answer by 2.
I run 54* of overlap on my 350 and get 14" of vacuum out of gear @ 800 rpm. 10" To 12" in gear 600 rpm.
Even if vacuum drops to 8" I can still operate lights and other vacuum operated items.
For the th400 a higher stall converter would help getting the engine in the meat of the powerband for launches with that 3.08 rear. The 3.08 needs all the help it can get. I highly recommend it. Worked very well for my stock and now non stock 350.
I also like the shift kit. With an adjustable vacuum modulator you get nice shifts for normal driving and good hard shifts for WOT stuff.

c3_dk

I have a good connection for AFR parts, if you are looking for AFR parts, then please PM me, and I will connect you to him.

oldchev

Hey DK, are the parts hot? Do I have to sneak them into the country?


REELAV8R, Are you saying the less number of degrees or smaller the overlap then the better the vacuum?

So I still haven't settled on a cam, heads or intake. But what I think I am hearing is that the small valve vortec head is too small. So with the large valve Vortec head, you get a 225cc intake, 2.0 & 1.55 valves, 66 cc chambers and it can handle up to .530" of valve lift. That sounds pretty good doesn't it. Remember I am shooting for about 400 hp. maybe 400 lb-ft torq. But I want it down in a driveable rpm range. If I'm on the highway at 65mph, at 2700 rpms, if I pull out and hit passing gear I am immediately at 3500 rpms and then up to about 42 or 4500 when it upshifts.
With what said here about cams, I'm looking at the Comp Xtreme Energy #8-423-8. This has duration @ .050 at 224/230. With a lift of 502/510. LSA = 110*. Does this seem too small. But the lift is kinda high isn't it.

c3_dk

No :- )

I bought my heads and intake (AFR) for my SBC 427 from him, he gave me a great price, and super service. I had to export them from USA, he is a US seller.

PM me if you would like to have his email address

96 lt-4

That cam would run well.I would consider some 1.6 rockers for more lift on some good flowing heads.With 3.08 gears I would be careful not to over cam it.You need some low speed torque so you won't need a high stall torque converter.
As far as heads go edelbrock rpm,trick flow,AFR,or even some of the chinese copies would all be fine at this level.I picked up a used set of trick flow 195's for less than you would think.
Intake depends on whether you want to stay with the q-jet or switch to a holley/edelbrock square bore and what will clear your hood.It is hard to beat an edelbrock rpm(they make one for the q-jet as well)if you have the clearance.Other options as well(Holley street dominator/weiand stealth etc.).

BKbroiler

So you're saying your trans upshifts at 4200 to 4500 rpms at wide open throttle? Are you planning on having the trans redone? Assuming you are, you might want to have the governor tweaked to raise shift points 1000 rpm, at least. Otherwise, with a stock converter and 3.08 gears, you're going to be weak from a standing start and the early shifts are going to drastically reduce performance after that.

REELAV8R

Yes, less overlap will give more vacuum. More displacement gives more vacuum as well.

That Comp Xtreme Energy #8-423-8 looks like a pretty decent cam.
A little short, but this would be good if you plan on keeping stock stall converter and rpm limit of about 5500-6000.
You'll get the 400 hp with a 383 and AFR heads with that cam. With a better cam you could get to 450 or better.
All the specs you read will be referencing a 350. So your idle, and running characteristics will be somewhat milder with the 383. Lift is good, don't be afraid of it. Any way you can fill the cylinder quicker is better, then the cam duration can be kept down. Also higher displacements are more tolerant of narrower LSA's. 110* on a 383 is a bit wide for me, but if you want a smoother idle it will work fine.

63mako

If you build a 383 with flat tops and 75CC AFR 195 heads with good .040 quench you will be at 9.86 to 1 compression and 8.00 to 1 DCR with this cam and 1.6 intake/1.5 exhaust rockers http://www.summitracing.com/parts/lu...0-16/overview/
with a great operating range for your combination and intended use. A Performer RPM intake to top it off. It might need midghrade fuel but likely will run on regular.
http://www.summitracing.com/parts/hr...make/chevrolet
A 2400 stall convertor would be a nice upgrade while it is apart but your TH400 has a 2000 stall now, it will be fine for street use. You want your trans shift point at higher RPM at WOT but it might be with this build and you can do that in the car if needed. Will be above 400 HP/TQ.

Before ANYBODY bashes this OP wants bottom end and midrange power, has a 3.08 with auto trans. and headers with no mufflers, chambered exhaust.

c3_dk

Almost like my 69 convertible.
355
195 AFR (75cc)
2.6cc dome pistons (69 L46)
Fel Pro 1094
1.6 Rocker arms
1 5/8" headers, 2½" exhaust
Hydr roller lifter (853-16)
Hydr roller cam (12 466 8)
EZ EFI.
Edelbrock 2701 intake

This gives:
10.04:1
8.13:1 (DCR)
0.04 Quench

415hp @5500RPM
432TQ @4500RPM (according to Dyno 2003)

3.70 rear
5 speed, 0.63 in 5th.

Patro46

Here's an idea...
http://www.digitalcorvettes.com/foru...d.php?t=210313