Although I'm not quite to this part of the resto yet I'd like to iron out some details with you guys for the drivetrain on my 72. This car will not be raced & will not ever be taken over 70-80mph probably. I just want it to be a good street performer that will make its best power in the idle-4500rpm range. All suggestions & opinions are welcome. Here's what I'm thinking:

Engine-
I have a 350 that has correct numbers 71 LT1 heads & intake. 010 block. I'm sure it was the real deal but the block has a replacement CE code on it so I can't technically call it an LT1 But anyway I still want to use it because I like the nostalgia of the LT1 heads & what not.
-487 casting number 75cc 2.02/1.60 160-165cc intake runner I believe
-have heads milled to 70-72cc & ported to 170cc-180cc, new valves etc
-have intake port matched
-block machined over .030/cleaned up etc
-Eagle rotating assembly
*Cast steel crank 3.48 stroke
*Forged Aluminum flat top pistons, 2 valve reliefs +5.00cc volume
*Forged 5140 I-beam rods 5.7 length
- With
-Custom ground solid lift cam & springs with lift spec depending on flow numbers of the heads after head work has been done.
-Holley EFI for fuel delivery
-Possible roller timing chain? Don't know if it's necessary.
-Not sure on rocker arm ratio. School me.
- Full length headers/custom header back exhaust
**Hoping for around 375-400+hp & good torque in a usable rpm range.

Transmission(s)-still undecided on auto vs manual, but here's my choices for both. Upgrading from my current TH400 (which is for sale)
-GM 4L80E 1st=2.48 4th OD=.75 would use with 3.70 or 3.90 diff
-Tremec TKO500 1st=3.27 5th OD=.68 would use with 3.36 or 3.55 diff

Differential-New differential from Duntov Motors
-Newer style Eaton carrier, with all HD upgrades that duntov offers.

-Aluminum radiator with dual electric fans.

Let me know what you think of what I've said here. I'm a sponge for your knowledge.
Thanks,
-Matt

 

Looks like a great plan to me! Only thing I would do is have Tracdogg build your differential. Would probably be cheaper and most definitely would be better built!

Bill

 

I prefer SCAT over Eagle as they seem to be better in the machining department. SCAT's rotating assemblies will cost the same but all of their rods are 4340.

Not sure how "Nostalgia" you are trying to keep, but since you are replacing the rotating assembly, cost the same to go with a 3.75" stroke 383. Easier power and no one needs to know.

Rocker ratio will be 1.5 or 1.6 which changes the lift. If you are having a cam custom ground, all that will be determined and provided to you.

 

Here is what I did that made my base 69 much more a pleasure to drive and keep it looking OEM (in order of effectiveness):

1) Power steering. I went with Borgeson.
2) 5-speed. I went with a OEM WC-T5 from a F body.
3) Wilwood aluminum brake calipers.
4) Max caster alignment.
5) Reduced rotational mass. Light weight wheels replaced Rallys
6) weight reduction off nose of car. Aluminum heads (L98), aluminum intake manifold (OEM '79), aluminum water pump, aluminum radiator, aluminum fan shroud, aluminum brake master cylinder (CPP), steel tubular exhaust manifolds (OEM '81/85), etc all took nearly 150 lbs off the nose of the car. All the aluminum was painted factory orange and I used L46 valve covers with adapters to hide the center bolt heads.

Notice that other than all the aluminum I left the original 300hp rated engine alone. The only "performance" enhancement I did to it was add 1.52 intake and 1.6 exhaust rockers. It has plenty of power for just tooling around town, the 5 speed really helps with the torque multiplier too making the engine seem stronger than it really is. To most non car people the engine looks factory correct for the "nostalgia" look,

 

A 350 with the original heads that is only revved to 4500 rpm is certainly not going to make 375-400 hp.

 

Agreed.


If you are changing the crank and pistons anyway, why not just go with a 383? It costs pretty much the same, and you will have a much easier time getting to your power goals at that RPM. For a 350 to make 400 HP you would need some good flowing heads and a decent cam, and it wouldn't be making that power till higher in the rev range most likely. A 383 could make that power at a lower RPM.

 

I would go with the 383, 5 speed and a 3:55 rear.
TKO 600 from SST which has a .6 overdrive + correct corvette shifter. They give a new driveshaft+ mounts.

I rebuilt the entire driveline on my 71 with MOOG, and Delco parts.

2.5" exhaust - ram manifolds and turbo mufflers to hear the radio.

Fun to drive - quick enough and good gas mileage.

I tried a friends 17" wheels and did not like them so I have 225-70 15's on stock rims.

Borgeson Power steering and a spreader bar.

Vintage air is next - then paint.. it's a good 10' car.

 

Is that a forum member? How can I find him when the time comes?

 

What do you think of the A41 auto kit from sst?

 

I believe I will go the route of the 383. I posted this same stuff on hot rod forum & they all said the same thing you guys said. Evidently the 487 heads aren't anything remotely close to the 1970 LT1 heads & aren't worth putting money into. They said to sell them to a circle track guy since they use them a lot. Perhaps I'll go with Dart Heads or equivalent. Just spent some time on summit piecing together a 383 combo:
383ci
SCAT rotating assembly
Forged crank 3.75
6.0 forged rods
Forged pistons +6.80cc
Custom specified cam/lifters/rockers/springs
Holley EFI fuel delivery
Dart 200cc intake runner 72cc combustion chamber heads
Not sure what intake though since it'll have to fit under stock hood?? I don't like those aftermarket high rise hoods. I like the original designs better.

According to the calculator that would be 9.91:1 compression with the deck height at .000
Is this a good cp ratio for a street 383 on premium pump gas or could it handle more compression?

What kind of power would you guys think this would make? Around 425-450?

 

Just a thought, you might look up Skip White Performance 383 stroker kits. He has some pretty fantastic deals and most people seem to be happy with those kits.


And yes, with the right cam, those heads are capable of supporting 450hp fairly easily (flywheel hp by the way, not wheel).

 

It'll be pretty difficult to make that much power below 4500rpm though.

 

Agreed. Though you could probably make his original 375hp goal at 4500 RPM with a 383 and decent heads and cam.

 

What do you think of the A41 auto kit from sst?

I have not had any friends use one, but have been told good things by someone who did. (73 SBC Vette automatic)

All the 5 speed kits I helped friends install fit perfectly (about 8 or 9 now) with no mods.

We put them into Vetts, Camaros and a Chevelle no issues. A great selling point is no searching for parts and a perfect fit.

The greatest selling point is that SST supplies a new drive shaft + all the parts to fit, so you can go back to stock in a few hours.

 

I like the specs on your second engine build. Your estimate of 425 to 450 hp from that is high. My 434 SBC with Dart Pro 1s 64cc, 195 runner heads, custom ground roller cam maybe at the 425 mark. It's a good solid 400 hp engine at 4500 rpm. Getting 375 hp from a 383 at 4500 rpm, probably pretty close and with a lot of torque, it'll be a blast to drive. T