Project HZ 1 Tonner

[intelliGEORGE]

Just thought I'd start a thread on my current pet project. It's a 1978 HZ 1 Tonner restore from the ground up. So far the vehicle has been stripped down to the chassis. Cleaned, painted and tared, surprisingly there was no rust to repair. Rebuilt the front and rear suspension, replaced every joint, rubber, bush and bolt.

Got the Cab off, few minor rust repairs in the usual places, sand blasted and prepped the cab for paint. Sold the old Kingswood single headlight apron and radiator support and bought a Premier twin headlight version. Also bought GTS guard flutes and welded them into the guards.

Tossed the 253ci and purchased a 350ci chev from a '72 Statesman. Stripped the motor down and sent the parts for acid bath and crack testing, all good. Got the parts back, decided to stroke the motor to 383ci, 3.75" stroke 6.0" Rod length with forged dish top pistons and 4340 steel crank. With all this torque I needed to make a few mods to the Turbo 400 box which were a 34 element clutch and full manual valve body conversion (reverse pattern).

And here are some pics of the transplant...











Will keep you guys posted on the build, and would also love any feedback and tips from personal experience.

[Godzilla]

Nice George, restoration is a real labour of love.

Is the block a 4 bolt?

Heads, cam, roller rockets, stud kit or are you staying resonably safe to keep costs down and/or for long life?

You meant domed pistons....you did, didnt you? Or are you keeping the compression down?....why? Piston height above gudgon pin height a problem? Pistons are normaly notched if valve/piston clearance is a problem.

6 inch rods are nice, they help the torque curve.

383ci engines are real torque animals.

Nice work George, keep us posted on progress mate.

[intelliGEORGE]

Yeah 4 bolt mains, forgot to mention the top end too can't believe I missed that bit. Using Pro comp 180cc cylinder heads with 3 angle valve job, 2.02″ x 1.6″ stainless steel valves, teflon valve guide seats, Hi-Performance Valve Springs, Holley 600cfm carburetor with electronic Choke, Edlbrock dual plane intake manifold and 0.5″ spacer, custom hydraulic street/strip Cam and heavy duty double roller timing chain and gear set.

Will be firing it up in the next 2 or 3 days so will post some audio on how she sounds. Mate reckons with the setup we chose to go with we should see dyno numbers around 350 - 400 horses.

[intelliGEORGE]

You meant domed pistons....you did, didnt you? Or are you keeping the compression down?....why?

I'm going to get a blower for it when I get some more cash, but at the moment I want to get it on the road beforehand, saves me decompressing the motor later when I decide to get it blown.

The aim of this project is to do most of the work with my old man and brother keep the costs as low as possible and sell it once complete. Seen heaps going for 15k-20k and so far we've spent about $3500. Gotta love Ebay(US) with our lovely dollar riding high!

[Godzilla]

Do you think a Holley 600 cfm will keep up with it?

Sounds a little small for a 383 chevy.

Nice head setup, dual planes are great for torque.

400 hp sounds good, id be interested in the torque curve.

Id guess very strong.

[Godzilla]

I'm going to get a blower for it when I get some more cash, but at the moment I want to get it on the road beforehand, saves me decompressing the motor later when I decide to get it blown

Pissing myself laughing, after i posted my first post it dawned on me.

I was thinking why low compression then thought "Doh" the buggers going to turbo or supercharge it. LOL

[intelliGEORGE]

Do you think a Holley 600 cfm will keep up with it?

Sounds a little small for a 383 chevy.

Well I got a book on Horse power building I was reading and found an interesting way to work out what I needed. The book had a good baseline formula which is (displacement x rpm)/3,456, that's based on 100% volumetric efficiency (VE) which is generally what a race motor is geared up for. But for something like mine it will be somewhere around 85% VE.

So what you do is take the results from the formula x (VE). You end up with something like this.

383ci @ 6,000 rpm. max (383 x 6000/3456) which = 664.73 x .85(VE) = 556.19 cfm air flow, so a 600cfm carby should work well, until I blow it

[Godzilla]

Im stunned. Yes i see your point......shit and we use to put 750 double pumpers on worked 308's and 850's on cleavelands......lol go figure

Yeah we probably were a little (cough bullshit cough) over carburated.

Edit just found this;
What intake and manifold should I use?
Intake should be a high rise aluminum and a moderate carb. The 383 likes to breath so a bigger intake manifold like the RPM or Stealth would be a better choice but the performer and action + manifolds will work. Carb also depends on application but on the street under 6000 RPM you could get away with a 650! A 750 would make more power but is the largest you should go unless you are all out racing!

Taken from here;

[intelliGEORGE]

pretty handy link, thanks Zilla