My 72 Z THANKS to the Nasty Z28 community

AEGIS43

Veteran Member
Lifetime Gold Member
May 16, 2008
302
Gilbert, AZ
Really just a beautiful car, and man, that is some hardcore restoration work. That's taking it d o w n. I love it. And that's a partial build thread, just without a lot of commentary from you, venture. I want to know all about that motor, whether that's an M20, M21 or M22. What rear gear, and how much rubber has been burnt off.
 

69venture

Member
Nov 11, 2015
80
Greenville SC
I apprreciate the the compliments.
The motor started out as SBC 350 that was in the car when I bought it.. It was running but I only drove it off the trailer and into the garage. Considering I was doing a whole car project and wanted to get the car on the road ASAP I figured I would just freshen it up if it passed a compression test and do a whole engine build later. It sat on the engine stand for a few years until I got to that point. The project evolves.... The engine had issues, It needed a full rebuild but was a virgin 4 bolt main block. The machinist and I did some horse trading and the next thing you know I was building a 383. here is the rundown
Scat crank and rods. nothing special
Speed Pro pistons
file fit rings
Z28 (lighter) flywheel
Rotating assemble fully balanced
Brodix IK180 heads (bought these when I was planning a 350 flat tappet motor) The IK200 would of been better suited for the 383. I changed the valve springs to accomadate a roller cam)
Cam is Howards 110325-10 with Morel roller lifters.
With the Cometic .036in. head gaskets compression is about 10.25:1
Another evolution of the engine project was the induction. I originally bought a Holley 750 VS, Edelbrock intake and distributor. I sold all that and bought the Edelbrock ProFlo4 fuel injection system. I've tuned many a carb over the years and really geek out on the tuning stuff. So far I am very happy with the system. One of the best decisions I made. Motor should make 400-450. So far im still breaking everything in. Engine, trans, clutch, differential so I havent leaned on it too hard but I can tell you it pulls like crazy and will haze the 245 tires at will....

Trans is a matching# M20. I rebuilt it. All internals are Auto Gear parts and the only thing I didn't replace was the case and the main shaft. Not having any Muncie specific experience I bought Paul Cangialosi's book and made it a Winter project. Not bad at all. Hurst competition shifter was on it. I just went through it.

Rear end is 8.5 10 bolt and proved not to be original. Had 411 gears in it. I went through the diff. Bearing, seals, Moser axles and 342 gears. I rebuilt the posi with clutches reproduced from a member here on Nasty Z28 (Camaro-Chevelle).
 

AEGIS43

Veteran Member
Lifetime Gold Member
May 16, 2008
302
Gilbert, AZ
My M20 has a leak from the front of the countershaft. I don't have the ability to go through it myself. Chuck's has a Muncie specialist contact that is going to look into that. If the cost of rebuilding it approaches $3k I'm seriously leaning towards buying a TKX.

What is your rpm at 75 mph with those 3.42s? I assume your 245 tires are 60-series, which is basically identical to my 295/50s at 26.6".

"I rebuilt the posi with clutches reproduced from a member here on Nasty Z28 (Camaro-Chevelle)." - That is really, really cool.
 

69venture

Member
Nov 11, 2015
80
Greenville SC
A leak at the counterbalance shaft could indicate that the bore in the case is slightly stretched or our of round. This is not uncommon on a Muncie that has seen a hard life. It can be fixed as I have seen some You Tube videos from Paul Cangialosi where he explains fixing it. Basically a sleeve and bore it but the transmission has to come completely apart to even do a good inspection to see what the cause is. Im not a specialist by any means If its not a matching numbers thing for you Auto Gear makes a "Super Case" that is a lot stronger and might be more cost effective. They were helpful and great to work with when I was acquiring parts. If you are not in love with the Muncie a step up to a 5 or 6 speed is what I would do before I spent that kind of money on a Muncie. I also converted my clutch to hydraulic and got rid of the Z bar. With a 26.6" tire and my 3.42 gear the math says 3240 RPM at 75mph in 4th gear. I am running 245/60/15.. Not a highway car.
 

69venture

Member
Nov 11, 2015
80
Greenville SC
You got my curiosity up. Here is snapshot of Auto Gear gearboxes.
AGE list.png
 

AEGIS43

Veteran Member
Lifetime Gold Member
May 16, 2008
302
Gilbert, AZ
You got my curiosity up. Here is snapshot of Auto Gear gearboxes.
View attachment 151935
That is fantastic information. Especially for the prices of doing something major to the Muncie. I guess I already assumed it would have to come completely apart for a meaningful inspection. I'm sure labor is at least $100 per hour. At least.

There's zero consideration for numbers matching anything on this car. So you would definitely go to a 5 or 6 speed if you were me? I already have Silver Sport Transmissions hydraulic clutch conversion kit in the car ... or did before the engine and trans came out.
 

69venture

Member
Nov 11, 2015
80
Greenville SC
The Muncie is nostalgic and does what is does... The purist get all gitty when they hear it's a Muncie. My first car was a 68 Camaro SS that was my dads. It had a M22 in it. My car is a true Z28 and my Muncie was numbers matching so that played into my decision to keep it and it also brings back memories. At the end of the day its a 50 year old gear box. I said these projects evolve and change as they go. I'm happy with my transmission and had fun going through it but If I have to change it and spend that kind of $$ I will put in a 5-6 speed. I think it would be a better driver. If you want to cruise around and put it on the highway it makes since. I guess it is personal preference.
 




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