I have a 2 bolt main 350 bored 30 over, flat top pistons, stock crank balanced & cut, stock rods, older heads milled etc..., a holly 750 dbl pumper, victor jr. intake, headers are on the way, It will be going in my 84' Z28

up untill now I have been flying by the seat of my pants more or less, getting a part here & there. Now about all I lack is the camshaft, the fella at the machine shop where I had the block work done said anything with over a 500 lift would work, does that sound right? Does anyone run a similar setup?

Also I have a muncie M21 4 speed transmission, (however 1st gear is stripped) & a Turbo 350 automatic, do you all think it would be worth the $ (performance wise) to have the muncie rebuilt or just throw the T350 in?

Any other tips or tricks you folks know would be helpful as this is my 1st complete build, and am learning as I go

Thanks
Cody

 

use the TH350, sell the Muncie to someone who needs it. Wouldn't be worth your hassle to get it to work in your 3rd gen, and someone else would probably be willing to part with their first born for it.

cough up detailed specs to get a good cam suggestion.
head casting #, what's been done to them. chamber size.
desired power band.

you used ARP bolts on the rods and mains right?

 

The head casting number it 14079621, I am not shure of the chamber size, I bought these heads off of craigs list, & the seller claimed they have LT1 springs and that he had the valves, retainers etc.. replaced, the valves do look new & they have a GM part number on them so I am assuming they are OEM replacements, I took it to the machine shop & had it tested for cracks, cleaned & milled the mateing surface & told them to look at the valves etc... & let me know if there are were any problems, they said they were good to go.

As far as the power band, A goodtop end is what I am after. I would like it to be a Sunday driver, plus the occasional trip to the drag strip. I hope to run a 75hp shot of nitrous eventually,

I just bought a 3.08 posi rear end (off craigs list again) the guy told me it was a 3.43 but after counting the teeth a 3.08 is what I get do you think it will work well with the combonation I have.


I think I will use the TH350 transmission after hearing your advice
I hear all sorts of talk about a "stall" on automatics at the risk of sounding completely stupid what does it do? do I need one?

I am sorry for the long winded response,
I doubt it, but I hope I can help you someday - this page is awesome

Thank you for your time
Cody

 

as for the APR bolts I assume the ones that came off were, I got this short block out of a junk yard & cleaned & reused all of the nuts & bolts

Thanks again
Cody

 

as for your cam selection, give comp cams a call and tell them all ur specs and they will hook you up. they know their ****...

as for the 3.08 gears i would say it would be good...but if you want a cam with over .500" lift most likely you will have to get a little lower gears. also if you call comp cams they will tell you whether or not the cam requires a stall converter or not. i was always told anything over 70 degrees valve overlap requires a stall, but thats just what ive heard at the racetracks from different ppl.

if you are planning on running more top end horsepower with a 75 shot u will def. want a cam specifically for that (which will most likely require a stall converter and lower gears) just my $.02

curt

 

ok, no. Let me stop you now, before you blow a bunch of money on a POS mismatched combo.

3.08 gears are too small. They will work, but then you should plan on going for low end power. Upgrade to 3.42 if you can get them. Look for a 3rd gen V6 car in the wreckers to get the ring & pinion from it. You know how to count the teeth, so that skill will soon suit you well.

621 castings are garbage. But you have them re-done and all that, so you might as well use them. I think they have 76cc chambers. You have ~8.5:1 compression. Bring those heads back to your machinist, and get them to cc them for you. Or try and mill them to lower your chamber size. Also use a thinner head gasket. You need to be above 9:1 or else you're pretty much wasting your time.

Use a compxe268 or equivalent. That should do you ok. A nitrous cam is not actually worthwhile, considering how much time you would be using the nitrous, and how much power difference you'd feel. A recent article from car craft I think did a test with nitrous cams, and showed they HURT more then they helped. Take that for what it's worth.

do a search on stall speed. You probably want ~2400RPM or so.

Ok, do NOT reuse your bottom end fasteners. Throw those out. ARP main bolts are $17, rod bolts are ~$35. That's VERY small potatoes. They are worth their weight in gold. Without them, your motor WILL fall apart very fast. The bolts come with ARP thread lube, use it, chase your threads before you put in your main bolts as well.

 

I've never lost an engine due to a broken fastener. My last build was the first time I used ARP rod bolts.

For what that's worth.

 

Just my two cents.....you will be selecting a cam by mostly duration and not so much lift. You can have a low lift cam with a bunch of duration that will run real lumpy. I have a .515" lift on my cam with only 210 degrees of duration and it's idle is buttery smooth.

 

I have a stock open 3.73 rear end in the car NOW, I was not aware that the ring & pinion gear were interchangeable w/ the posi out of an 87 RS that I bought, I will swap the gears, do you think that will be in the range I am looking for?

I still have the heads off & am going to have them checked for the chamber size, I hate to ditch em' I have a bunch of $ tied up in them, I will see about having them milled down a little more.


Thanks for all of the advice,

Cody

 

You need to know what carrier each gear set is. 3.73 are "3-series" gears, but the aftermarket also makes them to go on "2-series" carriers (3.08 and below ratios). If the '87 has 3.08 or below gears, posi or not, and the 3.73's are "stock", then they won't fit the '87 carrier.

How much money you've put into the heads you've got should not be a consideration in your future actions. What you need to consider is how much you need to spend from here to get where you want to be. If you want to get 400 streetable HP out of this engine, you could spend another $1000 on those heads and still not get there. However, you could spend $1000 on any of several different head choices and get well over that goal. Which makes more sense?

 

maybe I will just keep the open 3.73 gears & sell the posi I have, The only reason I bought it is I was told it was a 3.42 & got screwed, I have heard all the talk about posi being the ****, but I guess after you get off the line it does not have all that much effect.

I have done a little bit of research on heads since the prior posts & I am going to look for a new set, I figure mine will be good for someone rebuilding a stock engine, I can most likley get most of my money back

I have heard a lot of good things about camel hump GM heads, & dart heads what cc size should I be looking for for my setup?

I have some pictures of the engine & car & I will load them as soon as I can figure out how

Thanks again,
Cody

 

I have a 292H .500/.500, idle is pretty rought, make a lots of power but at 5500-6500 rpm and it need at least 10:1 or moreto run fine, great but two much top-end, it make you push it to the rev. limiter!!!

The 270H or 280H is a better choice for street use more low and mid-end power, the max power will be betwen 3500 to 5000 rpm that is much conservative for an SBC

hope this help