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Old 02-03-2011, 10:30 AM
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Rebuilding 73 SS Nova BBC w/ 4Spd Questions

I'm new to this forums and this is my first time doing this, so please bare with me.

I've finally started to start working/finishing my 73 Nova and want to finish by at least September. I have began buying everything for my front end (The vehicle tagged a tree ruining the sub-frame, and front clip, and his newly rebuilt EFI 350). I picked it up off him for $700 with a freshly rebuilt 3:73 rear end, all original dash/gauges, and now have a guy that always stops into work that conveniently wrecked the whole rear end on his 74 SS a while back, kept it barn stored and has been trying to get rid of it for a while now. The three issues I'm now having are:

1) My father and I have always wanted to do the whole BBC thing, and even though the 73 came with a 350 4bbl there's plenty of room and no reason not to go bigger. the PLAN is to use a 4 bolt 454 block, with the 427 pistons/steel (non-forged) crank, and some high flowing closed port heads (I've been hearing a lot about 781's and 409's). I'm wanting this to hit between 450-500hp on the motor with another 50-100 on the bottle bring the total to 550-560 on the strip, without an extremely high compression ratio (I don't need/want to run on rocket fuel.. 9.5 CR if at all possible) as I want this to be a street/occasional strip car. A summer weekend toy, that can be driven to work once in a while, that CAN hit high 10's in the quarter.

2) Managing to pick up a rebuilt BW ST-10 4spd w/ a Hurst Ram-Rod VGate with a couple hundred miles on it for only $800 total (Couldn't pass it up at that price). Now this isn't one of the fancy 904 nodular cases with nickle gears, just the late year aluminum with the 32/27 in/output shafts (I looked up the casting, to verify whatever it was). Will this be able to support that much power running that high OCCASIONALLY on the strip and having a little fun on the street?, I know they're only rated at 375, but I remember reading the Ford Thunderbolt using one in their stock vehicles back in the day with just shy of 500hp. A M22 is a little out of my price range but we DEFIANTLY want to go the 4 speed VGate route.

3) Lastly, the hardest part for us is what we're going to do with our intake. Reading up a lot about it, it's really between running a dual carb setup, MPFI, or EFI if it can find it at reasonable cost, ($3000 ain't gonna cut it!). I understand that the carbs can be pretty fickle with tuning but making that work won't be an issue.

I have my goal.. and a dream, and no matter what I'm going to make it happen, hopefully someone can just send me in the right direction!

-Justin

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Last edited by Wattsy; 02-03-2011 at 10:43 AM.
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Old 02-03-2011, 03:13 PM
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"BUMP", Keep on dreaming and gathering up the parts you need, and someone will come along and help you with your questions in awhile sometimes it takes a bit for some to find some of the post but when they do they will help. We have some awesome engine guy's around the site.JMO


Cole
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Old 02-03-2011, 03:31 PM
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Most economical/easy to tune is a single carb.

When the time comes to install the BBC. First take the heater core out and if you plan to use same, flip it. Then drill two holes in the cover box for the hoses.

If you plan on power brakes. Either use regular 68-70 Nova Camaro BBC frame/engine mounts (mounts engine lower and to the right) and off set power brake unit, or go with the modern smaller boosters.

Plan on replacing the rear end.
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Old 02-03-2011, 03:52 PM
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diff

I don't know if you bought the diff but I went to install a 74 diff in a 73 this last summer and was told it was the same but the spring pads were different widths so check, just a thought.
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Old 02-03-2011, 04:12 PM
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I do appreciate people commenting!

Quote:
Originally Posted by mud.man.rj
I don't know if you bought the diff but I went to install a 74 diff in a 73 this last summer and was told it was the same but the spring pads were different widths so check, just a thought.
Just to clarify, I am doing the build on the 73, and using the 74 for the remainder of the front clip that I don't already have! In all reality, I should now have everything minus the obvious engine, and some of the cosmetics which will hold until she gets up and running for the time being. I'm really just looking for some experienced insite as I def. am a noob.

But as for my budget which I forgot to mention earlier, roughly $1300 a month x8 months for my deadline (this budget is for the vehicle itself, and NOT including paint), but I'm still trying to do this quickly/efficiently, and would rather build/install myself with the old man, so I can at least get the experience and have it finished just the way we want it.

Last edited by Wattsy; 02-03-2011 at 04:18 PM.
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Old 02-03-2011, 04:41 PM
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Some more background from you...

Do you intend to make it hook well, with slicks or drag radials??

How dead set are you on 2 carbs??

Do you want hydraulic roller cam, solid flat tappet cam, or solid roller cam?? (I left hydraulic flat tappet off this list because BBC's are hard on non-face oiling flat tappet cams and no one makes face oiling hydraulic flat lifters, only solids).

How serious are you about the "occasional strip action"?? You want to go fast and be serious, or just have fun??

781's and 049's are both open chamber heads, not closed. You don't want closed for power anyway.

Any particular reason you want to make the engine smaller(454 down to 427)?? I makes your 10 second goal harder to reach.

The manual trans factor is going to make the clutch and driveline quite a bit more expensive than a good auto and converter, as long as you can accept that....
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Old 02-03-2011, 04:51 PM
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I've danced that tune back in the late 70's with a built 396 I put into a 70 Nova SS. 049 & 781 heads were the "best" flowing GM production heads but they are open chambered NOT closed (You DON'T want closed chambered heads!) The combustion chambers on these heads are pretty close, only issue with these heads is the "tend" to get cracks around the cent two exhaust ports if the engine gets badly over heated! However the 781 heads were made to "help" avoid this issue. I'd suggest bumping the valves size up to 2.19 & 1.88 ...will help make them flow even better!!! Next be sure you get heavy duty valve springs (about 120# seat pressure ...90# is stock) otherwise you'll float the valves over 6000 rpm. Next I'd look at a cam, but don't look at anything over 280 deg.s duration ...over that and you'll get into valve overlap and it'll kill your vacuum ...then you'll have to start getting into all kinds of "trick" stuff (keep it simple!) ...I never was a fan of the B/W t-10 ... but to each his own, remember the Muncie M21 isn't a POS! M22 is better but alot noisier! I like your 3:73 gearing ...had it myself, got mine off a 69 Camaro. For an intake I'd suggest a dual plane manifold ...it's "quicker" ...single plane is "faster". If your just burning across an intersection, quicker is better. But if you're running for 1/4 mile times faster is better ...hope that's clear!?? A good pair of headers! And the last thing you'll need is a sub-frame connector, my car would aways get sideways when I really got on it hard. A buddy suggested a sub-frame connector and I finally could bomb off the line straight as an arrow. Nice project ...Good Luck!
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Old 02-03-2011, 05:09 PM
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Eric, haha sorry about that! I've been looking through all this stuff for the past week, and thanks for the correction on the heads. As for your post:

I do intend to have Drag radials.

The two carb setup I would only use, if I wasn't using MFPI or EFI. I don't have a problem setting myself to one carb at all, I just want to do something a little different than the rest I've seen around here.

Solid cam, and def. I want it idling rough (without losing vaccuum of course).

As for the occational strip, I'm looking to be somewhere inbetween. I'm not going to start stripping out my interrior for weight reduction and what not. but the purpose of the car is to be fast, and fun.

Again, about the heads thanks for the correction!

As for the de-stroking, we've always liked the idea of a mid-stroke engine, (we were real close to doing up a 396 like the '79 Camaro we had when I was growing up before we started looking at de-stroking a 454) but obviously the higher you go, the better power options you have. Just really more personal preference than anything I guess!

I understand about having to put out the money for a nice clutch. (I actually work for an automotive brake, clutch, and gear company in the spare time between school and my military gig and can get a lot of the parts at cost). Drivetrain is a different story but I'll take the hit on it, before I'm driving an automatic! In addition to this, any insite on the ST-10 BW's? I've seen people use them on higher power applications than this, but just because it works, doesn't mean it'll hold up!

Last edited by Wattsy; 02-03-2011 at 05:17 PM.
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Old 02-03-2011, 05:40 PM
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Quote:
Originally Posted by 11echo
I've danced that tune back in the late 70's with a built 396 I put into a 70 Nova SS. 049 & 781 heads were the "best" flowing GM production heads but they are open chambered NOT closed (You DON'T want closed chambered heads!) The combustion chambers on these heads are pretty close, only issue with these heads is the "tend" to get cracks around the cent two exhaust ports if the engine gets badly over heated! However the 781 heads were made to "help" avoid this issue. I'd suggest bumping the valves size up to 2.19 & 1.88 ...will help make them flow even better!!! Next be sure you get heavy duty valve springs (about 120# seat pressure ...90# is stock) otherwise you'll float the valves over 6000 rpm. Next I'd look at a cam, but don't look at anything over 280 deg.s duration ...over that and you'll get into valve overlap and it'll kill your vacuum ...then you'll have to start getting into all kinds of "trick" stuff (keep it simple!) ...I never was a fan of the B/W t-10 ... but to each his own, remember the Muncie M21 isn't a POS! M22 is better but alot noisier! I like your 3:73 gearing ...had it myself, got mine off a 69 Camaro. For an intake I'd suggest a dual plane manifold ...it's "quicker" ...single plane is "faster". If your just burning across an intersection, quicker is better. But if you're running for 1/4 mile times faster is better ...hope that's clear!?? A good pair of headers! And the last thing you'll need is a sub-frame connector, my car would aways get sideways when I really got on it hard. A buddy suggested a sub-frame connector and I finally could bomb off the line straight as an arrow. Nice project ...Good Luck!
11Echo
Thanks for the post! (I'll probably never live it down about the heads haha but thanks for the correction!) I do understand what you're saying about the heads, and that's what I've been hearing as well. As for the Tranny, the Super T's hold up better than the original T-10's did and where some try to compare them to the M-22's I know they're not at that level. As for the M-21, it was between the two and I just couldn't pass up the offer for $800 including the VGate on my ST-10. For the tranny noise, I wouldn't mind hearing the sound of a transmission I know I'd be able to beat on for this application without breaking it . Not to mention that I do plan on having cutouts regardless of not having a cat, just for fun. Thanks for the insite about the intake, and I'll look into the sub-frame connector!
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Old 02-03-2011, 05:54 PM
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Okay, I'll start at the back and work my way forward. Rear axle is the 8.5" 10-bolt, it will handle what you want to do but will need some beefing up. I'd recommend upgrading from 28 spline to 30 or 33 spline axles, adding C-clip eliminators, welding the tubes to the center section, adding a rear girdle cover, adding a 1350 series U-joint yoke, and installing an Eaton positraction differential or a spool. If you do this before you blow up the 28 spline posi you will be able to sell the 28 spline stock posi unit or save it for something milder.

Driveshaft will need to be from a custom shop like Denny's Driveshaft, Mark Williams, Strange Engineering, Inland Empire Driveline.

To make the ST-10 live you will need a good adjustable clutch, like the McLeod Sof-Loc so that you can cushion the hit to the trans instead of hitting it like a sledgehammer. This is how stock class racers keep their transmissions together. A blowproof steel bellhousing will be rules mandatory if you want to even see the track once

I can't say I am a fan of destroking engines, it is just a step in the wrong direction, especially since you aren't willing to run race gas compression ratios and run the rpm(8500) to take advantage of the shorter stroke. I would stay at 454 stroke(4.00") or go to 489/496(4.25") so you can still make power with lower compression due to the engines size. A 10 second goal is going to be hard to do with stock heads unless you know someone who is a good head porter, and if he charges what his time is worth you will be within inches of the cost of a budget set of aluminum heads, all tied up into that old iron.

The '73 Nova will be close to 3550 lbs with a small block, my all steel '72 SBC car is 3350 lbs scaled and your '73 has much heavier bumpers and brackets. Aluminum heads would be a big plus here with a big block, if you stay all iron on the motor I could see the car getting to 3700 lbs+, and that is without the driver. Bigger the engine is the easier it wil be to move all that weight.

You'll need subframe connectors, and if the car runs faster than 11.99 you will need a 6 or 8-point rollbar(good to 9.90 if floorpan/firewall is stock). Solid aluminum subframe to body mounts, no rubber.

Think about how you want to do it, and we'll talk particulars on the engine.
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Old 02-03-2011, 07:07 PM
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Eric makes my head hurt. .

This is my new years resolution which is why It's going to be completed at a much faster pace now (that and breaking up with the girlfriend gives me a whole lot more free time and cash)!

Although I do think you're concentrating a little too much on the track portion of this project rather than what it's meant to be, fun!

I'll check the rear end when I get home, as I'm not sure if it's still a 10 bolt or not, much less remembering if it has posi (we believe it does but we're not going out there in the -2 degree cold to check)! I know factually it isn't stock. This has been one of those project cars that's been sitting without touching it for quite some time so I'm not quite up to par on all the details. My father has alerted me that it does already have subframe connectors from it's previous owner. Also after checking out the bellhousing I might already have one at home, the guy threw in a bunch of SBC parts on the sell of the frame and I'm pretty sure I saw the housing in there somewhere. Just found out earlier today SBC/BBC bellhousings bolt up the same except for whatever that red-headed stepchild engine is.

As for the engine, I'm going to man up and stand by my decision on here of de-stroking the 454, even if it does cost some extra cash to eventually get it where I want to be. Where I don't want to run the high compression so I can run pump gas, I suppose if I'm not knocking at 11:1, i won't lose sleep at night. Ultimately, remember I'm shooting for 450-500 all motor but still be able to support itself with a smaller shot from the bottle. The plan is to get this thing rolling on it's own first, then add on as budget comes in.. It's a lot more entertaining when I can actually play, then come back and work on her!

I not worried about the ET's I'd be running from the get-go, I'm just trying to get on a solid setup to reach this goal by the end of summer!

I do recall a stock 73 SS (350 4bbl) running at roughly 3,200lbs which did surprise me a little bit, that is if I did my research correctly.

The aluminum heads have been noted, and if I can't get a set of 781's or 049's done up with a good cost under the price of a pair of nice aluminum's, I think putting the extra money out would be the most cost effective. With that being said, what kind of heads would you personally recommend? Still staying with the oval, or bumping to rectangular?

As for intake you haven't mentioned anything yet, other than if I'm stuck on the duals or not! What are your thoughts?
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Old 02-16-2011, 10:40 AM
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Project

I've finally found a day where it's semi warm out, and managed to take the cover off my rear end. Found out that I got hooked up, and when the guy told us that the rear end was brand new he meant it. Posi unit looks like it was bought and placed in with no use, gears all look fantastic. After sitting for 6 or 7 years the 90WT still looks brand new. Found out looking at the markings rear end is a 10 bolt 30 spline with 8.5 RG/1.625? pinion. 3.73 Richmond gears (80-0434-1). Now all that I'll need are those c-clip eliminators, and a drive-shaft (I'm thinking Denny's nitrous ready just in case we decide to take this project further later).

I've also been thinking about selling my new Borg Warner ST-10 Transmission for more than I got it for (I paid about $400 for it in actuality) and just saving for a super-cased M-22 that's rated at 800ft/lb of torque. At only just under $2000 professionally redone by Midwest Muncies, I think that's a bet. Either way a dual friction clutch will break the bank on me, but I'll deal with it because this things going, its going to be pretty sweet when we're done.

All that's left is my front clip (waiting on the donor car which I'll tow to the house when it gets a little bit warmer out) and my engine.

Engines going pretty smoothly, still trying to find a good steel crank without dropping $600, a little machine work on the heads and block and I'll be ready to assemble. (I found a set of lighter-weight pistons for my 6.135 rods rated at 37cc (IC-766) at 842g with ring. I'm just going to bowl my heads out to the appropriate size chamber to give me my desired compression of roughly 10.5 (from 10.7 @ 119cc) Decided to go with a dual 500cfm carbs, not sure if we're going to run with Edelbrocks dual plane setup or just make our own quite yet, as the CompCam guys are giving me iffy answers about EFI with their solid mech flat tappet camshafts.

So far so good! I'm looking to at least roll by early June!
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Old 02-16-2011, 10:54 AM
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Quote:
Originally Posted by Wattsy
(I found a set of lighter-weight pistons for my 6.135 rods rated at 37cc (IC-766) at 842g with ring.
Be sure that weight is WITH the pin- the IC-9917 piston was 909g total (751g for the piston plus 158g for the pin).
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Old 02-16-2011, 11:01 AM
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Quote:
Originally Posted by cobalt327
Be sure that weight is WITH the pin- the IC-9917 piston was 909g total (751g for the piston plus 158g for the pin).
It is, that is why I pointed it out to him
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Old 02-16-2011, 01:15 PM
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Haha, I did say ring, but yes I meant pin! Thanks a lot both of you!
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