Fast355

iTrader: (2)

Flash stall is about 2,500-2,800 rpm behind a 350 depending on how much torque your setup makes. Behind a stock 4.3 they stall about 2,200 rpm. In my heavy Express van it would stall about 2,800 rpm. In the Firebird it could only be brake stalled to 1,800 rpm at light throttle. Above 1,800 rpm the tires start spinning. Hammering the throttle from a stop resulted in spin city so it is hard to tell the exact rpm it stalls. The 4.3 converter does have a lockup clutch.

loopy

iTrader: (1)

So, would this be a good choice for my build?

I assume it shares the same spline count etc as the TC on my 700r4?

What diameter is it?

Just seeing if there is a cheaper option than getting a high stall converter

Cheers

skinny z

Cheap is relative I suppose and I can't comment on the S10 converter working one way or the other except for anecdotal evidence posted here and there.
What I do know is the both myself and my racing friend have used the TCI 10" Street fighter converter. I'll say that I was happy with it's performance (and still am from a steet perspective) until my friend stepped up to a custom spec'd Yank 9.5" (all of the above with the lock-up function). He picked up about 2/10ths in the quarter mile and yet it still has all of the street manners the TCI possesed. While the flash stall is one thing, it's what the converter does during WOT and the shift that seems to make the difference. While I can say that I arguably flash to almost 4000 (as seen in the dyno video attached), I can only foot brake to about 2200 rpm. During the shift I'll drop to an RPM appropriate to the gearing. (6500 rpm shift point x 1.63 2nd gear ratio = 3987+/-). With the Yank, during WOT, at the shift, RPMs are never less than 5000 rpm despite the gearing indicating an RPM of 4000 or so. That's the function of a well designed converter and something that produces quicker ETs. At least in as much as I can tell.
Back to the cheap...swappng a transmission in these cars (or any car for that matter) is something I'd rather not participate in. That, to me, takes away from the cheap factor.



From this video, the test RPMs start at 3000 and at the hit you can see a distinct jump to 4000. While hardly conclusive (from an RPM perspective due to all of the other variables) that'll give you an idea of what you might expect out of the TCI 10" and a Vortec build such as your own.
By the way, the stall coverter is still one of the biggest improvements that I've ever made judging by the old "butt dyno". Yet still very streetable and highway friendly due to the lock-up.

By the way, check out those AFRs on the far right side gauge. 13.1-12.8 all the way. Sweet! That pull only produced 290 rwhp/290rwt yet pushed that 3750 chassis to 107 mph in the quarter. That's saying something.

loopy

iTrader: (1)

Its a tricky thing

Most of this stuff I have to import from the states at huge expense.

I am also looking to bring in a built up 700r4 as I have been told my 83 700r4 is unlikely to last the extra stress the vortec 350 will place upon it. I have trouble trusting local auto shops as US trans' are not that common here and I don't want to pay 3K+ for a trans build only to have it go belly up on me.

The TC is one expense that at the moment I prefer to shelve till all other concerns with the car are sorted. 99.9% of my driving is open road so the soft starts really wont matter until I have it ready for a little bit of motorsport (way down the track after paint, brakes, auto etc,

I am prepared to listen to arguments otherwise if you feel this is a mistake.

As always Kevin, I welcome your input


Cheers

Fast355

iTrader: (2)

Didn't even think about you having an 82-mid 84 700r4 with the 27 spline input shaft. Mine held up very well in my 83 G20 van better than the 92 unit that was allegidely built up a bit by a reputable local guy. For anything over about 350 hp the 700r4 will be on borrowed time regardless who builds it.

Night rider327

iTrader: (13)

The torque converter is one place your money really matters. I have never used the S10 unit so can't say 1st hand on that, but it sounds a lot like the 1970's and 80's "use a vega converter" trend to me. The stock chevy vegas had higher stall speed, so people would use those behind their hot rod engines.. You ended up with a weak converter that had a good flah stall, thats it.

Much more to a converter than that. I have used B&M, TCI, GER, etc. Not really fully happy with any of them.

A well built custom built converter only runs $150-250 more than an off the shelf unit is is soooo much better.

I have a th-400, custom built 9.5" 3500 stall in mine. Before that was an off the shelf 11" 2800 stall.

The custom built one drives around town almost like a stock converter. The car even pulls it's self forward at idle in gear some.

The off the shelf 2800 stall, reved up much higher driving around town, car would not move at all until around 1400-1500 rpm.

Fast355

iTrader: (2)

Far from the Vega converter fad. The S10 converter has the same stator as a LT1 Corvette converter with the "K" 2025 rpm stall speed. I saw a car move to a "custom built 3,000 rpm" stall that was supposed to match the build and witnessed the car slow down 2 tenths and lose 2 mph. Being an OEM converter it is driveable at part-throttle at less than 1,000 rpm and shift recovery was 2-300 rpm higher than the factory 1,600 rpm converter.

Night rider327

iTrader: (13)

Hmmm, that's great info to know. Like I said, I have no 1st hand dealings with the S10 converter.

Yes you are correct, not all "custom" converters are good. I like PTC, Jakes performance, Yank.. Freakshow converters, FTI, Edge converters, ATI, roadrunner converters, midwest converters, coan.

skinny z

From my personal experience (and you all can guess my HP and torque levels from my signature), my 700 has held up so far. It’s out of an early 90s Caprice and has the basic mods (.500" boost valve, TransGo Stage II shift kit, Corvette servo, etc) and has seen time on a builders bench reportedly to have had better clutches and steels installed. I beat the crap out that thing. I even towed a covered U-Haul trailer 3500 kms with no functional lock-up and engine temps in the 240 range (over 4 days @ 10 hours a day) and it’s still around and performing as well as it ever has. The engine failed shortly after that trip. Rod bearings went out of it. Now at half a dozen seasons and well over 50 000 miles on it. Is that an exception.? Possibly. Then again, 350-400 hp and torque isn't all THAT much.

My thinking is that the OP (Geoff aka Loopy) install the stocker and drive. There’s certainly NO sense in putting ANY kind if converter in the stock transmission unless you’re willing to say goodbye to it after the transmission shreds and fills everything full of clutch material and metal. (I suppose if an S10 converter comes your way for next to the nothing and you've yet to put the drivetrain together, then you haven't got anything to lose really. You'll certainly find out what having a little flash stall will do to wake up a performance package)
Just keep a tow truck number on speed dial so you can get home...

loopy

iTrader: (1)

At the moment my trans is all good, no cause for concern until the new engine goes in.

Maybe theres some steps I can take to help longevity such as servos, input drum, whatever etc

Would be interesting to hear some opinions about this......

loopy

iTrader: (1)

Interesting reading here, would be keen to hear more.

Thanks!

loopy

iTrader: (1)

Ok, some news about the heads etc.

The engine shop has blended the ports, done the screw in studs and guide plates and

measured the Alexs springs. The springs are exactly as advertised.

The head volume was only 62 CC so static comp ratio at this point is looking

to be 9.8:1 (this based on my measurements of deck height)

The snag is, the machining on the heads and block is too coarse to use shim gaskets.

I can get the heads and block machined to smooth them for a cost of $320, or get

just the block decked and use a thicker gasket.

Based on the machinists advice, I have decided to go with that as the cost to deck the block is only $160 vs $320 for both.

We will use a .040" felpro gasket to maintain the piston to head clearance and optimum quench value.

He wants me to get the scat rods and he will mock up the engine to check all measurements and clearances before machining.

Does that sound all good to you Kevin?

Cheers

skinny z

Certainly get the engine mocked up before you make a decision.
One thing to consider is how important achieving exactly .040" quench is to you. Is it worth the cost of machining? And I ask this because you had commented on your limiting the costs where possible.
Having said that, personally, the idea of a zero deck makes me nervous. It leaves no room for the next go around should there need to be one in the fututre. My current block has a .014" deck and I use the Victor Reinz 5647 head gasket for the "magical" .040" squish.
I'd like to run all of your numbers again regarding SCR and DCR and see where you might be at. I'm still thinking of low octane fuel.
Gotta go now but I'll be back.

Night rider327

iTrader: (13)

Decking the block is a great idea. If the budget is there for it, I recommed that every time. It just opens up so many more head gasket options for you.

With the stock decks, you only have a few options.. Fel pro 1094, 7733sh1, mr. gasket 1130G

With any major cut or 0 decked block you have atleast 15 choices for head gaskets.

Now Like Skinny said, I would think about down the road rebuild too. If 0 decked now, what happens 5 years from now if it needs a small shave.

I would look at maybe getting the decks cut to leave .010, .012, .014" piston in hole.

Then just go with .026, .027, .028, .030, .032 gaskets in that range there is at least 8 gaskets to pick from.

skinny z

Not to be too sinister about it but I DO have a question about the opinion of your machinist and how he knows the heads and block are unsuitable for the use of a shim gasket. They are new after all and it would seem to me they'd have a surface that's smooth enough and straight enough. I can't say for certain and having never used a shim myself, I have no experience in that regard. I'd just wouldn't want to see you handing money over to your guy when it's possible you might not have to.
This isn't to take away from the benefits of having a new deck as Nightrider points out however at this level of build there may be places the money is better spent.
Just putting that out there.

PS. What are the SCR and DCR scenarios just to refresh...

Night rider327

iTrader: (13)

I want to share something but I don't want anyone to take this as a fact and it will work every time. I know the risk and I took it, and it worked out for me.

A lot of people gets nervous about shim gaskets and thinks the surfaces must be almost glass smooth.

I have used 1094's sprayed with copper seal a gasket on factory stock 200K + mile decks/heads MANY times.. I used a file to draw across the surfaces to knock down any high spots, then used scotch brite roto pads on an angle air die grinder to prep/clean surfaces, then 1500 grit sandpaper pads on grinder over the surfaces, blow off, wipe down with paint thinner, blow dry.. I have done this MANY times with no ill results.

The high/low spots are the problem not so much the smoothness. The shims can't fill in any voids in the decks and can't compress to take up any high spots.

You knock down high spots with a file and spray both sides of gasket with copper coat and that fills any voids.

loopy

iTrader: (1)

He showed me the grinding marks from the heads which looked very coarse to me, but having had no experience with this to compare with I really felt I had no choice but to go with his advice.

I do 100% agree abut the 0 decking being a bit short-sighted.

I will go and pay for the heads which are now finished and get a photo of the markings for you guys to look at.

I haven't re-run the DCR figures so Don't have an answer for that yet

loopy

iTrader: (1)

I totally agree with this Nightrider, that was my thoughts while he was talking with me about it, thats why I came back to you guys for advice.

My machinist seems to think the .040" Felpro is the king of gaskets and really pushed for these. I my self don't have an opinion about gaskets either way, no experience at all, apart from having used felpro way back when I was young on a 351C build for my fairlane.

At the end of the day it will be my decision, my expense so he will have to go with what we decide here.

loopy

iTrader: (1)

Just looking at them makes me as nervous as hell too! Man they're thin.

loopy

iTrader: (1)

Skinny,

The machinist measure the heads at just on 62CC.

He then calculated SCR as 9.8:1.

He did this on a pad, didn't use any computer based calculator.

I haven't had time to sit down and rerun the numbers yet.

His calculation was based on deck height of .025"

skinny z

Hey Geoff, if it were me, (and it has been), I'd not go for a zero deck. Go for .014" down and get the gaskets I mentioned. They're cheap too but, I have to ask, are you in a hurry? Chances are your machine shop is going to be closed for a couple of days for New Years (You get yours about 17 hours before I do. It might be next year before you get this!!) Let's go over the numbers and objectives one more time.
Of course if you want to pull the trigger now, that's your call. Ultimately you'll have a well thought out engine. It's just a matter of flexibilty down the road.
Your machinist has based his estimates on an assumed deck height. Have the block assembled with your new rods and get a measurement as has been suggested. You can make an informed choice at that point.

skinny z

The time now is 6:30 pm MST (Alberta, Canada). I'm guessing 11:30 am, New Years Eve, in Blenheim, NZ. (I suppose I could look it up)

Fast355

iTrader: (2)

You can run the piston out of the top of the deck with a thicker head gasket should the need arrive. The last engine I had built 1.56" compression height on a milled deck and the pistons sat 0.05" out of/above the deck. I used a 0.43" compressed head gasket for a 0.038" quench.

skinny z

True enough but I would say that's about the limit...(and slightly beyond).

loopy

iTrader: (1)

I received this at 2.30 pm NZ Kevin

I can wait to rerun numbers mate. It'll be 2 or more weeks before any rods even turn up for mocking up the block.



Just an aside, they sent me a bill for head work $876 nzd. This after estimating the work at $500 plus GST. I wasn't too impressed and rang them. Thankfully they have decided to honor the original amount discussed . I just hope they don't think they can make the shortfall out of me during the next stage of my engine work.

skinny z

That's my concern regarding their opinion on the shim gasket. As always it's "Caveat emptor". Do your research. Ask questions. Don't be afraid to get a 2nd opinion.
Seems to me you're more than halfway there. Additional machining notwithstanding.
Do you intend to assemble the shortblock yourself? For what it's worth, I'd have a shop do it. If for nothing else other than having those nice new rods of yours and their ARP bolts stretched the appropriate amount. Plus all of the clearances can be checked and resolved without any additional effort on your part. Except opening your wallet.

Edit: The rods made sense in that they're almost the cost of having your others resized plus the bolts. (I hope you got the old ones back as cores you could sell). The machine work on the heads was a necessary evil however having him dig into the porting (bowl work and gasket matching ) I feel is a waste of time. For what it's worth, gasket matching returns very small yields on the investment. The bowl work, that's generally worth it.
Be careful....

loopy

iTrader: (1)

Good advice.

I haven't had any gasket matching done. All he has done is light port work removing the casting marks and smoothing the bowl radius's.

He reckons he has 10hrs work in it, that's with the screw-in studs and all the rest.

I was going to get him to do all assembly and have him onsite for the initial start up and running.

TBH, I just don't have the confidence to do it myself.


Anyways, off to a local pub for new years.

Have a good New years mate, thanks for all your help, and don't get in too much trouble tonight eh!

Same goes for all you other guys who have chimed in and helped in this thread, thanks very much and have good one !


Cheers
Geoff

skinny z

This is with a cam very similar to the XR276HR. My custom spec'd grind. Less advertised duration but more lift. The video doesn't really do the sound justice but you get the idea. That's at about 850 RPM. At 650, it has a more pronouced lope but nothing compared to a big cammed sound. After all it's a little cam by most standards.

loopy

iTrader: (1)

Kevin.

I'm really interested in your rationale behind you choice of what looks to me to be a very similar cam.

To make an uneducated guess I would think it should produce more power at lower revs?

skinny z

That's an interesting question Geoff and one that HAD a simple answer.
The plan was to get a new cam to compliment my new heads. RHS Pro Torker. They're essentially an upgraded version of the OEM Vortecs. Bigger valves. More port flow with the same sized runners. While the Vortecs are flow limited at lifts (arguably) beyond .500", the RHS heads extend that past .550". I needed a cam to suit. I didn't want to increase the duration as the old short block had a low piston to deck value and my max SCR was about 10:1. Any more cam would have killed some the low speed torque that set my car apart from a lot of others. I was also running the OEM rods and cast crank although I did have ARP rod bolts. My target RPMs were below 6000. The Comp lobe catalog had a couple of grinds that kept the .050" duration values the same but lift went up about 7%. Those heads and cam installed in the old short yeilded a DCR of about 8:1. That was up from the previous DCR of 7.93 (with the 276 cam). Pretty much the same.
Well that didn't last long. I had problems with that short block and had to take it out of service (another story in itself).
Enter the new short block. With a better piston to deck relationship of .014" and my .026" gasket I had a quench of .040" (nice) and an SCR of 10.4:1 and a DCR of 8.4:1. My cranking pressures were 205 psi+. That proved problematic. I think I touched on the troubles I had with detonation and ignition timing. Ultimately I had the heads worked over to add a couple of cc's to the chambers and fattened up the head gasket. Now the DCR is 7.94:1. Cranking pressures about 185-190 psi.
From the simulated data, I've gained about 20 ft/lbs of torque at the same 4000 rpm. HP goes up accordingly. These heads have a lot more in them. If I were to do it over again, I'd keep the 10.4:1 SCR but just go bigger on the cam to keep the DCR streetable. This short has a forged crank and Elgin rods so the usuable RPM range has been extended. I could easily (and have) spin to 7000 rpm. No point with my little cam though. Maybe the next build when I'll give up my fuel economy for the sake of an 11 second time slip.

XR276HR Old Shortblock





274 Cam Old Shortblock




274 Cam New Shortblock High Compression




274 Can New Shortblock Low Compression

loopy

iTrader: (1)

Thanks. that makes interesting reading. Puts you solidly in the 400;s with, I assume, roughly the same economy figures?

skinny z

Based on my trap speed, ET and weight (12.6, 107.5 and 3650 respectively) it looks to be in the 400's, yes. Some calculators suggest 360 rwhp/430 chp. Encouraging but optimistic I'd think.
Steady state highway mpg are about 22 imperial. Not the best I've seen and they seem to have worsened slightly not from the heads and cam but from the (poorly chosen) switch from my 670 Holley Street Avenger to a 750 Barry Grant Speed Demon. I picked up the BG because it had been modfied for full air bleed adjustability (which was a tuning aid I was after) however the low speed drivability has withered somewhat. Depending on how this new racing season pans out in early testing, I may move to a 600 cfm carb. I've found a couple that offer the tunability I'm looking for in the smaller size. 600 cfm is enough for my application.

At any rate, I hope you can benefit from my experimentation. I've only offered advice based on my experiences. Both good and not so good.

loopy

iTrader: (1)

Keep it coming mate. I have learnt a lot from your experience. Your posts are comprehensive and easy to understand (for a newb like me)
I shudder to think what I would have ended up with if I followed the advice from the shop where I brought my engine!

loopy

iTrader: (1)

With regard to carbs, doesn't David vizard suggest a much larger carb for our engines?

Night rider327

iTrader: (13)

Not sure if you want vac or mech. sec but holley street HP line has a 650 cfm with adjustable air bleeds but it's mech. sec.. Also the classic HP line has a 600 cfm, adj. air bleeds, but again mech. sec.

natdowson

The snag is, the machining on the heads and block is too coarse to use shim gasket.
[Quote]




What a shame you don't live up closer to me mate cause I work in an engineering shop we recondition engines and remetal an remanufacture whitemetal bearings So we have all the gear to do that!

loopy

iTrader: (1)

[QUOTE=natdowson;5861902]The snag is, the machining on the heads and block is too coarse to use shim gasket.
lol story of my life Nat

skinny z

I've seen those but as you mention they're mechanical secondary and for my application, not what I'm after. That's not to say they wouldn't do the job and perform well at the dragstrip but a VS carb would provide every bit the same performance while at the same time, deliver better fuel economy.

Night rider327

iTrader: (13)

Yeah, Skinny I kinda figured you were after a vac sec. I agree with you fully, I only like the mech. sec carbs on more track use than street cars.

I have the holley 4150 HP 750 mech. sec on my camaro.. Great carb, love it on the track. Hate the fuel mileage, but this car is more track that street now.

skinny z

"Track car" being the operative phrase here.
The rule of thumb, (as I understand it) is that if power below peak torque is not of a concern as would be the case in a dedicated drag car with a high stall converter or a stick, then a mech carb is entirely suitable. There's no downside to using a vac carb in that case but it does add another element of tuning to the mix.
That said, I'm vac sec all the way. I spend a lot of my driving in and around the city. Having a converter that always has my rpm at 2000 or more doesn't help much but the vac carb acts like it's very small and with only the single accelerator pump to deal with, in the city mileage isn't entirely off the wall.

loopy

iTrader: (1)

Can anyone comfirm that this is the correct part number for the scat rods for an L31 block


3-ICR5700P


Theres also this one at summit http://www.summitracing.com/int/part...-size/5-7l-350


I assume they are the next up the chain so to speak


Cheers

skinny z

Looks like it.

loopy

iTrader: (1)

thanks,


so is it safe to say that the L31 blocks share the same crank, rod, pin sizes as the Gen1 SBC's?

skinny z

Also yes.

loopy

iTrader: (1)

Cool, thanks Kevin


I'm gonna order the Summit ones today

skinny z

L31's are Gen 1's.
Yes it is with the exception of the 2-piece vs 1-piece rear main seal cranks.
The older Gen 1 (predating 1968 or so) also had small journal cranks.

loopy

iTrader: (1)

Awesome, thanks.


I thought they were but preferred to have it confirmed by someone that actually knows what he is talking about rather than assuming I was correct.




My Camaro chewed up a fan belt last weekend on the way back from Nelson after visiting Simon (Z28NZ from this forum). I have no warning lights and didn't notice the temp gauge until I heard a faint whistle from the engine bay. Turns out it was the sound of the steam coming out of the radiator overflow bottle.


I was in the middle of no-where with no cellphone coverage.
Luckily for me a passer by noticed me waving my cellphone around try to find some coverage and stopped. He was on his way home from a holdiday and still had quite a ways to go but still came back to offer help.


He ran me to the nearest town to get a belt and then back to the same place a 2nd time due to the belt being in the wrong packaging.
He helped fit the belt(he is a mechanic) and got me going again.


Turns out he owns 2 third gens both T/A's. Quite surprising really as they are not that common over here.


Anyways, luckily after a couple of runs it seems I have had no problems due to the overheat and am counting my blessings both for that and the unexpected help.

skinny z

Car people can be like that sometimes.
Nice story.

skinny z

Came across this today.
https://www.thirdgen.org/forums/engi...-carb-hat.html

loopy

iTrader: (1)

Thanks Kevin, I really like the look of that. I have contacted him.

Just a quick question. I tried to get the VR head gaskets you suggested from Summit and they don't seem to have them.


Where do you buy yours?