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496 Stroker with 871 Blower - Basics?

36K views 82 replies 16 participants last post by  Byronski 
#1 ·
I just recently picked up a 72 Camaro that has a fresh 496 in it. It also has an 871 blower. It is setup for prostreet as intention. I am not entirely new to BBC but it's been a while and I have never ran a blower. I've been in a different area (high HP turbo 6's) and am coming back to the good ole' BBC.

I am wanting to start from scratch on some basics and not just go off of the sellers "memory" or info he might have gotten from who knows where. Too much money to not cover the simplest basics first. After this then it is checking all other safety systems, wiring systems, and break in the motor.

The previous owner was running street gas and 20-50 engine oil. I usually use race gas (various VP fuels) in my other drag project(s) and feel the same on this but haven't deciding on which selections to narrow down as of yet. I also usually use a Redline Race Oil and had consider a 40wt race oil for in this engine. But am not sure and wanted to hear what others with similar engines/setups use.

Seller said he was told by where he got the car (see , we are getting into 3rd hand info now), to run 10 deg at idle then 28 at 2500. It has probillet MSD Dist in it but I am not sure what weights are installed.

Plugs in it are Autolight 65. I use NGK in all my other drag cars and have a deal for getting them but IIRC BBC can be finicky and not like NGK.

I am looking for the basics from other owners with similar setup and experience in a blown 496.

Like:
-preferred engine oil weight (not brand, just weight)
-fuel preferences
-spark plug preferences
-timing ranges

OK, below are the more detail specs. hope to hear from other 496/8-71 folks! Thanks in advance for any good tips or advice.

Cj


Engine details:

Mark IV 4 bolt main, 454 bored .060” over making a 496 stroker casting
Custom "one-off" oval port intake manifold also ported to match the heads.
Weiand 8-71 Polished Blower, and two Holley 750 double pumpers.
B-H-J 15900 Harmonic balancer (external balance) (Neutral)
Crankshaft SCA-445420 454 forged 4340 2-PC Rear seal External balance 4.25 stroke (Neutral)
Callies 4340 forged H-beam rods (Compstar)
SRP forged blower pistons
Total Seal rings
ACL "Race Series" bearings
JE Pistons (brand) Wrist Pins & Spiro Lock Retainers
Howards solid roller cam (.702 Lift, 308/314 Duration)
Howards solid roller lifters
Howards double valve springs.
Large GM oval port heads (3964290) ported & polished. The exhaust ports were also D-shaped for maximum flow.
Manley stainless steel valves, bronze valve guides.
Crane Gold 1.7 aluminum roller rockers and Manley guide plates.
Cloyes double roller timing chain
7qt oil pan, windage tray and crank scraper with 4.25 stroker clearance
high volume oil pump & pickup.
MSD Pro-billet distributor (not sure which weights/springs are in it right now)
MSD 7-AL box with a Stage-2 module (Rev-limiter).
Moroso high volume water pump
Dynomax headers 1-7/8" leading to 3" exhaust with 40 series Flowmasters. A.R.P bolts all around including main studs
Other:
Built 2sp Powerglide with a shift kit and a 3000 stall converter w/anti-balooning plates.
Hurst quarter stick shifter with a pistol grip handle
The rearend is a narrowed Ford 9" (with a back brace)
35 spline Strange axles, and 4.88 gears inside a locker center section.
Art Morrison ladder bars with a diagonal link
 
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#2 ·
Any more information, piston dish volume in cc's, head combustion chamber volume, etc.? Exhaust ports D shaped for maximum flow???:confused:

Did the previous owner have a build sheet with clearances and specs? Do you know which pulleys you have, are the carbs boost referenced, any idea what the static c.r. is?

Can you explain what a "one off" custom blower intake is all about? What's custom about it?
 
#3 ·
Who built the engine? Find out and talk to them. get it running and IT will tell you what it wants as far as fuel, plugs and timing is concerned. Every build id different and no one here can tell you want the engine will need
 
#8 ·
The problem is that the seller was, how to say, less than honest. He professed to have the build info and promised to send when he found it. Now the supposed "machine shop" has a phone number that will not answer or disconnected. He also failed to "find" this build paperwork. So yeah, people lie. But there is karma :)

The engine is running but before I run again I have to fix some serious issues like fuel lines against power cable, melted starter cable, leaks, and so forth. Things like running a FP gauge of 0-100, alternator wire of 14 gauge back to the trunk, + cable from trunk rubbing against SS braided fuel line (no kidding), fuel pump above sump, and so on. Goofy crap like that.

So this is why I wanted to get a starting off point. At least in the ballpark for the BBC/871. While exacting will come later I have discovered the previous owner was basically an idiot and there is a chance something like the spark plugs are totally wrong for the application.

Just wanted to know what others with similar setup were using. Maybe not exact but as explained it would be better than way off like I have been running into while putting the car right.
 
#4 ·
The info posted is all I have at the moment and as supplied from the seller. I expect to obtain the build sheet next week along with other paperwork being assembled. Sorry I don't have that specific info right now though.

I know that along the way I will find the plug range and all but as mentioned I wanted to know that I was starting at a reasonable reference point on these basics. Or to make sure what to stay away from.

I figured it would be a good place to start to see what some similar setups were running.

Like fuel - lots of choices even from just VP. I use Q16 on one of my other turbo high HP cars but have considered C12 or C16 for this one. I'd thought maybe there was a fuel that some might have settled on for x,y,z reasons of BBC/Blower likes more than another. Or also useful, any fuels to stay away from.

I can come back with specs when I get them.
 
#5 ·
That's just it. Not knowing the compression ratio or the amount of boost is what will pop the cherry here. You need to know all of that info before you start asking "what do you use"... Nothing we say will be anything more then a guess on our part.
You may want to look into a bit bigger head pipe for the headers also. 1 7/8ths diameter may be a bit restrictive once you get it up and running...
Mark
 
#6 ·
Hopefully will have all that soon. I figured I'd ask now anyway since I am shaking it all out and running over it all in the shop.

I can look at the headers issue easy enough. Stans headers is only 30 minutes away. But that's still a ways down the list to get things sorted out on changes and fixes on the car.

I still have to change things like the exhaust (straight back pointed at and blowing right at the axle), some fuel line reroutes, and electronic changes and additions.

I do know it has very thick intake gaskets to lower AR (again, 2nd hand info from the seller, but you can see them). What the exact CR is I am waiting to confirm.

Thx
 
#7 ·
OK, so here is what I have,

CR is 8.15:1

Piston dome effective volume -3 cc's
Head combustion chamber volume 101 cc's
Deck Clearance .022
Pulleys: believe it is currently at -2.8% under driven with 35 teeth on the top pulley.
The carbs were rated for the blower

Other:

Bore: 4.310 Flat Top
Stroke: 4.250 Top Ring 1/16
Rod length 6.385 2nd Ring 1/16
Comp Height 1.270 Oil Ring 3/16 plus spacer
Piston Weight 538
 
#9 · (Edited)
20W 50 is what all the old school BBC guys used for high performance and I agree with the 20w 50 because this car isn't going to be driven in the winter and it will offer good protection on engine components.

the information sounds correct to be honest with you. they don't use a lot of advance in boosted applications to reduce the chance of detonation.

either way if you throw more timing at it be sure to use a higher octane fuel.

It sounds like your doing your homework and if you keep at it you will be just fine. who is the machine shop/builder??
 
#10 ·
your total timing looks about right, your initial looks pretty low, 20 or so initial with 34 or so total, but take off a degree of total for every 1-2 psi of boost, and if you can run a vacuum advance. (this is where electronic timing control makes this a lot easier).
 
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#11 ·
The timing curve is very safe for pump gas at 25DEG MAX under boost on pump gas.

But the distributor curve set up is way off for this motor to run best.
Start by getting a Boost tming master box. or same so you can set up a blower motor friendly complete timing curve.

Blower motors with huge cams need more than 10deg initial base timing. More like 38deg base initial.
Then when uder boost you need to reduce the timing under boost,,, a bit , even, on race gas.

A LOT when on PUMP gas. You can see the curve is actually backwards, from the engines needs... The distibutor is not set up for this blower motor at all.

8:1cr 8-10 PSI +/- blower boost on pump gas. More.... with high octane gas.

If you want to lean on it hard (boost), high octane race gas or methanol is your friend.

You can make a ton of street power with 7-8 psi boost on good street pump gas.
But not with that distributor set up.

But I don;t see 8:1cr with 496 cubes, flat top pistons and 101cc heads on it.

That don't add up.

That is 9.5:1cr area. OK on race gas. Not OK on PUMP GAS.
Great for Methanol.

This is a high compression ratio stricktly Methanol or 110++ octane RACE GAS gas blower motor.

Street pump gas will only allow very modest blower boost combined with a good dose of boost spark retard.
OK for cruising around, just know the difference.
Find a shop that can Engine dyno tune this motor for you.
I have a good shop all lined up once I get things squared away and the right components installed. All I have is the word of the seller on the timing being 10 at base and up to 28. I have not ran the engine yet to verify anything because of finding a lot other wrong to fix before starting up again. I've no idea what the distributor curve is. Just that it is MSD pro billet.

I definitely plan on running race gas and not pump. C12, C16, or maybe Q16 (which I already use and order in qty on a V6 turbo car).

I have looked at the MSD PowerGrid. Maybe that will do the same as Boost timing master box. Haven't checked but it seems to be able to control those aspects.

I am a bit confused when you talk about the curve. I don't have any idea what the curve is, only what I was verbally told on base and at 2500. Do you mean that I should have the higher advance at idle (ie - 28) and less at boost? Or rpm?

You've given me a lot of info. Appreciate it. As for the CR, yeah, I've no idea at this point what's what on that.
 
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#12 ·
Get and install the starter motor brace bracket and get and install a ignition power interupt switch
so you can start your BBC blower motor easily, with 38deg intial base timing, instead of 10deg base inital , which is not near enough for this motor.

This motor should run real good when properly dialed in on race gas.

3964290 cylinder head. This is a odd ball 1970 head that came with both old style and new style (peanut plug) spark plugs
Verify which you got. They are not the same. The plug heat range will depend on how you will be using it at the time.
Look at BOTH HEADS.

race tune up..for racing it .... light duty street tune up lots of idling, not much WOT under boost and tame boost and timing...They are not the same.
Starter brace has been ordered. By ignition interrupt you mean crank and then kick in ignition power? I can manually do that now as it has separate switches for starter and ignition. I did a search to better understand the benefit. Just faster start and less strain on starter this method?

Thanks for info!! Any and all tips like this are much appreciated for sure :)
 
#13 ·
OK, so it seems that the previous owner was not only a bonehead but also quite dishonest about many things. So each week it seems I go backwards further to get this engine and car in order. The builder he supposedly used is no where to be found (non existent) and there are many things not adding up.

So starting with the rockers. They are all misadjusted (and he ran them that way) but they have all different adjusting nuts on them. Seriously. See pics below.

Can anyone think of any possible reason why the heck any normal or sane person would use all different adjusting nuts like this?





So besides having to get the mismatched cam outah there it seems the entire valvetrain is questionable. With the different date rockers and two oddball blue ones.

Plus the rockers themselves are a bit beat up underneath too. No visible reason for that either. Not on any of the business end of things, that looks okay (so far) but the bodies are not in greatest shape.

Sigh. If only I had an idea WHY someone would possibly do something like this. I didn't want to tear it all off and scrap it but trying to figure it out is getting to be worse as I keep digging.

Why do people do this sort of thing? (yes, I know, lots of tongue in cheek answers to this one!!)
 
#14 · (Edited)
Just a wild theory...

That short poly-lock might be right under the oil filler cap / baffle?

The rest of them are super long ... would that be for use with a stud girdle or something?

In any case ... yeah, I'd be tossing the whole mess into the garbage can and starting over with a good set of roller rockers. I'm looking at a set of low-profile Comp ARC Gold #19021-16 myself ... which they say will fit under a stock-height valve-cover.


Regarding Spark Plugs ... yeah, you need to be careful there.
5/8" or 13/16" hex size, gasketed or tapered, 1/2" or 3/4" reach are all options in that 1969 - 70 396 / 402 CID cylinder head.

The heads that I just picked up are 3931063 (1968/69 396) and used the

NGK #2851 (GR5) with the 13/16 and 3/4" reach
 
#15 ·
Yeah, was going to compression test before taking much further apart. At this point it is worse not knowing what specs to trust or not. He provided receipts and photos of the bottom end but who knows at this point. This is worse than starting with nothing on the top.

I had planned on replacing the cam for sure. And perhaps the only way to know whats-what is to replace it all. A very unplanned for added expense.

What I am in the process of trying to do now is know or verify what I see is totally whack and possible solutions other than just pull and replace. It becomes a slippery slope (as we all know) at replace this, then might as well do that too, and while we are at it, get these new,,,,and so on. LOL.

I have to pull the intake anyway too. It has so many coolant leaks it is not funny. At least 3 places on the outside and one on the inside. It truly was assembled by a person that hadn't a clue.
 
#16 ·
Just an update and twist to the story. Besides being a bonehead that had no business working on any engine it turns out the previous owner was not just a liar but a very devious one to boot. I caught that the 'receipts' he provided with the car were forged, fake, totally made up. He even had an actual car repair shop allow him to use their letterhead and make up all the performance parts purchases. No kidding!

I mean for crying out loud, there is fudging a bit and talking sh~t when selling a car but this is a whole new level IMO. To actually go through that much trouble/bother to cheat someone and a real business risking their name too. THE THINGS SOME PEOPLE DO! Sad and pathetic.

So at this point there is nothing at all I trust or believe without laying my eyes on myself. So the plan is to pull the entire engine out, send the shortblock to my machinist to get all tolerances and specs verified as well as the balance and replace all the bearings. If it is within tolerances and nice and new inside as it is supposed to then great. If not then I will just replace the entire shortblock with a nice dart block or something like that.

After that the plan is:

1. Dump these heads. Replace with all new performance heads as well as valvetrain. Leaning towards aluminum and either Edelbrock or AFR. Also replace ARP studs too. I haven't settled on any specific head yet but am trying to match up the heads with the valve train that I want.

2. Replace the whole valvetrain (solid roller) - which would work with the head purchase. Strict attention to the springs and already proven combo (I have no need to experiment or reinvent the wheel). To a degree that is. Some spec/combination and then await a couple builders A-OK on the plan. Camshaft spec all part of it as well. Leaning towards a COMP or ISKY setup but not solid numbers on that as of yet.

3. Ignition - the 6AL and MSD billet dist in there now I am going to toss. I may reuse the billet dist if it comes into spec but the trade off of time vs money is in play. I plan on either a MSD 7AL setup and/or the new PwerGrid system by MSD which also has a nice two stage mod that I like. Def will setup for retard under boost (which it hasn't got now)

4. Fuel system - this needs several basic fixes like the pump below the sump (seriously), and sump also turned to the back (no kidding, it is sideways right now). The two 750's I have check if they are even referenced for the blower. I may just pull off and replace with some new 950's that are the holley HP supercharge ones. Again, may be easier timewise in the long run to just pull them out. Will also need to closely inspect the blower that it is all in spec.

Other misc things too of course and to apply things on the shelf (like a nice new meziere hp water pump, preoiler, better cooling layout, etc.

The car itself will also be getting an entire new dash and electronics package (standalone cluster probably, I like the new LCD Autometer pack that was just released for nascar, very nice) and fixing some other things like window alignment/scratches, battery shutoff wiring (all F'd up), and so forth. N2O is possibility but only because of getting a sponsor 'deal'.

And then of course a complete new custom paint job to top it off. Just have to decide on color system and what, if any, airbrushing to incorporate.

So I knew it was a project and that was the desire at the time. I just did not realize that the project would require THIS much re-working to include the entire engine almost. Right now it is looking like about an extra $15K than first prep'd for budget-wise and then another 5-10 for paint.

The biggest issue right now is the combo selection on cam/valvetrain/heads. I will be sitting down with a couple experienced engine builders and then will combine my wants/needs with their advice as well as any from the forums that come from experienced folks there too. IOW - I do value input from the experienced people here and consider the forum a valuable asset for sure.

One main goal is to limit those parts on the shelf or floor that were a bad decision or had to be replaced 6 months later. I'm sure many know what I mean there, lol. So far in the last years and performance builds good planning early on saved a lot of that.

Whew, sorry for the long post. If it gets read (I know I don't like long posts either). Any input at all on heads/cam/valvetrain that are personal favorites are much appreciated and help in the decision process.
 
#19 ·
What are your goals performance wise? Is this supposed to break 1,000hp, or is it all just for show, or something else?

Since you used to do high hp turbo inline 6's I'm presuming this is more for show than speed?
Well no, I wouldn't put this amount nor those performance goals in for just "show". I build to be able to sustain real WOT and not just sitting. I still do V6 turbo applications too. Not sure why you presume that V6 turbocharged applications are somehow not speed or show only. There are many turbo V6 applications that are quite fast IMO (7's and 8's to me is pretty fast).
Anyway, getting off topic. I prefer to do both, show AND go on any build. Speed and performance is the actual goal but it is nice to do it with good looks and top quality (and able to meet all NHRA reg's also, hence the lean towards strip only builds).

I don't believe it is all about HP. There are lots of other parameters and things to measure success with. Times being one major one. Anyway, pretty basic stuff really. It is more the journey that I enjoy than the destination. LOL

Curious if you confronted the seller or the shop involved and what they had to say for themselves.

You called it right...pathetic!:(
I confronted yes. They both (the shop owner as well as seller) backpeddled and just lied some more. Their main defense was to refuse to answer. I have some other options that are still being considered :)
People that do this sort of crap usually always get their due.
 
#21 ·
Gets worse. Tranny was said to be "built" with hardened shaft, billet pump, antiballoon plates on converter, etc. Turns out bone stock smallest powerglide and stock Chrysler converter. So $3000 has everything back in order for the transmission by a great race tranny shop (1600hp input shaft, billetpump, 7 clutchpack, 1.80 straight gears, transbrake and then converter properly setup and set at 4200 stall).

Shortblock at machine shop. SFi flex plate and balancer junk now too since prev owner welded on them (eliminating the SFi rating) to balance instead of the crank. So getting all that taken care of.

Went with aeromotive fuel cell with A1000 in tank pump and going to put in hardline and also return line system.

Leaning towards AFR heads, perhaps their 345 aluminum ones. Lunati cam setup but not decided on specs yet. Then whatever matches up the AFRs best for rockers and pushrods.

Anyway, that's the scoop now. Only other thing to add to list is change out the 4.88 rear end since that won't serve my needs (1/4). Not sure which to go with on rear end. Any suggestions on a 871 blower on 496 with 32" rear tires? 1/4mi mostly but some street (on random occasions).
 
#23 ·
After reading this all I can say is Wow the guy you bought that from sounds like a real sob :mad:

I've been very lucky through the years buying high quality builds from others, it's always a gamble but when you get it right you can save an easy 50-75K. My #1 rule is I only move forward after I'm 100% comfortable with the previous owner (and the documentation he can provide), and I have walked away from many amazing vehicles when I wasn't comfortable.

In your case I would say there was obvious valve train trouble after that motor was built and they did what they had to do to make it run again. There appears to be 3 different rockers used on that one side. The middle two Rockers are a different color gold compared to the other 4 gold rockers, and then there are the 2 blue ones. Also there are marks and scratches on some of the Rockers, (the other side all appear to be the same)

You obviously know what your doing so all I can add is I have a Solid Roller 502 Gen VI with a 871 Dual Quad set up and I run 20w50 and although the previous owner ran it on 93 I only run it on C12. Also I would obviously run a girdle set up if your sticking with a Solid Roller & 871
 

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#24 ·
Thanks Rob.
Yes I agree but one doesn't expect the level of deceit to jin up fake receipts on internals. At least I didn't. He is indeed a real lowlife. Being an complete moron on engine building is not a sufficient excuse. The deceit was planned and purposeful. I have placed a viking curse on him. :evil:

Vinne, I don't place a lot of faith in the math calc for how fast a car is in the 1/4 based on just gearing and rpm. I have a V6 turbo vehicle that has 1000 to the wheels and needs to break over 150 to get into the 9s and is built to exceed 170. Of course much is the driver too. I don't profess to be very good compared to some others. But I've seen a lot of different time ranges with similar setups so there are just too many other factors to place a lot of faith in just calculating.

I had not planned on going that high rpm on a stroked motor. In the past going higher has handed me a spun rod bearing at the least. I think with the combination of the stroker with the blower a lower redline is indicated. Just my initial plan for now. So the 4.88 rear seemed to maybe not be the best choice was my thinking (I could be wrong).
 
#25 ·
I'm a switch hitter and also have a Pro Street Ranger I use for fun on the Street & Strip. I run a 4.88 gear with a 28x11.5 Slick and finish the run at over 8,000 RPM with a 10.61 ET @ 126 MPH
It's a 418 cu in 351W and also a Solid Roller & Girdle Set Up. The high RPM's have me a little concerned for longevity of the motor and I'm convinced it's slowing me down a bit. I'm going to try a 29 or 30" slick soon and hope to run 10.3's
 
#26 ·
""I don't place a lot of faith in the math calc for how fast a car is in the 1/4 based on just gearing and rpm. I have a V6 turbo vehicle that has 1000 to the wheels and needs to break over 150 to get into the 9s ""

what are your 60' times with this car?
MPH is an indication of horse power.
your car is either spinning the tires a lot,or the turbo takes a long time to spool up?
 
#27 ·
It is awd on 4 wrinklewall slicks. Not spinning. Haven't launched it over 6 psi (full out is 35PSI on a GTX42 turbo on Q16) as of yet. I also don't have time to go to the track every weekend. So, slow to dial it in. Anyway, I feel we are getting off topic. That's a totally different car.

I don't think one can always match HP to MPH. If you take two cars with exactly the same HP but other differences and drivers there can be a huge difference. So many factors as we all know at the track right? Heck I've done a 10.9 with trap speed of 140 before trying to dial things in.

Using the math to dial in a range or to help guide I am all for but it isn't exact. For me 4.88 takes me into too high of RPM versus the top MPH. Perhaps I am used to the other car at a much higher top speed (186MPH @ 7000RPM) but it is also is a 6 speed manual.

I just initially figured that with this blown 496 and stripped down Camaro that a rear ratio goal should be one that takes me a lot higher than 140ishMPH at over 7000rpm. So I am considering changing that out to something else. Was just wondering what others were using and how they liked their choice/setups. Same with similar camming setups and what people here like/dislike.
 
#28 ·
Quarter mile speed to HP calculators are only accurate if the MPH is truly representative of what the vehicle will run in the quarter mile, WOT, w/an optimized setup. If there are severe traction problems, the engine is over or under revved, shift points wrong, isn't run at WOT, or if any number of other things are either done wrong or are not correct, the calculator cannot give a decent estimate. But when used the way they were designed to be used, they're as accurate as you're going to get short of a dynamometer.
 
#29 ·
""Mild is boring. No fun staying mild right? Which is why the blower w/n2o on top of the stroker.""
"Using the math to dial in a range or to help guide I am all for but it isn't exact. For me 4.88 takes me into too high of RPM"

sorry,I'm getting confused,lol.
7200 RPM is not that high,,,,

just trying to help,but,,,I'm having a little trouble following you.
you said mild is boring,I think an 850 horse power 500 inch rat that revs to 6500 rpm as mild.
If you make over 1,000 to the wheels(2 horse power per cubic inch)
the engine will likely rev past 7,000
If you use a power glide transmission,you will likely have a stall speed around 5k
with a 5k race converter capable of working with a 1200 hp rat in front of it,you will likely run the traps around 7200 rpm.

If you build a "race" engine,you will likely rev 7500
please help me to understand?
 
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