Since I have been traveling extensively for work I have not had the opportunity to install the 406 that was completed more than 6 months ago. This engine is for my 1977 Vette with a th350 and a Gear Vendors unit.

I have now decided to make some changes to my current build. For some reason the picture does not display when I insert the link in the post. A picture of the current engine can be found at this link.

http://www.cardomain.com/member_page...225_1_full.jpg

Basically, I plan on changing the flat tappet cam to a hydraulic roller and the heads from reworked 3927186 LT1’s to AFR195 Eliminators. The proposed changes are noted in the build sheet .

I have a few questions:

What do you think of the proposed changes?

What would you do differently?

Is anyone interested in the new parts that will be removed? They have been installed in the assembled long block but it has never been fired. The parts are all brand new, except the heads which have been completely reworked. These parts would be perfect for someone who is rebuilding a stock L48. If there is interest from a Forum member let me know, otherwise they will be on ebay soon. Here is the list of parts I will be replacing.

3927186 heads
Lunati 60103 cam and lifters
One piece hardened stock length pushrods
Possibly the Performer AirGap manifold

Build Sheet

Block – Chevy 400 block - 509 casting, 2 bolt main, 2 freeze plugs. Most desirable of all the 400 blocks, thickest wall, strongest block available in stock form. Cleaned, hot tanked, magnafluxed, Bored .030 over (4.155), stock deck height (9.025), honed, cam bearings and freeze plugs installed, painted.

Rotating Assembly - 4.155 Bore, Wiseco PT020H3 Pro-Tru Forged Flat-Top Pistons Head Volume: -5.4cc, Scat 9000 internally balanced 3.75 stroke crankshaft part# 9-400-3750-6000, Scat Pro Comp 6" 4340 forged steel I Beam connecting rods. Part# 2ICR6000716, profiled with clearance for long stroke. Rated for 650+ HP, Plasma Moly Rings, Clevite “H” series Main & Rod bearings- rated for 650+ HP. Compression approximately 10.6 with these pistons and .051 gasket based on Wiseco calculator. Actual compression has not been measured. I would like to stay around 10.5

Intake manifold - Edelbrock 2601 Performer Air-Gap, Dual Plane, idle-5500 rpm, Aluminum, square / spread bore.
Carburetor – Original Qjet rebuilt by Lars Grimsrud - Teardown, hot tank, precision blueprint assembly, carb rebuild kit, custom setup per build sheet

Distributor – Original HEI rebuilt by Lars Grimsrud - Teardown, hot tank, precision assembly with KwikCurve kit, new vacuum advance control unit, hardened shims, custom calibrated springs and a custom advance stop bushing based on build sheet. Accel high performance coil, ignition control module, cap and rotor.

Cylinder Heads - 3927186, Camel Hump w/ accessory bolt holes; 2.02/1.60 valves; screw in studs, guide plates, 64cc combustion chambers, 170cc intake runner - Hot tanked, magnafluxed, bead blasted, pocket ported, 3 angle valve job, steam holes drilled, new retainers, locks, springs, bronze guides, positive seals, o rings
Camshaft - Lunati Voodoo 60103 Hydraulic Flat Tappet - High Performance street cam, likes 2400 RPM stall, 700 cfm carb, dual plane intake and headers. Operating Range - 1,800-6200 RPM, Duration at .050 - 227/233, Advertised Duration – 268/276 Valve Lift with 1.52 Rocker - 0.495./0.510, Lobe Separation – 110
Water Pump – Edelbrock Model 8812, High volume aluminum

Rockers – 1.52 roller tip
Pushrods - Hardened 1 piece, Sealed Power RP3212R Stock 7.794 length 5/16 dia.
Valve Covers – L82 corvette, aluminum

Timing Set – Procomp steel billet double roller w/ cam button part # 2201

Timing Cover – Procomp polished aluminum

Balancer – Professional Products 6 ¾” part # 8000

Oil Pump – Melling select 10% over stock volume part # 10522

Oil Pan / Gasket – Milodon 5 qt stock replacement part # 30700, Felpro 1 piece rubber/steel core, Thick seal part # 1880

Fuel Pump – AC Delco part # 41240, provides proper location and fittings for OEM fuel lines and Qjet
Transmission – TH350 w/ Gear Vendors over/under drive, 6 speed manual/auto w .87 overdrive
Rear Gear – 3.73

Torque Converter – Fuddle Pro series 2800 stall speed 1.9 STR

Shift Kit - Transgo

Headers - McJack's Headers, Custom "shorty" Ram Horn replacement – 1.75” tubing 2.5” collector, header outlet is at stock location for 2.5" ram horn

Exhaust pipe and mufflers – Allen Corvette Exhaust, Custom true dual 2.5" exhaust with Magnaflow mufflers. Includes X pipe with removable flanges.

 

quite a few members at nastyZ28 have built very powerful-yet streetable 400/406 motors, and you might find some answers at that site

http://www.nastyz28.com/forum/forumdisplay.php?f=5

Engine, High Performance Modifications, and Competition would be my guess.

 

Similar engine to the one I'm building for my '81. I'm going for lower compression with iron heads. I got a smokin' deal on the newly redesigned Bowtie Vortec heads with 225cc runners, so that's what I'm going with. I have SRP reverse dome pistons that will give me 9.7:1. It looks like I'm going to use the Lunati VooDoo 60122 hydraulic roller cam (231/239, .535/.550). I have the exact same block, mine was pulled from a low mileage running car and torque plate honed to a perfect .020. I had mine zero decked on a CNC machine since the decks were all over the place. I have the same crank but decided to go with a set of new cheaper Scat capscrew rods that I already have.
I think the Vic Jr would give you a bit back on the top end while softening it up a tad on the bottom, which might help with traction. I think this combo is right at the break-even point between a single and dual plane intake.
You may have a problem with vacuum, I'm sure others will chime in and address that issue. I understand the one I picked is about as rough as I can get while maintaining some street manners and ample vacuum.
Mine goes in front of a 4-speed and I'm replacing the aluminum differential with a solid rebuilt iron one, I plan to drive it hard.
Everything I've researched on this says I should be in the 450 - 475hp range with 500+tq. What are you figuring???

 

bump

 

Unless you change your intake manifold, dont bother with the other changes. It will be too much of a restriction.
Since you want to keep the Q-jet, I would recomend the Performer RPM # 7104 intake.
If you go with the Vic Jr, then its time to switch to a Holley carb.

The cam info that you have is a little messed up. The actual operating range of that cam is 2800 - 6400. Summit has it listed wrong.
That is a pretty big cam. Im not saying not to run it, but its going to idle pretty nasty, and you would probably want a looser torque converter with it.
Obviously the 5 speed would take care of that.

I also think that the shorty headers will be a restriction at that power level, but doubt that you are inclined to change them since you already have them.

 

I ran a flat tappet hydraulic (Comp XE-284) for a few years in my 406, and thought it was a fairly strong combo. Idle was 650 in gear with a 2000 rpm stall. The cam specs were 240/246 @ .050 and with 1.60 rockers lifted around .550 if I remember right. Overall power was good to 6000 or so, and would turn 6500 fairly easy. This was running the RPM Q-Jet manifold, and 3310 Holley.

The point is on paper it was too big for the street, ........but who's street? I'm not sure I'd waste the money on a little roller cam like the one you're looking at though. I went the cheap skate route and stayed with a flat tappet solid. Turns 7000 rpms, even with the RPM intake. The down side is the nasty idle,.....which I happen to love.

 

If you can get the scratch for a HR and AFRs, go for it, your power increase will be worth it!
The 406 will tame a 240ish cam, and the HR will have a little better manners also. Stil will be lumpy though if you dont mind.

 

Don't forget that most hydraulic rollers will float the valves at 6000 rpm, so either run a cam with an appropriate power band, or build a valvetrain that will prevent float above 6K.

 

I went with a big inch small block as a "temporary" motor for my Frankenvette, instead of taking a shot at the 13L monster mill that started the project (and even the selection of a C3 as the platform) 7 odd years ago....

...$140,000 ago...

...350,000+ miles ago....

...3 400 SBC rebuilds ago....

(Yeah, life is a set of linear equations to be solved, not a mystery to lived, but the path takes you where it takes you and you get to suggest the course occasionally...) I wish I had started with a Viper, but not by much. When I started this exercise in wretched excess, I was under 40 years old and over 400 pounds...now, because of pursuing and elusive goal of a McClaren killer for under .2M and later encountering a driven little business chick for 6 weeks on an SMG chat line, I am less in debt, twice the income and 185 pounds.

My silly mutant vette was the beginning of my own personal Renaissance and I'm content with what I've done to/with her since.

So...and yes, go with the GV as I have, but I would switch to a T400 - unless you like changing clutches. Even the best manuals with the best clutches simply don't handle much over 400hp for many tens of thousands of miles w/o frequently changing the damned clutches - auto is the way to go for long term durability (assuming you actually use the high end of your combo for 10+% duty cycle.)

1)The last rebuild switched from the hydraulic roller to the solid roller. GO SOLID ROLLER!!! Cut that stupid excess upper end oiling with the restrictors and go solid roller. I check the lash every few months (room temp and 0.010" at TDC) and rarely have seen anything more than a 0.002" variation from ideal. Take the 3-5% increase in peak power and 10-20% increase in summation power - and ESPECIALLY the 800-1,200 increase in redline - AND the 30% higher oil pressure from being able to reduce the upper oiling.

2)You need bigger heads with a high end 400+ SBC, no matter what cam you use. More *way, Way, WAY* past 195 or 210cc intake effective. If you're considering new heads, as I was steered to the during the last rebuild, consider only the best CNC offerings from Dart/Brodix/etc. with what, 220+ intake runners.

After the forged Eagle crank broke in half at a fault line which mandated this rebuild, I switched to the solid roller and wanted more power than the projected power from Crane's simulations with any cam possible. My old build was something like 284/302 duration (please understand this is all from distant, fatter memory) with .530 to .550 lift range. Now it's about 292 even with with like .560 lift. It idles at 450 with 21+ in vacuum at 1000+ and it's super responsive with the Holley 750 at all ranges. ....fine for the pathetic power brakes. I wanted more power, but all of Crane's simulations showed little increase in power for even over 0.600" cams with 300+ avg. duration, only less driveability.

Again, solid roller with great roller rockers and CNC heads from the big guys - BIG heads. Incidentally, the Holley produced no more peak power than the Edelbrock, but was enormously more responsive - and there's no way to determine cornering performance on a dyno.

Best "just home from work after 12 hour OT shift and getting drunk" response....

I wish I had signature enabled, but my particular car may be in my personal description. There are a lot of similarities.

 

I have been on this forum for many years. I have never figured out why it is such a difficult concept for 95% of the people on here to not be able to think about matching sizes.

You don't put a tiny port intake manifold on big port heads. Right in the product description it tells you recommended gasket and port dimensions.

You don't put little pipe headers on big exhaust ports to gain TQ.

A cam description for a base line 350 CI is very tamed down with additional ci.

Another fact is 95% of "TECH" guys for any company are numb nut bums that might have finished high school. They have never used the products they tell you about from a canned list of required reading and answers.

I worked at Summit Racing Distribution center. Go look in the employee parking lot. Your F..ing tech guys that make $14 per hour drive junky *** rice cars and beater mini pickups. They Might have seen a big block V-8 and are encouraged to read all the car rag magazines in the break room to gain some Knowledge. Summit racing has been the highest paying job in their life

I would impart some more wisdom, but I have to gather up my fire suit and helmet for a track test and tune day. I've never driven a turbo Porsche before!

 

Those heads flow about the same as the Vic Jrs. on my old 406ci. THose are the only small runner heads that would work on a 406ci, I have seen and believe the flow numbers, after flowing my 227's and they should work on a 406ci. Any other head and you want 210cc or more. If you ain't skeered of solid roller cams I would recommend the XR280R, nice cam and you would get about the same HP/TQ as below

 

ttt

 

Will a Vic Jr fit under a 1977 hood? The current Performer AirGap will fit with a drop base.

If I use the Vic Jr I will then have to forget about using the Qjet that Lars rebuilt for me?

What carb would you recommend for this 406?

 

Vic Jr fits under my '80 hood, Holley 750 DP 4779 will work fine on a mild 406ci, if you want to go with a solid roller and make a little more HP then look at the Holley HP carbs. If you like Demon then a 750 Mighty Demon will be plenty, actually that is the carb I would put on

 

Thanks for the suggestions. I am having a hard time letting go of my Lars Qjet but it becomes a problem if I go with a Vic Jr. What fuel line and linkage changes will be required if I go with the 750 Mighty Demon.

This will be a street driven car so I am starting to get worried that I am beginning to build something that will not be streetable. If I am not taking this to the track am I starting to go to far?

 

No

Here's the linkage, it is stock.


Here's the fuel line, you will need to fab that up


I haven't put mine on the dyno yet but I will, I am usually pretty close when it comes to estimating the HP as I pick all the parts and build the motors myself. Mine is easy to drive on the street and it will come in at around 650HP, I will find out over the winter when I pull it and put it on an engine dyno

For you, it all depends on what you want, but a 500HP 406ci can be nice a streetable combination if you do it right.

The thing is once you get into the power of a 406ci you will want more and more so get the AFR heads and Demon carb and you won't have to upgrade for a while

 

I went a much cheaper and milder route but I do expect about 400tq. I used the summit rebuild kit w/ 9.64 comp and dart heads

 

Nice detailed post...

Based on my own success with a similar build, I'd recommend the Edelbrock 7104 Performer RPM Q-Jet manifold. My '78 (not lightened) has a 800 cfm QJet and has done a best of 11.96 on MT Street ETs, however, with my best Holley 800 HP (and 3 different jettings), I have only seen 12.001 (in slightly better air).

I've thought about putting on a Vic Jr, but I need the torque for launches since I have a 3.08 rear end (1.79 - 60 ft). Cam is a Crower solid roller-234/244/112 lsa used with AFR 210 heads (9.5 CR), which is very streetable and has decent vacuum (16.5 inches at idle; 11.5 inches in gear).

Winter time project will be to add about 10 deg duration and run 3.70 or 4.11 gears with my TH-350 which has a tight 10 inch Continental converter (2800 stall with the 406).

Good luck with your mods!

 

You might wanna post your thoughts in this thread

http://forums.corvetteforum.com/c3-t...post1567826659

Congrats on such quick times from a streetable C3

 

Sounds like you are making some great choices on the build. It is frustrating to see guys who build plan one part at a time but never look at the car as a whole. Taking a systemic approach means that you have a much better chance of getting parts that perform well together and last a long time. I can't tell you how many guys call me and say "I built this honkin' engine, now my transmission is broken. I would like to see more complete plans like this before guys start laying out their cash.

When you are ready for the TKO let me know. We have a nice system with an industry leading warranty, 24-hour tech support and every part you need right down to the pedal pads. And by the way, 3.73 gears and the TKO600 get along quite nicely!