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eliminate VVT on 4200 Atlas I6
#1353728 Mon Apr 06 2020 04:37 PM
Joined: Apr 2005
Posts: 2,498
C
Shop Shark
Need to do some brain picking on locking the exhaust cam in place on the Atlas I6 engine. Would one lock it in the advanced, retarded, or some point in between. The 4.2 Jaguar has nearly an identical bore and stroke so thought about mapping a profile of it's exhaust cam and getting the split overlap reading. Then ?? could the Atlas cam be positioned the same? A possible fly in the ointment is the Jag is a 2 valve head and the Atlas a 4 valve so flow rates may be so different cam comparison is useless. Jump on board with any and all thoughts along this line. They are now offering a VVT eliminator kit for the LS3 V8 (not legal for highway use) so it must work but have no power output comparison between stock and modified. Don't want to knock a 25mpg ride down to a 12mpg one but would like to make something that doesn't scare an old pliers and screwdriver Stovebolt guy from opening the hood and getting dirty.


Evan
Re: eliminate VVT on 4200 Atlas I6
coilover #1353736 Mon Apr 06 2020 05:14 PM
Joined: Jul 2019
Posts: 243
B
Shop Shark
I would think you would find straight up zero and lock it there? Is it actuated from the cam gear hydraulically? If so it may need to be either welded in place or make a insert blocker to lock up the movement.

Re: eliminate VVT on 4200 Atlas I6
coilover #1353780 Mon Apr 06 2020 09:54 PM
Joined: Nov 2004
Posts: 1,701
J
Shop Shark
I like the idea of incorporating the Atlas in more of our bolts. Have you inquired with anyone from Inliners? At one time one of their members were toying with the 4200's.

Come to think of it, wasn't Jerry tearing into one awhile back?

John

Last edited by J Lucas; Mon Apr 06 2020 09:55 PM.

J Lucas





1941 Chevy 1/2-Ton
1942 Chevy 1.5-Ton SWB
1959 Chevy Apache 31 Fleetside
1959 Chevy Apache 32 Fleetside
1959 Chevy Viking 40

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Re: eliminate VVT on 4200 Atlas I6
coilover #1353830 Tue Apr 07 2020 03:08 AM
Joined: Mar 2008
Posts: 1,978
W
Shop Shark
The VVT actually is at full advance at idle, no valve overlap. At around 1500 RPM it goes to around 12 degrees, which is normal run mode. At 3000-3500 RPM the VVT goes into full retard, which is around 25 degrees. When driving a Trailblazer/Envoy you can definitely feel the difference when it goes into full retard. It's almost like the secondaries on a 4 barrel opening up.

As far as locking the phasers out, somewhere in the middle would be my best guess. On the other hand, why would you want to? I've never heard of any 4200's having problems. These engines have a good torque curve from 1500 all the way to 4000 RPM

I know the 3V Ford engines have had cam phaser lock outs and limiters for years. It has mostly to do with the reliability of the design.

The intake ports on the 4200 flow over 300 CFM, I'm guessing the 2V Jag falls short in that regard.

Marc, AKA, EFI-DIY, has done a bunch of playing around with the VVT setup on these engines, I know he had custom cams made and locked his out at one time. He still pops in every once in awhile at the Inliners forum.

Marc, showing VVT operation

https://www.youtube.com/watch?v=bdmiKhuehUM

Last edited by Whitedog; Tue Apr 07 2020 03:38 AM.

1954 3600 Chevy Truck
"The Fake Truck"
In the Stovebolt Gallery
More pix on Photobucket
Re: eliminate VVT on 4200 Atlas I6
coilover #1353982 Wed Apr 08 2020 12:47 AM
Joined: Jul 2019
Posts: 243
B
Shop Shark
Wait im confused. Why were you asking to “lock” the cam?? I was under the impression you wanted to disable the VVT. I wouldn’t do it personally but I thought thats what you were going for??

Re: eliminate VVT on 4200 Atlas I6
coilover #1353999 Wed Apr 08 2020 04:11 AM
Joined: Feb 2004
Posts: 20,194
H
Boltergeist
I was planning to make an adjustable timing gear so the cam timing could be set at a specific point during dyno runs. It appears that the cam is spring-loaded in the advance position, and a solenoid-operated oil pressure valve controlled by the computer moves it toward the retard position. I'm also looking at the possibility of adapting a HEI distributor with vacuum advance from a Toyota Supra driven off the end of one of the camshafts and a side draft Weber DCOE 2 barrel carburetor to the original intake manifold to make it a completely "dumb" engine. Once dyno numbers are available for comparison, a permanent exhaust cam timing position can be selected.
Jerry


The murder victim was drowned in a bathtub full of Rice Krispies and milk.
The coroner blamed the crime on a cereal killer!

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
Re: eliminate VVT on 4200 Atlas I6
coilover #1354003 Wed Apr 08 2020 05:56 AM
Joined: Apr 2005
Posts: 2,498
C
Shop Shark
Glad you jumped in Jerry. Really would prefer a "dumb" Atlas but would probably go with the FiTech 39001 2bbl tbi. It's good for 400hp, self contained and self tuning which alleviates a lot of worry from the carb guys. It will be a good while before engine work happens as first I will design and fab a firewall recess that gives uncrowded room for the Atlas (I don't think they make wheelbarrows that skinny) and second, to try and keep the lube system factory, a front suspension that allows a front sump pan to fit. We used to use Volare/Aspen cross torsion bar ifs but no need to go with something scarce now. Some of the modern GM rides have torsion bars but track width is too wide I'm sure. If the monsoon season ever ends I can start looking under and measuring both American and foreign set ups. About 1500 vehicles (not mine) down in the yard right now waiting for the crusher so have a big selection to choose from. Not me, but some have used the Ford Crown Vic ifs and since Ford has used front sump engines for years something might measure out right there. As some of you have guessed I'm not the brightest bulb on vvt but that's why I'm pulling your chain. 83 with an iffy ticker and diabetes makes me one they won't even waste a hospital bed on so may be a pest till the scare is over. Last, I have an option on a half dozen 4200 Atlas engines with one that's supposed to be good so if anyone else wants one to brainstorm with, let me know. The supposed to be good one has my name on it.


Evan
Re: eliminate VVT on 4200 Atlas I6
coilover #1354145 Thu Apr 09 2020 04:49 AM
Joined: Mar 2008
Posts: 1,978
W
Shop Shark
Why would you go with a FiTech system, when the OE Fuel injection is already tuned/made for the motor?

Anyhow, if one were to install some sidedrafts or ITB's that would cool. The achilles heel would be the ignition. There's a ton of belt drive ignitions out there for anything V8, just haven't seen anything for a 6. I just saw one for a newer 5.0 Coyote, which got my wheels spinning. If one were to get rid of the 4200 AC pump, build a bracket and mount a CCW ignition, like a Willy's 226, with the cap facing the firewall. Well, a belt drive ignition may be possible for the 4200... Drive cogs and belts are fairly cheap, it's the machine work that'll be the big issue.


1954 3600 Chevy Truck
"The Fake Truck"
In the Stovebolt Gallery
More pix on Photobucket
Re: eliminate VVT on 4200 Atlas I6
coilover #1354187 Thu Apr 09 2020 02:23 PM
Joined: Sep 2013
Posts: 1,011
M
Shop Shark
Whitedog said "Why would you go with a FiTech system, when the OE Fuel injection is already tuned/made for the motor?"

FiTech is a totally standalone unit. You install a wideband CO2 sensor, supply and return fuel line and that's about it beyond the throttle body injection unit and a simple wiring harness. No adapting the factory wiring harness or computer. The FiTech unit is self-contained with a internal computer to run the show. It looks pretty much like a carburetor and is tunable with a remote unit in the vehicle. You do install a 50ish psi fuel pump. The internal cpu can control fans and even ignition (depending on what you're running).

I could have gone with factory fuel injection on the vehicle I'm running a FiTech on, but wanted more of a old school (read 60's very early 70's underhood look) clean engine compartment uncluttered by wires and hoses. FiTech filled that slot. Clean looks with all the advantages of EFI.

RonR


1951 3600 with Clark flatbed, T5, 4.10 rear
1970 340 Duster
1990 5.0 V8 Miata (1990 Mustang Gt Drivetrain)
1951 Farmall Super A



Re: eliminate VVT on 4200 Atlas I6
coilover #1354192 Thu Apr 09 2020 02:38 PM
Joined: Mar 2008
Posts: 1,978
W
Shop Shark
Adapting the FiTech unit to a 4200 engine would be a Herculean task to begin with. A custom intake would need to be fabricated. Also, the timing issue, which we've already touched on. The 4200 is designed as a package unit. The factory ECM is bolted right to the intake. The Under hood fuse box is 6 inches away. You have a quick connect firewall harness, and couple other plugs, and hoses, then the whole engine is ready to come out. I'm sure it was designed that way for simplicity on the assembly line.

I won't deny that adding a Fitech unit and adapting some sort of ignition system, would definitely clean things up under the hood. On the other hand, it would open a can of worms elsewhere.

Last edited by Whitedog; Thu Apr 09 2020 07:48 PM.

1954 3600 Chevy Truck
"The Fake Truck"
In the Stovebolt Gallery
More pix on Photobucket
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