VORTEC 4200 FORUM

1965 Chevrolet Chevelle Malibu
06 4200 from a GMC Envoy. No clutch fan, AC, PS, or catalytic converter
TH400 with factory-type SBC torque converter (so very tight)
Factory 8.2 10 bolt, 3.08 open
Factory P12 ecu, VATS deleted by Limeswap
Custom oil pan from Eric Heinze (NOT the standard "stretched" 5cyl Colorado pan)
Shaved valve cover from Atlas Industries, powder coated Chevy Orange
Bellhousing adapter/TC spacer from EMTech
Starter adapter from PACCRacing
Engine mounts were factory SBC brackets. Welded a section of angle iron onto the top of each of them to make a platform for the factory 4200 mount to bolt to. Factory 4200 block brackets.
Used the factory engine wiring harness, powered by 100A fuse panel from Amazon
Relocated the battery to front drivers side to make room for factory 4200 air filter assembly.
Bought Eaton Detroit "OEM" springs for a 65 Chevelle with 194ci engine w/o AC. Thought was this would be the lightest front spring available. Car still sits high in the front.
Used the factory Envoy radiator with a cheap generic electric fan kit. Takes a lot of idling to get the fan to trigger, engine naturally stays quite cool.
Bought a front spoiler from an OBS chevy pickup, flipped it upside down, chopped some material out of the middle to get the width right, and riveted it back together for a front spoiler to help cover up the tall radiator sticking out under the front grille.

Clears the factory crossmember, and fits under the factory hood with only a small notch taken out of the hood frame.

Very disappointing power off the line. Once it's above 15mph, it picks up pretty good and zips along quite well. TH400, tight converter, and 308 rear end is not a lively combo from a stop. Doing ~2400rpm at 60mph, so I don't want to put a more aggressive rear end in it. Getting parts together for an AX15 swap (3.83 first gear instead of 2.48) plus OD will put me at ~1900rpm at 60mph, which is a common speed where I live on all the 2 lane blacktop roads.

very nice sir, thanks for all the details. Side note, when you do the ax15 swap you should note that "At just 1,800 rpm, 90% of the Vortec 4200’s torque is at attention" so with being at 1900, you should be sitting pretty for cruising. I also believe there is a post down in the manual section on the ax15 swap too, id have to look. Keep at it, Im just stacking parts and hoping to get "Hank" to 3rd annual atlas nationals...

PS, thanks for the post and sticking with the forum through the growing pains as well as keeping tabs on the FB about it.

That is the one upside cruising at 2400rpm, it has enough power on tap that I don't necessarily need to downshift.

For anyone contemplating an NA swap, be aware that these engines aren't "magic". You're still working with 253ci. Torque isn't bad, but it's not Big Block torque either. Comparable to a 292 in the 2000rpm range. I had a 402 in this same car, same trans, converter, rear end, everything. Punched 60 over, Peanut port heads, ~8:1 compression, Quadrajet, and a lumpy cam. Most people will tell you that makes a lame combination, but lemme tell you it'd roast the tires off-idle with no fuss.

The 4200 just doesn't have the same torque. Once you get some RPM into it, yes it comes alive and is quite peppy. But nothing (other than boost) makes up for 160 less cubic inches. Just something to be aware of. I'm strongly considering porting another 06+ head, reground cams, and building some long tube headers. But, AX15 first.