Q&A

Mailbag: Upgrading Valvetrain for Bottom-End Performance on 1976 Toyota FJ-40 with SBC

You’ve got questions, we’ve got answers. We work with the Summit Racing tech department to help you tackle your auto-related conundrums. In this week’s Mailbag, we discuss upgrading valvetrain components on a 1976 Toyota FJ-40 powered by a 350 small block.

Q: I have a 1976 Toyota FJ-40 Land Cruiser with a 350 small block from a 1973 Camaro. The engine has been rebuilt and is stock internally. The heads have a fresh valve job, and the engine features a Holley 650 cfm carburetor on an Edelbrock Torker II intake and Downey headers. I am using the stock four-speed transmission and stock axles with 4.11 gears and 33 x 12.50 tires.

I want to install a mild performance cam. COMP Cams recommended a hydraulic grind with a 203-degree/212-degree duration and .421”/.451” lift, and I really don’t know how much this cam will affect my vehicle. I want to have plenty of bottom-end, but I also want enough cam so people will be able to hear it. (I guess that’s the kid in me coming out.)

Will this cam give me the sound and performance I’m looking for? Will I need to change valve springs? I am also considering the use of 1.6 ratio rocker arms. I have heard that overhead valve engines respond well to short-duration, high-lift cams with wide-lobe centers (the COMP cam has a 110-degree lobe center). I have also heard that 1.6 rockers by themselves will give my engine the rough idle like a mild cam would. Should I use both the cam and rockers, just the cam, or just the rockers?

A: The COMP Cams grind is a good choice for your Toyota. It has an operating range of 1,200-5,500—rpm and offers excellent bottom-end torque. Matching valve springs to the cam is very important. If the spring pressure is not right, you can severely damage the cam and lifters. COMP Cams recommends its 980 valve springs. These springs have an open load rating of 230 lbs. @ 1.250” and a seat load rating of 85 lbs. @ 1.700”.

As for the 1.6 rockers, they don’t always produce the instant power increase that they are known for. The added lift creates a bigger “hole” in the powerband that the engine has to compensate for. That hurts bottom-end torque. Any power gains you get from 1.6 rockers will be in the higher rpm range.

You may want to reconsider your Torker II intake manifold. It’s designed for engines operating from 2,500 to 6,500 rpm; since the Torker is a single-plane design, it also offers limited off-idle response.

Something like an Edelbrock Performer dual-plane manifold, which makes power from just off-idle to 5,000 rpm, would be a much better choice.

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