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What radiator should I use for an LS swap in a C3 — budget vs direct-fit?

Direct-fit: companies like Afco, DeWitts and Frostbite make LS swap radiators for a wide range of vehicles. They drop in like a stock part, with the upper and lower outlets and steam port where the LS needs them, and you can often choose the finish and a single or dual fan shroud. The convenience is worth the price if the budget allows.

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Budget: keep a conventional radiator and adapt it. Speedway's LS swap radiator hose adapter (listed at $24.99) fixes both problems at once: a 1/4 in hose barb takes the steam line, and it adapts the LS water pump's 1-1/4 in upper outlet to the 1-1/2 in inlet on a typical radiator. Or use a universal double-pass radiator, which puts the upper outlet on the correct side and can cool better than a single-pass. Expect some modification to fit a universal radiator in the car.

Either way, plumb the steam line — On most LS engines the thermostat sits low, on the water pump, instead of up top like older small- and big-blocks. GM added steam lines in the cylinder heads to vent trapped air and keep hot spots from forming at the top of the engine.

We haven't verified a specific C3 Corvette direct-fit part yet, so check the maker's application list for your year.

What we recommend

There are two routes we've seen work in a C3. The budget pick is a 1998-2002 F-body radiator and fan assembly for about $200 total; it cools well, but the passenger-side outlet can rub the upper control arm. The buy-once route is the DeWitts Direct Fit LSX package at about $1,550 (radiator-and-fan combos run about $1,465–$1,715), which fits the stock mounts, puts the inlet and outlet both on the passenger side, and includes an electric fan with in-tank temp switch, a steam-port fitting and a wiring kit.

Check this first:

  • With the F-body radiator, check outlet clearance to the upper control arm

Based on what we've seen work across our own builds, our friends' builds and the wider LS community, reviewed by our lead shop tuner (over 20 years of LS and LT tuning experience). Every combination is different, so use at your own risk and check our safe tuning limits before any wide-open pass.

Go deeper

Try this, then this

  1. Budget universal aluminum radiator with fabricated mounts — half the cost. Worked if: temps hold
  2. DeWitts direct-fit — no fab, guaranteed fit. Worked if: temps hold

How you know it's fixed

  • New radiator holds temp in traffic

Still not fixed?

  • Add pusher fan or improve shroud sealing

Every option we know of

Maker / productPart #FitsPriceWhereStatus / notes
DeWitts
C3 LS swap radiator		n/a1977-1982 C3$1,552.99dewitts.comIn production
pricey but direct fit
DeWitts
radiator + fan combo		n/a1977-1982 C3$1,465-$1,715dewitts.comIn production
DIY
universal aluminum radiator + custom mounts		n/aC3 with fab workabout $300-500SummitDIY
needs custom brackets/shroud

Prices are approximate as of September 2026. We list every option we know of, including small shops and used parts we can't link to. Confirm fitment with the seller.

Time and cost: Radiator swap: 3-5 hours

How to connect the 2002 Camaro LS1 power steering pump to the 1982 C3 steering control valve in an LS1 swap?
What we recommend

Convert the connections to -6 AN and add a flow restrictor to the LS pump. Use a 5/8-18 to -6 adapter on the control valve return side and a 1/2-20 to -6 fitting on the pressure side, with matching fittings at the LS pump, and run Teflon-lined -6 hose on the pressure side. The LS pump puts out more flow and pressure than the C3 control valve expects (about 1000 PSI), which makes the steering twitchy. We recommend a Borgeson LS power steering pump restrictor or a Turn One Saginaw P pump flow restrictor to fix that. The OE hoses from the valve to the cylinder can be kept.

Check this first:

  • Use pressure-rated Teflon-lined hose on the pressure side

Careful: Without a flow restrictor the steering can be twitchy, which affects how safely the car drives.

Check this first

  1. Confirm the twitchiness is over-assist and not alignment, worn parts, or air in the system.
  2. Check pump pressure with a gauge before choosing a restrictor or shim stack.

Try this, then this

  1. Install the restrictor or shim kit.
  2. Bleed the system and road test.
  3. Adjust restriction until effort feels right.

How you know it's fixed

  • Steering effort feels normal at parking and highway speeds; no whine or shudder.

Still not fixed?

  • Still twitchy: add restriction; too heavy: remove a shim or step down the restrictor.

Key numbers

WhatValue
Restrictor fixes twitchy steeringA flow restrictor reduces the output orifice size on the power steering pump, and if the steering is twitchy, a restrictor will help.
Turn One restrictor installThe Turn One flow restrictor replaces the factory restrictor: unscrew the factory unit with a 22mm socket and install the Turn One piece, tightened to 40 ft-lbs.
Borgeson shim approachBorgeson's GM P/S pump pressure valve shim kit (899001) includes a clamping tool, 5 shims, and instructions for lowering bypass pressure; one user ran all the shims to get down to the 900 psi range.
Pressure targetsGM power-steering pumps produce up to 1,500 PSI; about 1,200 PSI is recommended for steering box applications and 800-900 PSI for Mustang rack-and-pinion systems; over-pressure causes twitchy steering at speed.

Every option we know of

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Maker / productPart #FitsPriceWhereStatus / notes
Borgeson
GM P/S pump pressure valve shim kit, clamping tool + 5 shims		899001GM self-contained and Type II pumpsabout $35-$50 (approximate)Buy
borgeson.com		In production
Turn One
Power steering flow restrictor		Saginaw pumpsabout $30-$50 (approximate)turnone-steering.comIn production
22mm socket install, 40 ft-lbs

Prices are approximate as of September 2026. We list every option we know of, including small shops and used parts we can't link to. Confirm fitment with the seller.

Time and cost: $35-$50 in parts; an afternoon.

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