'68 318 to carbed Magnum 5.2: Check my checklist
I've been learning and planning about this swap, and I believe I've got most of the compatibility issues worked out for my setup.
The end result is to replace a worn-to-a-nub '68 318 with a '94-97 Magnum 5.2 - possibly from a Ram Van, possibly not. The Magnum will be converted to a carburetor and mated to an A904 transmission. Mechanical fuel pump, V-belt drive, and provisions for a Sanden A/C compressor are part of the plan.
This said, following is my checklist for the necessary parts and modifications to achieve this goal. If anything sticks out as missing or wrong, let me know, as I'm going to use this thread as my shopping list:
Magnum 5.2, modify as follows:
- Magnum cam snout extender, or - preferably - roller cam from 89-91 LA 318 w/long snout.
- LA fuel pump eccentric (from donor)
- 1979-90 LA timing chain cover (seal from front, timing marks on driver's side - my cover is a '67-earlier with a bolt-on tab) w/Magnum 5.2 harmonic balancer (separated pulley style)
- LA 360 center-sump oil pan (or Summit SUM-G3536) and pickup tube.
- LA oil pan gasket (Milodon crush proof) or Magnum gasket with the ends chopped off and the LA timing chain cover gasket installed in its place
- LA '70+ water pump with passenger-side intake - easier to find (RockAuto) than '69 A/C style and cheaper.
- 1970+ style 26" radiator to match up with '70+ water pump (eBay)
- 1980's-era LA accessory brackets from an M-body (junkyard) or similar, thus adapting directly to the later water pump with provisions for the Sanden compressor and the earlier alternator (don't quote me on this, but I believe one hole in this bracket may need to be revised to adapt to the Magnum head - am I correct?).
- V-belt pulleys from the same M-body (junkyard)
- 1970+ lower radiator hose, upper determined by new radiator (RockAuto)
- Speedcrap China Magnum intake, which will allow for a carburetor swap on the Magnum AND retain the LA-style thermostat outlet, which provides the necessary room to mount the Sanden A/C unit with the M-body bracket. (eBay)
- Factory 340/360 SBM throttle cable bracket for 4V carburetor (FABO wanted ad)
- Weld extension to factory 2V A904 kickdown rod or source used aftermarket kickdown cable that isn't prohibitively expensive
Ideally, this requires the Magnum 5.2 donor, plus a good junkyard 89-91 for cam and timing chain cover, and possibly a mid-80s donor for the brackets.
One of the things not on this list and not clarified yet is whether the Magnum clutch fan will fit - and which radiator shroud will work for this updated combo. Also not sure whether the '68 power steering pump will fit the later M-body bracket, or whether I should adapt the later Saginaw to the existing PS gear (in which case, do the pressures differ, or is it plug-and-play?)
Exhaust on the existing car is trash, so I'll be using the Magnum manifolds with no problems.
Have I forgotten anything?
-Kurt