Thermoquad on a 318?

[BudW]

There are 4 different 318 4-bbl intakes made for FMJ cars.
- There is the normal 318 4-bbl intake (318 cylinder head port size) that used a Thermoquad ('76ish to '84)
- There is the '85-91ish (pre-Magnum) 318 4-bbl that uses the Rochester Quadrajet. This intake has the same casting number as the one mentioned before – but the external choke thermostat is NOT machined. The Quadrajet uses an internal choke thermostat vs. external choke that Thermostat's used.

- There is the same two versions used for the police 318 4-bbls – which use the 360 port size heads (which ironically is the same intake used for pre-Magnum 360 4-bbl pickups/vans). The '85-92ish 360 intakes are also not machined for the external choke thermostat like the normal 318 4-bbls are (as mentioned above).

There is a lot of machining needed to make a Q-Jet intake to work for a TQ – to the point I will not recommend it.
That said, a TQ intake will work just fine for a Q-Jet.


Now off to a different subject. The combustion chambers are much higher (cast deeper into the head) for 360/police 318 heads – so taking 360 heads/intake (or police 318 heads/intake) and placing on a 318 2 or 4-bbl engine will knock your already low compression engine down even lower – to the point it's like shooting your foot with both barrels of a shotgun (instead of of with a 22).

Even using police 318 pistons will still result with compression being less than desired.
If a person was to get aftermarket or custom pistons for the 318, to get compression to a more desirable number – then you might have a winning combination.
BudW

 

[Mikes5thAve]

There are probably more then 4 different 318 4bbl intakes because most intakes were changed for 1979 to the offset thermostat.
Actual factory 318 4bbl intakes are pretty rare. Most are the 360 style.
I thought the quadrajet intake still had the choke pod only it wasn't drilled and tapped for the hold down bolt which isn't too big of a deal.

 

[BudW]

There are probably more then 4 different 318 4bbl intakes because most intakes were changed for 1979 to the offset thermostat.

There are probably more then 4 different 318 4bbl intakes because most intakes were changed for 1979 to the offset thermostat. True and a point i forgot about. I can't recall seeing a 318 4-bll intake with the older centered Thermostat before - but I'm sure a few were made.

Actual factory 318 4bbl intakes are pretty rare. Most are the 360 style.

I would agree there, as well. More pickup/van 318 4-bbls were made than those put into cars.

I thought the Quadrajet intake still had the choke pod only it wasn't drilled and tapped for the hold down bolt which isn't too big of a deal.

The choke part was cast into the intake. The top part is not machined flat, nor screw hole tapped/drilled. More importantly the choke well is also not machined - which would be hard to do (without using powered hand tools). I had a '86 360 pickup intake and tried to insert a couple of choke themostats I had (one electric and one pre-electric) and neither one would fit into the well as is (without machining).
Personally, I wouldn't use a cast iron intake unless I had no choice. The Edelbrock Performer 2176 intake is so much lighter and flows better than the (any) iron version does - I don't see why I wouldn't use it for a street driven car (or another version for other applications).
BudW

 

[Mikes5thAve]

Good to know on the choke part.
Years ago at least one of the magazines did a test of intakes and found the performer wasn't any better then the stock ones. I've never noticed any performance difference between the two. The only reason for using the edelbrock is mainly readability and weight savings.

 

[LSM360]

I remember seeing that magazine flow test.