Spread bore to square bore adapters

Edelbrock list one for a Thermoquad- part no. 2691. Most adapters are made for Q-Jets. There is a difference. The TQ adapter has more meat between the 2 rear bolt holes, the Q-Jet has less. If you use a Q-Jet adapter with a TQ, the passages on the bottom rear base of the TQ will be uncovered causing a major vacuum leak. Most gaskets are for the Q-Jet also so make sure you get a base gasket that covers all the passages. Edelbrock has one for Q-Jet and pictures of both. Make sure you get the 2691. If you watch swap meets you can find one once in a while also. That's how I found there was a difference.