I'm a newbie here, to rx-7s, but not to cars and mechanics.

Purchased a 94 base FD. Previous owner had told me it had hot start problems due to the rebuild he put in the car and it having low compression. No real major modifications other than coil relocation to under the steering shaft. It starts fine when engine is cold.

To start, should I be doing compression checks? I know I need to get some accurate gauges for engine vitals because the stock stuff is usually useless. The under hood temps seem crazy after the 20min drive home.

Any helpful links/pointers would be great.

 

When you say "hot start problems", do you mean it doesn't like to start when its hot?

Does it ever over heat when driving or just idling? I would think a hot start would be more likely related to an electrical issue than a mechanical issue like low compression.

 

Yes, that's the place to start. Getting entirely accurate compression on a rotary is a little more difficult, but a standard compression gauge can be used in a pinch. You want to see three relatively even pulses on each rotor...one pulse per crank revolution (per rotor face) On a standard gauge I think anything around 100 psi would be fine. Lower than about 90 and that would likely indicate your problem. Can only speculate 'why' there's low compression on a recently rebuilt engine, but it's a common explanation for hot-start issues and would require another tear down.
Found a link that should help.... Rotary Resurrection home of the budget rebuild.
Something the FD is known for. Remember that with the stock twins there are two turbo hot-sides down there, probably also with a downpipe that could be wrapped or heat-coated. Depending on where you live and mods, there are some other things that can be done to improve that.

 

@jahjahsqc: Yes I mean a restart after being driven. Car up to running normal operating temps. Well, as "normal" as my non-accurate stock gauge indicates.

@sgtblue: The PO mentioned that he had bought this rebuild and had exceeded the warranty period when he did the motor swap. Needless to say, he ran into issues and towed it to a rotary shop here in the Bay area and they said the engine has low compression. I will have to test myself to confirm this. I have a wrapped down pipe ready to go in, as well as PFC. I don't want to throw parts at the car until I can be sure I have a good basis of a car.

 

Also, when it doesn't restart when the car is hot. What's the trick to get it going again? I've cranked and cranked. Cranked with throttle open and was able to get it started. But it's a bit unnerving to feel like I'll get stranded somewhere.

 

No "trick" that I'm aware of. Doing what you did....or maybe parking on a long steep hill?

 

fairly new myself but just too add my 2 cents, would the infamous flooding of rotaries be an issue