Just installed a header on my 1979 RX7 stock12A & have pulled off all the existing exhaust system & want to replace it with a modified system ( smaller cat converter & smaller rear muffler.) Not put a header on a vehicle before so I'm not familiar with impact it makes to previous engine operation. In the RX7's case it started & ran very well before I yanked all the stock stuff off - now it starts extremely hard & runs poorly. Afraid to even drive it around the block!! HELP!!!

 

Manifold vacuum leak?

 

that was one of my thoughts that there is a vacuum issue. Another is with the heat exchanger gone the pipe to the air pump is an issue, I did block it off, but maybe not well enough!?

 

Put a ACV block off plate on it and be sure the header has a good gasket seal. You will need to adjust the idle mixture and speed as well.

 

I've blocked the ACV, dried the wet NGK plugs & still not getting it to fire up!??

 

Well I finally did get my '79 12A going after I installed the header! Several attempts with drying out the plugs & making sure the battery was sufficiently charged were necessary. Starting it the same way as before, always with the fear that it will be flooding - it takes several tries & on the last one that just seems to be the flooding point it will out it will mysteriously fire up & then starts running. A little disconcerting, but has reliably started up ever since.

 

Seem to recall the Nikki's are set to run richer WITH the factory reactor (79, 80), so maybe too much now with the Header install.
Is the emission stuff still in place. removing the Rat's Nest requires some thoughtful routing/blocking or various fittings on the intake mani. Archives here should detail this.
AND-
generally to get all the extra HP out of a header, Racing Beat suggests you need a free-flow muffler (like *cough* theirs) to get any juice.

Stu Aull
80GS
Alaska

 

You need to readjust the nikki a bit. It actually should be a bit lean since the header is on there now.

 

Yeah, rat's nest removal is in the archives with a few great writeups on getting the system out of there. I never noticed much of a difference with it removed but that's just me (entire car was stock when I did it).

I'd say to go with a MagnaFlow muffler since they are extremely free flowing, although they are a touch on the noisy side. Of course an entire RB exhaust setup would be the best way to go, but you have to have the money to invest in it.

 

Just rip the whole emissions rack out, block all the ports at the carb base and, run a split vacuum line from the 2nd carb port to the distributor vacuum pots, run a fuel line from the upper oil filler neck port to a port on the carb air filter, and then put a tiny breather on the port on the base of the oil filler neck. Done. Takes 20 minutes. Start it up, adjust fuel mixture and timing.

 

Call the EPA, this man hates emissions

 

Thought I'd pull the air pump & its corresponding belt first off. Any repurcussions for doing this?!

 

Perhaps, most advise to run a dual alternator pulley so that the WP is still driven by two belts.

Search for this, it will have the part # of the pulley you need and the two identical belts to run.

Also make sure to block off the hole left behind in your air cleaner. The air pump taps into the filtered portion...

 

The fan will also slip at 5k. Also no good.

 

Air cleaner not an issue - got a Racing Beat unit!? Found a slightly smaller Fram filter to use vs a stock one or the pricey RB unit. Any comments on that as a compromise for air flow!!!

 

You need a different (non OE) water pump belt is all. THIS one

Yoohoo Belt

is made for the job.

Stu Aull
80GS
Alaska

 

Stu -
Thanks for the link. I'd seen this referenced before & kinda lost track of it. Just ordered one yesterday!

 

Just got the Pineapple belt today - was expecting it to be a little bit wider?! Will give it whirl when I get that air pump off. May try to sell this one now as is - see how the '81 sale goes.

 

Get ready to get angry putting that belt on lol, i did, but i took it right off cause i didn't like how tight it was, i was worried about it putting to much stress on my water pump and e-shaft bearings