urquhartglen

i have a 12a secondary bridge and extand port primarys. running match ported tall port manifold and a 6port cosmo 4barrel nikki wit venturies bored out from 17mm to 20.5 mill and copyed mates same set up with jet sizing and mine goes crap. any1 got and specs for jets as a starting point for my bridgeport. we cash allows i will go ida but thats bot a year away and its my daily driver

rotatrix

ive got some specs but one is a s1 rx7 carb and the other is a rx3 carb,duno if it will help but here goes,s1 rx7 pri ven =24mm,sec ven=28mm(standard) jets-pri=130 sec=170 rx3 carb pri ven=22mm sec ven=30mm jets-pri-120 sec-175,hope this helps,both carbs were of 12a bridges that were running good,the float levels in both were on the higher side aswell

urquhartglen

thankyou. will try that. got 1mm primary jet and 1.60mm sec jet in at moment with 20.5mm primary venturies and 28mm sec. ill mill them out to 24mm prim and 30mm secondary and up prim jet to 1.2mm and see what happens. this be last try 4me before i book it into rota workshop and hand over my life savings. its starting to give me grey hairs hahaha. thankyou for yhe input ill let you know if it helped

urquhartglen

taken it to roary shop and had carb sorted out. got 25mm primarys and 30mm secondarys ans 1.20mm prim jets and 1.60mm sec jets unsure what they did with air bleed jets etc. runs better. still got bad miss on secondarys tho. as soon as you open them up anytime eg 3000 to 6500rpm. like havung fouled plugs

rotatrix

true,what shop did you take it to?did they have any ideas on why its missing?

urquhartglen

took it to al marsh automotive in christchurch. they were great guys and really knew there stuff. hed vhad to sort my carb first then started on my miss. after rebuilding my dizzy etc and it was doge then doing my timeing he thinks it a prob with my coils or elec system. he may have been able to fix it just i ran out of coin and had to drive it home so we stoped.

rotatrix

yer al marsh is algood,i know the early rx7s need relays for the the coils added as they suffer from voltage drop(ive had to do this to all the 7s ive owned)and this will cause a miss on power,mine were never missing as bad as you have described but its something you should look at doing if not already,ive seen the voltage be as low as 10v were it should be 13-14v!!

urquhartglen

thanks for that. were abouts are the relays? ive had the wiring loom unpicked and cut out all the wires that went no were...... hope i didnt make what ever prob i had at the start with old eng stronger or that points not up to doing my new engine..... i have applyed battery voltage to both coils (eg 13.8volts) and it didnt help at all.

rotatrix

ok well applying battery voltage to the coils blows my theory out the door!!that would have fixed it if that was the problem(still myt be worth doing later on tho to improve spark)you may need to take it to a dyno and get everything cheaked under load,its easyer to spot a fault with the engine put under various loads with the car stationary,how ever its generaly not cheap!!just a question tho,when the motor was built was it built from parts or was it a complete engine striped and then rebuilt?the reason i ask is that all the motors had different timing marks on the pulleys due to the spark plug locations on the housings changing over the years,so if you had a different pulley for the engine the timming could be out by alot yet the marks would still line up?

urquhartglen

true. i built the engine (got trade in engine building piston engs tho).
had a std 1984? 6port 12a.
bought sum secondary bridgeport tall port s1 end plates and center plate.
got new s1 housings that exhaust had been ported on for a bridgeport by kiwi re.
reused my 6port rotas (with carbon apex and new seals) 6port e shaft and weights,front cover etc. used front pulley off a 1985 6port cosmo. (note my engine now is a extand port secondary bridge tall port 12a with i think s1 housings)
thought all 12a housings aprt from twin dizzy were the same)
these housings dont have the alloy step around spark plug hole. you can use any socket to remove plug. wasnt there frm new hasnt just been ground off. any ideas?? all engine ports are 6port with 4port endplates and housings??

urquhartglen

i ment in last part all eng parts are 6port with 4port end and centre plate

rotatrix

im not sure with the 6ports to 4ports what the difference is,i know thats theres about 10dec difference between 12aturbo pulleys and the older 4port ones,it might pay too track down a older pulley and cheak the marks?it may not be the problem but could be a factor,hope it helps!!