Dual carb 61x

[shepster]

Hi guys just on the off chance to save me some work, is anyone running dual 38's on 61x cases. Just after some jetting specs for a mates Blaster with usual mods and NO porting.

Many thanks

 

[Flat Brapp]

I have seen the intake manifolds around on the boards but I haven't seen that setup run in person. Sorry no info on jet specs for a 61x case motor.

 

[shepster]

Anyone ? Its currently go 75 pilots, 120 mains and a 17 psi pop off, 2.3n/s.
Do these sound about right ? ?

 

[DCRocks]

You say usual mods...

What pipe? What head? What size domes? All these affect jet sizes.

 

[shepster]

Ok ada head 35cc domes 185psi compression .050 squish, riva red pipe!, twin 38's, msd enhancer, stock reeds, single cooling. running 40-1 fuel/oil, tauceti flame arrestors.

Hope this will help

 

[DCRocks]

I think that covers everything. I am not sure as to the correct jets, but I do remember all the specs everyone asked me to list, when I was asking for help with mine.

I think you listed everything that is needed to make a recomendation at this point. I will try to point a couple jetting guys this way! :scratchchin:

 

[shepster]

cheers

 

[shepster]

bump ??

 

[Ottis]

I use to run those on 61x cases, they work very well, but will load up if you let the boat idle. as I remember I think we ran 100 mains 75 pilots 2.0 ns 80g springs high speed screws at 2 turns and lows at 1 1/2 turns. Anyone else?

 

[Matt_E]

Dual 38's on T-cases run 55psi popoff, 70 pilots, and 130 mains.

Granted, X cases are different.....but I think that 120 mains (or even 100 mains as Ottis suggested) would be leaning the top out quite a bit.

 

[shepster]

Dual 38's on T-cases run 55psi popoff, 70 pilots, and 130 mains.

Granted, X cases are different.....but I think that 120 mains (or even 100 mains as Ottis suggested) would be leaning the top out quite a bit.

Im going to try these 62t specs this weekend to see how it runs, thinking will mabe need to lean off some.

Cheers guys

 

[Foximus]

Dual 38's on T-cases run 55psi popoff, 70 pilots, and 130 mains.

Granted, X cases are different.....but I think that 120 mains (or even 100 mains as Ottis suggested) would be leaning the top out quite a bit.

55psi? wtf? thats redic high.

 

[Ottis]

I have to call pro-tec today, I'll ask them and let you know

 

[shepster]

I have to call pro-tec today, I'll ask them and let you know

Sweet, if you could that would be great. Many thanks

 

[Matt_E]

55psi? wtf? thats redic high.

Stock settings.

 

[Foximus]

Hrmm... Interesting. I didnt know that. When I checked mine it was up to 60 psi and didnt even pop, I thought that was really odd. It was using cut down gold springs. I changed over to .65 blacks to put it at 30psi.

 

[Ottis]

I called pro-tec they said 107.5 main, 65 pilot, 2.0 ns, 80g spring I allways ran high speed screws at 2 turns and low speed screws at 1 1/2 turns, my plug burn was always perfect, I ran that on several boats. as allways no two boats are exactly the same, so I would start there check plug burn and make adjustments. One thing I ran into was they would load up if you idled to long, the explination I was given was that the 61x cases had a smaller intake area and could not use all the fuel that dual carbs had (this might explain the smaller jet sizes). again right of of idle and on they work very well and I allways thought they ran as good as 62t cases with the dual 38s. hope this helps you!

 

[shepster]

Ottis, many thanks :beerchug: Will try them this weekend and see what happens.

James

 

[Philip Clemmons]

You guys ever figure this one out?

Got a similar one now that wont come close to running off idle with those specs. Just way too lean off the hit. Pop off is around 19 psi.............

Upped the pilot and made the ls adjuster absurdly rich and it helped quite a bit, confirming that its starving down low. These are taper bored 38s.

Wonder if that kills signal at idle? I know it should help airspeed but it could be channeling it towards the inner venturi, away from the bypass holes at low throttle valve openings................

Anyone?

 

[Foximus]

With my newly ported 61x cylinder (62t case), I filled the crossover in the manifold and now im running 70 pilots and its still a bit rich....

Id suggest filling in the crossover if you have a 62t case.