4k Cams. Any Cuts Better Than Others?

[altezzaclub]

That's good!

 

Waggott said $120 & $15 mail for a cam cut and $180 all up with lifters ground.

 

Crows said $170 all up for the 606 (best option for what I need) & I really should shell ot $65 for the Holden valve springs #4823.

Edited November 4, 2009 by altezzaclub

[Felix]

You gotta keep in mind those 3k-b carbs are from a 83HP motor, and will cause a restriction in the top end.

 

I guess you could play around with different aisan carb bits. The 3k-b carbs have 19mm primary venturis (good for low end), can't remember the secondary venturi size off hand. Other aisan carbs have larger venturis you could possibly swap around. At the end of the day the aisans are a lot more limited in tuning compared to other carbs. Airbleeds aren't changeable for one, which can make a massive difference in trimming the fuel curve.

 

Higher airspeed through a carb means finer fuel particle atomisation which gives a better cleaner burn.

 

SU's are great carbs being constant velocity carbs, only opening the slides when the motor actually needs the airflow. Way better street carbs than webers/dellortos. 1 1/2" twins are ideal for a high reving 4k but are on the small side for a decent 5k.

 

32/36 dgvs are to big for any k series motor. ADM's are massive off a 4.1L falcon. The DHSA2 would have been very well suited if you had of drilled the primary throttle plate or opened the secondary slightly.A big cam has SFA vacuum so needs the throttle platws cocked open more at idle. Those not in the know (probably 95% of the population) open up the primary throttle plate bypassing the idle/progression circuit. :)

[altezzaclub]

The DHSA2 would have been very well suited if you had of drilled the primary throttle plate or opened the secondary slightly.A big cam has SFA vacuum so needs the throttle platws cocked open more at idle. Those not in the know (probably 95% of the population) open up the primary throttle plate bypassing the idle/progression circuit.

 

OMG! Quite a bit of the ol' school cleverness in there Felix!

[KE55PIG]

Il look into changin to 3k carbs if I'm runin outa puf or c if i can use the the venturis or maybe save for some su if u thinjm they would be a big benefit. I got a head4 it now with bout 33mm ports to go wid me 32 ml runners and I'm going to polish the combustin chamber and exaust port

[Felix]

LOL. Bigport heads. In standard form the ports are already too big for the stock valve size.

 

Look at the following image and tell me how much advantage you would gain by hogging out the straight section of the port and not enlarging the valves or doing any bowl work.

 

[rob83ke70]

why did toyota make a bigport head if they didn't have an advantage? marketing? like the o2 advantage in the 80-90's?

 

I'm going to match the ports of my 3kb inlet manifold to the head and play with extractor sizes and stuff to get it all neat and tidy, and smooth any un needed corners and so on.

 

I have a toyota 4y manifold to neaten up and port match on the weekend, good fun :y:

 

Robert.

[KE55PIG]

Wel i dont100 percent agree as the bowl around valve is larger then standard port thers proven hp from it but i think its worth it and its had bowl work .

[Felix]

why did toyota make a bigport head if they didn't have an advantage? marketing? like the o2 advantage in the 80-90's?

 

Robert, you should ask... why did toyota start with bigport heads, then drop them and go to small port heads, still keeping the same valve size? Then, what did toyota do differently with the heads on the later dished piston motors, and why?

 

KE55PIG the point of that pic is that port size is only a very small part of the equation. The thing to note is that it is far more important to encourage the intake charge to change direction and flow past the valves with minimal restriction.

[rob83ke70]

you do make a perfectly valid point and I agree totally that its all about smooth unrestricted gas flow. Might require some further thought then in terms of my inlet manifold and 3kb carburettors.

 

I'm planning on a 2" exhaust out of the extractors, 2" ID perforated tube resonator maybe 18" long, then step the pipe to 1.75" before the diff, and a 1.75" straight through perforated tube muffler with a 1.75" tip on my corolla, and maybe on the ke55 as well, should be a good flowing exhaust that isn't too loud!! its all about the gas speed instead of the pipe size.

 

Try and explain that to either bogans or saddlefriggers!

 

Robert.

[KE55PIG]

I c where ure coming from so how do i fix it geting the valver ground ? Certian bowl work ? Also with the manifold. Ive ground the bit were the carby sits under the circles on and angle / to help it flow beter faster into the head. Witgj the carbs i think theyl do me if not il look at biger throats and stuf i just want it runing the litle time on dyno c what can get out of it also felix wats done to ure head ?

Edited November 7, 2009 by KE55PIG

[altezzaclub]

Felix, Datsun did the same-

 

Early on from 1968 to early-70s they made small-ports on the Deluxe and big-ports on the SSS. Then they changed to the A87 medium-port for all. Naturally the small-ports were the most popular with people who modify cars as you could make your own shape & size.

 

KE55 you can re-shape the back of the valve yourself if you're keen, or just polish them in a drill with wet

n dry sandpaper and some kero or 556, but don't touch the seat itself. You can get a triple face ground onto it for a smoother curve.

 

Felix will have a nice picture of a full-flow valve I'm sure! This sort of thing-

 

http://books.google.com/books?id=283b4kk20...ape&f=false

Edited November 7, 2009 by altezzaclub

[KE55PIG]

Ok wel for know il just polish them up as much as i can .

Also if i could pik up 2 40mm dellorto for 280 no manifold r linkages would it be worth buying them ??

like are we talking a big gain over my 3k-b manifold or not really and for 280 would it be worth buying and maybe resseling

Edited November 8, 2009 by KE55PIG

[altezzaclub]

I'm a Weber man myself, but I'm sure full side-draughts beat downdraughts at the top end every time.

 

However, who knows when those carbs were last on a car, and what sort of condition they are in... It would be good if they were on a car as you bought them, or at least on a manifold with the linkages and had been running in the last month.

 

Just bare carbs with a doubtful history are not worth much, so $250 would be fine. I recently sold my Datsun twin Webers, on a manifold with everything just as I rallied them, for $800.

[KE55PIG]

Carbs were rebuilt a yr ago. But once buy manifold and linkages wil be like 700 but ahwel may stay wid me 3k-b carbs nt sure

[Felix]

You could always buy yourself one of these:

 

Remanufactured DCD Weber

 

The price is pretty good considering it has been remanufactured to new specs. You'd also need a DGV adaptor plate to fit it onto a stock single carb inlet manifold and a filter. You won't get a better allround performance/economy carb for a street K motor. Love the way you don't even have to remove the airfilter to change the idle and main jets. :)

 

You could always sell the twin aisans to subsidise the purchase.

 

Sidedrafts are great for ouright power but are very expensive to setup, expect little change from a grand.