By Joe M 1979 Date 2011-07-25 23:41
OK well i started to buy some parts for my engine and will be posting pics soon parts i have got so far is a new aluminum engine case with 10mm studs and a 82mm crank 5.352" h beam Chevy rods and 90.5 cylinder kit all the gaskets scat lub a lob lightweight lifters Jaycee push rod tubs what i do have a question on is the cam and heads that i should go with i am using dual Weber 44 carbs it is going in a dune buggy looking for a hard take off though i do not want to lose all of my top end ether what are your suggestions
By Brad H 1498 Date 2011-07-26 14:31
Just an FYI the Scat lube-a-lobes have a bad rep for falling apart at low miles. I personally use the CB lightweights and never had a problem. As for heads and cam, what sort of compression do you want to run? For heads I would suggest something with a valve size of 42x37.5 if you want good top end and sacrifice a bit of bottom end or 40X35.5 if you want more bottom end. Check out the Los Panchitos or Banditos heads by CB. They are a little more money but youor heads make the power. Something like a 120 cam would do pretty good for an engine you displacement. Big lifts and durations start needing big valves and high compression to work right
By Joe M 1979 Date 2011-07-27 01:53
i am going with the 42x37 heads that i have found and a 125 eagle cam thanks for the advice on the lifters i will keep them for my 1600 rebuild what rockers would you go with the 1.1 or the 1.25 and what brand
By Brad H 1498 Date 2011-07-27 14:10
You could go with the 1.25 rockers. The 125 cam has kind of an aggresive ramp so will be a little hard on the valve train. That said, I'm running a 130 with 1.25s now, but have been considering going to an FK-44 or FK-8 for a new cam. The FK series has a little less lift at the cam and a bit longer duration so the valve speed and load won't be as severe with ratio rockers. The more lift and shorter duration, the faster the valve and springs have to react. It's OK when using 1.1 rockers, but as soon as you start trying to open the valve more with a ratio rocker everything is speeded up putting more stress on parts. Ideally, if you want big lift at the valves, you would choose a lower lift cam and make up the lift with your rocker ratio. The ratio rockers will also move your power band up a bit when compared to the 1.1
You'll also need to order some cut to length pushrods and set up you rocker geometry with the bigger cam wether or not you run ratio rockers.
As far as brands, I've used genuine VW ratio rockers for 15 years, also Scat and I just bought some CB 1.4 rockers for my next motor. Aside from the shaft that broke on my Scat rockers at Bonneville last year they are a nice product. After I got back I inspected the shaft that broke to see what caused it. I found that the block for the #4 valves had a void in it and it crushed when I bolted it in. At 7200rpm any imprefection shows up and with the high spring pressure and severe valve action (130cam 1.25 rockers) it let go and the shaft broke. Inspect all parts well before you put them together. Don't just assume they are clean or good. I was in a hurry as I got them 3 days before I left and just cleaned and bolted them in. My old VW rockers got me through the rest of the racing and are still going strong in another motor.. I've also heard some good things about the ratio rockers from AJ Sims. They are cheap and people (that I trust) report they are holding up well in their race cars. Pretty much everyones rockers are coming from the same supplier so unless you are going to something exotic like Pauter you're just shopping by price
By Brad H 1498 Date 2011-07-27 16:14
Another thing to consider when running longer duration cams is that you have to run a higher static compression, as the running compression is lower becasue of bleed off due to longer valve overlap. A 125 you need to be running around 9:1 to take full advantage of the cam.
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