Cam advice

[Bruce67]

Hey guys, I'm in the process of rebuilding my drag motor and I want to see if I can get a bit more power out of it without changing the displacement or heads at this time.

2165, 46.5x37.5 superflows, 33cc, 1/78 exhaust, fk89, 1.4 rockers, 13.8 comp. valve notches on pistons. ( dont have any flow #'s)

I was thinking about changing the cam to something with a bit more lift and duration, but I think an fk97 might be a bit much.

Really looking to maximize the power of the current old superflows before I replace them later in the year...any thoughts?

Thanks!

[Udo]

FK 89 is hard to beat and more than enough in degreese and lift for that combo . Don't go too big with the cam try some work on the heads and manifolds
Do you have some dyno numbers ?
Udo

[Bruce67]

Udo, the heads are ported and polished with matched intakes and were done by the guys at EMS. No dyno numbers, but car has gone 10.92 at 1500 pounds or so, at high elevation.

Do you think changing to a set of 1.45's would help to make a bit more power?

Thanks for the reply.

Hows your dragbug these days...I remember watching it race out here on the East coast, was always one of my favorites.

[spanners]

I'm with Udo on the cam, but you could change to 1.5s and see an improvement, and going For for the lightest valve train possible and reducing spring poundage would be about all that's open to you, ti valves and retainers and a set of smith bros push rods maybe, but could be a step to far with new heads about to appear, I'd be concerned about the new piston notch depth required for safety.

[Udo]

If Bill Duncan was on the heads there is not more to do :-)
Yes , like spanners said i would switch to 1,5 rockers like Pauters . 10,9 sounds like good power
My car does well , did two 9 sec passes since i own it. goes straight like an arrow . Warren did a great job tuning the chassis and shocks

Udo

[Bruce67]

Spanners, I do have ti valves and retainers and I'm just about to order some new springs. The old ones look to be k-800's, but cant tell for sure with no markings. Is there a better choice of springs?

Pushrods are chromo and have a little weight to them...what are the Smith Bro's?

Thanks!

[Bruce67]

Udo, glad to hear your dragbug is working out for you.

Maybe I need to just make the necessary refreshments on the motor and run it. I just thought while I was there I would see what else I could do.

For a relatively small motor, I thought it made good power also, and everything inside looks real good...

Is it worth going from 48's to 51's?

Thanks!

[Jim Ratto]

I wonder if you can make some gains with changing cam timing... not the cam. Let's say MPH is off, but 60' and 1/8 times are good. Maybe retard cam so intake center lobe is 110-112 ATDC?

Depending on gear ratio and rpm drop, of course.

There's always emulsion tube tuning too.

[Udo]

Yes some 51's can help too .
I bought that car because i knew it is one of the best running car that was ever build. So i only have to take care of engine and gearbox .

Udo

[Bruce67]

Jim, thats an interesting idea with the cam timing...I wonder what kind of an effect it would have on the top end, with a small stroke trying to push a 3.88 r/p...I would think it would run out of steam, right?

Udo, yes, a very well built, good running car...I miss seeing it along with Warren and crew racing it. Do you know if Warren will be back racing again?

[spanners]

Bruce, it sounds like you have most bases already covered on the light valve train, I'm down to 275lb OTN Spring pressure but I only go 7500, I just got a huge 52gms off each valve, the only trouble I see with making engine changes is you may end up with a development season, I'm a circuit racer so not qualified to go head to head with the qualified experienced names already advising with you, but I recon the basics are the same or very close, IE the detail in the chassis and wheels and tyres may be the way forward for you, confidence in the car is king as you know, maybe get some weight out of the car, rules permitting of course,  then put the effort into next seasons motor. Good luck whatever option you go for.

[Jim Ratto]

Jim, thats an interesting idea with the cam timing...I wonder what kind of an effect it would have on the top end, with a small stroke trying to push a 3.88 r/p...I would think it would run out of steam, right?

Udo, yes, a very well built, good running car...I miss seeing it along with Warren and crew racing it. Do you know if Warren will be back racing again?

Retarding the cam 2-4 degrees should shift powerband up- you're closing intake valve later. By your engine specifications, power band should be from 4400 to 8000, a good spread of 3600 rpm. If the engine is indeed strong at this low of an rpm, depending on your gear stack, you could retard cam and probably see only gains. Combine change in cam timing with higher lift rockers and I bet you'd see the improvements you're after. Again, don't rule out carburetor tuning.

[Bruce67]

Spanners, your more then qualified to give me advice. I like to ask questions and the more people who respond, the more I learn. My goal has always been the same, to have an excellent running drag bug and street car, so others outside of our hobby can see what our cars can do. In order to have that, it takes the knowledge of many, in my opinion. I really appreciate everyone giving me advice, and I say keep it coming...

[Udo]

Udo, yes, a very well built, good running car...I miss seeing it along with Warren and crew racing it. Do you know if Warren will be back racing again?

I hope so , he still owns the old Bubetz turbo car that is stored in his garage for many years now.

Udo

[Bruce67]

Jim, you are a buffet of knowledge....I understand now. Yes, the motor pulls hard from 44/4500 rpm to 8000 plus...The trans in the car now is 4.11 2.36 1.65 1.22.
The trans that ran the 10.92 is sitting as a freshened up spare, and unfortunately, I dont know the gear stack. It was included with the car.

So, I can retard the timing 2-4 degrees, up the carbs to 51.5's, change to some 1.45's (because I have a set of Bergs already) and tune on the carbs...

How will this change ignition timing? More, less, same???

[Jim Ratto]

Jim, you are a buffet of knowledge....I understand now. Yes, the motor pulls hard from 44/4500 rpm to 8000 plus...The trans in the car now is 4.11 2.36 1.65 1.22.
The trans that ran the 10.92 is sitting as a freshened up spare, and unfortunately, I dont know the gear stack. It was included with the car.

So, I can retard the timing 2-4 degrees, up the carbs to 51.5's, change to some 1.45's (because I have a set of Bergs already) and tune on the carbs...

How will this change ignition timing? More, less, same???

I wouldn't change it all at once. Make one change and look for consistency
the easiest change is rockers, start there. Next would be removing oil pump and changing timing on cam. Carburetor mod would be most involved.
Retarding cam timing might allow more total advance, or possibly just more initial, if you're running an advance curve (not locked).

[spanners]

Thanks for kind comment Bruce, Jims bang on with one change at a time, and the rocker change and cam advance too, slight contradiction there, but the two go together,, almost, the only thing to watch is your push rod length and p/v clearance at overlap, you MUST check only with light springs so you can hand operate the valves, trying it with the race springs on playdo is dangerous in that you won't feel any contact, and the motor can kick over on Spring pressure alone, plenty of aside checks with apparently small changes eh, with the 1.5s an eye out for coil bind and retainer contact with the extra lift too don't forget. 

[Jim Ratto]

Thanks for kind comment Bruce, Jims bang on with one change at a time, and the rocker change and cam advance too, slight contradiction there, but the two go together,, almost, the only thing to watch is your push rod length and p/v clearance at overlap, you MUST check only with light springs so you can hand operate the valves, trying it with the race springs on playdo is dangerous in that you won't feel any contact, and the motor can kick over on Spring pressure alone, plenty of aside checks with apparently small changes eh, with the 1.5s an eye out for coil bind and retainer contact with the extra lift too don't forget. 

Good points! Sorry I didn't mention, if you go to higher lift rockers, it isn't just bolting them on... you gotta go through the motions, check piston to valve AND full spring travel to coil bind (checking springs requires using real springs). I mock the motor up with cam, 8 lifters, real pushrods, rockers (geometry set) lash caps, zero lash, and dial indicate all 8 valve full lift. I then put each head in a drill press, like Berg's blue book describes, and dial indicate coil bind. On a race motor, I would look for .050"-.075" between full lift and bind.

[Bruce67]

Guys, thanks so much...your knowledge and advice is greatly appreciated. I'm at the point where I can start getting the short block together and I'll be placing an order to Bergs for some new springs and shims. New rockers are ready to go and I have a new set of pushrods, so hopefully I can get to a longblock in a reasonable amount of time.

Stay close as I'm sure I'll have some questions as I move along...G.B. 801 is a great tool Jim.

[spanners]

You're right about real springs Jim, cam deflection etc, but I do initial rocker change set up and valve contact checks with light springs on the changing  bank To get in the ball park, berg 1.5s are giving some serious lift, about .624". It will be interesting to see Bruce move forward, gotta love developing an atmo motor, you turbo guys so miss out on the love lol

[Bruce67]

Spanners, lol ...

Okay, case, crank and rods are cleaned, new bearings are in and I'm ready to assemble the rods to the crank. I was reading through G.B. 800, and Gene said he liked to grind grooves on the rod/cap face for extra oil spill off. Anyone ever done this?