TT5.9mag
Two atmospheres are better than one
I hated math in school/college but it’s because I was forced to do it. Now building engines I tend to like it. It’s definitely a love/hate though.
Overlap Triangle
- Thread starter Danny Bellmore
- Start date
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You are correct about the engine builder, they should have the information to select the proper head for the intended application but the correctly designed cam will, for a lack of a better word, fine tune the velocity.
Yes i'm the same, unfortunately my math skills only go so far.
Yes i'm the same, unfortunately my math skills only go so far.
There's probably no formula that's gonna give you the 100% ideal cam no matter how much specs are accounted for, there's probably always gonna be room for improvement. Questions is, is it gonna get you in the ballpark better/consistently than other methods.
and even if you did unless a gear drive is used that 1 degree will vary with a chain
Danny Bellmore
Active Member
They are 5/16.
Newbomb Turk
Well-Known Member
Ok, let me find some lobes that aren’t so aggressive.
The valve train won’t take that with 5/16 bolts although I know someone will say they are running 280 on the seat and 650 over the nose with 5/16 bolts.
I don’t like that.
Danny Bellmore
Active Member
BPE by Rod Bloomer.
Danny Bellmore
Active Member
The last cam I ran was Comps 20-718-9
PRH
Well-Known Member
As a point of reference………That cam isn’t hard on parts.
Danny Bellmore
Active Member
PRH
Well-Known Member
Understood.
But there was a comment where someone was searching for lobes that weren’t aggressive.
I’m just pointing out the lobes on your current cam aren’t.
But there was a comment where someone was searching for lobes that weren’t aggressive.
I’m just pointing out the lobes on your current cam aren’t.
Newbomb Turk
Well-Known Member
Newbomb Turk
Well-Known Member
Ok so it’s 269/276 .654/.655 on a 109. That’s a pretty nice grind.
I’ll look around and see what I can find but they have a 271 lobe that would be nice for the intake.
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PRH
Well-Known Member
It’s a 106.
Grind # RX302S-R6
I’d be curious to know what springs and installed height the heads were set up with to go along with the 1.6 rockers.
Grind # RX302S-R6
I’d be curious to know what springs and installed height the heads were set up with to go along with the 1.6 rockers.
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Newbomb Turk
Well-Known Member
Danny Bellmore
Active Member
I finished tearing the engine down. Seems like losing a bronze gear plays hell with everything. I’ll be sending my block to the machine shop this week. One thing I’m confused by is a local engine builder suggested that I go from a solid roller back to a solid flat tappet cam. Isn’t this like taking a step backwards?
I was taken back by that suggestion.
gzig5
Well-Known Member
Step back in what regard? Power potential, yes. Reliability, could be argued either way. If you had a SFT, you wouldn't have shredded a bronze gear because there wouldn't be one. SFT may have issues on break-in with current lifters if they aren't made right, but a roller is a more complex system and has more failure opportunities. Everyone has different opinions and experiences on the topic. Both systems can work great, or be a nightmare if something breaks.
Danny Bellmore
Active Member
On this set up I used Bam bushed dlp coated lifters. The gear issue kinda pisses me off because I really had to search high and low for one. Milodon was out and now I’m finding out that they may have had a bad run.
PRH
Well-Known Member
If it’s primarily a street car that will see a fair amount of mileage annually, I can understand the lure of the SFT cam.
The problem in my mind is, there really isn’t what I consider a readily available reliable known quantity lifter solution.
I know of some people who have had good results using tool steel lifters, but I’ve also seen some strange wear issues with them too.
For a roller, I think you made the right call on the lifters, but got bit by the gear.
(I’d suggest a melonized steel gear for the next go around if you stay roller)
It’s a little catch-22 ish.
The problem in my mind is, there really isn’t what I consider a readily available reliable known quantity lifter solution.
I know of some people who have had good results using tool steel lifters, but I’ve also seen some strange wear issues with them too.
For a roller, I think you made the right call on the lifters, but got bit by the gear.
(I’d suggest a melonized steel gear for the next go around if you stay roller)
It’s a little catch-22 ish.
Danny Bellmore
Active Member
Newbomb Turk
Well-Known Member
There is no way I would go from a solid roller to a SFT for ANY reason.
You've already spent the money for the SR stuff and that's the hard part.
That roller is much more reliable than a SFT. I think some people confuse the lower spring loads of the SFT make it more reliable. It's not.
No way would I change that out. The gear issue is bad though. That still wouldn't sway me from the roller.
EDIT: I just read your last post. No way in hell am I running a bracket car with SFT lifters. That's a huge step backwards in any case.
Danny Bellmore
Active Member
PRH
Well-Known Member
For a race car, staying roller makes the most sense.
Danny Bellmore
Active Member
I will be dropping off my block off at the machine shop this week. Would you tube the block or bush the lifter bores if it were yours?
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