Planning for 408 - Possible Solid Flat Tappet cams

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Im currently running a dinky hyd 232@.050/.517”/106lsa with Air Gap, EQ heads with small intake valves and it’s plenty fun on the street. Runs high 11’s in the 1/4 too. Very streetable as is, but can become a handful in an instant. Around town with 4.10 and 3500 stall it’s a blast, from a stop it blows the tires off all the way into 3rd until I let off, so I go easy and romp from a roll. Doesn’t take much cam to do what I’m doing with the 4” stroke if everything is matched and tuned right. Don’t really think you’re going to get a specific cam recommendation here only that you can go bigger than you think (250’s@.050”) but if you go conservative (230’s@.050”) you’ll still have a beast of an engine. Of the three shelf cams you listed that Howard’s 238@.050” would do, why not fill out their request form, then follow up call them and see what they would spec?
 
I did mention a duration like that but tend to slip up and make that mistake thinking at 360 cubes. My bad.
I’ve been off over the last few...
My brains clutch is slipping....
 
you can go to the lobe profile section of his website and look up the .006 from the duration and lift
not like Hughes
Good thoughts as usual NM -- rally is closer to street than bracket racing
I would suspect Mike shortened the intake and kept the exhaust to hold some top end
 
Filled out custom grind cam form from Howard’s cams. I’ll see what they come back with.
 
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? Did you give jones your head flows after you worked out your Compression?
I would suspect he would fine tune his recommendation as his computer program is based on valve motion and flow and works backward to the cam
ps hope you are thinking solid with EDM lifters
rocker ratio also makes a difference so ask him if 1.6 are needed on In EX or both
Iron rockers will be fine for your build
lots of other places to spend your $$$ than on roller rockers and the B3 kit necessary to be reliable especially with the autocross usage
I'd ask b3 which rockers for those heads as I hear that some work better than others
 
jones cams used the trick flow numbers they publish with their heads. Yes planning on solid edm lifters. Spoke with b3 already about the geometry correction for trick flow heads and he recommended the prw stainless steel roller rockers and a shim kit.
 
cawcislo said:
The car Will be mostly for fun on the street, so it has to have torque and not be a dog until high rpms. For max rpms I put 6200 for cam specs for that cam from jones cams. Should I be Revving this 408 higher? No advertised duration from jones cams. I did request a street cam from them and not a race cam. This is not a single purpose drag car. Car weight 3000 lbs.
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My stroker experience is none. They are just naturally more RPM limited, based on piston movements after TDC. 6200 RPM seems like it is high for that IF you are road racing/ autcrossing.... not that it can't run there but will be naturally rolling off and so the cam needs to be more duration to get there RPM. Pushing the cam to work at that RPM range will raise the bottom end of the RPM range and there is the issue of concern for me.

If the RPM range is 3000 to 6200 with a bigger cam, then the usable RPM ratio is 2.06. If the RPM range is dropped 500 RPM at both ends with a smaller cam, that is 2500 to 5700 RPM; usable torque range ratio is 2.28. To get to that RPM range ratio with the bigger cam, the lower RPM now has to be 2700 RPM with the big cam. But you are off the torque curve of the big cam at 2700.... You don't have a torque converter to allow the RPM's to rise up.... you are stuck with the narrow RPM range ratio.

That will make a difference with that 4 speed, and hard running like on autocross. Trust me, you will find corners and speeds where 2nd gear will be too low and 3rd gear will be too high... So the real reason to stay smaller is to get a bigger RPM range ratio, with your intended use and the 4 speed.

Just an experience: I had a 1.6L rally car with a solid 2500 to 6500 RPM range (2.6 RPM ratio), that was hands-down a much better rally car than a higher HP 1.9L with a 3700 to 7500 RPM range (2:1 RPM ratio). Both 4 speeds... the bigger engine would get into spots where you could not find the right gear and RPM combination.... the RPM range ratio did not work with the gears. I revved it past 7400, sometime to 8200, just so the RPM drop going into 3rd did not kill the torque. The smaller engine with the smaller cam was never in that kind of situation.

Hope that helps.
 
Requested a custom grind from Howards cams. I got a reply back with an off the shelf grind from them. 254/260 duration @ 0.050, .550/.555 lift, 108 LSA. Wow that's a pretty big cam for a street car. I thought I was pretty clear that this isn't a race car.
 
cawcislo said:
Requested a custom grind from Howards cams. I got a reply back with an off the shelf grind from them. 254/260 duration @ 0.050, .550/.555 lift, 108 LSA. Wow that's a pretty big cam for a street car. I thought I was pretty clear that this isn't a race car.
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I've got a 408 with TFS heads and 391 gears, 4 spd. Cam (hyd FT) is 251/257 @.050, .565/.565 lift (but I went to 1.6 rockers for nearly .600 lift) and 110 LSA (howards had a grind I wanted more, but was several more weeks out.. should have waited, but oh well). I would call it a street cam. Runs about 8" of vac at idle. Cleans up quick and I can cruise at 2k in 4th with no issues, no bog, etc. My idle is ~900, FWIW.

Biggest difference with the cam you list is the 108LSA and it's a solid (right?), it will idle a little rougher but should get a little better mid-range and will still probably clean up quick. Being a solid, depending on the recommended lash, it may even act a little smaller and be better behaved. Id want to see more lift to take advantage of the TFS heads, but that cam in your motor should still be very stout. I'd run it without any worry about being too 'racey'.
 
cawcislo said:
Requested a custom grind from Howards cams. I got a reply back with an off the shelf grind from them. 254/260 duration @ 0.050, .550/.555 lift, 108 LSA. Wow that's a pretty big cam for a street car. I thought I was pretty clear that this isn't a race car.
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Hmm, they recommended a 274 advertised, 246@.050”, .384” lobe lift, .615” w/1.6 rockers on a 108LSA for my much racier request. I went with something else a bit bigger. They may have misinterpreted my “a little street use” notation. Cams can be sooo confusing. Take the Jones and Howard’s specs and split the difference...call it a day!! :eek:
 
cawcislo said:
Requested a custom grind from Howards cams. I got a reply back with an off the shelf grind from them. 254/260 duration @ 0.050, .550/.555 lift, 108 LSA. Wow that's a pretty big cam for a street car. I thought I was pretty clear that this isn't a race car.
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No way does it need a 6 degree spilt. That's nuts. I'd look at 250ish on both sides, use a 1.6 rocker for the extra lift and get it ground on a 106.
 
Not trying to sell you anything but for what you are wanting to do I have a new cam (just listed it for sale on here) that would be a good fit. I would consider this a good street/strip cam, it was for my 408 with trickflows but I decided to go with the lunati I originally wanted. get some opinions/do some research and if you are interested let me know and we can talk.

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Just something to keep in mind is that most of the lobes mentioned here will require you to shim the springs to yield approx 140lbs+/- seat pressure on the TF’s. All of the lobes I considered (which were in the range of many mentioned here) required this. The seat pressures of the springs as delivered on the TF’s is 120lbs so make sure you get those specs from any grinder you contact.
 
I'd go to the Howards website and match up the lobes then use the springs and pressures howards recommends
some think Hughes spring pressures excessive and losing lobes
that "some think" means IDK from personal experience
 
The Hughes springs (PAC) aren’t excessive IMO
 
It's how there set up
do you need 145 on the street
wrong lobe family
 
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or it could be a offshore knock off
are Lunati pacaloy springs pac?
Isky labels their pac springs as pac
and "tool room" springs have been custom wound by associated
but once someone private labels they can sub in whatever they want
 
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