Converting LA 360 to roller cam

[Infecteddog]

Just curious- was thinking this looks like the cam I want to run:
https://www.summitracing.com/parts/lun-20200715

2000 stall 904 NLU, 2.45 gears, M1 MPI, stock Mag heads, manifolds now but plan to go back to headers. Plan to build a 42RE for it and probably swap to 4.10s.

Was thinking Morel lifters at this point- not really sure what the best bet for lifters would be. Just want to not have issues in the retrofit of the '73 block 408.

 

[magnummopar]

There are about 100 cam grinds I would use before I put that in my engine, specially if you are running FI.

 

[boingk]

If you're chasing lifters, try looking at the Rhoads type of pump-up lifters. They are almost like retro-tech variable valve timing, and bleed off cam duration up to 3000~4000rpm before then giving you the full profile. This lets you have more vacuum and better torque down low and still have everything on offer up top.

If not that, I'm using fairly basic Elgin lifters in my build as I have heard that they are a good, reliable unit so long as you aren't flat-track racing at 8,000rpm... which I won't be.

- boingk

 

[B3RE]

Just curious- was thinking this looks like the cam I want to run:
https://www.summitracing.com/parts/lun-20200715

2000 stall 904 NLU, 2.45 gears, M1 MPI, stock Mag heads, manifolds now but plan to go back to headers. Plan to build a 42RE for it and probably swap to 4.10s.

Was thinking Morel lifters at this point- not really sure what the best bet for lifters would be. Just want to not have issues in the retrofit of the '73 block 408.

With your combination, I think that is a pretty decent cam. A fairly wide lobe seperation, and tame duration, for use with the computer and MFI, and perfectly sized for the converter and axle gear. When the gear is changed to 4.10 with the OD, adding a set of 1.6 rockers would make it even better.

The Morel lifters will almost certainly be fine, although there is always the possibility of the block casting getting in the way, no matter what lifter you run.

 

[magnummopar]

B3RE, if OP has magnum heads, he would have 1.6 rockers stock. Why do you think the cam needs so much exhaust duration and so little lift? The 1.62 magnum exhaust valve along with a nice exhaust port(for factory) should not need added duration with a fast ramp of a roller. I would rather see around [email protected]" but more like .500-.520 lift on both I & E. I will admit my ideas on cam design differs from about 80% of the planet, just interested in your opinion as I know you understand valve train geometry better than most.

 

[B3RE]

B3RE, if OP has magnum heads, he would have 1.6 rockers stock. Why do you think the cam needs so much exhaust duration and so little lift? The 1.62 magnum exhaust valve along with a nice exhaust port(for factory) should not need added duration with a fast ramp of a roller. I would rather see around [email protected]" but more like .500-.520 lift on both I & E. I will admit my ideas on cam design differs from about 80% of the planet, just interested in your opinion as I know you understand valve train geometry better than most.

You know, your right. I was reading the notes for the cam, which is a long snout with shaft rockers, and overlooked the magnum heads. In that case, that wouldn't be the right cam for something using MFI and an electric pump anyway. Something around 215-216 @.050" with the 1.6 rockers would be a good choice, as you mentioned. Occassionally I have one get by me. Good catch.

 

[Infecteddog]

You know, your right. I was reading the notes for the cam, which is a long snout with shaft rockers, and overlooked the magnum heads. In that case, that wouldn't be the right cam for something using MFI and an electric pump anyway. Something around 215-216 @.050" with the 1.6 rockers would be a good choice, as you mentioned. Occassionally I have one get by me. Good catch.

I'm using the old cover and I don't think I'm going to the new one anytime soon. I run an RV2 on my M1 to be special- if I switch I'll probably go to the '79-up style Sanden since I can. I have a Saginaw power pump as-is. I have a stock '96 318 Ram computer. I may end switching to a stock '98 318 Durango computer if I go OD quickly if my buddy swaps his LRE around to MPI around that time since it'll stay 727.

I wanted to keep the lift low- swapped over to stud-mount roller rockers but retained the 1.6 stock rocker ratio. I didn't see anything at 215-216 @ .05 in the final runners up on both, I didn't want the duration so low on the intake that the 'rango's 5.2 cam would be about as good with 1.7s. 213/219 and 221/225 were the ones I came down to. About all of them I've seen in shelf cams have a pretty steep split like that. Because of being a 408 I don't want the duration to be too low even though it's just around 8.8:1.

 

[magnummopar]

That is the thing with injection, you dont need tons of duration. With a quick ramp roller cam and lots of intake speed you can use higher lift to your advantage when used in conjunction with a shot of fuel right into port timed for valve opening. You will get more power than with a standard flat tappet hydraulic cam gradually opening, trying to keep fuel suspended while in intake. Just look at the difference between the lobes of a FTH vs roller, FTH opens up slowly and isnt open all the way for long, while roller opens all the way super quickly and stays at max lift a lot longer. Non roller MPFI Engines are not very common

 

[magnummopar]

I wanted to keep the lift low- swapped over to stud-mount roller rockers but retained the 1.6 stock rocker ratio. I didn't see anything at 215-216 @ .05 in the final runners up on both, I didn't want the duration so low on the intake that the 'rango's 5.2 cam would be about as good with 1.7s. 213/219 and 221/225 were the ones I came down to. About all of them I've seen in shelf cams have a pretty steep split like that. Because of being a 408 I don't want the duration to be too low even though it's just around 8.8:1.

The factory 5.2 cam is only about [email protected] so going to 1.7 would be no where close. The lift is only .439" on 5.2 factory. The problem is that most of those box grinds are based on GM engines or at best LA type cylinder heads with weak exhaust port/valve from 20+ years ago if not the 70's. They are not designed for strokers either meaning you are leaving a lot of power on the table. Without a proper flash, you are leaving a lot of power on the table too....both those combined together could easily cost you 75+ HP, maybe more. You need a custom grind and flash plus some larger injectors and throttle body. Then save up for some 1.97 intake valves and a bowl hog but I would step up from factory heads before I spent anything more than a valve job on stockers due to cracking.

 

[Abodybomber]

That is the thing with injection, you dont need tons of duration. With a quick ramp roller cam and lots of intake speed you can use higher lift to your advantage when used in conjunction with a shot of fuel right into port timed for valve opening. You will get more power than with a standard flat tappet hydraulic cam gradually opening, trying to keep fuel suspended while in intake. Just look at the difference between the lobes of a FTH vs roller, FTH opens up slowly and isnt open all the way for long, while roller opens all the way super quickly and stays at max lift a lot longer. Non roller MPFI Engines are not very common

BAM!..You nailed it,airflow optimised,

That is the thing with injection, you dont need tons of duration. With a quick ramp roller cam and lots of intake speed you can use higher lift to your advantage when used in conjunction with a shot of fuel right into port timed for valve opening. You will get more power than with a standard flat tappet hydraulic cam gradually opening, trying to keep fuel suspended while in intake. Just look at the difference between the lobes of a FTH vs roller, FTH opens up slowly and isnt open all the way for long, while roller opens all the way super quickly and stays at max lift a lot longer. Non roller MPFI Engines are not very common

THANK YOU!....

 

[barnett468]

why do you want to keep the lift low?

that cam is too small for 4.10 gears

i would make sure you have at least 9.5 compression