emo-vet

hi guys,
how are ya!
well i typed in search engine cam shaft fire order swap,no results.
ok i was just wandering if any one can please reccomend what cam fire order swap to do ??
im ordering a new billet roller comp cam cam 236/242 duration @.50 " in 112 lobe sep with about .585 " lift and advanced duration of 288/292.
i spoke to comp cam tech guy again and asked him about changing the fire ordering with the cam!!
what are your opinouns of this please ??
suppose to help with less harmonic vibrations and free up a bit of hp as well.
he said do the 4-7 swap!
but i also heard you can do as well the 2-3 swap also
so you can do a 4-7 & 2-3 swap all at once just like the Ls series engines have.
that will give a fire order of 1-8-7-2-6-5-4-3
any ideas and help please r.e all this?
thanks
shae

emo-vet

any ideas please guys ???
thanks
shae

cv67

Dont think youll see any power gain from it, but your wallet may feel lighter. Some people like to have something different though, some claim it may change the exhaust note a bit. .
Just my .02, opinions may vary.

No Go

Not worth the concern at this level...maybe once you exceed 600 hp.

A bit more money spent tuning will get you much further.

red L98

i run the 4/7 swap and my motor gained 12 Hp on engine dyno. they say you only see huge HP gain on big inch SBC and BBC

emo-vet

hi guys,
thanks for the replies.
i also heard that it inables a better idle there fore you can run a larger duration cam ??
shae

Iroc57

You asked for opinions so here is mine

Run as designed.....spend your time and $$$ on other things.

again...just my $.02

genefree3

Do you think maybe the guy you talked to works on commision?
There's an old saying, "a fool and his money are soon parted"

hgh pwr

I agree with the above statement,don't waste your time or money.

Slalom4me

Hot Rod used to have an article "Which Firing Orders Improve
Performance?" but it no longer comes up. Here is another one from HRM
along with so other links. While reading, consider the intakes discussed
and how their behavior differs from your IR set-up as far as firing order
changes are concerned.

Testing Lunati Cams - Swap Cam Test
Can Changing Your Firing Order Actually Make Extra Power?
writer: David Freiburger

camshaft 4/7 3/2 swap

firing order swap on 4&7

Can i program my LT4 to fire in sequence?? 12345678

.

staugur

Hey Shae I was trying to find an old post about some guy trying to get his vette to sound like a mustang(God knows why).Someone suggested changing the firing order to the same as ford.Can't find it but have to say the old GT40's sound a lot sweeter than the C6R's.Heresy I know.

emo-vet

hi there guys,
thanks for the replies coming in
thanks slalom4me for the links as well.
so far from doing varoius searches on google and other engine forums i have read this about cam swap firing orders,

better idle
runs smoother
possible better sound
cylinders get better cooling
broader torque curve
blocks,crank,main bearings live longer
possibly reduced harmonic vibrations
possibly some small hp gain

this swap btw guys from comp cams only costs another $ 50.00.
cheers
shae

Slalom4me

Check the last link in the post immediately above yours.

Can i program my LT4 to fire in sequence??

Here is another post about firing order.

.

Slalom4me

As per my earlier post, absorb the sections containing speculation as
to why some of these benefits are realized. Does your EFI IR intake
w/ its discrete stacks & filters stand to benefit to the same extent
from changing firing order as a 4bbl single plane whose runners converge
on a common plenum?

Also, does your intended ECM require re-sequencing of injector pulses
and if it does, is this configurable?

Erson is also a source for OEM-roller, stepped-nose cams, they ground mine.

.

rodj

I figure you have enough on your plate trying to get the right tune in Oz with your setup as it is; just adding more trouble.

rodj

Interesting comment from above links.

"I only charge $99 to balance any cam, and that'll reduce valve train harmonics MORE than changing the firing order.
"

Slalom4me

Enthusiasts often don't think much about the camshaft, beyond
ensuring that the basic install issues are addressed. Greg Gore has
written in the past about the preparation that goes into the cam
area of a serious effort.

As discussed in the link, cams with the mechanical fuel pump lobe would
be expected to benefit the most from balancing. Cams for EFI apps
lack this FP lobe.

And reduction of valve train harmonics isn't the primary reason I became
interested in the 7/4 swap.

.

emo-vet

hi rod and slalom4me,
thanks again for your replies.
yeah i proberely are taking om more head aches than i need but i want to be sure that i have every angle covered in all parts i buy for this monster 388 c.i motor im in the process of getting built.
r.e tuning ,now tht i have the haltceh after market ecm to be able to run the 8 t/b inake i will be able to get the tuning done live and on the dyno so hopefully i can get it tuned ok.
btw rod i got that 16 lb external balance flywheel now machine balanced to NEUTRAL balance now to suit my internal rotating assembly.
spoke to a very good mate of mine kevin (badss) about the fire order swap and he said that just stick to the 4-7 swap as it will sound better than the 4-7 & 2-3 togeather.
but from what i gather so far from varoius comments/searches thru out the internet and books now there is some good to come of doing the cam fire order swap.

any way thanks for your interest and ideas guys.
cheers
shae

cv67

One thing I have heard that is positive is the 5 and 7 cyls dont fire consecitively so the 7 isnt struggling for air at higher rpm. Honestly I dont know if thats a real problem or a perceived possibility...