Going from 402 to 416 and Bigger Cam !!!!!!

[Dirty Howie]

I was going to just replace my oil drinking 402 short block but am considering moving up a little and would appreciate any advise or comments.

Right now I have a 402, 224/228 cam, AFR 205 Heads, 30# Injectors, LS2/Fast Intake.

Considering changing to a 416, 228/232 cam, Porting the AFR's, and 36# or 42# Injectors. Intake will remain the same.

Concerns:
1. don't want to loose any quick reving off the line or down low performance
2. still needs to be very behaved as it gets 400 miles of stop/go freeway and
city driving.
3. car is also used in open track racing....will I get down the straights faster?
4. any mpg hit ???
5. anything else I should consider
6. should I just leave the present combo alone

Also will it be drivable for breakin and awaiting dyno tune by just adjusting the cylinder size and injector flow rate and quick VE/MAF adjustment or will idle or other issues need immediate attention.

Thanks.......


DH

[Dirty Howie]

27 people have read this and not one comment on engine, cam, tuning ????

Not even a wisa ass comment


DH

[SSUte01]

I was going to just replace my oil drinking 402 short block but am considering moving up a little and would appreciate any advise or comments.

Right now I have a 402, 224/228 cam, AFR 205 Heads, 30# Injectors, LS2/Fast Intake.

Considering changing to a 416, 228/232 cam, Porting the AFR's, and 36# or 42# Injectors. Intake will remain the same.

Concerns:
1. don't want to loose any quick reving off the line or down low performance
2. still needs to be very behaved as it gets 400 miles of stop/go freeway and
city driving.
3. car is also used in open track racing....will I get down the straights faster?
4. any mpg hit ???
5. anything else I should consider
6. should I just leave the present combo alone

Also will it be drivable for breakin and awaiting dyno tune by just adjusting the cylinder size and injector flow rate and quick VE/MAF adjustment or will idle or other issues need immediate attention.

Thanks.......


DH

Depends what you wanna achieve to be honest, if you need to freshen up the engine anyways then why not up cubes a little and increase the cam a little as well. Again where do you see the balance between driveability and power, seems like you enjoy the circuit stuff a fair bit and wouldn't mind the slight loss (if any) in civility and economy.

Which ever cam you choose, this is 'my' thinking on my experience with only a few different cams, go aggressive with lift and if peakiness and every last hp isn't for you choose a reasonably wide LSA, say 114 is a good daily driver IMO. I think something along the lines of 232/234 114LSA and around 0.600" lift. Dunno if anyone makes a cam like this without going custom (I think Comp have something like that) If you dont think your current cam is too radical then you may not notice too much extra from what you suggested above (depending on current lift). The only other consideration is that 3000 stall might not be enough for a cam that large - not sure, don't drive autos much.

On the heads, again just my thinking is go as high of a compression ratio the regular fuel you use can support. Match all this together with well chosen exhausts and intake (P.S - Ditch the MAF ) and it *should* fly

1. I think your stall should take care of this or at least most of it depending on the path you choose
2. See 1.
3. I cannot see any reason why not
4. I would say some, but not a great deal unless you spend a long time in v.low or stop/start traffic. Although extra compression will offset some or most of this
5. Get lots of opinions (face-to-face if possible and never solely trust opinions on the internet ) Also if possible test drive something similar, if at all possible to see if you can live with it.
6. Dunno how much you have to spend and how happy you presently are - this one is up to you, but if you are very happy then perhaps the old adage, if it aint broke, don't fix it (the H/C combo, not the oil consumption I mean)

These are just my opinions but what does your engine builder suggest, no doubt he would have some advice. I think it is important to match your mods your desired outcomes and driving not the other way around.

Hope that is what you wanna hear, no doubt you will have another ripper combo

[Dirty Howie]

Thanks for addressing my questions and for giving your opinion and advise!!!

I got alot of C6 Z06's and Vipers and an occasional Porche Turob or Ford GT to deal with down the straights. So I'm leaning towards the extra displacement


DH

[WS6FirebirdTA00]

Don't touch the heads, I would only unshroud them if you have not already. If you change the cam, I would mill the heads to offset the change in DCR. This will help prevent low end losses (given cam specs are similar, just a later intake valve closing).

On a motor that size, you could probably go with a 232/238 without any issues. If you change injectors, I would recommend GM 36#ers from the GTP (really 39# on our pressure). They should be good for just over 500 hp at 80%. Is the intake ported?

[MNR-0]

That is such a wimpy cam for those cubes. Massive gains to be had by upping those lobes to something like 256-260

[WS6FirebirdTA00]

yeah, I just think he is trying to keep this semi-tame though lol

[Dirty Howie]

Don't touch the heads, I would only unshroud them if you have not already. If you change the cam, I would mill the heads to offset the change in DCR. This will help prevent low end losses (given cam specs are similar, just a later intake valve closing).

On a motor that size, you could probably go with a 232/238 without any issues. If you change injectors, I would recommend GM 36#ers from the GTP (really 39# on our pressure). They should be good for just over 500 hp at 80%. Is the intake ported?

Thanks for stepping in.........

Looks like I have another week till my car goes in.

I don't really know what unshrouding means. I was over at AFR and Tony Mamo showed me how the topof the chamber around the valves is opened up??

My builder wants to use the 36# also .... he's sure it enough even though I suggested the 42#

Both my builder and guy who's tuned my car and know me agree that the 228/232 cam is okay. I think its easier to smog also. I don't want to get into a big lopey, slow reving setup. I'm sure your advise on the cam size is good. I will bring it up with them.........I can always put a bigger cam in some day.


DH

[Dirty Howie]

That is such a wimpy cam for those cubes. Massive gains to be had by upping those lobes to something like 256-260

I must be a cam pussy ...........


DH

[WS6FirebirdTA00]

yeah cam size really depends on what you want to do with it. Did Tony do the work on your heads? If so then he prob took care of them. The critical thing in my opinion is keeping that DCR up.

I also have a DCR calculator so if you need a hand figuring it out, shoot me a PM.

[Dirty Howie]

yeah cam size really depends on what you want to do with it. Did Tony do the work on your heads? If so then he prob took care of them. The critical thing in my opinion is keeping that DCR up.

I also have a DCR calculator so if you need a hand figuring it out, shoot me a PM.

No Tony will not be doing the porting ....... due to circumstances beyond my control.

The porting will be done by the builders source.....or I may just pass if its something that can cause issues if screwed up. I'm sure the guy is reputable as A&A Corvette is ultimately responsible if the heads get screwed.

When I went over this with A&A he already figured my CR would remain at 11:1 and if necessary the heads would be shaved.

Thanks for the calculator offer but probably would have no idea what to do with it.

What is the D in DCR ........ (dynamic ??)

THANKS


DH

[WS6FirebirdTA00]

yeah it is. Only reason I would not mess with the heads is I would be afraid the airflow quality would be messed up, esp at low flow for low end power.

[MNR-0]

I must be a cam pussy ...........


DH

Hehe.

I used to be a small cam guy, like 212-220 for my 346. Now I have a 236-240 in it and it drives better than the 212-220 ever did. I am not convinced that big cams are suckers to drive, it just depends on how well you tune it down low. Perhaps I didn't know enough at the time of tuning the 212-220, but if I had my way again I would go even bigger for the 346.

With those cubes, IMO a big cam will not hinder the part throttle response at all. A mate of mine has a 256-260 in his 346 and reckons it idles way better than his 232-234 ever did.

You wil always get different points of view on this subject, but all I can say is don't be scared of big cams. EFI tames em down quite a bit.

[EC_Tune]

However, Howie is in Commiefornia so he has that to deal with....

[Dirty Howie]

However, Howie is in Commiefornia so he has that to deal with....

So what do you think about cam size Doug ??

I could just stay with a 402 ........


DH

[Dirty Howie]

UPDATE !!!!!!

Looks like I am moving up to AFR 225 heads !!!!!!!!

I decided that with a new short block I wanted new heads also.

Couple of people said I definately should move up to the 225 heads with the 416 block. And I took WS6Firbirds advise and not mess with porting the heads.

So the combo is Stroked L92 (416 CI), 228-132 LSA 14 Cam and AFR 225 Heads..............

So now I will sell my AFR 205's and let some one else freshen them up !!!!
By the time I got done with costs for porting, the new upgraded AFR springs (which come on the 225's), maybe valve guides it made more sense to go new and bigger for just a little more money.

Comments ???????


DH

[EC_Tune]

Sounds like you are going to have too much fun.

BTW: Car with a 228 236 cam just passed smog.
I know who tuned it too......

[Dirty Howie]

Sounds like you are going to have too much fun.

BTW: Car with a 228 236 cam just passed smog.
I know who tuned it too......

Thanks Doug

I've been told that this is the magic cam threshold.

I'm going to try and break this thing in right with the new upper end and hopefully get the rings seated properly too this time.

Scoggin Dicky recommends thousands of miles with non synthetic Rotella or similar oils. What do you guys do....easy miles first or just go for it .... seems like different ideas out there.

Definately not going to worry about the dyno until some breakin first.

I'm hoping I can just change the cylinder size and injector tables for startup. Then adjust the VE leavinig it in OLSD during breakin. Any advise would be welcome !!!!!!!!!!

Hoping I can hit 500 RWHP and pull the new Z06's down the straght at WSIR


DH

[EC_Tune]

I've heard about running "standard" oil for break-in. Sounds like a plan. And if you're really paranoid (or safe ), slap a FilterMag on your oil filter to catch any iron particles that are floating around early on. Then after the initial 50-100 miles, change the oil. That gets rid of any small bits and any assembly lube and other break in goodies. Then after 2000 miles on "standard" oil change it again and start running Mobil 1.

My personal favorite for breaking in a motor though, is to drive it like you stole it...

[Dirty Howie]

I've heard about running "standard" oil for break-in. Sounds like a plan. And if you're really paranoid (or safe ), slap a FilterMag on your oil filter to catch any iron particles that are floating around early on. Then after the initial 50-100 miles, change the oil. That gets rid of any small bits and any assembly lube and other break in goodies. Then after 2000 miles on "standard" oil change it again and start running Mobil 1.

My personal favorite for breaking in a motor though, is to drive it like you stole it...

Doug

Many people subscribe to the just drive the shit out of it the soon as it starts up. Others recommend not going over mid rpm but varying it for first 500 miles. I wish I knew for sure what the best way is. Never heard the change oil after 50-100 miles before. Magnets sound like a great idea ........


DH