now sbc 400 possablities

[Wes Harden]

I think I know the answers but want to hear from the tribe.

1 will advancing Cam timing bring the peak torque lower in rpm curve.

2 Aluminum vs cast iron heads all specs the same, will aluminum ease or lessen preignion ?

 

[sweetk30]

aluminum heads i have read a lot on they say you can go 1 full comp ration higher over iron before the same level of pingging .

i know a local guy here with a TRUE z28 302/4speed car and he kept popping the 1 head almost every 10 years to the day for the little time he drove it . he swapped to aluminum heads and never had this problem again and the extra performance was a CRAZY bonus he said . . . and i should of done this years ago he said .

as to timming ? ? ?

 

[Bent77]

1 yes
2 yes

 

[Wes Harden]

Is what I believed. I have to reseal my mouse motor, timing seal pan and I am going to advance my cam 2°. Not sure if I am going to go aluminum heads on this engine. I have a 6" rod 355 that has a static compression of 175psi with a .047" gasket and .020 steel shim, I am going to put aluminum heads on that one and run it in my Chevelle. But all this has to wait till after the moving is done.

 

[Bent77]

What cam is it?

 

[Wes Harden]

IIRC this one https://www.summitracing.com/parts/sum-1103/make/chevrolet built this motor in 95 ish in it's second truck. 1st one was same 1977 sub but manual and beat to *^%$, wish I still had that truck ......

So this engine really starts pulling over 3k. I only get 3k plus in 3rd. 65 mph is @3500 rpm.
In 4th 65 is 2500ish

 

[Bent77]

Most aftermarket timing sets are cut for 3 settings -4/0/+4

I might run it +4

 

[Wes Harden]

I had considered 4. I think there is a 3 setting gear in there. I know it set straight up. Summit has a 9 setting chain set, one of them is 2.

I am opening this motor an fixing the leaks late October or early Nov. But I do have a sbc 400 thats needs a crank and rods, spun bearing. And new heads the ones on it were miss matched casting numbers and junk heads. Might be the original engine to the truck, was rebuilt at least once so.... I also have a 4 bolt main with a forged crank but that would be a waste for a low rpm thumper. Is another fresh 355 long block at my brothers that currently has no purpose thou that one has dish pistons and not balanced. does have a nice Engle cam in it.

 

[Bent77]

Those dish pistons will come into their own at 20 psi
But don’t try 28. The heads will orbit the block

 

[sweetk30]

If the 400 block is good . . . Stroke it out since it needs a crank . Got to buy 1 anyway .

 

[Bent77]

If the 400 block is good . . . Stroke it out since it needs a crank . Got to buy 1 anyway .

You have to notch the block to do that. Actually have to notch the block to run the 5.7” rod

 

[Wes Harden]

bigger stroke than 3.75 ?

 

[Wes Harden]

So investigating stroker cranks, I looked at a few rotating assemblies kits. I am not sure all the work and $$ to stroke a 400, is right for my needs. Might be worth the cost an effort in drag car. Not sure there is a benefit for big heavy truck, towing, you couldn't coax out of the stock stroke.

That being said the kits I saw mostly had longer rods 5.7 and 6". I like the idea of internal balancing with the longer rod, and might just do the 5.7". So just how close does this move the wrist pin to the oil control rings.
a small base circle cam what are the down sides, not very familiar with these.
I am warming up to the idea of redoing this 400, but if the cost get much over $5k I think I'd be better off getting a NEW GM performance 383 for $7kish

 

[Bent77]

These questions are best to ask @folkenheath

 

[Wes Harden]

I was hoping involve @folkenheath if /when I got closer to this being a reality. esp when heads cam and induction choosing. If wishes to discuss this I'll listen.

 

[folkenheath]

In general yes, and yes, but I am sure there are exceptions, especially on the cam timing.

I use and stock the 9 keyway timing sets that have 9 settings, -8, -6, -4, -2, 0, +2, +4, +6, +8.

I always degree the cam in and having only -4, 0, or +4 doesn't give you much options. However, I don't trust the units that you swivel it or pivot it and then tighten the screws down, because they could move. With the 9 keyway units, you can be within 2 degrees and it cannot move.

I do think the adjustable timing sets would be good for dyno tuning with a 2 piece timnig cover. But for running it long term the 9 keyway is the way to go for most people.

 

[Big Ray]

Soooo.....what's the latest?

 

[folkenheath]

The latest is cam cores are harder to get than they were over a year ago. The cams are mostly the same.

 

[Joel Wilson]

IIRC this one https://www.summitracing.com/parts/sum-1103/make/chevrolet built this motor in 95 ish in it's second truck. 1st one was same 1977 sub but manual and beat to *^%$, wish I still had that truck ......

So this engine really starts pulling over 3k. I only get 3k plus in 3rd. 65 mph is @3500 rpm.
In 4th 65 is 2500ish

Changing the tire size can change when the engine starts pulling hard, too. It can be cheaper than changing gears. My 400 starts pulling hard at around 2500 up to 3700. I am running 35's, 3.73s and a TH350.

 

[Wes Harden]

Yes, larger tires lower the rpm range for all transmission gears.
For me going from 33 to 35 will lower my cruise speed 125ish rpm.