[Biscuit6447]

I just recently put in a built 355 in my 1988 camaro.

engine has:

close to 13:1 compression
2.02/1.60 stainless steel valves
.510 solid lift cam with pretty long duration
significant valve overlap that causes really low manifold vacuum at idle
600 cfm carb
stock t-5 and a 3.08 posi rear end
stock brackets and pulleys of 305 tbi
Dual 2.5" exhaust, no cats
redline @ 6800rpm
poor low end torque

Questions:
Would 3.73 or 4.10's be better (currently 75mph @2000rpm in 5th)?
Would a bigger carb be better?
Would underdrive pullies add significant rwhp?
is 400 whp a good estimate?
would a cowl induction hood be better for the air intake?

other mods have been made:
-exhaust, headers
-mallory fuel pump, 140 gph
-new distributor, 10.5mm wires, ngk plugs
-dual radiator fans, 160 thermostat
-running 170 degrees during casual driving.


considering all the components of the motor, i have a terrible launch and poor 1st gear acceleration. I put the heads on and used arp studs. did a compression test; all good. any other suggestions to make it perform as it should? Really i am looking for the best acceleration and 1/4 ET, but it is my only car for driving 4-5 times a week, 30 miles each trip.

 

[barnym17]

With that cam gonna need some gear at least a 4.10 maybe deeper.

 

[lowandloud91]

____________

 

[techinspector1]

"pretty long duration"

ummmmm, what exactly does this mean?

 

[automotive breath]

With a standard transmission unlike an automatic; you will need as
low of a gear as you can handle.

 

[Biscuit6447]

I don't have the exact specs but something like 280int/280ext
I have a 5 speed manual with overdrive.

 

[cobalt327]

I don't have the exact specs but something like 280int/280ext

Is this advertised duration? I know that's not @ 0.050" (at least I doubt it is) so the 0.050" duration is somewhere around 230 degrees.

What is the p/n of the cam- if you don't know the specs?

What heads and intake? Do you have headers? A 600 carb is marginal at best. Which carb is it?

How are you figuring 13:1 CR, and why so high? With that much CR, you need a TON more cam to take full advantage of it, but this will hamper "drivability" by making the engine peakier, and it won't have enough vacuum for power brakes.

But w/13:1 CR, you will need race gas anyhow. So unless you plan on lowering the CR to a reasonable level (say, 9.5- 10:1 as a WAG) to match your current cam, you might as well cam hell out of it, put 4.56 or 4.88 rear gears in it and have fun.

The way it is now, it is mismatched, IMO.

 

[Biscuit6447]

Thats the problem, i don't know the specs of the cam or pistons. It was built by a hot rod shop so i imagine that is it decently well matched. It was sitting in my dads garage for a while, and i had the motor go out in my Camaro. I didn't have the money to replace it with new one, so naturally i used what was available to me. The motor was built, and had like 10 miles on it. I had the heads done because the valve guides were bad, and I put the heads on, and used ARP studs. The pistons are dome top, and the heads are "double hump." For now it is my daily driver, but i don't drive that much, and not that far.

Luckily, my dad has tons of sbc parts so i had no problem doing the switch, plus i live in an emissions free county (Weld County, CO).

The carb is an edelbrock 1405 - 600cfm, single fuel inlet, 14" x 3" k&n air cleaner. Have shorty headers, with true dual 2 1/2" pipe, dual mufflers and it dumps out before the rear axle I measured the cam lobes with a micrometer, and yes it is a .510 lift cam with the current rocker ratio. Has billet roller rockers, a double timing chain, and tall style aluminum valve covers. The intake is a high-rise with an open square hole, and you can see the intake ports on the heads just by looking into the intake.

Currently, i have all the bugs worked out, the a/f mixture as best as possible, the idle good, and it runs great using 91 octane. It seams to have good power, but the gears are so mismatched i can't launch worth a crap and my 0-60 is like 7 seconds.

So really, what will the difference be with 4.10's compared to 3.08's? Like not traction in first? a faster 1/4 mile? I don't know because the is my first car with a v8, and i have only had 3.08 gears in this car.


Couple other questions:
How many miles should this engine last assuming drive it normally about 95% of the time and hot rod it the other 5% of the time? how often should the oil be changed? What would be the best oil to use?

Thanks for the help
Josh

 

[Biscuit6447]

Here are some picture when i put the rebuilt heads on:

 

[firestone]

If you are looking to change things with the motor, I would switch to a performer rpm intake and a holley 650 double pumper. As for changing from a 3.08 to a 4.10, it will not even feel like the same car. Gears make a HUGE difference when you make a change that significant. Just keep in mind that it will also significantly increase your highway RPM. Unfortunately, I agree with the compression being too high. Do you run racing gas in the car?

As for power, I would estimate around 350 at the motor which would probably be around 280 at the wheels if you have racing fuel in it. I would imagine that you would run into pretty significant preignition on pump gas.


Adam

 

[ap72]

What is your hot cranking compression?

 

[cobalt327]

You might want to think about opening up the push rod slots in the head casting some. What is the casting number of your heads? Looks like it might be 487 but not sure... Looks like the number under the ports ends in "87".

 

[jgh64pkup]

did anyone notice this or is it just me
the domes are even with the block
aren't domes supposed to stick up past the block and the main surface of the piston even with the block
can you post a pic at TDC

 

[cobalt327]

did anyone notice this or is it just me
the domes are even with the block

You looking at the same engine as I am? The domes ARE protruding. A lot, considering it isn't at TDC.

FB88- I cannot make out the c/n from your thumbnail (or his) photo.

 

[Biscuit6447]

Thanks for the feedback.

To f-bird'88:

I have already fixed the distributor so that i have 24 at idle and 36 max. The distributor is a procomp with billet aluminum construction. using 10.5 mm wires with about half the resistance of 8mm aftermarket wires. it will idle at 900 - 1000, but i really need underdrive pullies. when i turn the wheel hard, the motor dies a little because of the power steering pump kicking in.

Also, 5th gear is .73 not .63. i checked the rpo.
The intake is a single plane something like the Weiand 7532, just not the newest product.




To Clarify: The motor was ran by my dad in a chevy nova for like 4 passes and the he sold the car and kept the motor, that was about 2 years ago. All the valvetrain parts fit right, and it is currently running in my 1988 camaro rs. I am running 91 octane with not pinging or detonation. i have put about 700 miles on it so far.

i am currently using NGK plugs; 14mm thread, 13/16 hex, 3/8" reach, non-resistor, hot 6. (p.n. R5670-6)
What should i be using??

After changing the rods and jets to 8% leaner, the plugs are a nice tan color: compared to charcoal black with the stock rods and jets. Is there a chance that the plugs could be fouled after running rich for so long?

Also, i am using mobil 1 15w-50. I heard somewhere that 10-40 diesel oil has a high zinc content and that it would work good. Any suggestions???


At TDC, the "flat area" on the pistons are about 1/16" lower than the block surface. The domes stick up really far past the block.

I am 19 and in college for engineering. I really only plan to do a full on drag race a few times a year, and also plan to get a second car that is practical. I am paying for everything, so i really can make all these changes at once. I am current ordering gears, but a bigger carb will not be for another month.

 

[Biscuit6447]

I did a compression test and got arond 180 psi in all cylinder, but im at 5000 ft (12.2 PSIA). Also, the cam is installed at 12deg advance. The machine shop that did the head suggested to test for valve clearence by putting some clay on a piston, putting on a head and cranking the engine over to see how thin the clay is. seamed fine, not mashed to thin. But i still think that the CR is higher than normal; the deck clearance in not that much.

When the motor was all put together, you can see the side of the dome from the plug hole, but you can't see the top. The heads were milled (same as decked???) by the shop .007".

With 4.56 gears i will be at 3200 RPM @ 75 MPH in 5th
little much? or will it be worth it for 1st gear?

Would a 850 cfm carb be too much. i am thinking the edelbrock avs series with dual inlets.

 

[techinspector1]

"the cam is installed at 12deg advance"

Are you sure about this?

 

[Biscuit6447]

12 degrees after dead center

ohhh so that would be retarded 12 degrees. my bad.

"12 ADC" is stamped on the harmonic dampener and the crank.

 

[ap72]

By engineering school I assume you mean like engineering management?

The 12º means nothing about your balancer or your cam.

The good news is that due to your high elevation you can run that engine on pump gas. the bad news is that if you ever take your car to someplace like sunny Florida- well it'll never make it to sunny Florida. Your car is restricted to staying on the mountian unless you want to run race fuel.

 

[cobalt327]

12 degrees after dead center

ohhh so that would be retarded 12 degrees. my bad.

"12 ADC" is stamped on the harmonic dampener and the crank.

Not trying to rag on you, but what would that have to do w/where the cam's installed?

A camshaft will be installed advanced or retarded in relation to the crank position, and is done w/the cam gears, not the damper and can't be read w/a timing light, per se. And the amount of advance/retard is usually on the order of 2-4 degrees. Not 12.

BTW- What's the casting number of your heads???