[vinniekq2]

My engine is street driven,92 octane tuned
Its 434 cube,10.75:1 cr,227 cnc darts with additional work,vic jr, 950 hp,jere stahl 1 7/8 step headers.dart little m block,6 inch rods,msd 6-al with rev limiter,light weight steel flywheel,tko 600 trans,3.5 gears,27.5 tall tires

[vinniekq2]

camshaft,,,,, 256/264 at 50 with 420 lobe liftX 1.5/1.6 shaft mount offset rockers,comp cam, 108 icl and 108 lda

[oldbogie]

Originally Posted by Icejeep

Well guy's I have decided what i'm going to do..
I'we got my hands over a set of GM rods that have been worked, Arp bolts, beam polished and weight matched, so they should be up for the task. As far as piston's goes i'm decided to buy flat top pistons from speed pro.
I can get a set of ported 461 Double hump heads that are in good condition. would that be acceptable choice for this mild engine, and work well with my other components ?

So what we are talking about here is 350 sbc w. 10.25:1 compression ratio.
Ported #461 double hump heads, Edelbrock Performer or Edelbrock Victor intake manifold, haven't decided yet. Holley HP 850 carburetor
Camshaft is street roller from comp cams #12-769 - 12-769-8 - Xtreme Energy
1.3/4" headers with dual 3" exhaust.

Best regards.

This is a fairly mild engine in terms of power output, but I'm guessing that going into ajeep for rock crawling it's going to spend a lot of time in the high rev, high power out put range with probably a lot of shock loading from frequent excersions up and down the throttle.

If those assumptions are good, I certainly wouldn't use hypereutectic pistons and rebuilt stock rods. This kind of usage drives on a better rod and a forged piston, however it doesn't need to be a 2618 alloy take me racing piston; the high silicon types of VMS 75 or 4032 alloy offer high strength, though not as much as 2618, but with better in-bore dimensional stability. Given your climate I think that the high silicon alloy will be better as it can be run with a tighter skirt clearance when cold, where the 2618 has to be warmed up to get the proper clearance and if shock loaded before that happens they risk cracking a skirt especially with piston that have no pin offset as these allow the piston to snap over hard as the thrust loading changes direction. The high silcon alloy's tighter fit and especially if combined with an offset pin keeps you out of this area of potential damage to the piston and provides a more stable ring alignment which is better for oil control and power output. I'd run a gapless second ring set on this like the Total Seal or Childs and Albert.

For a rod that perfoms way up scale from what it costs the SCAT 6 inch (also in 5.7), floating pin part number SCR6A7 is one tough customer. It has several features I really like in a high RPM engine in that it uses cap screws to retain the cap, 7/16ths ARP in this case and it has a centered strap section on the cap to beef it up so it doesn't distort from the jerk loads at high RPM when the piston is pulled down on the intake stroke. In addition, toward reinforcing this problem the cap locates into the shank with dowel pins which help react the resulting pinch loads from the jerk down, also, the interface boss is extended outboard of the fastener which enlarges the pinch load reaction platform to also help keep the cap from both side loading the capscrews and from bending the cap to where it pinches the rod bearing inward at the cap to shank interface. This is the sequence that is the start of the most common rod failure. As the piston is jerked down the bore at high RPM, the cap wants to stretch in the center. This causes the interface at the shank to bend open on the bearing side and close outboard of the bolt. This wants to bend the bolt and push the bearing edge into the rod journal. When this happens, the oil wedge is wiped out, the bearing overheats grabbing the journal then it spins in the rod's big end bore. When all this finally seizes the rod gets ripped apart just above the big end. The design of this SCAT rod provides as much resistance to this initiating event as you can put into a rod. you've got to look upscale to Crower and Lunati rods to find a comprable design. For some close up pictures of this thing follow the link White Performance Detail Description This is a lot of rod for the money.

Bogie

[Icejeep]

Thank you for your answer Bogie. As you may not have noticed i'we decided that this engine is just going back to my strip car, but with some modifications. Last time it was together it had stock bottom end with aprox 9:1 compression ratio, the comp cams street roller cam #12-769. Heads are and will be 235cc RHS with 2.08"/1.6" valves, the intake was regular Edelbrock Performer. It has 850 cfm holley hp carb and pro billet msd dissy with 6al ignition box. So as you answered my question really well for offroading. Does a drag race engine take the same abuse as you mentioned above or is the abuse different regarding pistons and rods ?

As the engine was above it ran 118 mp/h in the 1/4 mile at nearly 3000 lbs. But now i want more compression along with maybe bigger camshaft. Also i'm going to put a single plane Victor intake on the engine now.

[Icejeep]

Just sayin...

[cdminter59]

With more compression (12.5:1) it will have more cylinder pressure to make more power. Then going with a larger camshaft (mechanical roller) is addition power. The Super Victor will be ideal for your race engine. Don't skimp it's time to play.

[Icejeep]

I like this plan, except that this engine must run on 93 oct pump fuel so i belive 12.5:1 compression is out of the question. I also would like to use flat top piston in this engine, or at least with as small dome as possible. Camshaft will ofcourse be solid roller. Just haven't decided if i should go with wilder one then this i have now... Everything else is pretty much sorted out though !

Best regards.

[Icejeep]

So it would be a strong combo with 10.25-10.5:1 compression ratio and the #12-769 cam with the Victor intake. Where should this engine make it's peak power ? Just thinking if my 4.10 gears are good enough for this moderate combo!

As stated above this particular engine with a Performer dual plane intake and only 8.75:1 compression ratio ran 118 mp/h in the 1/4. But now i like to go faster !!!

[F-BIRD'88]

You are all over the map with this motor.
Post your complete combo and purpose.
The big heads are fine. (you don;t need to dummy this down) But you need a race cam for a race motor.
The lil street roller you got is way too small for power.

[F-BIRD'88]

Here is a nice example of a 355cid SB with big heads that makes great power on pump gas.
And amazing power on nitrous.
Yes big heads work on 350's. The tunnel ram is simple, powerfull and way cool.
(do not use small CFM carbs) use 650+ holleys or 750 edelbrocks
Substitute the Lunati solid cam in the article for a similar duration solid roller cam and you are there.
(260in 268 ex @.050" 108LSA) will run very well on and off nitrous.

10:1 to 10.5:1 is just right.

Chevrolet Small Block - Engine Buildup - Tunnel Ram, Nitrous - Hot Rod

[Icejeep]

Ok here it goes the complete run down..

Block -GM 4bolt mains #3970010
Crankshaft - GM cast #3932-442 3.48" stroke
Connecting Rods - GM x-type with ARP bolts and polished beams.
Pistons - Probe flat top -4cc VMS75 forged 10.5:1 compression
Heads - 235cc pro topline, 2.08"/1.6" valves 64cc cnc chambers
Intake - Edelbrock Super Victor #2925
Carburetor - Holley HP 950 cfm
Headers - 1.5/8" long tube w. 18" collector extensions (thought they were 1.3/4" but I'm wrong)
Ignition - MSD Pro Billet distributor with locked timing and 6AL

Car weight is 2900 lbs race ready and has following parts.
Th350 (now w. T-brake) and 5500 stall 8" converter.
GM 12 bolt with 4.10 gears and spool.
Tires are 29.5"x13.5"x15" slicks.

I'm also thinking about running a small nitrous kit next season, 150-200 HP nos cheater kit

[F-BIRD'88]

Hell you can drive this to work and back its so simple.

Looks fine. Consider the street tunnel ram intake .
A example of the base line roller cam for this would be
a Comp #12-911-9 (but could be ground on a 108LSA)

I want you to :
Call Comp Cams or your favorite camshaft grinder to get set up.
The 4.10's are fine for getting a base line and a good compromise for Nitrous.
if the exhaust headers are dinky street headers (the outside diameter is 1-5/8" and the inside diameter is less)
You can step that up.

[Icejeep]

Thanks for your advice sir. I do have a couple of questions though !
What do you think about my gear ratio ? Should i lower them gears or just try it out as is ?
This cam seem's huge for my compression atleast bigger than what i had in mind,, but i take your advice on it sir !

As well as i like the looks of a Tunnel Ram i think i will stick to the Victor intake for now. Because this time the money goes into rebuild this engine and purchase a nitrous system and bigger fuel system along with the new transmission and converter.

Thanks again !

[F-BIRD'88]

Degree the cam in and start on a 100 to 103 intake C/L. Move it as required. The car will show you what it likes best. You can play with the lash too.

[F-BIRD'88]

There are lots of these street tunnel rams floating around used. Even in Icyland.
Most people don;t know what to do with them.
Edelbrock 750's are dirt cheap too. Agains lots around used. $100-$150 each.
Your big headed motor will really like this intake w a pair of eddy 750's.
They are not fussy to tune. (set it and forget it dirt simple to tune)
More power and torque than a single plane and 950hp
You probabily won't even need the nitrous.
Cause you will now have areal motor under the hood.
The comp cam I showed as a example is none too big.
(its a "small cam" for this combo.

The Edelbrock Dual carb Performer RPM nitrous kit is just right for this
motor w/ street tunnel ram. The price is right too.
The whole Edelbrock system I just outlined will make more power, go faster and cost less.