[D. Miles]

What do you guys think? A while back, I built a 358 sbc for my uncle (tried to convence him to go Pontiac!) who just got back into drag racing after 20 years. His last car was a back halfed 68 Camaro with a 396, we found him a beautiful back halfed 69 Chevelle rolling chassis. I wanted to build a 406 or at least a 383 stroker but he decided to go 350. So we started with a 2 bolt block, found a set of .040 over 13.5 to 1 pistons for 6" rods on Ebay had the block bored with .004 piston to wall clearance Federal-Mogal chromoly file fit rings 6.0 Eagle steel H-beam rods Scat knife edged steel crank 230 CC Dart Pro-1 heads with 2.08 intakes and 1.625 exhaust PBM 1.55 roller springs with 240 lbs. on the seats @ 2.00 installed height 650 lbs. open Lunati roller 50140 camshaft 276/284 @ .050 .645/.645 106 LSA we had it in anywhere from 96* to 104* (started out with 1.6 roller rockers went to 1.5 shaft rockers) had a Edelbrock Super Victor on it now has a Holley Strip Dominator we tried several differant carbs a regular 750 Holley DP a 750 Proform DP an 850 Holley DP and the 8896 1050 Dominator off my wagon which it ran best with. Fuel system is a 5 gallon cell with an Aeromotive A-2000 350 GPH pump 1/2 line to a Holley Big Port reg. #6 line to each bowl. Ignition timing anywhere from 35* to 42* with MSD 6-AL and crank trigger ignition. Converter is a Trans Specialties 5000 stall trans is a T-400 with a TCI brake rear is a 12 bolt with 5.14's and Goodyear 14 x 32 slicks the car weighs 3200 lbs.

The best E.T. was a 10.49 @ 124 MPH in 40 degree air with my Dominator and cam installed @ 96* (timing set was off, we checked it after the 10.49 pass) the 60' was 1.410 leaving off the brake @ 3000 RPM. For the most part, the car would only run 10.70's and 10.80's. The weirdest thing I realized is the fact that the motor will not make power over 6500 RPM's we built the engine with the intention to shift it @ 7500 (another 350 I built with 12.5 to 1's stock 5.7 rods 220 cc Pro Topline cast iron heads with a solid lift Lunati cam 268/276 @ .050 .576/.586 lift motor pulls hard to 7200 leaves @ 4500 off brake 1.82 glide 5.14 gears 14 x 32 tires in a 2700 lb. car 1.39 60' 10.19 @ 131 MPH) With the 358 we have left as high as 4800 and if you try to push it to 7500 at shift points E.T. falls off to 10.90's. The 10.49 was when I drove it and since I have that feel by the seat of the pants I could feel the power nose over way before the shift light and I pulled shifts @ 6500. Back in my dark days after I graduated high school I tried a couple sbc's a 350 and a 400 and both would make power well into the 7000 range especially the 400 with unported 1970 294 angle plug "new style" camel hump heads (from a 350 Z-28 I was told)

We tried everything! even pulled the motor to check bearings because it almost acted like it was trying seize up. The cam is currently installed @ 100* and the ignition timing is at 40* with the Proform 750 DP and ran a 10.68 @ 125 last weekend. Our goal was 10.00's or 10 teens @ the 130 mark but at this point we'll settle for anything better than 10.50... What do you guys think??? All serious opinions welcome! Thanks D. Miles

[72Ventura]

Personal opinion: I think those heads are too big for the motor.

Guess on nose over: Something in the valvetrain. You might be bouncing valves off the seats or getting into a spring harmonic. Have you tried the beehive springs?

[BVR421]

Im not knowledgeable about chevys anymore but I think its running pretty damn well. If it wants 6500, do it. How big are the headers? High rpms need big pipes regardless of motor size. Should those heads support the rpms and power you were expecting?
What other cars at your track are running that well with that weight and 358ci NA?
None around here that Ive noticed. Maybe Id better pay better attention. LOL
Why icl at 100º? Is that usual for a windy small cube motor?

[RAIV55]

Both of your combos are good in my opinion, although 230cc heads are overkill. I've used the same Lunati roller installed @102, they pull hard to 7800 with less spring so I don't relate the issue with a spring problem.

You mentioned a Transmission Speciality converter. If it's spragless, that is what I'd look at first. Nothing I've built has pulled hard on top with that style of converter. Truthfully I don't care for spragless in any application I've found.

[D. Miles]

I get confused when I hear people say that the 230 CC head is too big when if we would have gotten a set of 215's we would have had to have them ported to death to acheive the level of power needed to make a car that weight run 9.90's. I thought if you have too much head or too much cam, you won't have any torque or responce and in a race situation the car will leave soft or have a slow 60' time, this car has been 1.41 with suspention issues that we eventually worked out. Last year I met a guy with an all steel and original glass 65 LeMans with 10" tires running a 383 sbc with 245 CC Pro Topline heads going 9.50's @ 139-140 MPH, over the winter I was told he did some motor work and back-halved the car and he's now going 9.30's @ 145.

Yesterday, my uncle went to Cecil and got backed off the line twice for leaking transmission fluid, he checked seals, lines, gaskets and everywhere, couldn't find the leak, he got back to the shop, I jacked it up and fired the motor, the converter was split wide open! It's not a spragless converter but it has a mechanical diode (ratcheting sprag) The converter was not built for this exact combo but it did work well in the solid flat tappet combo I mentioned in my first post. We intended to have the converter set up for the Chevelle but now it's shot. Last season my uncle went to a test n tune session and ran a 10.23 then right back to a 10.47 so we called it a fluke although all the track increments (330' 1/8 mile E.T. and MPH and 1/4 MPH) were accurate, I can't recall what the 1/8 E.T. was but the MPH was 105. That's the only E.T. slip we can't find to analize. The car has been 1.41, was consistant mid 1.40's but now we can't get it back into the 1.40's. We are pretty sure that it is the converter though, I had a converter done by them (Transmission Specialties) back in 1995 when I was only running 11.20's, the sprag broke in half after less than 20 passes and Bob Maze basically told me Oh Well, you make too much torque, I sent it to ATI and have been running it since!

I will be pulling the converter out this week to have it cut open, I will keep you updated. Thanks D. Miles

[Mr. P-Body]

D,

While the runners in those heads may or may not be "too big", the valves are definitely too big for the bore size. The small block is just like the Pontiac, where the intake charge will collide with the cylinder wall. The 2.05" valves are marginal in the 4.040" bore, but the 2.08 will suffer. Those heads are more meant for a 400 small block bore size (4.125-plus). But the Pro-1 is among the better heads out there.

Jim