I just built another small block motor for an upcoming Pro Street Camaro that I will be building next summer and would like to gather some feedback on this build from some of the knowledgable people on Team Camaro. More importantly, I would appreciate some feedback on this camshaft selection from people who may have used it. Desktop Dyno 2000 shows 460 HP and 436 FT.

Component Selection

Professionally Machined 010 Block @.030
1182 Forged Crank (Std / Std)
PM 5.7 Rods (only started in a crate motor & then resized and issued to this block)
Clevite 77 Bearings
ARP Rod Bolts
Wiseco 11:1 Forged Flat Tops
File Fit Plasma Moly Rings
Entire assembly balanced
True Roller Chain
Comp Cams EX290S (Solid .540/.558 - 252 @.050)
NOS GM Bowtie Haeds 184cc Runner / 64cc Chambers(pocket ported)
GM Performance 202 / 160 Stainless Valves
Studs, Guide Plates, 1.5 Crane Roller Rockers
Crane Dual Springs 1.47 OD
472 Hi Rise Intake
780 Holley Carb

This combo will be hooked to a 4 gear in my 69 Pro Street Coupe complete with a narrowed 12 bolt and 411 gears. It's the first time I have used a solid of this size on the street in a power brake car and would like to hear what anyone can offer about this setup. Good bad or indifferent.

[ 12-15-2003, 10:11 PM: Message edited by: hugger_sixty_nine ]

I am assuming this is a 383 (flat tops and 64cc heads w/383= approx 11-1, while flat tops and 64cc heads in a 350 are closer to 10.2-1)? I also assume that since you have a narrowed rear end you will have much taller than stock rear tires. We really need a few more specifics but I will say this...that is a whole lot o' cam. With a true 11-1 383 and iron heads it probably wouldn't bleed off enough compression however to run pump gas, and it won't run very well under around 3500 rpms. If you are using the typical pro-street type 30"+ tall rear tires, 4.11's probably wouldn't be enough gear for either a 350 or 383 with a 4 speed. It ought to be plenty lumpy though.

No Travis,

This is not a 383, but is a true 355 cube using an early stock GM forged 1182 crank with 5.7 rods. The Stage 1 Bowtie heads are a true 64cc chamber and the pistons are flat tops with 11:1 so this should balance out around 10:2-1 or slightly higher. Should run the premium pump gas alright. As for the gear ratio, that's still for consideration. I mentioned pro street but should note that this would be a mini tubbed car and not a full back halfed ride. I am more concerned with this motor building power than the drive line at this point, as the motor is already done. I would like to hear from anyone that has run this type of small block on the street using a big solid camshaft and what the engine worked like, or possibly someone who has dyno stats of this cam in a street motor.

In a 355 that cam will certainly turn some RPMs with a rough idle. A little big for a street car IMO.

Like Travis I am a little confused as to how you get 11:1 with flat top pistons in a 355 unless those bowtie heads have been milled down to about 58cc. Flat tops typically make a hair over 10:1 with flat top pistons and 64cc heads in a 355.

I read some info on the Bowtie heads once, but I see so little of them these days I kind of forgot. I hope you get yours ported, because I think the older factory bowtie castings were pretty weak out of the box, but responded really well to some basic porting.

I am not familiar with the 472 intake.

PS. We posted at the same time. I think your combo will be closer to 375-400 HP if you really spin it. Not much TQ down low. I think your heads are limiting your power output.

Hugger,

With the exception of the heads my 350 is pretty close to yours, actually my cam is just a tad bigger. Streetablilty is not a problem. It idles around 900 and makes 8" of vacuum, of course I don't have power brakes but I suspect they won't work real well on 8" of vacuum. I don't think I'd like driving it every day to work, but for a week-end driver it's okay. Runs just fine on 91 octane.

Eric,

As I stated in this post, the pistons are flat tops and I said that they will run at 10:2-1 with the 64cc heads.

As for the heads being weak, I am a little caught off guard by that statement. The heads are almost identical to the Phase II Bowtie heads which are refuted as being one of the best flowing cast iron heads on the market and are almost exclusively run in factory production class racing. They have 184cc intake runners and are also pocket ported. I am further told these Phase I heads will out flow any of the early production heads even if ported. In their bare untouched form, GM claims they will out perform any production head. The intake and exhaust ports are identical on both Phase I & Phase II heads. The runners are designed to satisfy air flow in competition engines (off road only) while enhancing mid range and bottom end torque. If anyone can offer some flow research or data on Bowtie heads I would be greatly appreciative.

When I entered all of this info on the desktop dyno, the results showed the horsepower I am looking for, and running stock 186 heads with a lot smaller hydraulic cam produced the type of HP you are claiming I will see. Thanks for your input though Eric.

Fuji,

Thats what I had calculated was 8" of boost. With that in mind it is wise to state that I already have a Comp Cams Vacuum Cannister to keep a reserve air charge there for braking. Sounds like our engines will be very close to one another in HP and TQ. I was hoping for a low 12 second time with this combo and looks like that will be achieved judging from your 1/4 times. Did you dyno your setup?

Well, I hope you are right about the heads. I wasn't trying to dis' your Bowtie heads, just going from memory. So I looked up some info for you in David Visard's book "How to Build and Modify Chevrolet Small Block V-8 Cylinder Heads".

There is some flow info on the Phase 6 Bowtie heads which are a later design than yours (should flow better?). Here are the numbers for a slightly modified head "that has had attention to the port bias and a general cleanup of the port on the intake." The intake runners were 188cc. Visard claims this head would be enough to support 425-450 HP.

Lift__Intake__Exhaust
.100___58_______54
.200___119______95
.300___170______128
.400___219______162
.500___240______188

I guess those numbers aren't "weak" but as a comparison, my mildly worked TFS 23* heads flow 260 cfm @ .500 lift. Not trying to brag, just pointing out that new aftermarket heads really rock, even when compared to older race head designs.

Again, no offense is intended, just trying to offer you an honest opinion. If you want more info on your heads you might try posting the casting number or try contacting "GMPP Dave" at Team Chevelle.

Good luck.

Eric68, 472 are the last three casting numbers of the Z/28 alum manifold.

Hugger,

Sorry no dyno or head flow numbers for you. According to the charts, 112.76 in the 1/4 @ 3400 pounds, equates to around 370 RWHP. Accounting for drive trian losses, I'd say around 450 FWHP. Be sure to post some times if you get it to the track.

I will get it to the track Fuji. Might not be for a while, but it will be there.

Eric, thanks very much for that info. I know many of the new heads rock, but wanted to keep it all GM if you know what I mean. Nevertheless, some great info so thanks very much. I will forward the casting numbers to Dave to see what he has on these old style castings.

I have a 250@.050 solid flat tappet in my 10.3-1 388. It isn't something I would want to drive on a daily basis if I had to contend with stop and go traffic. A 4 speed with a big cam is even more of a PITA in stop and go traffic, IMO. I would seriously consider stepping down 1-2 sizes on the cam. The xs290 would probably like a 4.56 gear (or more) in a 350 if you are looking for max performance.

nice car.What was your combination for your engine,conv,cam,compression,etc .I have a 355 trying to dip in 11's .12.40 110 best i think i need a solid cam swap and a better converter.

nice car.What was your combination for your engine,conv,cam,compression,etc .I have a 355 trying to dip in 11's .12.40 110 best i think i need a solid cam swap and a better converter.
Really gotta watch the dates on the "related posts" and searches. This post is over 3 years old, and the guy who posted it no longer hangs around here.