406 SBC buildup - Please Comment!

[Guest Anonymous]

Some more food for thought, I am running Edelbrock Victor JR. Alum heads on my 355 cubic inch SBC, and they work great! 10 to 1 comp, solid flat tappet cam, Victor JR manifold, full lenght headers to dual 3" flowmasters. 11.90's in the 1/4, pump gas, 7000 rpm all day long. Lots of fun!

[Guest Anonymous]

There is not enough room with a 3.75 stroke to go all the way to 6.2" rods. 6" pushes the compression high pretty much to the limit.

[Guest Anonymous]

compression height even

[Guest Anonymous]

Tis is a done and proven deal in Hot Rod Magazine, check this out web page Pete wants to use 6.00 inch rods why not get some longer ones with some short JE pistons for even better fire at higher compression wait a minute fast do you have one of these 352 engines

[pparaska]

Tomahawk: I like the idea of higher compression and that engine's supposed high detonation resistance. But that engine gives up 50 cubic inches and 1/2" of stroke to a 400. Sure, the higher compression might be worth a few ponies, and the much higher rod/stroke ratio may even bring some small amount of power increase, but I think you have to measure that on a per cubic inch basis. 400 cubes at 1.2 hp per cube is 480hp. 353 cubes at 1.25 hp per cube is 440 hp. I gave the higher compression and higher rod/stroke ratio a 0.05 hp per cube advantage, and I bet that's generous. The 353 still loses, for the same level of build (head, cam, etc.)

 

I just don't see any reason to leave stroke (torque) and cubes on the table by decreasing the stroke of a 400. Especially on the street where it'll be below 5000 rpm most of the time and never rev above 6500 at the drags.

 

Like lethal280Zchick points out, I'm near the ragged edge of a streetable compression height on the pistons even with 6" rods. 1.125" compression height, 1/16",1/16",1/8" rings and the oil ring package is still in the pin hole. 6.209" rods would not work, without giving up a compression ring, etc. NOT streetable, IMO.

 

To use the 6.209" rods, you'd need to use the 1/2" shorter stroke 3.25" 327/307 crank. You could do it with a 3.48" 350 stroke crank also, but with short compression height pistons, around 1.2".

 

fast240: What cam are you running? Also, how does it run down in the 2000rpm range. That's my cruise rpm in 5th. Yeah, I'm thinking of trying the dual plane first and then the Vic Jr. I have both. My cam is a 280/288 (244/252@.050) .518/.536 solid flat Crane 114681, and I'm concerned about the low end response from 2000rpm. No worries, I have a Comp Magnum 270 solid flat (224/224 @.050) and a Comp Xtreme solid flat (236/242 @.050) cam also if that's too much. 11.90s sounds like a blast! What tires are you running?

[grumpyvette]

BUILD AND RUN THE 400 sbc/114681 cam/10.5-11:1 cpr/PERFORMER RPM combo

having built and run that combo many times with good heads

(Canfield 195cc, Pro Top Line 200cc, or AFR 195cc 64cc chamber, straight plug,TRICKFLOW 23 deg ® series)

I can tell you I SERIOUSLY doubt youll feel underpowered!!!!!

[pparaska]

 

It seems I have a vote of confidence from grumpyvette!

 

The shortblock is being assembled soon. All the parts are in to the builder - including the 114681 Crane cam I sent him. Unfortunately the 400 main internal balanced crank is NLA where the builder was buying (although flatlander had two a week ago or so, I found out), so he's going to internal balance it himself. He has a nice riciprocating balancer setup with calibration jigs. BTW, that crank part number I had in the post was wrong - its for a 350 main crank. Anyway, I figure with these rods and light pistons, the balancing may not be too bad, as the pistons are 440 grams as opposed to the typical 600 grams a 5.565" rod 400 piston weighs. Oh well, Mallory metal isn't cheap, but it's cheaper than a new balancer and flywheel!

 

Based un grumpyvette's, Crane's advice, I am starting with the 114681 cam. It's probably as big as I'd go (never say never!) and wanted the rods clearanced for large end of where I'd go. Of course if I went to a roller later, I'd have to re-clearance check the rods.

 

Grumpyvette - Do you think there's enough difference between the Holley 300-36 (copy of the old LT-1 High rise dual plane) and the Performer RPM to make it worth getting the Performer RPM? That's a few hundred bucks I could save.

 

I'm still up in the air on the heads. Pro Top Line heads are tough to come by in the US, unless you can find someone with them in stock. Summit Racing for instance is no longer stocking or ordering them. Pro Top Line didn't even answer my email about where I could find them in stock. I'm thinking the Canfield 195s (aren't these the same as the "Jeg's" 197 heads?) or the AFR 195s. I'll either clean up the bowl area (just get rid of any ridge) myself or have them bowl ported. Unless someone has any advice on where to get already professionally ported AFRs or Canfields without paying AFR CNC porting type prices. I figure $300 or so to have the bowls cleaned up is what I'm looking at.

[nullbound]

competition products seems to have the best prices on canfields: http://www.competitionproducts.com/page11.html

[nullbound]

that crane 114681 is a great cam, but it seems a bit much for a street car. the rpm range is listed as 3400 to 6800. in the beginning of this thread, you said you wanted something in the range of 1500 to 5500. the solid flat (236/242 @.050) cam might be more up your alley. grumpyvette's combo is an awesome combo, but i feel like it might be a bit much for what you want your car to do.

[pparaska]

Ryan, thanks for the tip on the Competition products site!

 

Also, you have a good point on the cam rpm range. Remember that they usually use a 350 to come up with those, so it'll slide down a little bit with the 400, but not more than a few hundred rpm. I agree the 236/242 will probably be a better fit, but I'll see how the 114681 does in this app. The light weight of the car, gearing, etc. may allow it to work o.k. at lower rpm. The real test is, after the TBI and Megasquirt and Ignition are optimized for the 114681, will it pull cleanly from 2000-2200 cruise in 5th. If not, I'll swap in the smaller cam/lifters.

[grumpyvette]

if you already have the 300-36 I would not waste money on the RPM intake the differance will not be that much. both the canfield and trickflow 23 deg heads are good choices but the afr heads do have a slight edge in performance

[nullbound]

hey pete, you're more than welcome for the link. competition products has a lot of good stuff for cheaper than you can get it at most other places. yeah, i usually subtract 200 from each side the rpm ranges listed in the catalogs when the cam is for a 400. that's a safe estimate. it will be interesting to hear how well it works with the tbi.

 

right now, my 377 has a comp cams 280AR magnum mechanical roller, part# 12-702-8, 2500-6500rpm, 236/236 @.050, 110 lsa. it pulls hard and runs SMOOTH. my engine was in my friend paul's drag car and brought consistent 6.90's at 100 mph. his best time was a 6.89 at 101 mph with a 1.48 60' time... it was open header, but on pump gas with an alternator and water pump. his car weighs about 300 pounds lighter than my car and he has a welded up 3.90 diff. the moral: it's plenty for a street car, almost more than enough.

 

it's all relative, though. i think you're going to have a pretty radical car in terms of motor when all is said and done. i'm not at all trying to dissuade you from your choices. traction is definitely going to be a problem for you. and it's definitely going to be a huge step up either way from your 327. and, at the same time, i cant say much to dissuade anyway since i just bought a comp cams XR280R extreme energy cam: 2500-6500, 242/248 @ 0.050, 110 LSA. it's the same rpm range as my current cam, but definitely more radical.

[MAYHEM]

I have one friend at the local race track that is building one at this time. "Boy that's no help" I've been wanting to this for some time Tomahawk Z. But no funds as of yet.

The first time I read that article I was very impressedback in the late '90's. But following that article there were quite a very people writing in about there experiance with the motor. All of it being positive. I'll see if I can track any one down.

 

 

Originally posted by Tomahawk Z:

Has anyone have experiece or whatever concerning using the forged 6.209 rods from a 300 cube in line Ford 6 with short pistons in a 400 SBC > I understand with these long rods the compression can be 11 to 1 without detonation on pump gas.

[MAYHEM]

Just as a side note, pparaska. I did a build up in my old 76 Vette awhile back. I put in a roller 383, Trick flow heads, jacobs ignition, blah, blah..and a 3:55 ring and pinion along with a Tremec TKO 3550. What a mistake. The tranny was great, once I got over the clucky shift. The problem that "I" had, was the 3:55 rear with the 3:27 first gear in the trans. I could give gas and had the shift "... oh !! in about... 3 feet" it seemed like. If I was to be aggressive off the line launching out of 2nd gear was the way to go. I might be blowing smoke, but that was my experiance with my heavy vette.

 

Originally posted by pparaska:

Datsun 240Z, near 2700 lbs with driver

5spd trans (Tremec TR-3550)

3.7:1 limited slip differential

255/45-17 rear tires (26" diameter)

[pparaska]

Mayhem, I know what you mean about that 3.27:1 first. Mikelly, if you're listening, and doing a custom ratio'd Tremec 5spd, think about a steeper gear for first, etc.

 

I start in 1st on the street when just driving easy,etc., and I've tried using the tires as the clutch by starting out hard on a launch in 2nd, and that works.

 

Radical can be fun, but I'll see what this ends up like. If too much, I have the other two cams/lifter sets that are broken in to just swap in there .

[nullbound]

radical certainly can be fun. that's why i bought the new cam, hehe.

[Mikelly]

Pete, I wnt to chat with your builder and see if he'll balance my rotating parts... Thats an impressive setup you are going to have. I wouldn't worry about lugging around in 5th at 2000RPMs based on your torque and the weight of the car... You should be fine. As for the tranny, I missed out on the one I wanted, but will defenitely be going with something I can hand pick my ratios for... Since I'll be running the Infinity Q45 rear with 3:54 gears, I'll want to get a better selection than comes stock...

 

Mike