Thanks Gary. I like the novelty of the older Bow Tie block and the seller wanted to see it get put to good use, so I'm gonna honor that. On the crank, it's got a couple of really small balancing holes, but I am assuming it's still external balance. We'll see where it's at with the new pistons. I'll need a new balancer and flywheel no matter what.

 

That crank is going to need a crap load of Mallory to get it to balance.....I would consider a different piece as adding slugs is $$$$$.
It could work though if you wanted it to.....

If I were doing this I would call up M2 or Modern Cylinder Head in Michigan and see if they have a program for those heads.....you already have them and it would be money well spent.

Go Fast is correct about that block.......they were highly sought after in the early 2000's......what what reason I am not entirely sure.....but it is a damn good piece.....albeit it is limited to a 4.560 bore....(per GM, I have seen them go 4.600).

The inner head bolt thing is not a real issue if no power adder......

A Hyd. roller in the 265/270 range with .700 lift would be a stomper....

Pick an intake......they all will flow at the sub-700hp level.....oddly the Brodix intake keels over at 860 or so with the ProFiler coming out on top.......but a Wilson CNC Edelbrock will outflow them all.....but again $$$$$.....

Have fun!

Jebby

 

Thanks! I will check out M2 and Modern. I will also look into Wiengartner, Chad Speier, and CFM. I'll probably keep it external balance like I think it is already. Mike Lewis set the heads up for a .600-.650 hydraulic roller (Comp 938's I think). I'll probably stay in the 240-250@.050 range in the intake side unless you guys think that's too small. The intake has to fit under and L88 hood; no compromises there even if it costs big horsepower.

 

You need a bit more duration....it is a 500 cubic inch engine....you can get away with it.......go as close to max lift as you can......I remember the 938 was a popular hyd. roller setup, but do not remember all the specifics.....

Intake wise I am unsure about the L-88 hood......but keep it a single plane......maybe the Victor Jr. BBC?

Jebby

 

Its a Howards cam (see attached for spec) I looked carefully at manufacturers advertised flow rates for heads. Wanted high port velocity at low rpm for good streetability and fuel economy. Considered that there was little point using cam with more than .600 lift as flow rates with streetable oval port (and smaller rect port heads oddly enough) didn't warrant it. 'Old school maxim of 'get the valves open wider than you really need cos' you'll flow more at early opening and closing points of lobe" just don't hold true with modern cams. Logic (to me anyway) is to select a cam that opens as quick as possible - stays open as long as possible - and closes as late as possible, allowing the maximum intake of fuel/air mixture pro rata to the flow rate of the intact tract. So a cam with 'agressive' lobe opening and closing ramps is essential. The selection of a good roller cam is a no brainer. Some of you guys may disagree with my logic - but Jim indicated to the effect 'that its all in the heads" and he is 100% correct. A cam is secondary in importance to a well designed cylinder head.........but, a carefully designed and selected cam matched to the head and flow rate characteristics will make significant differences in power. Apologies fella's if you disagree

 

Most BBC's (especially "big-bore" ones) we build here all get .700" valve lifts or higher. One of our most preferred Comp Cams lobes we use has .714" net lift on the hyd-roller platform. Another popular lobe here is a .680" net lift BUT we use this one with 1.8 rockers on the intakes. You'd find this lobe possibly on a smaller BB platform. We are talking "streeters" here for the most part.

Most of our builds of this type see peak HP around 6100/6200. Like I stated above in my earlier post, I doubt very much I would consider any "oval" heads regardless of brands. A typical 509" (4.500" bore) pump-gas build here would get a set of RHS 320's and likely be in the 700 HP range!

Thanks, Gary in N.Y.

P.S. The cam card specs shown directly above here are indicative of one we may choose for a "typical" 383" SBC, no where near the numbers for any 4.500" bore BBC? Those specs on a 383" pump-gas deal will be in the area of 500 HP. BBC "big-bore" units want a good supply of air AND fuel, almost every N.Y. "streeter" we do here also ends with a 4500 carb!

 

The problem for most of us here in the UK is the crippling price of premium fuel which is probably close to triple your prices in the 'States - we need to think carefully about any build that takes mpg's down to single figures - for me driving in the congestion of a London suburb a 'conservative' build is essential unfortunately. It's interesting that some of the latest BBC race heads for seriously big cube engines are of an oval port design.

 

You want to ck the valve job on those heads. I would use a Isky 238/248/110, this cam peaks @ 6200 RPM on my oval GM headed 496 builds, and make 650 easy HP, it has very mild lobes. I would use a performer RPM air gap intake. A 509 can get all over a 496, its a much better package in every way.

 

I wouldn't listen to this guy! Wink nod... also that Howard's cam looks like flat tappet numbers to me.

 

Thanks Mark. Is that a custom or shelf grind from Isky? Assuming the valve job checks out, what would you recommend with the heads - run them as-is or touch them up first? They have the flow I want, but I don't want them nosing over too soon due to the extra displacement. Can I fix that with the right cam (i.e. run a little more duration to get the heads to hang on a little longer)?

 

"I wouldn't listen to this guy"

I agree....he's a internet know it all. You could do a port tune up job, a re valve job will be mandatory, play with back cut angles on the intake valves. That cam is on the shelf, I couldn't see it peaking at less than 62-6300 RPM, I run the 228/238 hyd roller to 7000 RPM in the lights.

 

have always been impressed with Alan's Vette, that car speaks volumes you damn know it all!

 

In another recent thread, Alan said he was peaking at 5,750 with that 238/248 cam in his 496 and shifting at 6,000-6,100. I'd really like to get another 500rpm out of mine. I've got a T56 and a 4.11 rear gear and the car blows right through the torque curve and then it's time to shift. The car could really benefit from some additional rpm. With 20 more cubes and 500 more rpm, I'm thinking another 8-10 degrees of intake duration....but only if the heads will support it.

 

Alans 496 was built years ago, since Alans 496 was built I developed the exhaust port of the 049 head, this resulted in 670 plus HP and 6200 RPM peaks. My peanut port 467 with the Isky 228/238 not the 238/248, peaked @ 5800 RPM 585 HP, @ 6400 had 570 HP, and is run 7000 RPM through the lights. Just my experience.

 

These are great data points. I would guess that your 049 port is likely better than the Brodix exhaust port.

 

This guy knows a lot about BB chevys, the only thing I may disagree on is his cam choice as I always ere on the side of caution, and go a little bit smaller. I would keep it in the 240-250 range@050 and have as much lift as the heads will allow, but definitely over .600 at least.

 

I have run cams similar to these duration specs, but with quite a bit more lift, and with roller lifters, with good results in numerous 496 engines with GM open chamber rectangular port heads.

 

Sell that 4" stroke piece and buy a 3.76" crank.

 

You make a good point on the extra lift, those heads will like that. BUT when the hyd roller lobe gets more aggressive (short duration lots of lift) they do not like to rev. Example: .714 lift, big heads, 6200 RPM peak, how could I be happy with that when my GM 049 oval port 496s peak @ 6200 RPM with a 238 @ .050 hyd roller that doesn't tear anything up, I had that 239 @ .050 lunati voodoo on the dyno, peaked @ 5800 RPM @ 6100 it was down 90 HP, I was pissed, I tried every spring lifter combination known to man.........same results, I couldn't get that junk out of there fast enough, a wasted week on the dyno.

 

no t to hijack this thread but just wondering if you have tried any of the Crane shelf grinds, they offer .630 lift or so with similar durations as the Isky. I have also heard it said they use milder lobes that rpm well too. I think "Big Joe" has said he used their stuff on sbc with good success/rpm/stock roller lifters. Any specifics on the VooDoo valvetrain, stem diameter, hollow stem, +.100 length etc? Thoughts on using a limited travel lifter?