496 building advice needed
 

We are in the process of putting together a parts list for a 496 that will be in our dragster. I will have to use stock heads for the first couple years. I need advice on pistons, cams, lift and expected HP of this engine. Thx M

Depending on what stock head are you using ? oval ports, square port, 990's, ported or not ?

Do you want to run race gas or alcohol ?

I have both syles of heads available. We will be using Alcohol. To make it simple, just tell me what you would recommend, since I haven't started building it yet the sky is the limit....thx MM

IF THE SKY IS THE LIMIT BUY SOME GOOD HEADS. By the time you fix up old stock heads you will be half way to a good set.


14-15 TO 1 COMPRESSION, SOLID ROLLER AROUND .750 LIFT WITH dur @.050 270-280 range 112-114 LSA VICTOR 454-R

JMO although I would probably ask an engine builder. Use the rectangular port heads.

X2! unless you have something useful to add, this is a very good starting place..

ok great thank you. Right now I have to keep the stock heads due to funds. I will get a list of parts With the stock heads about how much HP can I expect? Thx MM

Skys the limil just have to use stock heads !!!

Start with a good block, Go with a good billet crank, a set of aluminum GRP rods with the best bolt they offer, set of diamond or JE Blower pistons gas ported and buttons with about 13 to 1 compression, a good blower cam from comp cams around a .750 lift with a 7-4 swap, top all of it with a 871 supercharger with around 10 lbs of boost with enderlie bird catcher on alcohol approx 1200 HP. 8) 8) How you doing ???

496
 

I am comfortable saying that Tod's combo in the above post, with a good set of heads will make around 800HP. maybe even a little more. That should work for you
JMO

ok thanks this is good info.. The two sets of heads I have are 781 and 049 oval ports. What do you think of these? My rods are Eagle H beams 6.385. I will get a Lunati 4340 4.25 crank soon. With the stock heads what advice and what HP can i see with these? Is there any issues with too much crank case pressure when running high compressions? Thx

496
 

049/781 oval port cast heads are the best stock heads. However, even mnoidified, they will hold back a 496 engine above 5500 RPM.

To do them right you need to add 2.250"/1.880" valves, unshroud the bowls, port match, have bronze guide liners installed, mill the decks, add good rocker studs and guide plates. Then figure in good valve springs, titanium retainers and 10 degree locks. But they will still be less than 290 CC intake ports. Too small.

A set of RHS/Pro Topline 320 aluminum bare heads can be bought on RJ if you look for $1000. They will take the same parts but the machine work will be done already. They will make 75-100 more HP. And they will have resale value.

If you have to use stock heads, sell your 2 sets and buy a set someone else already spent their hard earned money on doing all of the above, for about $500.

MARK WHAT ABOUT THE 088 casting rect port heads? Are they any good? They can be bought new,bare,cut for 2.25/1.88 FOR between $400- $500 From a guy here in Indianapolis. of coarse they are still cast Iron and weigh 75lbs each.

P.S. I would do my homework before you buy new heads if you go that route. There are lots of cheap aluminum heads out there. It is tempting to go that route because the price sounds too good to be true. I have no experience with them but they do not have a very good reputation so ask people who have used them.

496
 

The 088 is similiar to the 188/990 and would be a step up from the 049/781 because of the rectangular ports extra flow potential and the bigger valves.
They take a diffferent head gasket than the older heads, but otherwise everything interchanges. Good suggestion. Should get a 496 up to 6500+ before they stall out. A custom grind roller cam can make or break the combination with these heads.

How much flow can one get from the 088 heads?

http://speedtalk.com/ go here. That board is FULL of professional engine builders. LOTS of very good info there. not saying there aren't smart people here,nor am I trying to run you off,just saying,lots of those guys do this for a living. :)

Re: 496 building advice needed
 

They key to me is that you said stock heads for a couple of years. That means you plan to rebuild and next time build a bigger / more hp motor. If I were on a budget I would go with a set of aluminum heads and intake out of the box for now. They will flow better than the iron heads already, but you have lots of room for improvement later. If you spent money on iron heads now it's just gonna be a waste. Save yourself a bunch of money in the long run and go with a good set of heads now.

Re: 496 building advice needed
 

great advice again! always found it cheaper to buy the correct part(s) the first time!!!!!!!!!!!! if it takes longer to get to the track, oh well....you will be pleased with the results in the long run! :wink:

Yes I agree. We raced jr dragsters so Im well aware of buying good parts from the get go. I was planning on building a stout rotating assembly and then upgrade the heads down the road. Can you find good aluminum heads (used) for 600-800$$? I have a friend that can work the stock heads but once again I dont want to get it out for the first year and wish I would have spent the funds on bigger better heads. Can I run 14:1 compression with stock heads and keep those pistons with aluminum heads? make sense? thx ... the more info and advice you can give me the better..... thx MM

I know this is more than you were looking to pay for a set of heads, but given the extra parts that come with these heads the deal may be pretty good. It's a listing on RJ in the engine section. I think they would work o'k with the 496.

JMO

Zip.

http://www.racingjunk.com/category/1...325-HEADS.html

yes it is a bit more than I want to spend bu that is a descent price.. What is the max CFM you can get out of stock heads? and do you know the max lift on stock heads? Thx MM

Abit off the subject but what is the max bore for a BBC... Found a block that is 4.382... I believe that is about the max.... You tell me?

Here's the answer on the stock 781 heads. i copied this from another forum, but they don't do much in performance compared to today's alum heads.

The heads now have 2.190 / 1.880 Manley Super Duty Stainless valves, full port work and the valve spring pockets are cut for 1.625 dia springs. The egr ports are filled. The head guy never did fill out a flow chart for the heads, but did say they flow 320 cfm on the intake @ .700 lift and 240 cfm @ .700 lift on the exhaust. About the only thing left to do to them is angle mill them. I've thought of doing it, but I think I'm done with them. I want to upgrade to a set of AFR 335 cfm heads.

Here is the flow charts for stock as cast AFR 325's, you'll note that they flow 384 CFM out of the box @ .700 lift. That's more than Brodix BB2 Extra heads flow fully ported. You can also see the heads cost $2200.00 from Jegs which make that deal even better on the RJ advertisment especially with extra parts.

http://www.jegs.com/p/AFR-Airflow-Re...56123/10002/-1

Zip.

Some blocks will go .125 over===4.375 bore, i just built a 481 that was actually a little too big on the bore 4.377, but it's what the customer had to work with on the budget build.
The problem with the block you mentioned is finding pistons for it. It's not a standard over bore so you may have to have them made (EXPENSIVE) probably over $1000.00.

JMO

Zip.

I agree. After spending most of the day on here researching I can see this is not the ideal block for me.. Right now we do have a basic 454 passenger car block that we will use.... good info and thank you

Re: 496 building advice needed
 

either of the gm heads will work very well. a good 496 can be had very easily and cost effective with the Scat crank and rods with Mahle or Wiseco pistons. a rotator capable of making and handling up to 1000 hp is around 2000.00 with 4340 int/bal crank and good rods w/ 2618 material forgings. as far as keeping the cost down, i would just keep it basic. an engine like this with alky and either heads will make from 700-775 hp. so just use common sense and if you don't have money for heads, use what you have let alone go buy a billet crank and rods! keep it simple and it will do the job.