Hot Rod Forum banner

Building a BB Chevy. I want 500HP

28K views 30 replies 11 participants last post by  454C10 
#1 ·
so I have an old Mark IV 454 block thats already .060 over. I have one closed chamber head and one open chamber head, both with the stock size valves. I have it all at the machine shop right now. he has some old head cores laying around and can match either the closed or open head. If this motor doesn't need bored, then i'm going with the closed, since the pistons in there now are flattops, which i think will give me close to 9.5 to one (haven't ran it through the compression calc yet, just going by what the machinist said). If it has to be bored, i could go with either head and just buy the pistons accordingly to get my 9.5:1. Am I going to be able to make 500HP with a minimum (without boring) of 468 cubes, 9.5:1 compression, stock oval port heads (closed or open), stock valves, and a big nasty cam? Really don't want to do a roller cam just because of $$$$. I was thinking the comp 292 cam. I have a Wieand Stealth intake, and an 850 street demon carb, but might upgrade to a Victor Jr at some point....
Thanks in advance for any advice!
Tom
 
#4 ·
I like the 292H cam in a SBC but never ran one in a BBC.

Most likely will need more than 9.5:1cr to run that cam. I run 11:1 cr with a sbc using that cam with pump gas. 10:1 CR should be a good value to go for, but 9.5:1 isn't that bad when used in a 454.

In a 350, that cam has no torque under 3000 rpm but comes on like crazy from 3 to 7K. With a 454, you will need at least 3.73 gears and a 2800 rpm stall with an automatic, and headers. And don't forget the stronger springs and rockers.

500 hp should be easy to get with that cam. However, bigger valves and a little bowl work would help a lot.

With a good set of aftermarket heads, a 350 can make about 450hp with that cam, so 500hp with a 468 should be easily obtainable if the engine is set up right (valve train, exhaust, intake, carb, ignition, et.)

And remember to use diesel engine oil with your new cam.
 
#5 ·
Thanks for the info guys. Sounds like I need to spend some more $$$ to be able to run the 292. I might step back one size on the cam. You guys aren't having trouble at 10 or 11:1 with pump gas? I guess my biggest decision right now, since the block and heads are at the machine shop, is which heads and pistons/compression ratio to run. I plan on running stock cast iron heads for now, then stepping up to aftermarket aluminums later. Should I shoot for 10:1? My machinist was talking between 9 and 9.5, but will obviously do whatever I tell him. I'm having him put the short block together and just do a valve job on whichever stock heads I end up running, then I'll put the cam and the rest of the motor together myself. I plan on racing this thing at the local 1/8 mile track but keeping it street legal at least at first. I am going to run a 400 tranny with a 2500 or so stall and 4.10 gears in the stock 10 bolt for now, just because someone gave me the gear set with a limited slip carrier. Eventually, after saving up more $$$ I'll probably do a mini tub, 12 bolt or 9" rear end with a spool or locker, aluminum heads and a 100 shot of nitrous, but first I need to get this short block built. I've done several SBC's, but this is my first BB. The last sb I built was a 383 with sportsman II heads with 9.75 cr and a comp 268 cam, and I wish I had gone bigger with that cam. It is in a boat though and I was worried about bottom end. It runs great actually, but doesn't have that nasty cam cackle that I wish it did. Anyway, any suggestion on pistons and heads would be appreciated!
Thanks
Tom
 
#6 ·
As someone else (454C10) has eluded to, make sure you use a motor oil with a ZDDP additive which is crucial for breaking in a flat-tappet camshaft in any engine.

The problem is that many engine oils have dropped this ZDDP additive from thier additive package ... including many of the "diesel oils". Newer engines with roller cams don't need it, and the EPA is forcing oil mfrs to drop it because the zinc plugs up catalytic convertors when the engine begins to burn a lot of oil.

There have been a lot of discussions here at HR.com on the subject of ZDDP.
ZDDP discussions

I am at the point that the next cam I buy WILL be a roller cam.
 
#7 ·
500 is possible, but you will need the right heads. I would look for a set of 049 or 781 heads. Just any set of oval port heads will not get you what you are after. I think sticking with 9.5-10:1 and going with a little smaller cam would be a good idea. In order to get a solid 500 hp, you will need to get heads like the ones above along with getting some 2.19 1.88 valves installed. I would also recommend getting some clean up port work done on the heads. As for the cam, I have a couple of recommendations depending on what you are willing to do with the converter. If you are set on the 2500, I would not recommend going wtih anything larger than the XE274H (230 236 @.050 .552 .555 lift). The only thing about this setup is that unless you get some pretty serious port work done on the heads, I dont think 500 hp will be attainable. In order to get the 500 hp you are after, I would recommend something like the comp xe284h (240 246 @.050 .547 .578 lift) along with a 2800 stall. Comp recommends 9.5:1 compression with this cam along with a 2800+ stall. I think that this cam with a little porting and larger valves in a set of 049 or 781 heads in a 9.5:1 468 will get you the 500 you are after.

Here is a motor my friend built that will show you what it takes to get the power you are after.

461
9.5:1 compression
ported 781 heads with 2.19 1.88 valves (flowed 290 cfm, so they had some decient work done on them as far as porting goes)
victor Jr intake ported and port matched to heads (I would recommend a dual plane with yours)
comp hyd roller cam 242 248 @.050 ~.600 lift

This motor made 560 hp @ 6100 RPM and 560 ft lbs on an engine dyno.

Adam
 
#8 ·
049 is what my open chamber head is. Those things are like 120cc chambers though. It would take a pretty sizeable dome to get any compression with those, but I have heard that they flow good. I could go for 9.5 with the 049 heads then step up to the aluminum heads later and get 110cc chambers to get me up a little higher. Not sure i really want to do things twice, but I know drag racing is going to require lots of wrenching anyway. Maybe i'll should pop for a roller cam setup. How much more $$ does the roller cam and required lifters run as compared to flat tappet? decisions decisions....... No matter what I do, I think a 468 in a 70 Nova with a stall and a 4.10 rear end is going to be alot of fun! I'll check what my closed chamber head casting number is. BTW, my closed chamber head is a 3904390 which mortec shows as a 98cc head.
 
#9 ·
Wow! Thanks F-Bird 88! Sounds like some sound advice! I agree with doing it right the first time. I haven't done any bowl work before, but I have read up on it and I have done some porting in the past, so I'll give it a shot. There is a wealth of information available on the internet! Open chambers it is, and 24.5 domed pistons as well. Once I get a mate to my 049 open head, which my machinist says he thinks he has, I'll take them back home, do the bowl work and porting, then take them back to him for the bigger valves. I'll have to find out what he'll charge me for machining out for the bigger valves.
Thanks again, I'll keep you posted!
 
#10 ·
You should calculate the dynamic compression ratio (DCR) to find the best static compression ratio (SCR) to use. DCR is calculated using rod length, stroke, and advertised intake closing point (not at 0.050" lift). There are a lot of free, on line, DCR calculators to use.

With a detonation prone BBC, you should go for about 7.5:1 DCR. And with out doing the math, I would guess that 10:1 SCR used with a 292H will make about 7.5:1 DCR in a 454. I wouldn't go below 7:1 DCR or above 8:1 DCR for pump gas.

I think the 292H will work OK in a 9.5:1 454 with 049 heads with stock valves and some bowl work. Not ideal, but it will certainly run a fairly low et.

Old 112cc, semi-open chambered, #820 BBC heads flow well. They especially have a good intake to exhaust flow ratio due to the exhaust valve being unshrouded in the chamber. The combustion chamber is much more open around the exhaust port which runs even with the edge of the head and not angled toward the exhaust valve like the 049 or 781 heads.
 
#11 ·
Sounds like I am going to be very close with my cr depending on what the cc's are exactly on the 049 heads. Mortec has them listed at 122, but how do I tell exactly? Do you fill them with water and measure the water? Whats the standard procedure? I haven't heard back from the machinist on the bore yet, but if he has to bore this already .060 over block, its going to be .100 over and then my compression is going to be a problem with the 24.5cc pistons.
 
#12 ·
I use a 1/4 inch thick flat piece of clear plastic with a 1/4 inch hole drilled at one end, squirt bottle, bearing grease to seal the plastic to the head, and a digital scale.

1cc of water weighs 1gm.

Subtract the weight of the squirt bottle before and after filling the combustion chamber.
 
#13 · (Edited)
vaseline and a cd! Very clever. I'm all over it. I have also found that fel-pro makes a bunch of different head gasket thicknesses, inclucing .020, .031, .040, .050 and even bigger I think. I think the speed pro forged 24.3cc domed pistons are the ones i'm getting. At least if he can save it at .060. I don't think that piston is offered in a 4.35 (.100 over) bore. Playing around with the cr calculator with the 24.3 pistons, and different gasket, I can get 9.6-9.8 pretty easily.

Now for porting the heads. I asked my machinist about it and he claims on a big block it wont buy you much if anything. He says on a small block yes, but not worth the effort on a big block? you guys obviously think differently right? I still need to get a price from him on machine work for the large valves. How important is porting and valve size guys??? The heads I ended up with are the 049's.
Thanks
 
#14 · (Edited)
I would also recommend getting the heads ported. As was already said, you dont have to go with anything too extreem. I would recommend finding a good head guy and having him do the port work. I dont want to assume the intentions of your machinist, but I have found that when people make comments like he did about the BBC heads, it sometimes means that they just dont want to do it. That is fine, if you force someone to do something they dont want to, it will cost you more, and you will probably not get as good of a job done. Doing it yourself is a viable option. I would try to find a old set of heads to practice on first though. Other than that, I think you could get a pretty good job done for $500-$700 depending on what you want to get done. Here are some prices to give you an idea of what you can expect to spend.

They are all from this company.
http://www.revolutionaryperformance.com

Porting - V8 bowl blend $225

Porting - V8 Econoport - includes bowl blend plus narrowing intake guide and full exhaust porting $500

Porting - V8 Stage II - includes Econoport plus gasket match intake end of runner and polish intake port $700

I have heard that, as a rule of thumb, on a relatively high performance street motor, you can expect around 2 hp per cfm of flow increase. If you assume that you will go from ~260 cfm stock to ~300 cfm with the porting and new valves, that equates to an 80 hp gain.

Adam
 
#15 ·
#16 ·
OK, now I am really confused. According to the Chevy Hi Po link firestone posted, the 049 heads have 2.06 intake valves and have 253 cc intake ports from the factory, and flow 232 cfm on the CFM at .400 lift. That seems pretty high! All the other stock heads are like in the 150's on CC's, and low 200's on the cfm at .400, with even smaller valves. Even some of the aftermarket heads don't look much better than that. The machinist told me $40 a hole for the machine work to put bigger valves in which is $640 , and the Manley severe duty valves (which he recomended) are $320! Then I would still have to port them and work on the bowls. Crap!, for that price, I'll buy some aftermarket Brodix or Edelbrock heads for $1800 or so. I don't want to skimp on the heads, since thats where the power is made. Are these numbers right for the 049's?
 
#17 ·
tommytempest said:
OK, now I am really confused. According to the Chevy Hi Po link firestone posted, the 049 heads have 2.06 intake valves and have 253 cc intake ports from the factory, and flow 232 cfm on the CFM at .400 lift. That seems pretty high! All the other stock heads are like in the 150's on CC's, and low 200's on the cfm at .400, with even smaller valves. Even some of the aftermarket heads don't look much better than that. The machinist told me $40 a hole for the machine work to put bigger valves in which is $640 , and the Manley severe duty valves (which he recomended) are $320! Then I would still have to port them and work on the bowls. Crap!, for that price, I'll buy some aftermarket Brodix or Edelbrock heads for $1800 or so. I don't want to skimp on the heads, since thats where the power is made. Are these numbers right for the 049's?
if i understand you correctly your machinist wants $40 for each valve to be enlarged :nono: :nono: i would ask what he has on the shelf already done,most shops will have this just waiting to put springs on to mach your cam or set up stock.that price should half that and your valves should be swirl polished,i'm thinking this guy don't want the work or don't know you anyway here in illinois you would be looking around $700-$750 with resurfacing at least were i go and yes it's good work.
 
#18 ·
The flow numbers sound right.

http://www.chevyhiperformance.com/techarticles/41598_cylinder_head_flow_bench_database/index8.html


250 cfm at 0.500" but the exhaust is a little low at 177cfm. Maybe you should install some bigger valves on the exhaust side and do a little bowl smoothing on both valves.

Beware that installing bigger valves can hurt flow if the valves aren't smoothed into the bowls and some unshrouding is done around the valve near the chamber wall. The bigger valve can lose flow when they get too close to the chamber wall.

A set of world products street oval ports might be a good option. They go for around 1200.00 complete.
 
#20 ·
tommytempest said:
OK, now I am really confused. According to the Chevy Hi Po link firestone posted, the 049 heads have 2.06 intake valves and have 253 cc intake ports from the factory, and flow 232 cfm on the CFM at .400 lift. That seems pretty high! All the other stock heads are like in the 150's on CC's, and low 200's on the cfm at .400, with even smaller valves. Even some of the aftermarket heads don't look much better than that. The machinist told me $40 a hole for the machine work to put bigger valves in which is $640 , and the Manley severe duty valves (which he recomended) are $320! Then I would still have to port them and work on the bowls. Crap!, for that price, I'll buy some aftermarket Brodix or Edelbrock heads for $1800 or so. I don't want to skimp on the heads, since thats where the power is made. Are these numbers right for the 049's?
$40 per hole is way to much money IMO, your machinist must not have a bowl hog. If he's using stones to do all that material removal he's wasting way to much time and charging you for it.

I had a pair of 049's milled, new guides installed, hardened seats, spring spacers installed and pockets enlarged for roller springs, 5 angle valve job, valves enlarged to 2.19/1.88, ARP studs installed with 3/8 guideplates, PC seals, and stainless valves. I supplied the valves but the rest of the parts and labor cost me just under $600 assembled.

You will not need severe duty valves. Check out WWW.competitionproducts.com for some good valves, guides, guideplates, and springs
 
#21 · (Edited)
I can relate to that $40 a hole deal.I have 3 different machine shops I use,and one of them just closed up because the owner was ready to retire and the property the shop was on was worth 7 figures{you gotta love urban redevelopment} so he sold off all his machines and cores and moved on.I made out like a bandit when I went there with a few hundred bucks and cleaned out all his good bigblock chevy stuff and got a fully machined 400 block too.

Now back to the question.I use a "race only" machine shop to do any engine that I am building wher the long block will be costing me or the customer more then about 5 grand.I also have a corner parts store that does cylinder heads.

The old timer used cutting bits to machine the heads one angle at a time which was petty labor intensive,and he wasnt really interested in upsizing valves AND doing the job right,so when I made him do it,I payed the price.My race engine shop used the same quipment up until recently,and they charged less since they knew the tricks of the trade a little better,but they are 40 miles from my house,so I dont like to run to them all the time.The parts store is now my go to head shop.Years ago they had a good race engine machinist there,and he got them to buy a ton of equipment including short block stuff.After he left,they sold off the boring and honing stuff,but they had a ton of other good stuff.While that machinist worked there I sent a lot of work their way,and they bought a lot of oddball stuff that I have helped the subsequent machinists put to good use.They have a really good Serdi valve machine with a ton of bits,and they can bang out valve jobs including top cuts and bowl cuts faster then most other shops can do a single valve job.The down side to their work is that I need to hand blend it all since it leaves a big ridge where their bits stop cutting.I got them to order a few cutting bits to enlarge spring pockets and arbors to cut down valve guides,and they are happy to machine heads for bigger springs,and PC seals for me,but since their tool selection is limited I sometimes find myself mixing brands of components just to know for sure that they can do the job.For instance all my big roller stuff uses the 950 K motion spring because I know that they have the tools and know how to set that spring up in just about anything.All my flat cam race stuff uses the crane 896 spring becasue I know they have the tools to set that one up to.These sort of things are something you pick up along the way.

I used to hate the Serdi machine because I felt that it did a generic valve job and that a good machine shop could do a better job with custom taylored angles,I still feel I am sort of right,but I also learned that sometimes it just isnt cost effective to go for that last little bit when the money can be better spent elsewhere.Back when that race machinist was at the shop,we pioneered a setup that made good power for low price on a smallblock with stock heads.Knowing that most stock heads are beat to death and need everything,we found a way to take advantage of the Serdi machine's biggest assest,and that is speed.I came up with the idea of using feria 2.08" intake valves with 5/16" stems.He figured out a quick and easy way to set the guide reaming tools up to cut the guides offset and he would put bronze liners in to bring them back down to 5/16,and the entire job cost the same as doing regular bronze guides.Then he would piut the 2.08" intake valve in centered over the new guide.The difference was that we only had to lightly clean the chamber wall side of the valve seat and most of the material was taken from the side of the seat that face the exhaust valve.The Serdi machine had no idea it was doing such trick work,it was just doing business as usual.After the machining was done,I only had to do the heavy blending work on one side of the bowl and the chamber didnt need to be cut since the valve wasnt any closer then the stock 1.94" valve,and if I did cut it,it was to get even more flow.This solved a problem I was having with using 2.02: valves in stock heads with a lot of relief on the chamber wall which resulted in cracking.I could get the same flow with less work.The final trick was to cut the spring pockets out for oversized springs which also recentered the spring on the valve.All this trick work ended up costing no more then a regular rebuild and the performance was better.As for the rocker arms,the valve was moved about .030" over which was insignifigant in regards to roller contact with the valve tip.Had it been and issue,adjustable guideplates would have worked,but the truth is that I even did this trick on some heads that had no guideplates at all.

So I guess my point is,that maybe you need to find a shop that can do the work you need at a lower price.I also wouldnt run severe duty valves in a 500hp bigblock.If you were going to upgrade to 2.19" intake valves,I would go with a set of new stock replacement steel valves such as Speedpro.I would also notch the tops of the bores to closer match the chambers,otherwse you wont find any power.Aside from that,I think you could make the power you are looking for with a good valve job and light blending on the stock valves.

Good luck.
 
#22 ·
tommytempest said:
OK, now I am really confused. According to the Chevy Hi Po link firestone posted, the 049 heads have 2.06 intake valves and have 253 cc intake ports from the factory, and flow 232 cfm on the CFM at .400 lift. That seems pretty high! All the other stock heads are like in the 150's on CC's, and low 200's on the cfm at .400, with even smaller valves. Even some of the aftermarket heads don't look much better than that. The machinist told me $40 a hole for the machine work to put bigger valves in which is $640 , and the Manley severe duty valves (which he recomended) are $320! Then I would still have to port them and work on the bowls. Crap!, for that price, I'll buy some aftermarket Brodix or Edelbrock heads for $1800 or so. I don't want to skimp on the heads, since thats where the power is made. Are these numbers right for the 049's?
Hmm..... 40 bucks a hole.

That sounds a about right.

If he was a hooker!


;)

tom
 
#23 ·
This machinist is semi retired, and yes he's the same one that told me porting, bowl work, and bigger valves are just a waste of money. He used to do all the racers motors but I think he's just wanting to do stock stuff now. Sounds to me like he shot me that price because he doesn't want to do it! I'm taking the heads elsewhere or buying aftermarket ones. There is another speed shop in town, and hell, NAPA has a machine shop as far as that goes, not sure I would trust them to put in bigger valves, but I'll ask them. I'm getting a kick out of all your responses to his prices! Funny. I hear ya loud and clear though. i'm just going to pick up the heads from him. i think I will still have him do the short block though.
Thanks guys!
 
#25 ·
#26 ·
firestone said:
I dont know what the casting numbers are, but you can get a set of assembeled heads from this shop for $600.

http://www.revolutionaryperformance.com/

If you scroll down, you can see where they talk about them

"BBC OEM heads, matched set, 3 angle valve job, surfaced, new 2.19/1.88 stainless Manley valves, springs, retainers, Manley 7/16 studs, locks and positive seals $600"

http://www.revolutionaryperformance.com/products.htm

Adam
Not a bad price. It would be worth taking those heads to GOOD shop and have them checked out. Many times done heads just need a good valve job........

tom
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top