Was thinking about something like this for a 406 package off ebay Wondering if anyone had experiance with this setup and will I have to grind on it to make it clear my cam (XE274) or 400 block? Also how much can I knock the compression down. My heads are 67cc. What kind of head gasket is out there? Will I be able to knock this down to ~10.4:1?

Those rods will clear a stock cam. It's still the stock 400 stroke after all, and they have no bolt heads, since they use capscrews instead; and the XE274 is higher lift than stock (therefore smaller around most of their lobe) so there should be no problem at all.

I don't think you are going to be able to lower that combo's CR that much by using a thicker head gasket. The thickest I know of is .051". For reference, I run 64cc heads, that gasket, and 8cc dish pistons, and I have a CR of around 10.4:1.

Call the company and see if they'll build you one with some D-cup pistons.

There is no way to be absolutely curtain weather these rods will clear any particular cam. ( especially a roller cam) You have to check for yourself. part of the joys of building a 400sbc.
Yo can grind the rods if nessessary before balancing.
You can buy small basecircle cams for this too.
You have to check and verify block clearance and counterweight clearance anyways, so.
There is no 400 head gasket that will reduce the compression ratio enough. This method is not the best anyways because
it increases the "quench clearance" making the motor more detonation prone any ways. Your head's combustion chambers should have lots of meat that will allow you to unshroud and
lay back the combustion chamber walls to reduce compression and increase breathing at the same time. You can also have some pistons machined for a small "D dish". Just about all sb cylinder heads will benefit from this chamber profiling on a big bore 400 anyways.

Plan on having this bottom end assembly "balanced". This may or may not require some mallory metal to balance. Be aware of this and the cost in your budget. Generally it is not econimical to buy stuff that does not fit your requirements. It usually costs more than its worth to modify the parts to suit you build requirements.
I would build a 400SBC for street pump gas with D dish pistons
for 67cc heads.
Price out the cost of ordering the right parts to start with and the required machining and assembly costs before you commit to buying this bottom end.

My heads have already been opened up so can't be done to help compression.
I was thinking though the thicker head gasket. Also though most blocks aren't zero decked. So wouldn't that help, or is that a bad idea? What about fly cutting the pistons?

Basically want to take the top end off the 383 so its bought already Just want a stronger bottom end.

Why not run a little more radical cam to bleed of some of that compression? I have run that same bottom end on premium 93 with (sometimes even 89 if it was all that was available with no problems) I ran a284 extreme in one and a crane sat. night special 300 516 in the other. The 300 with its 106 LC sounded wicked with a nice "pissed off bumble bee sound."

Over camming the motor to try to get a high compression ratio to run on pump gas will only work for easy street cruising at part throttle. Don't expect this motor to operate at WOT with decent
ignition timing without knock.
This "bleed off effect" is only effective at low rpm below peak torque. Once the motor is at WOT and "on the cam" it will need a higher octane to make good power without detonation.
Kind of a bad crutch that will result in a motor that will be less than it could be with the right cam and compression.
Not to mention the poor gas mileage.
You'll end up with a compromised engine tune that neither
runs right or makes all the power it could on pump gas.

Listen to what F-BIRD'88 says because he is right on the money. The only time heavy metal is used to balance a 400 is when you balance it internaly. If you want to use the small flex plate so you can use your stock starter and have the header clearance you will need you can use what they call a pork chop that bolts to the flex plat for the proper external balance.

Auggie

Auggie, This is not true, Depending on how bad the crank is out of balance
from the manufacturer, heavy metal may have to be added even when doing an external balance. My understanding is when useing 6 in rods it is easy to internally balance a 400 so why not do it internally? If he is going to have this balanced anyway, why would he want to use that balance plate between the crank and flywheel, rather then just having one welded to the flywheel (if external) And if he did use a small flexplate trying to use the stock starter keep in mind you have to drill and tap the block as they come with the bolt pattern for a big flywheel starter. It doesnt really sound like you have much if any experience with 383 or 400 engines.

Finally, I would have to dissagree with F-BIRD'88 about those particular rods not clearing the cam, I have compared these rods to stock types (which need to be clearanced) and there is more clearance in the area that goes near the cam than you would think. Needless to say these Eagle rods are considered their 3d stroker rods, that were designed to help ease the pain of clearance issues, so I wouldnt even worry about those not clearing unless the cam had over .600 lift.

Aaron91RS
Sounds like a nice strong bottom end though, I would agree to go with some D-cup pistons instead and also I have seen other identical packages on ebay balanced for that price or less.
Good luck with your project!

Do you honestly believe a 284 extreme is to large for this combo?
What are you building tow trucks? Anyone buying a $1400 bottom end is going to be doing some racing. No crutch intended he could
very well run 89 Octane gas with this cam and 34 degrees of Total timing. And if you Think its compromised how about some
11-sec. timeslips with the matched set-up.

Well, this is a reply to "85TPI400. You are partly right. I have never built a 383. I have built a few 400's though. I built a 406 for my brothers 1987 Monte Carlo and here is what I did. I started with a (4) bolt 400 block (casting #3951511) because we had it and bored it .030" to 4.155. The block sonic tested out to an average of .280". The block was alinged bored, cooked ect. ect. I used a stock 400 forged piston from TRW (#L2352-30) and a set of stock 350 5.7" rods. The crank was a stock 400 (3.75" stroke) turned .010"/.010". Rod and main bearing clearance was set at .0025". Because the stock 400 uses a 5.565" rod and I used a 5.7' rod the piston at TDC came out of the block .120" which I had machined off for 0.0" deck clearance. This also raised the rings in the block. Set ring end gap at .025". The machining removed all of the dish and 99% of the four valve reliefs in the TRW pistons. Useing a Fel-Pro .038" head gasket this gave this engine a very nice quench of .038" but a 11 to 1 comp. ratio useing 75cc heads. Even with that tight quench and steel heads I didn't feel that 92 oct. would handle that comp. ratio on the street. So I had a "D" shape dish machined into the top of the piston for a finel comp. ratio of 10.59. I was a little worried about running that high of a comp. on 92 pump gas but with that tight of a quench I felt I could get away with it. As it turned out I was right. Anyhow it was my brothers engine, right!! The cam was an UltraDyne 221*/231* at .050" with 112* L/S and did interfer with four rods. #1, #2, #5 and #6. The rod bolts were ground off for a clearance of .035" As far as the balanceing goes for this setup, it balanced out fine and we did not have to use any heavy metal because we lightened the pistons. You are right about useing heavy metal when balancing int. or ext. because of the use of a lot of aftermarket parts. We did use a stock 400 flywheel (14"/168T) and a stock 305 starter moter with a 400 alum. starter drive houseing which we regreated using. By the way most 400's come with both sets of holes already drilled for the starter. This block did!! Because of the larger flywheel dia. this moves the starter away from the block which interfered with the SLP 1 5/8" headers. He has had a lot of exh. leaks on the pas. side because of this. He fixed this problem last summer with some grinding and welding. The 400 that I am building now will use a 12.75'/153T flywheel and a pork chop for the balance to prevent header interferance with the starter. Total cost of this eng. was $2987 (I did all the labor free) and it dynod at 421hp and 468 lb. ft. of torque, idles at 650 rpm in drive and has all of the emissions working. It passed all emission testing with flying colors. If you need to know anymore info about this set up let me know .

Auggie

I'd say your compression ratio is not near as high as you claim.

probabily have 72/76cc heads
and/or some deck height clearance. Low 11's is very impressive for a street running fbody. Good stuff..
I will go along with Auggie as above at around 10.5+/-:1 or so.
matches what we're seeing at this end of the world.

bringing back an old post.

it seems like all the 400/406/408 guys are in here. I am looking for some recommendations on a 406/408 setup.

I have an engine that is a 406 already but it has a few minor scores in the bores. also one cylinder got a bit of moisture in it and got a little surface rust on the wall. I was wondering how close does the bore have to be to the 4.155 mark to be good. can it be a couple thousandths over and still be okay?

The scores are light and I dont think the little rust will be any problem. I was thinking if I could just have it re-honed that I may not have to go to .040 over yet. What do you think?

as far as buildup goes, I am looking for around 400-430 hp and 430-460 lb-ft of torque. I am wanting to do this with a modified TBI. I am willing to retrofit a roller cam also. It currently has 882 heads (steam holes drilled) and a Weiand Xcellerator single plane intake. Not sure of cam yet.

some feedback.....PLEASE.

Yes you should be able to clean it up with a good honing.
Modern hypertectic pistons like KB's or federal Mogul are suprizingly tolerant on bore size fit. They don't seem to mind being loose at all.
And a racing forged pistons likes loose too.

The more you plan on pounding 'er the looser the better.
If you plan on spraying 'er at all, you almost can't be too loose.
The heat of combustion expands the piston at WOT.
The more combustion, the more heat.

My friends 700HP 18 deg head 406 is so loose he uses gap checked .040" over rings on a .030" over piston. Has almost .010" bore clearance.

It see's such large doses of NOS (500/600hp shot) that she heats every thing up real quick and needs that much clearance.

We etimate it's hitting 1300hp on the spray. No dyno shop is brave enough to let him dyno it on the spray.....

When your done honing, if you cannot feel the score or pit mark with your finger nail don't sweat it. It will run fine.
Use normal rebuilder rings like Hastings. the are made to work with cylinders that are less than perfect. A expensive moly ring
won't be as tolerant.


Hastings Rings

get rid of the 882 heads. no power there. Lucky if it will make 350hp.

Just about any other head choice is better.

A set of vortecs on that motor will require a neck brace when you punch 'er.

A nice set of home ported , big valved 441's,920's or 487's will do if you want a large chamber head.

Even a set of cleaned up cast L-98 TPI heads would be good (083)

There are lots of head choices out there. The 882's will severly disappoint you.

Sell off the Accelerator and get a Performer RPM.
Does this motor hae a dished piston?

$$$Retrofitting a roller cam is expensive.$$$ Put your money into a set of aftermarket cylinder heads or Vortec and a roller cam is absolutely unnessessary. A moderate performance hyd flat tappet will more than hit the mark. A motor will not make power with a good cam and bad heads. Always use the best head you can afford.
The Protopline Iron lightnings are real nice too. Price is right.
Choose 200 or 220cc ports and 64 or 72cc chambers depending on compression desired.
When everyone sees your taillights on a regular basis you can tell 'em its a lil roller in there if you want. Moms the word.....

www.protopline.com
http://www.shaverracingheads.com/index.htm

I just ran your combo to get 10:17:1 cr. Here is what i did, using Pat Kelly Calculator here is what I got.
Bore=4.155
Stroke=3.750
CC Heads=64
Head Gasket Thickness=.039/Fel-Pro1014
Head Gasket Bore=4.200/Fel-Pro1014
Deck=.000
KB-Dish Pistons 18cc
Comp Cams XE
Advertised duration 274/286
Duration @ .050" 230/236
Lift =.487/.490
Lobe separation=110

Desktop Dyno Says: Dart Iron Eagles Heads 220cc 2.02/1.60
Carb=750
Intake=Dual Plane

TQ=450@4000
Hp=400@5000

DTL, that is actually close to the setup that I am considering. I dont know about the aftermarket heads though. I could swing the price but dont really want to. not yet anyway.

what are going to be the best head choices for an inexspensive cost? I am a machinist by trade so some home porting and rebuilding them myself doesnt bother me but I dont have any experience in doing this work. any tips and/or instructions would be appreciated.

also wondering if a nodular crank could handle my 600 hp shortblock idea. I wont really NEED that capability but would like to have it in case I decide to give the motor a little more later. once again I dont really want to spend cash on an unneeded forged crank.