I'm going with a setup, that i could use some help on. 91 computer-only map, everything new, not purchashed yet. Money is no problem, just want 2 spend it in the right direction. Car has Moser 12 bolt, 4 link, qa1 single adj coil overs-from SKI_dwn_it, 4-10 gear 325-50 15 MT drag radials. Going to a turbo 350- ditching the black tag.Car has gone 11.90@115 on motor, 358, lots of porting on factory heads, TPIS MINI-RAM 52 mm throttle body, ZZ4 cam. ON 150 shot, plate with 2 fogger nozzles, dedicated fuel sys, ALL NEW. Only could spray it in 2-3-4 went 11.61@125.04,on the limiter at 6500 in all gears and at 1200ft. CLUTCH IS NEW BUT SLIPPIN ALL THE WAY. My question is any adapters 4 the 350 trans or make my own, Second i'd like to go with the MINIRAM but i'm thinking of going AFR 227 competition port heads, Dart little-m sportsman block, 3.875 stroke on a 350 main in a 4.12 or more bore,6 in rod and pump gas it. Will the mini ram be suffice-maybe mono blade it, and id like to hook up a speedo to it, i drive this all the time. And t-d shaft rockers, I was wondering if anyone has any info on anything,CAM choice, what STYLE TURBO 350 OR ANY HELP ON A TUNER. Or just go 18 degree head and some F.A.S.T EFI or BIG STUFF, id really like to keep the mini ram ,and im going 2 spray it. ANY INPUT PLEASE. All interior guages work, G-S clone, except for the Street Lites. Have G-S wheels just sitting.

 

It all depends on RPM goals as that is where you will find HP. I will say for sure you can not get fit a rod that is too long in the block with that stroke if you want to rev it at all. 18 degree heads are a bare minimum if you are serious about going fast 14 degree if they are in the budget. The whole head cc deal is the most non-sensical way of describing a head I have ever heard of. The dimensions that really matter are minimum restriction area valve diamters and angles and runner length. Ports are all about shape and dimensions not volume. An extreme case would be compareing a straight tube to an hour glass both the same volume but completely different in shape. It is no doubt used to in one way dumb down the selection process as the mentality bigger is better so people buy cylinder heads too big for what they need if they look at minimum cross section need 3 square inches well then would't 3.5 be that much better. Probably not just like if 235 dgree intake lobes are good for an application then why not 250?

Possibly stating your goals and a real budget might make the most sense to start.
How much HP
How much torque
Max rpm
Max $$$$$$$$$$$
Pass smog in any way

Dave

 

If your going to build a big engine like that I would ditch the Mini Ram and go with a converted single plane intake with a sheet metal elbow and a mono blade or LSX TB. Your leaving alot of power on the table with a Mini Ram and going to spend big $$$ to get it ported to the point where it will even keep up.

As far as 23* heads go - The 227's are not really big enough for a serious 421. Don't get me wrong they will make decent power but the 235's are better suited and AFR has a bigger port one as does Chad Spier on a Profiler casting. With the best 23* head a serious 421 is going to be done around 700ishHP and 7500RPM.

18* degree stuff is 15yrs old at this point.... No one but a few old Comp and Bracket racers still run it on anything. No I take that back some of the nostalgia NASCAR road racers still have them . Many of those heads are no better than the newer 23* AFR 235.... Some are worse. I usually won't even touch one these days because of the cost as compared to power output.

A modern cyl head like the Brodix GB, BD or the Dart 11*, 12*, 13* heads that we run on Dirt Late Models will make upwards of 890HP and feed a 421 to 9000RPM. If your going to spend "roll deck money" on an common intake port wedge cyl head at least spend it in the right place.

The ever popular SB2.2 is another route if you want to spend $$$ and make massive SBC HP - but honestly compared to what your running, at this point, even an AFR 235 headed 421@700Hp is going to seem like a rocket ship and set you back $15-$20K for an engine instead of the $35-$50K (NEW) for a more modern GB, BD or SB2 engine.... but if your inclined I know where there are a number of fresh engines for the low to mid 20K range. Straight out of a few World Of Outlaw Late Models, near 900HP and will run forever in a drag car. Will run on the street fine as long you can afford the gas.

I like it when I guy comes in the shop and says "money is no problem".

I also wouldn't run a TH350 with over 600HP on radials. The car will be inconsistant and harder to hook up with that low 1st gear. I'd recommend a Power Glide. Everybody makes parts for them and with a SBC a good one would last forever.

Keep in mind. People can spend you $$$ for you very easily. Some better than others. I'd really need some more info on what you hope to accomplish with the car before I can give you more than broad generalizations on engines.
Will

 

What kind of HP are you after? I think the miniram is fine up to a certain point. A few guys over the years have made excellent power with a miniram.

Will makes a few valid points.

 

I am amazed at the help, on the forum (THAT IS) to the extent that people will go, to give feedback on a post. Honest hp# 700 on motor would b fine, MONEY is really not a problem, also since i get parts at wholesale, LITTLE M SPORTSMAN 1670.00, not bad huh, NEW. Seen to many guys at my engine builders shop, bring him stuff. FRESH FROM THE MACHINE SHOP USED, complete junk, titanium valves not cut or even lapped, springs have no usable compressed pressure, cracks down the valve guide. On a set of 12 degree Pontiac Big Chief heads, at 9500.00 and 4 valves had corrosion from brake clean. My cost is only parts, so i'm very cautious of used stuff-many people can relate! But u never know, some are honest people. Going with the sportsman block to reduce harmonics when spraying it because of the caps. If anyone has anything else to add, please do. I THINK ITS PRETTY MUCH CLEAR NOW, IF STEVE SEES THIS, WITH HIS (EASY) BUTTON, CALL ME 708-878-4458, I MIGHT B INTERESTED IN HIS STUFF. I lost his info???????? Thanks EVERYONE.

 

Talk to TPI421Vette. He's got a lot of experience with 421s. He can build the motor and get you the AFR heads very reasonable. He's an AFR distributor. I believe he's running the Miniram with a mono blade. He's building my 396 now but I'm sure he is capable of multi-tasking.

 

You really haven't said what your goals are as mentioned. What kind of rpm, hp and tq, pump gas or race gas. Are you going to build it yourself, or are you looking for somebody to build it for you? A 421 just like any other engine, there are a million ways to do it.

 

IMO go bigger! with the right heads power can be yours. There is a 461 CI, and since you can get good prices, get a 9.325 deck height block and go big 700 HP plus without having to spin it up to 8000 RPM

 

A tall deck opens things way up! Bigger is better. How about a 4.25" stroke and 472ci. Standard deck height is a different story.

 

I like the way you think!!

 

Johnny,

Hey good to hear from you. If your going to be building a big hammer you can contact me and I can give you all the specs for my motor which is still very streetable, runs 10.0s at the strip. Essentially with the solid rear you have, a swap to the T350, your setup would be identical to mine and I will assure you that you will be more than impressed with the power on the street, and blow peoples minds on the strip. This setup will all fit under the stock hood and be completely stealth looking.

Alternatively you could go to 18*, but things get more expensive (headers, shaft rockers, etc) and I have seen 18* stuff go slower than mine at the track. If you can pick the right combo they can go faster, but I don't have that recipe to share with you....and it will be more money and likely less reliable.

Give me a jingle and I would be more than happy to give you all the specifics.

Oh yeah and for a T350 contact Rossler Transmissions and get one of their T350. They are by far the best T350 builder out there and nearly EVERY professional drag racers uses their stuff. He can get you the adapter piece and all you have to do is give him the tailshaft from your existing setup. It will go right in. I have one in my vette and we also have one of his T350 in our 4000lb 67 chevelle with a 555ci motor and it runs 9.6@144 and it has 5years worth of runs on it!!! They only run around 1300 for a brand new setup! Tell him that Jesse Azzato sent you.

 

did u ever end of building a 421?