I was wondering if a set of 18 STDX Brodix heads would work with a set of off the shelf SRP -31cc Blower pistons in a 383 kit? Anyone know for sure?

 

If you are asking whether or not, it is an 'install blind, with zero issues' question, I'm not your guy.

With that stated, I will add, not knowing your experience/knowledge level, the primary problem I see (ignoring any flow issues), with using (without modifications) pistons intended for a specific head design, on heads with different valve angles, is the piston to valve clearace. This MAY be a mute point, with a piston having a deep wide negative dome the crown. Of course, you would know better than others, what valve lift will be utilized. So, it is you, that will determine whether piston/valve clearance, for the given cam used, warrants checking. If perimeter of negative dome, is a concern, in regards to coming in contact with valve OD, check it.

 

Arnie

What kind of dope do you smoke?

 

LMFAO Denny!!!!

LOL Hey there are several off the shelf pistons made now that will work. Most came out in the last few month's.

 

would anybody like to guesstimate on how much closer somebody would be to having clearance problems if they wanted to try putting 18* heads on a stock bottom end LT1?

 

I think the answer here is a custom set. They don't much more than off the shelf pieces and you can have them custom built to your chamber size, valve angle, etc... Give Diamond a call. You'll be supprised at the prices.

 

With the size of the valves in a 18 deg head you are going to have little and none P to V clearance on a production Mahle LT1 piston. Time for a Isky Valve relief tool. Then again a 330cfm head probably shouldn't go on a stock bottom end.

18 deg heads for the most part need custom pistons, custom headers and shaft mount rockers. The 18 STDX solve some of these problems but DO A CUSTOM PISTON! Diamond does have a off the shelf 1.250 CH 4.030" Bore piston.

Bret

 

Bret,

Do you have any experience with the 18X Head? What's your opinion of it and using the Brodix 1800 Manifold converted to EFI?

Dave

 

That Brodix intake is a direct bolt up, and I would expect it's similar to a Super Vic so it would be a good way to go.

The heads are a 10deg face angle like a 23 deg head so maybe something like a Edelbrock 2926 might fit, all depends on port height.

I'm a big fan of Super Vics for any engine when you have the space for a taller intake.

As for the 18X heads, they are going to get you more flow than a 23 deg with standard rockers. A 23deg head that requires shaft mounts might be able to get you more flow. 350-370cfm is possible on top of the line stuff but it's not cheap. The big advantage to a 18X is the valve size, but then again the bore limits the flow potential. The 2.140" valves in the 18X are 53% of the bore size of a LT1, if it's on a 400block then your doing even better. A 18 C is more expensive but there is a lot more flow potential in those heads.

Basically the 18X is a great way to go if you want to stick with Stud Mount Rockers. They are going to get you a ton of flow for the money, I would just want to see them on a 383-400+ cube street motor, or a high RPM 355. Not Nextel Cup high RPM but a healthy drag car with a big stall and a 7,800-8,000rpm shift point.

Bret

 

thats my next project!
i just finished my forged 383, but like any gearhead, im already planning the next upgrade.

im thinking about getting some brodix 18* std heads with a good port job, and have the 1800 manifold converted for EFI. (unless a vicjr is lower and would work?)

i have to ask you advanced guys though, should i go with a 4bbl tb and a custom elbow like hotrodhawk uses, or to get a wilson-style elbow and bolt-up a large ls1-style tb. i think the wilson style ends up being lower overall, which would be good, as id like to stick with an lt1 ramair hood if possible.

would the new kooks 1 7/8 step headers choke those heads, or would you need a custom set?

 

I am currently exploring all my options. I have looked at some of the top of line All Pro and Pro Topline heads and even the Brodix 18 Clones. While they all flow a ton, they all get cost prohibitive pretty quickly compared to the 18X even before you consider that they require shaft setups. Because I really don't want to sink a ton of money into an LT1 as sooner or later I will be going bigger in a traditional SBC. The only reason to stick with the All Pros or Pro Actions would be if I wanted to run in some the LS1Tech based racing series and avoid the 300lb penalty for nonstandard valve angles.

I have a set of bare AFR 227s on the way that I am considering selling to run the Brodix 18X's instead. I can pickup the 18X's complete for $2000 and I figure I would have at least $2400 in the 227s by the time they are completed.

I think the 18X's have a couple of advantages over the 227s in that one the 18 degree valve angle should be a little less shrouded and flow better on the smaller bore even with the larger valve. The 18X's also appear to have much better low and midlift numbers than I would probably get out of the 227s. Additionally the intake bolt holes on the head don't have to be modified for the traditional SBC intake bolt pattern when converting to a single plane. And although I have heard you could order the AFR 210/220/227 with the bolt pattern already machined.....AFR told me that I could not when I ordered the 227s.

Looking around I have found that Hedman sells a 1 7/8" spreadport header for fourth gens which would allow me to take advantage of the 18X SP's spread exhaust ports which offer a pretty substantial flow increase over the 18X STD.

I am trying to balance flow and power with cost. I may still get some true 18s (preferably with intake and rockers) if I can find a set for a reasonable price. But then I am back to modifying a production header or going with some Lemons all at additional cost versus the 18X.

I don't mind intake height as I just ordered a 4" Glasstek Hood and the car is pretty well gutted to be on the ragged edge of street/strip.

The heads are being considered for the refreshening of my 392 (.010 Over / 3.875 Stroke) LT1 and I am not too afraid of rpm as that is the reason I recently purchased a FAST system. Although I would like to keep the rpm within reason as I am using Eagles with L19s and a standard weight Cola crank.

I have spoke with Wilson concerning the 4 Barrel Throttle Body versus using an Elbow with a 90mm Throttle Body. They did not think there would be much if any power difference, but did recommend a spacer for use with the Elbow setup.

I'd like to give you a call sometime and get your input if you don't mind. Lloyd gave me your number discuss manifold options with for the 227s when I was giving them more consideration.

Sorry for writing so much...but I think everybody could learn from the discussion and see that there are a lot of different things to consider besides just changing pistons.

Dave

 

Dave,

Sounds like you really thought all of this out.

The 18X heads are hands down a good bargin.

If you have talked to Wilson I'm sure you know they charge $650 for the EFI conversion too. It's a lot of work and they do a awesome job but thats a ton for the job at hand.

Bret