Aluminum Block-heads

[fancyboy]

I am considering going with the Bow tie aluminum block (10051141), but can not seem to distinguish if they offer corresponding (aluminum) heads with the rwd design/intended for carb manifolds.

Am I stuck with cast iron?
I can not believe no one offers aluminum heads, especially the aftermarket.

[geoffinbc]

No sorry no ones got em. There was a super rare set of aluminum heads based on the cast iron design made by potter racing. But good luck.

Just use the Gen III heads and run the SFI setup backwards to make it RWD. Works great. Plus EFI is leaps and bounds better than a carb in ever aspect of performance and tunability. There is simply no contest between the two.

[fancyboy]

I have several reasons for opting for carburetion but most of all, simplicity and ease of installation and to be more aesthetically correct with the theme of the car (classic).

I would also have to educate myself thoroughly on the tunability of a 3800 FI to the 3.4 with a mechanical roller cam..not to mention how to tune.
The cam would be the same duration @.50 inch lift as its flat tappet cousin, (Cranes # 253941), but of course with more lift.
I will be opting for the mechanical roller, thanks to this board.

Check out this comparative test that Car Craft did of a the same engine with FI and without (carbed)...

RPM carb FI
TQ HP TQ HP
2600 375 179 425 210
2800 377 193 434 231
3000 387 221 435 248
3200 396 241 440 268
3400 400 259 *448 290
3600 403 276 443 304
3800 407 294 437 317
4000 410 313 429 327
4200 414 331 421 337
4400 *419 351 410 344
4600 417 365 400 350
4800 413 378 386 *353
5000 408 389 368 351
5200 403 399 344 341
5400 396 408 - -
5600 388 *414

This was obviously done on a V8 engine (small block).

[fancyboy]

that did not work out too well. The first row is RPM, the second is carbed, and the last row is the FI test.

[geoffinbc]

Well then have you considered making an intake? It may be the only route. CNC guy has made his own.

[fancyboy]

CNC, are you interested?

I am going to contact Potter Racing, they may hopefully have a pair laying around.

[Guest]

I think if you can afford the aluminum block then you can probably find someone to fab up a lower intake manifold to work with those heads and then adapt a carb to it still allowing the use of the distributor.

Then gen 3 heads will flow way more then fully ported iron heads. So you can put a carb on the iron heads but the iron heads won't flow what the al heads can and you will be down power.

Are you using a Distributor or the DIS system?

I had a rare set of these heads of the gen 1 knock offs but made in aluminum. they had the smaller LO valves on the intakes and exh. Quite a bit of work would be needed to get them to flow anything so I sold them. From a performance standpoint they arent' good heads. I currently know someone with another set of these heads but he isn't going to be selling them.

I doubt potter has anyting either as far as Gen 1 look alikes in aluminum. THey might have custom stuff though.

[TurboZ24]

Then gen 3 heads will flow way more then fully ported iron heads.

Actually, they can flow a lot with a lot of work, but I do mean a lot of work.

[fancyboy]

Funny, there is a company offering a conversion kit using the FWD engine, and their headers measure 1 3/8" at the primaries and 2 1/8" at the collectors..seems restrictive.

These naturally aspirated engines tend to drop off at the 4000 rpm mark.
I want to push and improve the upper end..the mechanical rollers will help here dramatically while boosting the lower end torque further.

What would be the recommended header sizes to compliment the newer heads?--with or without porting (?).

I was thinking 1 1/2" without porting, and 1 5/8" with.

[geoffinbc]

1 1/2"

The reason these engines dropped off at the top was due to the intake and the cam.

The cam was the biggest killer. I remember my old 2.8L was almost useless after 4200. Throw a nice cam in it and you will love it. It doesn't even have to be a roller. But if you end up using a bowtie block use a roller cam and hydraulic lifters. Then you never have to re adjust it. You wont need solid unless its gonna be working at 7000RPM.

[fancyboy]

betterthanyou, wasnt it you who had recommended mechanical rollers because of the limited oil circuitry?..or does that just apply to the iron block?

I did read that the bow-tie block (aluminum) is improved in this area.

[Wolf]

betterthanyou, wasnt it you who had recommended mechanical rollers because of the limited oil circuitry?..or does that just apply to the iron block?

I did read that the bow-tie block (aluminum) is improved in this area.

just applys to the gen 1 & 2 blocks

[RacerX11]

1-3/8" is too small, and IMO even 1-1/2" would be a tad on the small size. I would use 1-5/8" primaries even on stock gen3 heads (I assume you mean gen3 when you say 'later' heads)

Marty

[fancyboy]

Racer, that would be naturally aspirated? (1 5/8").

[geoffinbc]

The Bowtie block had priority main feed like a GEN III block. So use Hydraulic roller.