383 Aluminum Head Dilemma

[Tempest 455]

Just a few thoughts for the OP:

Sounds the reverse but very lean will give you a worse eye burning sensation. Rich will as well but honestly, a very lean idle condition will make your eyes burn and clothes smell like you will not believe. Its called a lean misfire. Typically its a result of the retarded timing, people crank up the idle speed past the idle circuit and it' now idles on the primary circuit w/ no idle enrichment. You will know for sure if your idle mixture screws do nothing.

Regarding aluminum heads, (another makes but same principal) I installed some on a car about 15 years ago in place of some ported cast iron heads. Car went .40 quicker in the 1/4 w/ just that change. New CAD designed port shapes, valve work etc. will be a vast performance improvement over most factory stuff. The increased flow and ability to run more compression are significant benefit. Just depends if you want the car to be stock or not. Some cars I would do this, others I would not even consider it.

I built a motor for a buddy a few years ago and we painted the Al heads and even made casting #'s using epoxy.
I swear it's just a "stock" 400! ;)

Well maybe around 70 ci more and a few other things.

 

[Meep-Meep]

Nice Yak motors. Do you need a set of CV1 heads? If you do PM me.

 

[Photon440]

With all the talk of which heads make more power, even if there was no improvement I'd still want the aluminum heads...just for the weight reduction. Every little bit to help with handling.

Just my thoughts.

 

[99ss]

I don't have the magazine right here with me, but when they switched to the 75cc E-Street heads, they gained 30+ hp and 20+ tq, TO THE REAR WHEELS. The 383 was being tested on a chassis dyno.

For the cost it isn't bad at all.. it would pep up a car for sure. Anyone milled them and bumped the compression to like 10 or 11:1 ? Can you run that much in one of these motors? I don't know a lot about old school iron block engines.. ptv clearance?

 

[natas33]

Here's my thought process. A: Replace the XE274H cam with something with less duration with the hopes that A/F mixture and is improved. $B: 1) leave the cam, replace the heads with E-Street heads, increase compression, but with standard head gasket .065 quench $$ 2)leave the cam, use 516 heads with steel shim gaskets, increase compression, maintain .045 quench. $$C: Tear the engine out. Deck the block, re-ring the pistons, touch hone the cylinder walls. Reassemble with same cam, and piston (if possible), retain stock 346 heads

Some milodon pro flo race valves in std 2.08 intake will increase airflow substantially on your stock heads, because of the undercut stem design. They're around $150 set. Best flowing valve for the money. Milodon don't do the pro flow in std exhaust size, use a manley or ferrea for exhaust.

Cheap gain. And don't be afraid to mill the heads if you have enough p/v clearance. The 5 bolts cylinder and felpros always seal well. Run a 160 milodon high flow thermostat.

Mopar bb's also have a very tight piston/wall clearance from factory for low rpm's. I once had a standard bore 440, had it torque plate honed 0.005, reused the stock pistons with valve reliefs cut in them, moly rings, made 550hp with ported 906's and ran very hard. Used no oil. The machine shop who honed it for me thought 'this will be funny'.. until they saw my car run.

If you mill your 346's and swap out the stock valves with some good undercut stem race valves, especially the milodon pro flo intake, wont be far off the e-street heads.

Spend the difference on a mopar solid cam and some roller rockers instead. Solids with higher lift just work much better in these engines than hydraulic cams, more low end, more vaccum from a higher lift solid, with the same or more top end power.

 

[Banzaiii67]

Finally got around to doing a dry compression test. Engine ran 2 hour prior, was still warm. I also may be incorrectly did the test wrong, I checked each cylinder with the remaining 7 plugs in. I guess your supposed to test with all the them removed and wot. I just cranked it over.

1-118 2-127
3-115 4-130
5-133 6-125
7-130 8-123

The tapping I keep hearing sounds like it's coming from 6 or possibly 8.. all of the cylinders held good pressure and did not drop, so I guess supposed that might eliminate a bad valve(s). The Plugs were medium brown color, none were excessively oily, gaps were consistent and correct.

I set the timing to 18* initial, still has the stinky exhaust, not terrible but noticeable. I still can't get the a/f mixture screws on the edelbrock carb to make any difference. You can turn them all the way closed and it's doesn't kill the motor. I've tried several times to check for vacuum leaks around the intake and carb, never once found a leak.

The frustrating part is the car runs really strong, it's not misfiring nor does it have any off-idle stumble, it pulls hard from 2500-5500rpm.

Regarding the heads, I talked to a couple of machine shop around here, one specifically has more Mopar building experience (Portland Engine Rebuilders, the shop that actually rebuild this motor) Ted King (owner) suggested to cut the heads .050-.060, cut the intake side of the heads, order shorter smith brothers pushrods and some roller rockers, and use a shim head gasket to get the best quench I can.

 

[Banzaiii67]

UPDATE:

Over the course of the next couple of weeks, I'm going to pull the motor and once and for all put to rest the uncertainty of the bottom end.

So, what it's looks like is... the machine shop is going to dissemble the bottom end. Deck the block and get it as close as they can to zero deck height without having to use aftermarket rods if they stockers can all be equalized. Crossing my fingers the cylinder walls are in good shape so I can either reuse the KB 162 pistons or swap them out for Speed Pro's. Still undecided on what I should do there, any advice?

I'm going to dump the comp XE274 cam and put it a Voodoo 60303, lunati 80440LK or a comp 265 DEH.

Head's- Still very much up in the air.. For the moment I am inclined to go with the E-street 75cc or 440 source heads if budget allows. The only other option would be milling the rebuilt 346 heads I have and having them ported but i'd be another $500 into steel heads and another $150 for custom pushrods. Just not worth it..