300 with gm ls3 head

[fastbarry]

who on here has first hand experience with running a GM ls head on a 300?


i have found that ls3 heads can be had for a pretty reasonable price and i would like to build a one.

now i am completely capable of joining the heads properly, i just want to talk to some one who has done the same thing or been involved in a project like this.

i would also like to hear from any body with input on this topic. what do you see as the pros or cons of building an alum. head for a street vehicle?


thanks,
barry

 

[fastbarry]

nothing?

 

[80broncoman]

One guy on this site did the GM LS series head on a 300 combo. I do not know if he ever finished the intake and exh and had it start.
THere were pics here but i think they are gone. It was done a few years ago if I rememeber correctly.

 

[fastbarry]

i read about one guy that did it. i believe it was 6bangerbill? i am basically interested in hearing from any one that has had a composit head of any kind.

 

[Emerald 74 4X4]

Did you find any posts from a couple years back using search? He has a build up of the head I believe. It was 6bangerbill, I remember reading it though.

I think as far as a con, besides the labor intensive measure a bajillion times, cut once, weld once, since it converts the engine from a U flow to a crossflow, and obviously different intake and exhaust with the GM mounting, manifold construction is a player. If you can make the heads fit, I see no reason why some simple manifolds would be difficult.

I read something about getting the length correct before welding to account for shrinkage after weld and cool. And I think there were some special valve train requirements. You should see if you can search it. It's on the forum somewhere.

 

[fastbarry]

i did end up finding the posts by 6bangerbill.

fabricating a manifold and a header would be a non issue for me.

i just figured that with all the guys that are hot rodding the 300's that people might have a bit more input on this topic.

i am going to purchase a set of ls1 heads off of ebay and see i can come up with.

 

[Lazy JW]

....

now i am completely capable of joining the heads properly...

Please, please post pictures and notes as you do this project

 

[THE FRENCHTOWN FLYER]

i am going to purchase a set of ls1 heads off of ebay and see i can come up with.

Before I did that I would go buy a LS head gasket and lay it on a 300 block.

 

[Stubby]

There can be major problems with welded aluminum heads. Do your homework. 6bangerbill wasn't interested in input that differed from his ideas. Great guy, just closeminded. Last I read, he sold the head to some guy in Canada without installing or testing. I don't know how it turned out.

In fifteen years of building race engines, I saw many welded heads. The most common probblem was soft aluminum. This results in blown gaskets, seats coming out, can't remove guides without having to ream up to a larger size.

I have seen some very good results also. Brodix was by far, the best I ever saw. I have been out of so long, I don't know about them now. I have seen them put a chamber back in. Brodix used way better aluminum on their heads than GM ever did. I don't know what GM used on these production engines. I do know older bowtie heads didn't weld very nicely, unless you talked someone like Brodix to into fixing them.

Good results require good prep work, good welds with the proper rods, heat treating.

 

['68falconohio]

I can't speak for the welding of heads specifically, as I've never done it, but this is for the welding of aluminum in general. Very general.

Roughly 50% of the strength of aluminum is lost using conventional(melting) welding processes. A lot of this strength loss occurs in the Heat Affected Zone(HAZ) of the weld. This is the area adjacent to the Weld Metal Zone(WMZ) that does not reach the melting point but reaches a temperature high enough to drastically change the grain structure(physical properties) of the material. Heat treating restores this strength. Peening the weld can cold-work the WMZ and increase its strength but the HAZ is never built-up by welding so peening it would most likely leave underfill.

To limit the effect welding has on the HAZ, a good joint design that allows the weld to be made as quickly as possible can be used. This is because the level of degradation and HAZ size is affected by the Heat Input(HI) of welding. A lower HI results in a smaller HAZ. Using 100% Helium instead of 100% Argon for shielding gas can increase the travel speeds possible due to the Helium's higher arc efficiency and lower the HI. Making multiple 'stringer' welds to fill a joint with low HI vs. one 'weave' weld with a high HI will help limit the HAZ size. If a welding machine with pulsing capabilities is available, this can also be utilized. The pulsing current allows melting to be achieved with an overall HI that is lower than a non-pulsing unit. One of the newest GMAW-P(pulse mig) machines with the ability to program ramp-in and ramp-out of the weld schedule would probably be the best conventional method out there for keeping the HAZ happy. It would also be a son-beach to set up for a sound weld every go, requiring multiple test coupons.

People like NASA use solid-state welding processes like Friction Stir Welding on the shuttle's main tank because it doesn't trash the HAZ area. I sure as hell don't have the dough for that kind of setup though.

 

[fastbarry]

now this is the kind of input i am looking for!

thanks for posting up guys.

'68falconohio: i am aware of the heat affects and annealing that you speak of. that is the largest obsticle that i see.

i do not have a cool modern tig machine with pulse function. i do have two 15 year old syncrowave 250's and a syncrowave 350.
i repair broken alum cyl head castings on a regular basis.

i typicaly use 5356 filler and peen the living h**l out of the weld and the surrounding areas. most people that i talk to recomend 4043 filler on cast. 4043 is softer and resists cracking more than 5356 but it is also weaker.

i have yet the have any problems like valve seats falling out near the repair zone.

now i dont claim to be the best welder or anything i am just speaking from my own experience.

i am completely open to any advice and input on this topic. it really intrigues me to think of making this head work.

thanks,
Barry

 

[garyt120r]

A cylinder boring torque plate would be your best friend I think. Bolt it down and then make another one to fit the top where the valve cover goes. That would make it the most stable. I am debating doing the same thing although I am not much of a welder. But I do work for a large airline and we have an amazing aircraft welder. Companies come from all around to contract him. He said he would weld it up if I had everything prepared for him.

 

[StrangeRanger]

I wish this question were about steel, I know a bit more about it. (I basically know squat about the metallurgy of aluminum or the weld procedures) Nobody has mentioned pre-heating. It's a way to reduce the temperature gradient between the weld itself and the HAZ. It's required with thick sections of alloy steel, with thick sections of a material that conducts heat as well as aluminum, it might work even better. However if the HAZ loses that much in physical properties, the proper approach might not be simply on minimizing the losses but also on restoring the pre-weld properties. What about post-weld heat treatment? Is it applicable to AL alloys too? Have you talked with a local heat-treater about can be done?

 

[CNC-Dude]

Instead of using the LS style head, why not use an aluminum Ford Small Block V8 head, theres almost as many choices out there for those heads as there are the Cheby engines. It was done with the cast iron Cleveland heads 40 years ago, and all the other SBF heads(302,351W)have the same bore spacing and valve spacing as the Cleveland does. Those heads should also be on the cheap side since the 5.0 Mustang craze has died down and good brand name(TFS, Twisted Wedge, Brodix, Dart, etc...) heads should be easy to get.

 

[StrangeRanger]

Just guessing here but there are several factors which could lead to a preference of the C***y head over the Ford:

Order of the intake and exhaust valves. The order of SBF head is exactly opposite the Ford 300. This necessitates a custom camshaft. The new C***y heads now use the I-E-I-E order but I have no idea whether they match the SBF or the 300. If it's the 300 that would be a major factor

Location of the holes for the head studs and water passages. This can obviously be re-worked but closer is usually better. If the C***y is closer than the SBF it could be easier to adapt.

Unfortunately, the C***y bore center distances do not provide a benefit. To use a pair of SBF heads with 4.38" bore centers on a 300 with 4.48" centers you have to cut one in half and cut the ends off the other and make two welds; all the resulting combustion chambers are .05 out of line with the cylinder bores The C***y center distances are slightly longer at 4.40". It doesn't appear that it would be possible to cut only one cylinder off each and make only one weld. If were the case, it would have been a huge plus.

 

[Anonymous]

Fastberry, when you get it all figured out, and fixtured, sign yourself up for a night-school brush-up, at a place where they have some of the new pulsing MIG machines with push-pull guns. For a welder, the first time you run one of these is the most erotic thing ever!! :wow:

Pre-heat around 175F, I'd guess. I'd agree on the 5356; machines a little better.

 

[fastbarry]

Fastberry, when you get it all figured out, and fixtured, sign yourself up for a night-school brush-up, at a place where they have some of the new pulsing MIG machines with push-pull guns. For a welder, the first time you run one of these is the most erotic thing ever!! :wow:

Pre-heat around 175F, I'd guess. I'd agree on the 5356; machines a little better.

i have run pulsed mig spool guns. they are the ish! one of my tig machines has some less than impressive pulsing capability, but it is ancient and can only manage 10 pps. i have run my spool guns off of it in the past though.



on the filler metal, the 5356 machines a lot better. 4043 tends stick to the cutters and ball up and what not.

 

[9500rpm]

i think the ls3 heads are to small. if you think about it the six is 300ci in six cylinders. it takes a 420ci v8 to be the same volum as the 300ci ford. just my 2cents thanks billy.

 

[Firepower354]

Set up to center #2 & 5, you'd have less trouble, maybe?

LS series heads flow a lot more air than a 300 head, regardless of original ci/hole, right?

 

[80broncoman]

Set up to center #2 & 5, you'd have less trouble, maybe?

LS series heads flow a lot more air than a 300 head, regardless of original ci/hole, right?

I think thet would be correct.

And If I recall correctly 6bangerbill did his head with 2 welds (between Cyls 2and 3 & and 4 and 5)