83 Crossfire TA

iTrader: (2)

Here, I started another thread in the DFI/ECM forum about my setup and crazy VE, tuning, and generally more info:
https://www.thirdgen.org/forums/dfi-...ml#post6078082

A few of you here I recognize from assorted tuning/turbo/MS... forums/groups. I'd appreciate if you poked your head in there and commented if you have some ideas

Vanilla Ice

How the hell did they not take one look at your VE table and see the issue?

anesthes

iTrader: (12)

The issue is the combo is wrong for the application/intended use, and he's trying to tune around it.

High rev small bore engine, operating like a low rev large bore engine.

The 5 speed isn't helping because he's loading the motor in places it shouldn't be.



-- Joe

83 Crossfire TA

iTrader: (2)

Not sure I understand, are you saying you know what is going on or are you saying "how can they look at that and not see the massive peak?"

83 Crossfire TA

iTrader: (2)

Joe, what do you mean by that? I am looking for some wisdom, which is the reason I posted the other thread (I'd rather have this conversation there and leave this discussion to actually converting them, but for the most part the conversation seems to be happening here), but I'm not sure what you're saying in your response. To elaborate:

High rev/small bore: It's a small bore engine intentionally, the only reason it revs is that it has quite a bit of available airflow even though the ports are still reasonably small (I cc'ed a few of them and they were all just under 200cc). The cam is about the smallest I could go and get the dynamics and opening and closing points I wanted down low and honestly I'm terrified of spinning a SBE to >6500 and will likely not do it at the track in the interest of keeping the bottom end from flying apart.

How is it operating as a low rev/large bore engine?

Heck, are either of those really a thing? Typically people can't get enough airflow out of a small bore engine to get it to rev, and unless it's a truck engine with a large displacement with tiny heads (think big block with peanut ports) a large bore engine is rarely a low rev engine.

WRT to this discussion, typically small bore engines are less detonation sensitive and large bore engines are more so. Big blocks with large bores tend to need higher octane fuel compared to a small bore setup (and typically also need more ignition lead to get all the available power out of the A/F charge), while small bore engines typically are both less detonation sensitive/limited and also need less timing to get the most of the a/f charge. This is the reason why when GM designed the LS series engines, with much better flowing heads they also made them closer to square (smaller bore, longer stroke) then SBC's that fit the same nitch, because they didn't need the large bore to get the same airflow and might as well take advantage of a smaller bore.

Orr89RocZ

iTrader: (20)

What he is saying is, goin 80 mph in 5th gear at 1800 rpm and inducing high loads is NOT what that engine is built for and is not what you want to do, so dont tune that. Downshift to a different gear as was suggested.

Thats lugging a motor down low.

190's cc head on 305 cubes is not a low rpm motor

83 Crossfire TA

iTrader: (2)

Yea, I can make it do things that you couldn't with an auto, but I wouldn't agree that I'm loading it someplace where it shouldn't- It's not crazy for it to be at 1300-1500rpm on the highway and want to slowely pass someone, which could about cause this situation.

Vanilla Ice

It's hard to say this in a nice way, the automatic is smarter than you. It was designed by people smarter than you. If you can't get an automatic to hit a load range at an rpm then it's because they didn't want you to do that because it's a stupid situation to be in. THINK ABOUT IT. You are causing explosions to accelerate a shaft without enough leverage. You are breaking your engine. Stop driving like that or change the engine setup.

Vanilla Ice

I was irritated with my last car that wouldn't allow me to get into 4th gear in my neighborhood without constantly having to shift into 3rd for the slight hills. Tuning helped by didn't fix the problem. The PROBLEM was 4th gear was not right for the situation. Third gear was. 40mph and having to be in 3rd was really annoying. But I didn't force the situation I just shifted correctly.

anesthes

iTrader: (12)

Justin explained what I meant, but yeah.

Even my 6.0 has trouble in that RPM range, and the transmission is constantly shifting and unlocking the converter to make it work.

These posts should be split off onto your other thread though.

-- Joe

Daveyg

I joined here specifically because this site seems to be the best on LT1 head conversions. I also got a set of LT1 heads for pretty much the value of the scrap aluminum so I want to do this as well. I'm a manufacturing machinist with access to a Bridgeport mill so I can do the head deck myself no problem once the plugs go in, but my question is this, could the plugs be installed using 'aluminum brazing' rod? I don't have access to a DC tig welder, but I've had good success working small parts with aluminum brazing (basically soldering with a low-melt point aluminum) would this work to seal the coolant holes? Also has anyone modded the LT1 heads enough to bolt right up to a Gen 1 intake? I've got an Edelbrock intake I want to use along with the LT1 heads on my project motor.

fullsize fun

Hate to rain on someone's parade but vortec head ports where modeled after Iron LT1 heads, so just get vortec heads and get the same results without all the extra work. Also Iron LT1 heads flow about 20% better than the F body Aluminum heads.

robertfrank

iTrader: (27)

True but where's the fun in that? Sometimes it's not about the extra "work". Hell for me it's about the fun of the challenge. Plus, who doesn't want an affordable aluminum head? I can pick up a set of stock LT1 heads for $50 or less. Even after the conversion work it's still far cheaper than buying a set of E-tec heads.

robertfrank

iTrader: (27)

As far as I know if prepped properly you could get away with the aluminum brazing but for me I wouldn't do it. It wouldn't ever get hot enough to melt but the constant stress would cause problems down the road. You can easily use a regular sbc intake with LT1 heads. I'm running a hurricane intake with LT1 heads. I did have to shave the upper sides of the intake to get passed the valve cover rails for the heads and redrill the in take to match the LT1 heads but its a no brainer. Guys have used the Victor E intake on Lt1 heads plenty of times.

83 Crossfire TA

iTrader: (2)

They're similar but not the same. The Iron LT1's are closer. The 350 Vortec heads have 64cc chambers which would kill the reason that I did them (I wanted small chambers for a 305, mine came out to right around 57cc). There are 305 vortec heads but they are completely different.

That said, I got mine for like $23 and the pair weighs 50# less then a set of vortec heads.


I did mine on my bridgeport, and there is more to it then just decking the head. As far as brazing the plugs in, I wouldn't trust it, I've seen failure testing of the various rods and they typically crack if stressed. If one cracks it dumps the full load of coolant into the lifter valley in a matter of seconds wiping out the engine.

You need an AC TIG to do it the standard way, but you can do it with a DC TIG or even a stick welder with a tig torch and some He in the shielding gas.

anesthes

iTrader: (12)

You can stick aluminum as well.

I've been fixing aluminum trailers lately that I cannot fit inside my shop, and using DC stick with aluminum rods has been working fantastic.

-- Joe

83 Crossfire TA

iTrader: (2)

I was mostly just commenting on his DC TIG comment.

Huh, I've been wanting to see some aluminum stick welding...

As far as what will work, I have no experience with aluminum stick and something like a cylinder head. I TIG'ed my coolant passages, but I MIG/spool gunned my bolt holes and when I filled in part of the exhaust ports and re-shaped them (it started because I had major core shift in one of my castings and hit water when I was porting them, I used the spool gun because I realized I needed to lay down a lot of metal and didn't feel like spending the time on it and the machine shop that I had pressure test them sent home a few sets of heads with me to weld because they were so impressed by how mine came out). I've since built a modified spool gun for another project (one that can take a lot more heat) and will likely use it on the next set of LT1 heads I do.

anesthes

iTrader: (12)

How do you like the spool gun?

My MIG pushes aluminum wire ok, as long as I keep the heat up I don't birdnest.

Lately, every time I'd needed to weld aluminum has been on a trailer that won't fit in my shop, and welding outside with the wind is nearly impossible no mater what you use for gas settings (or lense if its a tig). So stick welding works best.

Sticking aluminum is so easy a cave man can do it. You end up with a big tall weld, so it's not for pretty applications but for structural it's fantastic.

I've even used it to build up ports on an intake manifold when I was out of argon at 10PM.

-- Joe

83 Crossfire TA

iTrader: (2)

Originally it drove me nuts. I got a spoolmate 100 with a MM211mvp and it worked OK at lower power settings (not like you can weld all that much MIG aluminum at lower power settings), but as soon as you turned up the power the tips would just fry with a "pop!" after running a little bit of bead. Add to that for some reason the tips are different than the regular Miller/Hobart tips, physically smaller and cost 5x as much... I ended up modifying it to work with the standard Miller tips and I'm much happier with it.

My older Hobart Handler (which came with a Miller gun) seemed to push aluminum fine through the standard gun with the standard gun liner as long as I tried to keep the gun lead from making any tight turns, like it was fine as long as the length of the gun was straightish or a single smooth arc, but one you got into compound bends I sometimes saw birdsnests.

Huh, I may have to get some stick rods just to try them out just to have another means of welding aluminum, I currently can't get anything largish in my garage, so far I've gotten lucky with dragging the MIG out to the driveway when I've had to weld larger aluminum things.

Honestly, I'm not happy with my TIG (MM synchrowave) and I kind of wonder if I'd be more likely to use it if I had a more modern inverter based machine (I've never used one), of course it could just be a lack of practice with the TIG because i don't like using it

anesthes

iTrader: (12)

I have an older Miller Econotig - AC/DC machine but doesn't have a foot pedal. Which means it sucks for aluminum. It does have high frequency.

I can tig steel, stainless pretty good. but aluminum typically requires you to vary the heat. It just plain sucks.

The machine is fantastic for stick welding though. I use it to do big stuff.

The newer inverter machines are great, but I don't do enough tig work to justify it. I use my mig on 99% of the stuff in the shop. I have a 40 foot 8 gauge power cord for my tig/stick machine so I wheel it outside when I need to do a trailer frame or something.

-- Joe

tylercamaro

iTrader: (1)

Gonna bump this for the hell of it, couldnt you potentially be really hillbilly and use quicksteel or some aluminum based epoxy to fill the coolant holes? For whatever backwoods reason ive seen people use it inside of engines, not that its a great idea but rated for up to 500 degrees i could almost assume it would hold. Then just port what you want and redrill whatever intake of your choosing? Obviously welding them shut and decking them is much more preferred, but i have so many sets of these and my welders are in transit that im almost willing to try it for the 7 bucks itll cost me.

anesthes

iTrader: (12)

If it fails you dump coolant into the oil..

-- Joe

83 Crossfire TA

iTrader: (2)

Those coolant holes are fairly large, maybe about 1.25" across, you'll never seal them up with just epoxy. Also, as I noted there is a coolant passage behind them which needs to be kept open, so you need to keep the plug down to about 1/4" thick or so, maybe 3/8" at most.

You might be able to get away with making the plugs like I and a few others have suggested, slathering them in epoxy and the holes and then tapping them in and if you get lucky they might seal up, but why risk it? If these things leak they dump all your coolant into your lifter valley killing your engine.

All that said, even though plugging those passages is what everyone focuses on, that's probably the easiest part of the job. Filling the existing intake manifold bolt holes and figuring out the new coolant routing took me way more time to do.

rockosocko

Bringing this back up again!

Cant find a set of GOOD 305 vortec heads for my 283 (to bump compression) and have a few sets of aluminum LT-1 heads that I wouldn't mind trying to convert.
A good friend builds aluminum trailers and could probably weld a head up in about 15min. His welders self regulate the amperage for the thickness of material !!!.
Really cool.

Anyhow, you guys that made the 'plugs' what was the thickness (1/4" or thicker) and material (i.e. T6 or _____?)
Would REALLY like more info PLEASE! Even a PM with more pics would help a lot.
Heads are bare and ready to do this.

Thank you for any GOOD help.
E