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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
It is switzerland again! (last thread) So first sorry for my bad english!
My friend and I have just finished our last project, wich was to adapt LT1 heads on a LO3 305 sbc with Performer EPS manifold and LT4 Hotcam.
We have seen some people saying they will try it but no feedback at all... Thus we will try to make one!
It is our very first serious project. We do not know a lot in engines, thus if you see we have done something wrong, please let us know, we would apreciate!
THese heads seams to be made with A356 casting aluminium (full of silicium)
We had to weld 2 cooling holes for it can fit the LO3 sbc.
Of course the best is to weld with a TIG, but since casting alloy can have a lot of porosity, we chosed to use a MIG, wich we hope will less "mix" the "impurty" of the casting alloy.
We uses AlSi5 – AA4043 as solder. Wich was, lucky us, a great choice ! No crack at all and a very little porosity.
Last edited by davidmoret; Jun 19, 2016 at 04:05 PM.
Because the block deck was in a very bad shape, we had to use some thicker gaskets (FLEPRO-1010, 0.039- GREAT PRODUCT!!) and thus reach to the 50cc by milling the head.
Last edited by davidmoret; Jun 19, 2016 at 03:31 PM.
We triple check the cc of combustion chamber and where really surpise to realise that one of them was 5cc below the others! Wich is A LOT!!! Seams to be because of a bad casting... We had to increase the volume of this veryone...
As you may have notice, LT1 heads do not have the same threads positions and angle as Lo3 heads. Thus we had to make new one to adapt our PERFORMER EPS intake manifold.
Ho by the way we have only put this bloody TBI on the intake to try if everything was ok. We will of course modifiy the intake and adapt 8 injectors. TBI is of course a NONSENS!
Everything seams to be find! No overheating, no waterleaks. So far so good!
Wow, that quite a project and really a great effort! I like how you overcame the poor condition of those heads as sold to you. I am curious why u used remote cooling lines for the intake t-stat instead of match marking the head and drilling out the passage in the head to match the intake?
Congratulations and I think you will have a very peppy, maybe even awesome L03.
.....Everything seams to be fine! No overheating......
No overheating just sitting there idling , or no overheating when actually being driven ? I ask because in my opinion you have reduced the coolant flow by a considerable amount when you look at the size of the ports you replaced with those tiny little hoses . Sure , it may not overheat in test runs idling in your garage , but till ya see it stay cool in warm weather stop & go traffic I'd be somewhat skeptical of proclaiming the cooling system to be perfectly functioning . Just curious , how hot does it get in Switzerland ?
Every other aspect of this build is just downright great "home engineering" , and considering the relative scarcity of parts for these cars in your part of the world I can perfectly understand the motivation behind it . What the folks who say "why do it to a 305 when it would be SO much better on a 350" don't understand is that it's not like you have thousands of junkyards (now called "automotive recyclers" ) around to just pop in and buy a good condition 350 for such a project . I'll bet it would cost a pretty penny indeed to get an engine shipped to Switzerland !
final thought of this post ;
Where those heads were advertised as "good condition" with the additional monkeyspank of "ported" thrown into the mix , and showed up just about trashed and only your good machinist's work saved them , I think you ought to let us all know the name of this Ebay scammer so none of us end up getting screwed by him as well ! Now I realize you were able to "make a silk purse outta a Sow's ear" but not everyone else may have a machine shop available to them to rectify this seller's lies in the future . In my opinion also , you are owed a refund of at least part of your purchase price due to the vast difference between the seller's description VS the actual condition of the delivered product .......
What type of pulley do you have on your alternator?
Homemade pulley. On the alernator, the pulley is twice bigger than the stock one but still have enough volts. I made them so I can use cheap belts! , and of course made them very ligth...
I am curious why u used remote cooling lines for the intake t-stat instead of match marking the head and drilling out the passage in the head to match the intake?
Congratulations and I think you will have a very peppy, maybe even awesome L03.
Yes we had the same idea at first.. but if you have a closer look at this piscutes, you will see it is almost impossible!
No overheating just sitting there idling , or no overheating when actually being driven ? I ask because in my opinion you have reduced the coolant flow by a considerable amount when you look at the size of the ports you replaced with those tiny little hoses .
First, thanks a lot for your kind remakrs, we do have the same mind!
Yes it still ok on the road, even if it started to heats a litle more than usual, but thanks to the fan no problems, even with the full trottle! For now we have only try the car for about 5 hours in town and countrside as well. No problems at all.
Ho I have forgotten to mention that the car is running without the air conditioning cooler and without thermostat.
But since we do not have installed yet our home made injection and still run with the blood TBI, it might heat a little more with more HP!
By the way I am not shure if we reduce the holes that much. Maybe we even increase them a litlle. Indeed the water hole is big on the intake, but it is really small on my stock heads because of the gasket. I do not know why they do not make this hole bigger even on the stock engine (any idea?). OnN the picture the hole is about 2mm diameter, whereas our bypass pipe is about 6mm, wich makes a section 9 time bigger than the stock one!
Someone nows why this hole (stock gasket) is so small?
That's not the cooling port. That would be from the rear of the engine where a cooling port is not used. The holes you are utilizing from the LT1 heads are intended as a steam port as the water goes in and out of the water pump on the LT engines and can build an air pocket on the rear of the cylinder head and cause overheating issues.
The correct port size is the size of the port on the intake manifold and is roughly 1.25in x 1.00in. many, many times the size of the pinhole on the gasket in your picture. I have seen this conversion done where they use 3/4in heater fittings to a thermostat housing and I don't believe they had any real cooling issues. Good luck and awesome work!
Yes we had the same idea at first.. but if you have a closer look at this piscutes, you will see it is almost impossible!
Wow, thanks for sharing that.
Well ya know Smokey Yunick (RIP) bypassed the entire t-stat on the SBC he raced by drilling into the heads right where you did because coolant flow would cycle behind the t-stat from the highest temp head to the other. He plumbed in a large Y before the radiator hose. He also used a large fender washer/orifice to maintain back pressure and eliminate vapor pockets.
That's not the cooling port. That would be from the rear of the engine where a cooling port is not used. The holes you are utilizing from the LT1 heads are intended as a steam port as the water goes in and out of the water pump on the LT engines and can build an air pocket on the rear of the cylinder head and cause overheating issues.
The correct port size is the size of the port on the intake manifold and is roughly 1.25in x 1.00in. many, many times the size of the pinhole on the gasket in your picture. I have seen this conversion done where they use 3/4in heater fittings to a thermostat housing and I don't believe they had any real cooling issues. Good luck and awesome work!
Wooow Thanks a lot! It seams my understanding of the cooling flow was really bad!
We have added a pipe at the other side of the head to prevent the air pocket. Hope it will work!
So I will ASAP increase the diameter to 3/4in. ! Even if cooling seams to still ok now, I do not want to take any rirks!
I think you ought to let us all know the name of this Ebay scammer so none of us end up getting screwed by him as well ! Now I realize you were able to "make a silk purse outta a Sow's ear" but not everyone else may have a machine shop available to them to rectify this seller's lies in the future . In my opinion also , you are owed a refund of at least part of your purchase price due to the vast difference between the seller's description VS the actual condition of the delivered product .......
Here is the Ebay ID of the "mean" guy!
Do not worry we mannaged to have a full refund from Ebay for those heads! (price+shipping+customs). Then we ask the seller if he wanted those heads back... His answer: "KEEP THA F.... HEADS!!!"...
Here is the maximum temperature (in °C) we have reached for now, that was a 1h trip in the mountains, so heavy hills and low speed thus low cooling. From 1300 to 4300 feet. The average outside temperature was 55°F
So I am pretty shure now our small hoses are just big enough. But we will still increase the thread to 3/4'', it will be very interesting to see how much the temperature went down.
My friend will do further test. I let you know in few days.
Thanks everyone!
Last edited by davidmoret; Jun 21, 2016 at 07:03 AM.
Do not worry we mannaged to have a full refund from Ebay for those heads! (price+shipping+customs). Then we ask the seller if he wanted those heads back... His answer: "KEEP THA F.... HEADS!!!"...
Well, we did keep them...
Thank You David , I have added that Ebay name to my "do not buy from" list . I am very happy to hear that the cooling system does have enough flow to keep it cool during driving with bursts of wide open throttle . It's funny , I've spent a bit of time in Europe (Greece mostly but France & the UK as well) and have seen first hand the lengths folks go to keep old American cars running , with such great machinist's work as you've done there . It's a whole lot different when ya can't zip over to the local "pick & pull" yard and buy used parts in good condition cheaply . When I saw your first pictures of the heads I thought for sure this was gonna be a "someone done me wrong" thread and you saved those heads nicely ! The marks on the one head that were like hundreds of gouges look to be witness marks where a bolt or screw had somehow gotten into that cylinder and been pounded into the head by the piston , and that seller thought that merited a "good condition" description ? I'm glad you got your $$ back and was able to turn that which would have been abandoned as scrap here back into something usable again .
PS , you've mentioned your English , buddy believe me , your plenty understandable and I have had no problem with understanding your writing .
If you look at those burp holes that you used for running the coolant you'll see that enlarging them won't help, making them bigger will run them into the intake manifold bolt holes (If you straightened them like the stock SBC holes in that area) and the coolant passage behind those holes is actually fairly small and almost blocked off by the casting. GM only intended them for releasing air bubbles, and only had about a 1/4" line coming from them and T'ed those together into one line.
I have a 305 running LT1 heads and I came to the same conclusion that you did WRT to drilling passages in the stock SBC location, it would be pretty difficult to do considering the LT1 heads have their oil return in that area. I ended up drilling into the front of the head and putting a large port where I had the largest opening into the coolant passage and keeping it as far as I could to the inside of the head to prevent it from getting in the way of the accessories more than it would have to. Sort of a modified version of the Smokey Yunick mod (he didn't need to run accessories on a race car). I also ran -6 (about 3/8") lines from the burp holes in the back of the heads to the thermostat housing to relive any air bubbles in the water jacket that GM worried about.
I suspect that if you tried driving it in much warmer weather you'd have overheating issues. At 55* mine gets up to the thermostat opening temp (it's a 160* thermostat that actually seems to open around 168* according to my datalogs) and it never gets to my fan turn on temp (175*). As long as I'm not sitting idling for a long time I don't need my cooling fans at all till about 70*F, and I seem to be able to maintain >180*F up to about 98*F with a stock radiator and 4th gen cooling fans (I've never driven it above 98*F).
No overheating just sitting there idling , or no overheating when actually being driven ? I ask because in my opinion you have reduced the coolant flow by a considerable amount when you look at the size of the ports you replaced with those tiny little hoses . Sure , it may not overheat in test runs idling in your garage , but till ya see it stay cool in warm weather stop & go traffic I'd be somewhat skeptical of proclaiming the cooling system to be perfectly functioning . Just curious , how hot does it get in Switzerland ? 
) around to just pop in and buy a good condition 350 for such a project . I'll bet it would cost a pretty penny indeed to get an engine shipped to Switzerland ! 
