TPITuned Port Injection discussion and questions. LB9 and L98 tech, porting, tuning, and bolt-on aftermarket products.
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I'd like to use Gen1 intake with coolant crossover; have an idea of routing coolant lines. When you'll look at front of any EFI intake, there're at least 2 sensor holes, how about enlarging 'em to ~1/2" size and connecting with unplugged holes in frnts of heads? This way I could use stock thermostat housing; rear ports in heads could be connected to the heater or heater valve. CTS could be placed in T-joint together with one of new lines.
There're going to be clearance problems with serp. system brackets but I think they'd be soved with little amount of grinding...
What's your opinion?
edit: LT1 intake gaskets are positioned with pins and small hole in head surface, these holes must be welded or plugged of course
Personally I think by the time you're done accomplishing that you've negated most the benifit of the LT1 head on a SBC combo which is the combination of the heads and LT1 intake, which becomes a direct bolt on instead of a conversion. The conversion is almost entirely in the heads. Not to mention to use a SBC1 intake on LT1 heads entails alot more modifications to get coolant to flow through the original coolant passage of the intake for the thermostat.
I wouldn't bother if it was me, unless using the LT1 intake.
In my opinion an LT1 cam is hardly worth your time taking the engine apart, its a stock cam for a stock cam, you can find plenty at decent prices to avoid one.
I'm running flat tappet so it wont help you but anything in a 230° range with a 112 lsa and as much lift as you can afford will match the heads well.
Oh, it's not a stock cam. I'd rather not post the specs though.
It's somewhere in the area you recommended though.
Any idea on how much lift the heads can take in stock form? If I have to get screw-in studs I'll just run guide plates and save some money by using non-self aligning RRs.
Just picked up the cam the other day. I still need to find a deal on heads/intake/fuel rail and '93 TB [usable w/ 700R4].
I scored an LT1 intake with fuel rail for $20 locally, I thought I was only getting the bare intake. Too bad I already had a fuel rail coming from ebay for $50 I guess it'll just go back on ebay.
I started calling around to machine shops today to see if anyone has any LT1 heads laying around. One shop said they've only got iron ones and the other thought he might have a few laying around, I'm hoping he'll call back tomorrow.
All aluminum LT1 heads are fine, right? I haven't heard of any significant performance difference.
Once again, thanks for the pics tpi-roc. I'm going to bring them into the machine shop so they know exactly what needs to be done. How's your project coming?
__________________ 3rd gen Firechicken. Midwest region American Iron #134
My heads are done except for the hardware. I just blew up another rear so that dipped into the LT1 head funds for now but after buying some springs they can go on.
No no news, they're done but the car still sits needing a rear. If anybody knows where I can get a smoke'n deal on some 3.73s or a solid rear for a low price let me know so I can put the heads on the engine.
Have any updates on this? I'm going to do it soon. I'm abandoning the LT1 intake swap and am going to do the LT1 head swap using a stock LT1 intake.
Did you have to re-drill the head bolt slots at all? There is something in that one link that mentions the head bolts being at a wrong angle, unless they were referring to the intake bolts because I know the intake bolts are different. It appears that in that link they ONLY swapped the heads and use the ZZ3 intake.
Can you put up some details (or PM me, either way) on what kind of drilling you had to do for the coolant holes? I'll probably be using the stock brackets and serpentine setup since I just got my 1LE pulley in. The only accessories I have are alt, p/s, and w/p.
I don't have the heads here yet, I'll be sending the money in a few days. $250 shipped gives me LT1 heads with complete valvetrain, stock LT1 intake, and 24# injectors. Should be more than enough for a 305 with headers and an LT4 Hot cam.
Anyways, I'd like to get an idea of all the work that is needed to actually mount the intake and heads. I know how to deal with an LT1 intake by itself, and I have the remote tstat housing already. I'll still need to make up some fuel lines and coolant hoses, but that's no big deal. I can take this stuff in to school and weld the aluminum plugs in for free and then take it off to be milled (the mills at school are no good for heads and that type of stuff).
How hard is the coolant crossover, and what is the easiest way to do it? If you could send me some pics (dean@xibase.com) of the LT1 heads from different angles, that'd be awesome so I could see what I'm dealing with before it gets here. What do you have each of the fittings connected to on the remote t-stat? I don't know what connections should go to what fitting.
Also, if I did the math right, this will raise compression on a 305 from 9.3 to 9.8 using a stock .018" head gasket, right? That'll be perfectly fine with 89-octane with aluminum heads and stock (for the most part) timing.
Sorry for all of the questions, but its hard to figure this out without many pics or the actual heads in my hand. PM me or email me at dean@xibase.com with more info.
__________________ 1997 Corvette LS1/A4, slammed with Bilstein Sports 1998 Trans Am LS1/A4, GMPP hot cam, 3500 stall, LS6 intake, LTs/ORY, lid/muffler/3.73s (wife's)
1988 Trans Am, 355ci with LT1 head/intake conversion slammed on C5's. SOLD
Last edited by DuronClocker; 09-13-2004 at 02:13 AM.
From what I've read, the only thing you have to do to the heads with an LT1 intake is to plug the end coolant passages and weld them, then tap the intake for coolant ports in the back. I believe you have to drill a hole for one of the locater pins as well, where you had to weld in the plugs.
-TJ
__________________ 3rd gen Firechicken. Midwest region American Iron #134
I'd just use the 3/4" nipples or the AN equivilent that everyone's been using for converting the LT1 intakes. The 3/4" lines are tried and true. Also using AN fittings you should be able to find something with a 3/4 nipple and a 90 degree turn on them. On the heads you'd be able to turn them 360 when your threading them in, so it wouldn't be a problem like on the lt1 intake.
If I was going to do this though, I would place the nipples in the back of the heads, although it might take a little suggestive clearancing (enter the BFH and some wood to spread the impact a little). If your not running accessories you could have room in front of the heads.
__________________ -Ryan
1991 Miata Daily driven STS car
1988 Trams Am GTA, LT1/T56 setting up for track days
Personally I wouldn't run them in the back of the head. The LT1 engines have an inherant coolant system problem that comes with a sorta fix you can see just by opening the hood. There are already coolant holes at both ends of the head to help purge out air bubbles that cause cylinder hot spots and detonation. Since the engine tilts towards the tranny the highest point is the front of the heads, if you coolant exits there you have the best chance of blowing out those air bubbles. However the LT1 is reverse flow and this swap isn't so the problem might not even exist, I just wont risk it myself.
:/ I was looking out the front and 90* nipples would be easier, but even then I don't know if I could squeeze the 3/4" hoses through there. 5/8" would probably work. I tried checking out the back but as mentioned, it'd require some serious clearancing.
Okay, on the drive side head, the coolant will exit out of the rear as there is plenty room on my car. On the passenger, there is NO room behind the head, so it will have to exit out front where there is a little room. There will be much more after some grinding.
Did have a question though. The coolant port on the rear of the passenger head has no plug in it, and looks like something was screwed into it. I'm assuming this was a coolant line. If these heads on an LT1 could use such a small coolant line, why can't they on my motor?
Originally posted by DuronClocker Okay, on the drive side head, the coolant will exit out of the rear as there is plenty room on my car. On the passenger, there is NO room behind the head, so it will have to exit out front where there is a little room. There will be much more after some grinding.
Did have a question though. The coolant port on the rear of the passenger head has no plug in it, and looks like something was screwed into it. I'm assuming this was a coolant line. If these heads on an LT1 could use such a small coolant line, why can't they on my motor?
I have a 406 small block with flat top pistons and 2 valve relifs. Its new, has no heads.
I also have a complete lt1 parts car with a damaged block/crank (beyond salvage).
I could do this lt1 swap onto the 406 with lt1 intake, holley commander 950 ecu and harness, this combo could work. But what about Lt1 heads being able to handle steam holes for the 406. Also, I think the compression would be too high. 11:1 I could handle, any more I don't think I could.
What is behind the coolant passages that are blocked off? Is it a big hole or just a little passage? I am wondering if it would be easier to pour molten aluminum in there instead. You might be able to stick some thing in the coolant passage so that the molten aluminum doesn't flow too far.
I'd like to put some LT1 heads on my 305 just for the weight savings, but i don't want to go through all the trouble of welding and crap.
Does anybody that has worked on LT1 heads have an opinion on this idea?
__________________ LT1 headed LG4 305 beast! Comp Solid lifter XS-262-10S, 1.6 Roller Rockers, 10.2:1, Holley 4160 600cfm, modded Weiand 7502 intake to fit LT1 heads____ Custom cylinder head cooling. Weiand 8208 Short Water Pump____TH-350 3 series 3.73 with 2 series posi and spacer____ Hedman Hedders 1 5/8 headers and Y-pipe 3in Exhaust, Dynomax 3" Bullet muffler ____Moroso Ultra 40 Wires ACCEL HEI Super Coil ____Competition Engineering 3120 Bolt-on SFC's____Homemade: Wonderbar, solid tie rod sleeves, Aluminum LCA and Panhard Rod with spherical rod ends, alternator and PS bracket, Strut tower brace, and Decoupling torque arm with telescoping link.
3000lbs
"The liberty of a democracy is not safe if the people tolerate the growth of private power to a point where it becomes stronger than their democratic State itself. That, in its essence, is Fascism - ownership of government by an individual, by a group or by any controlling private power."
-FDR
"If this were a dictatorship, it'd be a heck of a lot easier, just so long as I'm the dictator."
-- President George W. Bush
During a photo-op with Congressional leaders on 12/18/2000.
There's nothing you can put in there to block molten metals flow, that you're going to be able to get back out, or that wont melt itself. You're also going to be pouring liquid hot aluminum into aluminum, which probably has a better chance of warping or damaging the deck surface. Then you still have to mill. You're not saving any time, trouble, or money.
The project has resumed. The heads are now fitted with 2.00 1.56 valves and brass guides. They're fully ported and machined ready for install. I'm buying all the valve train components, they came out with a 1.81" instaleld height affording me .600 lift so I'm ordering a custom grind of .550, with enough room for 1.6 rockers later. I'll take pictures and post updates as it progresses. I earnestly hope to have the engine installed and running by a month and a half from now.
Originally posted by tpi_roc The project has resumed. The heads are now fitted with 2.00 1.56 valves and brass guides. They're fully ported and machined ready for install. I'm buying all the valve train components, they came out with a 1.81" instaleld height affording me .600 lift so I'm ordering a custom grind of .550, with enough room for 1.6 rockers later. I'll take pictures and post updates as it progresses. I earnestly hope to have the engine installed and running by a month and a half from now.
Perfect, and on January 14th, I also passed emissions, so my project can begin. All I need now is a pair of headers, an alternator bracket, get my intake drilled for dizzy, and the necessary gaskets. I have the aluminum plugs, just need to grind them to shape now and get them welded. I'm sticking with the stock 1.94/1.5 valves for now with the 305 and whenever I swap to a 350, they will get the 2.00/1.55 treatment with the lightweight LT4 valves.
My first step is going to be the alternator relocating stuff over the next two weeks (depends on if I buy headers this week or next). Hopefully you'll get it up and running before I do, so I can hear of any issues Good luck with it man and keep me updated either on this thread or in PMs.
Just an update. I pulled the 355 out of the car this weekend. The final assembly on my 385 shortblock is done. I'm waiting on my water pump, custom grind, and valve springs. After that I'll be finishing the block and installing it. The longest out item is the valve springs due Feb. 18th. So that weekend I may be installing this beast and can report on how they run
What head gaskets did you guys use? I'm going to be swapping my modded LT1's on my 305 soon and am seeing head gaskets that can not be used on lightweight castings. Whats the difference? Are the LT! heads modeled after the earlier heads or the lightweight casting GEN I designs. I want to use a .015" steel shim head gasket, do you think its a good idea?
__________________ LT1 headed LG4 305 beast! Comp Solid lifter XS-262-10S, 1.6 Roller Rockers, 10.2:1, Holley 4160 600cfm, modded Weiand 7502 intake to fit LT1 heads____ Custom cylinder head cooling. Weiand 8208 Short Water Pump____TH-350 3 series 3.73 with 2 series posi and spacer____ Hedman Hedders 1 5/8 headers and Y-pipe 3in Exhaust, Dynomax 3" Bullet muffler ____Moroso Ultra 40 Wires ACCEL HEI Super Coil ____Competition Engineering 3120 Bolt-on SFC's____Homemade: Wonderbar, solid tie rod sleeves, Aluminum LCA and Panhard Rod with spherical rod ends, alternator and PS bracket, Strut tower brace, and Decoupling torque arm with telescoping link.
3000lbs
"The liberty of a democracy is not safe if the people tolerate the growth of private power to a point where it becomes stronger than their democratic State itself. That, in its essence, is Fascism - ownership of government by an individual, by a group or by any controlling private power."
-FDR
"If this were a dictatorship, it'd be a heck of a lot easier, just so long as I'm the dictator."
-- President George W. Bush
During a photo-op with Congressional leaders on 12/18/2000.
I took a mic and measured the inside wall dimensions of the coolant jacket to find the best pad to drill for a 3/4" NPT fitting, which is a somewhat large .9219" drill bit + threads. Here's a pic of what I came up with. Oddly enough the measurements are exactly 1 1/4" from each side for a perfectly centered hole.
Because the coolant passage there isn't large enough. If you drill into it you'll block half of your coolant fitting and seriously reduce flow. Also if you put a 3/4" NPT fitting in that area you wont be able to use either of those accessory holes. But good luck.
let me how yours turn out. I might change my mind and drill in a differnt location. I was planning on having the hose fitting exit the rear of the heads because it is usually the hottest there and the leat amount of air cirulation. But I could be wrong?
Thanks
Originally posted by ajclark7 I was planning on having the hose fitting exit the rear of the heads because it is usually the hottest there and the leat amount of air cirulation.
Thanks
which head gaskets did you use? just wondering if felpro gaskets for l98 will work or if lt1 haskets are needed. Are there any modifications needed to the head gasket at all?
is the intake gasket the same as it would be for any lt1 fourth gen? Do you have a part number?
I guess it'll just go back on ebay.
