Has anyone done it recently? I am considering it after downloading a bunch of info. Does not seem to be a big deal. I am not one to write a big check when i can fab it up myself. Long range plans may include a 420 cuber. Looking for pitfalls to avoid.

 

Looking for the same info.questions with shiming of the distrib.so I don't eat a cam or gear,Tv/accel cable bracket,and any other tip that may help or save money.

 

i've done 4 lt1 conversions in the past 1-1/2 years--well actually i did 2 and wore the ''foreman's hat'' for the next two....there are about half a dozen others that i have seen at local cruise nites--one of those is claimed to have been done with NO machine work ( only "hand" power tools) and the final installation is not pretty but it does lay down rubber .....total investment for most is well under $500 reusing existing tpi ecm/ chip, one guy has a custom chip that runs very nice-sez he spent $500 on that alone tho (mine ran fine on the oem 86 chip altho i have a hyper in now for fan control )....basically the lt1 manifold fits the sbc-1 block/heads perfectly, just no distrib mount or cooling outlets and none of the manifold/ cyl head bolts line up..expect the same minor issues you would see when doing a carb/ manifold change in the old days, like hoses and brackets--seems like everybody has a slightly different solutions to these and they all work.

only real pitfall is water/vacuum leaks when trying to use cheap intake gaskets--spend the $20 for the good ones with silicone rings around the holes....and don't weld on the lt1 manifold, it warps if even a hot chick breathes on it and then needs flanges resurfaced (note that factory uses rtv at front/rear seals and the manifold dimension is diff from the old sbc at this point, no machining req'd unless for some reason you want end gaskets instead of rtv)...baffling tiny prob that the manifold/ cyl head bolt hole locations vary a tiny bit and need a little file ''adjustment"--common problem--make a paper tracing of your set-up and match the new holes to it seems to work best but the manifold castings are soft--take care not to go too far....one hole (under the pcv valve) is a pita--use a 3/8-16x1-1/4 set screw threaded into the head and back it out after setting on the manifold to put a small nut on, or some just forget it altogether like the new gm/vortec/efi manifold

the distrib needs a 5* wedge 1/4" thick to sit properly and seal on the lt1 manifold (height is not critical--the guys that designed it 50+ years ago deserve credit here)....we do the wedge/ spacer, dist hold-down, all on one small piece of 3/8'' alum plate bolt-on that also reinforces the lt1 manifold ( its a bit thin where the new distrib hole must go)

my local machine shop has made up a machining fixture to properly locate the distrib hole/wedge plate.. also mills off the egr mount and taps the rear water outlets...for off-road use only, of course.... if somebody walks in with old airplane or old outboard motor parts,everything stops....

 

Hey "redrose" a question for you.....you say the EGR boss is milled off, did you weld on blank off plates if you removed it completely. I completely removed mine but I'm not sure about welding on plates that I made to cover it. I'm afraid that it might warp the manifold with the heat from welding. Should I epoxy on these plates. I see other guys just weld on these plates.

Ken

 

if you weld it, the manifold will ''banana'' a bit and need a ride on the bridgeport (ask me how i know)....now we cut a small aluminum block to fit into what is left of the center egr passage, drill two 1/4'' holes for countersunk screws down thru the lil block, drill and tap the bottom of passage, finish with j-b weld (epoxy) to assure seal and look oem...after the egr mount is off, you'll see what looks like three chambers but the two outer are just remnants of the transfer passage and may be left open for cooling or plugged for smooth look but only the center passage needs to be plugged functionally.....all this if you chop most of the egr mount off to use the big HEI, leave a little of the mount to stiffen the manifold

 

Looks like I own a manifold now. I will post my progress once I begin the project.

 

Pete, are you installing this on your 383 as it stands now, and removing the Superram?

 

Brad, I am not installing it on my current combo. I am quite please with the super ram 383. I have 2 blocks and 2 rotating assemblies in storage, I plan to build them both and sell them. I will use the funds from those to begin a 420 or 434 project. Although I like torque and the super ram combo, I realize that big cube motors in a street car are starved for air. Both intake and exhaust. Rpm seems (to me) to be nescessary to squeeze out most of the power. I have no real plan as of yet, but I love a project and a challenge. With all of the great info on the forum, I am confident I can do this conversion with everyones help

 

The only thing I don't like about the lt1 converts is the remote thermostat housing, the lack of cooling (the fittings you tap into the manifold are way smaller than the coolant ports in the heads), and the fact that some members have had manifold sealing issues, and distributor alignment issues.

-- Joe

 

Pete, Please keep us informed of your progress, as this is something I may do to my car this winter. I think the LT1 intake, new slighty larger injectors and a set of headers would make a big difference.


Good Luck!!

Randy

 

i didn't like the large cast remote t-stat housing for several reasons, but a much smaller billet housing from the machine shop cured all that....shared your cooling concerns--took a t-stat, heated it to wide open and measured orifice ,calculated vs two 3/4'' heater hoses and the hoses won; all coolant on my blown big block jet boat is fed thru ONE 3/4'' hose which needs a throttling valve to run warm enuf; first thing when i got my lt1 intake running was to (temporarily) install mechanical gauges in each rear outlet hose (i was also concerned with flow balance)--no problem observed...the new carb manifolds we use on the race cars all have 4-corner cooling with tiny steel lines at the rear outlets to prevent steam pockets--i liked that idea and put 3/8'' hose outlets from the front of each side ''just in case'', but nobody else has them or shows any need....just pulled a b+m/mercrewser blower off a big block-it had two 3/4'' hoses at t-stat outlet
i've only seen one leaker--change to good gaskets cured it...if you weld anywhere on the manifold it must be resurfaced to correct warp.
machine shop that does our distrib holes made a special fixture to locate the hole for the first manifold that he did, no guesswork/ no problem....location of the distrib is actually done by the cylinder block; the oem manifold distrib hole is 1-3/8" dia and the distrib itself is 1-1/4''; the distrib is by design at a 5* angle off vertical and this must be accounted for to prevent oil leakage-the lt1 manifold surface needs a 1/4" build for correct depth--we do both at once with a small plate bolted on the manifold.

 

I was thinking the same things. I am fortunate. A good friend owns an Engine building company and he is also an outstanding machinest. I will use his talent to be sure the distributor alignment (and the wedge shaped spacre) is dead nuts accurate. I plan to think this through pretty well before beginning. Keep the great tips flowing

 

Who on the board has had distributor problems with this swap??Would like to know how to check for proper alinment before firing up

 

Check thirdgen.org


-- Joe

 

Randy,
I sure will. I likely will not be able to do a thing before next winter. A bit overwhelmed with work and have quite a few transmissions to build. I also have access to a dyno shop. Even if my motor is not built, but the manifold conversion is done, I may swap it on a stout small block and do a carb vs miniram comparison. When my motor is on the dyno, I may do a super ram vs miniram comparison. Should get some good data regardless.

 

www.lt1intakes.com is worth looking at. Scott looks like he has his act together. Sells most of the trinkets so cheap, I will likely buy them from him. Block off plates, distributor shim etc.

 

I tried to get a complete set up from them,got a reply that he was moving and would not be doing them right now.

 

I just finished my LT1 conversion in my 89 L98, so I offer a few comments:

1. I replaced the heads with Dart Pro-1 's at the same time so I do not know if my issues were unique to the Pro-1's or not.
2. Everyone says the front and rear bolts line up but I found that the manifold had too move back and down to get the ports to line up properly. The siamesed intake ports on the heads got too thin if I tried to port match without moving the manifold back.
3. I welded an additional 1/4" to the manifold where the water ports were, the manifold just covered the port but it was too close for comfort.
4. I also filled in the original bolt holes with aluminum rod and welded them closed.
5. I didn't have the manifold milled but hand planed them with a file after I welded them. Seems to seal fine.
6. I also welded in a plate over the EGR bosses.
7. The bolt hole under the PVC port is a PIA. If I did it again, I would seriously drill and tap a new hole in the head and avoid this altogather. Ironically, I did not end up using the PVC connection as my valve covers already had a PVC port I reused that and plugged the one in the manifold.
8. Spot facing the bolt holes to the proper angle is difficult without the right tool. I found a cove router bit that I used backwards in a high speed dia grinder. This worked eventually but took a week of scrounging to find.
9. I found a Distributor Shim and Bushing Kits Mr. Gasket # 2822, that I used in lieu of the shim. I just drilled an oversize hole in the manifold, mocked up manifold and distributor in the right position and then tach welded the mount in position.
10. Throttle cable needs to be shortened.
11. The air pump control valves hit the IAC and had to be moved over slightly.
12. I also deleted the AC so I had some room to move things around slightly.
13. I ended up using two 90 street ell's at the manifold to keep the coolant hoses out of the distributer.
14. I used the original LARGE distributer and didn't replace it with the small diameter.
15. I mounted the remote thermostat on the pass side between the radiator and the upper control arm mount. It is not as low as I'd have liked but the radiator hose is basically the same height as the radiator. I just a swivel mount 90 degree water neck and ran back across the radiator for the return line.
16. I could not find a corvette fuel rail so I used a camaro rail and rotated the inlet line 90 degrees. This worked out ok but put the fuel rail access fitting at the bottom in an inaccessible location. I need to add a tee fitting for gauge, ect.
17. The fuel line fittings are a Saginaw fitting that is nearly impossible to convert to anything usable. I found a Saginaw female to female adaptor on GMpartsdirect and used a fuel repair kit available from the local parts store then a short piece of fuel inj hose to connect.

Hope this helps, most of the conversions that I found on the net were for camaro's so they didn't have the same plumbing problems I had.

 

Yeah I found the same thing, since I am in no real big hurry I have been collecting the necessary parts for the install. Didn't he say the end of June he would be picking back up?

 

How does it run?Would you do it over again?Could you have done it without removing the A/C??? Did you have to grind the egr bosses to use the large distrib.?Sorry for all the questions.Thanks