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Will a double roller fit under early LT1 timing cover?
I’m collecting parts for a late 2018 can swap in my 94. Initially I wanted to keep an LT1 timing set to have the option to go back to a cam driven pump, I run an electric. I thought it over and I’d rather go with a better timing set and eliminate gear driven pump parts.
I’m finding conflicting info on what SBC timing sets will work. From what I read, converting to a later 95+ timing cover is needed - which I believe necessitates a vented Opti as well. My dilemma is that I run an OEM Opti and LTCC. Meaning, I only use the resolution signals from the Opti and not the high voltage side. Since I have a good Mitsubishi sensored Opti I don’t want replace it to convert over to a later timing cover and vented Opti (which would be hard to find and $$$ for one with mistu senior). Chances are I’d end up with an inferior Opti with a non Mitsubishi sensor. Seems some clearancing of the cover and/or block is also needed to clear the double roller.
Is there a double roller setup that will fit under the early LT1 timing cover? Better yet, one that doesn’t need to be clearanced? If not, I’ll stick with a stock replacement timing set.
I’m collecting parts for a late 2018 can swap in my 94. Initially I wanted to keep an LT1 timing set to have the option to go back to a cam driven pump, I run an electric. I thought it over and I’d rather go with a better timing set and eliminate gear driven pump parts.
I’m finding conflicting info on what SBC timing sets will work. From what I read, converting to a later 95+ timing cover is needed -
Is there a double roller setup that will fit under the early LT1 timing cover? Better yet, one that doesn’t need to be clearanced? If not, I’ll stick with a stock replacement timing set.
Early 1992 and 1993 timing chain covers are different; the opti is driven through a small hole; also the "early" style camshaft sprocket has a small splined hole in the center to drive the opti; I assume yours is the "late" style which as a larger smooth hole in the center of the camshaft sprocket and uses a pin drive to drive the opti
1994 through 1997 covers are the same except that 1996 and 1997 covers had a provision for mounting the crankshaft position sensor
option one, stay with the LT1 stock pin and link timing chain
option two, upgrade to stock LT4 single roller timing chain
option three, upgrade to LT4 "extreme duty" timing chain, which is a single roller, but very large links, think something out of a sawmill.
Any of those timing chain sets should work..without having to change out your opti.
Thanks mtwoolford. It seems I’m mistaken and the timing cover is not the limitation I face. Rather, my desire to keep the 94 Opti is the issue that relegates me to the above 3 mentioned timing sets.
Is there a cloyes or other brand single roller equivalent to the LT4 set? If I’m not going double roller then I think I’ll keep the water pump gears in place should I ever want to revert. I don’t think I can justify spending $300+ on the LT4 Extreme Duty set.
Yes the desire to keep the 92-94 spline shaft driven opti is going to limit you to LT1 timing sets only.....
Melling PN 3-509SB.... it's $90.00 That is the PN to the stock LT1 replacement chain and gear set. FYI everybody else re-boxes it. Lunati, Cloyes, Dyna Gear ect.... so you can pay more but you are still gonna get the same product. I know this because I have had every "brand" in my hand at one time or another.... It's the same PM gears and link type chain.
There is no upgrade where you can keep the shaft driven Opti.... Even the LT4 Extreme duty requires the later 95-97 pin driven Opti conversion.... it dosen't have the splines in the upper timing gear to use the older shaft driven Opti.
Will
Last edited by rklessdriver; 12-18-2017 at 04:20 PM.
Thanks mtwoolford. It seems I’m mistaken and the timing cover is not the limitation I face. Rather, my desire to keep the 94 Opti is the issue that relegates me to the above 3 mentioned timing sets.
Is there a cloyes or other brand single roller equivalent to the LT4 set? If I’m not going double roller then I think I’ll keep the water pump gears in place should I ever want to revert. I don’t think I can justify spending $300+ on the LT4 Extreme Duty set.
there are no double rollers that maintain the outer gears that drive the water pump; however both an LT4 and LT4 extreme duty are substantial upgrades over the LT1 link and pin style chain. And the Extreme Duty set up in expensive and probably not needed.
Yes the desire to keep the 92-94 spline shaft driven opti is going to limit you to LT1 timing sets only.....
Melling PN 3-509SB.... it's $90.00 That is the PN to the stock LT1 replacement chain and gear set. FYI everybody else re-boxes it. Lunati, Cloyes, Dyna Gear ect.... so you can pay more but you are still gonna get the same product. I know this because I have had every "brand" in my hand at one time or another.... It's the same PM gears and link type chain.
There is no upgrade where you can keep the shaft driven Opti.... Even the LT4 Extreme duty requires the later 95-97 pin driven Opti conversion.... it dosen't have the splines in the upper timing gear to use the older shaft driven Opti.
Will
If you own an 94 you know more about it than I do, maybe there was some transition during that year, but my information comes from "HOW TO BUILD Max-Performance Chevy LT1/LT4 Engines" at pages 45 - 46 which gives 1992 and 1993 as the "early years" which had a spline opti drive and 1994 through 1997 which had pin drives, so I assume that the O.P.'s 94 would also be pin drive, allowing him to keep his existing opti, along with being able to use any pin drive LT1 or LT4 timing gear set.
and yes I know to "assume' is to make an "*** out of you and me".
Hope this helps the O.P.
Last edited by mtwoolford; 12-18-2017 at 05:00 PM.
Thanks mtwoolford. It seems I’m mistaken and the timing cover is not the limitation I face. Rather, my desire to keep the 94 Opti is the issue that relegates me to the above 3 mentioned timing sets.
Is there a cloyes or other brand single roller equivalent to the LT4 set? ..... I don’t think I can justify spending $300+ on the LT4 Extreme Duty set.
try a Lunati true roller pn 92126 at around $112.00...yes the Summit photo shows a link / pin style chain , but the summit description and the Lunati web site make it pretty clear that this is a roller style chain probably the same as the oem LT4 chain (but not the "extreme duty" chain).
If you own an 94 you know more about it than I do, maybe there was some transition during that year, but my information comes from "HOW TO BUILD Max-Performance Chevy LT1/LT4 Engines" at pages 45 - 46 which gives 1992 and 1993 as the "early years" which had a spline opti drive and 1994 through 1997 which had pin drives, so I assume that the O.P.'s 94 would also be pin drive, allowing him to keep his existing opti, along with being able to use any pin drive LT1 or LT4 timing gear set.
and yes I know to "assume' is to make an "*** out of you and me".
Hope this helps the O.P.
The only 1994s that got a pin drive Opti are the B Body cars, Impalas and such... Corvettes and F Bodys didnt get it until 1995.
Without pulling it apart - I’m only guessing. The FSM for 94 shows an offset pin but also speaks of marking the distributor shaft.
Also - how do aftermarket cams accommodate all Opti styles? Do they have the necessary splines and pins to match any Opti? Would suck if I bought a cam not compatible with my Opti.
I didnt think picking a timing chain chain would be the hard part! Lol. Appreciate the responses.
Last edited by jmgtp; 12-18-2017 at 05:35 PM.
Reason: pics
I converted to 95-96 tkming cover, opti and lt4 extreme duty timing chain.
i am having great luck with the lt4 extreme duty chain set.
there were some 'dummies' who had problems with it because they cut corners. Mostly on the camaro z28 site.
They didnt use the included water pump drive gear and tried to reuse the stock gear -causing metal shavings (since the metal hard ness is different) to be generated.
Or didnt use break in lube on the gears.
cloyes makes a version of the lt4 ed timing chain that also has advance and retard cam keyways.
Thanks this is getting more clear for me. I’ve not had it apart so I’m a bit ignorant on the differences. Is the only purpose of the pin in a 92-94 to locate the gear correctly? And on 95+ motors the pin is extra long and also used to drive the Opti? Hope I got this right. Seems like a standard LT1 replacement set is in my future.
Thanks this is getting more clear for me. I’ve not had it apart so I’m a bit ignorant on the differences. Is the only purpose of the pin in a 92-94 to locate the gear correctly? And on 95+ motors the pin is extra long and also used to drive the Opti? Hope I got this right. Seems like a standard LT1 replacement set is in my future.
If you are worried about having to switch Optis because of drive differences and losing your good Mitsubishi sensor, don't worry. You can just take your good ol' Mitsu sensor out of the old case and put it into the next 'unknown' brand and it will work just fine. That's what usually croaks in these cheap aftermarket ones anyway. Clean off the sensor photo cells with some glasses cleaner and a Q-tip and it will be good to go! Just be gentle with the sensor disks and don't bend them. I always like to go through an Opti to make sure everything is ok and the screws in the rotor are treated with lock-tite and the cap is sealed around the edges with "The Right Stuff" gasket sealer to make it water tight.
Don't ever throw away an original Opti with the sensor still in it unless you KNOW its a bad sensor. They are like gold to have a good original sensor as a spare!
Thanks for this info Klondike. Do we know for certain that the sensors between vented and non-vented Opti are interchangeable? Seems like a great solution if aftermarket Opti's will universally accept OEM Mitsu sensors. They'll just bolt right in?
For those that have converted to a vented unit, how to you get the wiring right, I believe the connector is different between vented and non. I'd probably also eliminate the rotor altogether as I don't use the high voltage side of the Opti and it would be one less thing to fail. The concern I have with my existing Opti is that the bearings are probably showing their age.
I suppose if I can get a newer Opti/timing cover in there, with my existing Mitsu sensor, and a double roller I'll have a pretty good setup.
Since you are NOT using the high voltage side of the opti and just using the optical disk and sensor, I don't think you would need the vented case at all. The vented cap is mainly to pull fresh air through to vent out the ozone produced by the spark jumping from the rotor tip to the wire terminals. That Ozone is highly corrosive and needed to be vented out. The positive vacuum ventilation also pulled moisture out that would collect in the bottom from the incoming air. Since you don't have that corrosive atmosphere in there any more, I see no need to ventilate it, and I think you could just leave the rotor and tin plate separator/shield out of the opti and seal it up with the cover like a diver's watch. Ventilation is optional for you but keeping the sensor dry is still important. As far as I know, all years optical sensors are the same size and are interchangeable. I could be wrong, but all of the ones I've seen so far are the same. The only one different was in the MSD Opti and everything was different inside. It's a shame nobody has made an adapter to use the MSD case, because it was the best part of the whole thing. It has a really heavy duty ball bearing shaft that would never wear out. Too bad their electronics inside was not any good.
12-18-2017, 01:06 PM
Will a double roller fit under early LT1 timing cover?
. Ventilation is optional for you but keeping the sensor dry is still important. 
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