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History of v6 Motoring - A British Sports Car v6 Conversion Article

Last Updated on Saturday, 05 June 2010 15:19 Written by Brian McCullough

I write this article first assuming that the majority of readers are converting an MGB (a rear drive car made between 1962-1980) with GM’s very common rear drive 60 degree V6 motor, and a GM T5 five speed or possibly just looking for various year and generic information on parts changes during the years of the GM 60 degree V6. Everything here is based off this assumption. More information will eventually be posted in regards to automatic conversion, Front drive motors and more.

Generally speaking, a newer motor can be backdated but most motors cannot be updated. There is also a bit more difficulty to backdate front drive motors and it is generally felt that FWD motors are not worth backdating nor possible to go carbureted as of this writing on FWD. FWD motors are possible to use and can produce more power, but at the cost of more time or money spent to convert. Also, being as though the modern thought is to squeeze as much motor into a given size engine bay such as the MGB, I will make the assumption that the average conversion using the GM 660 is a car between 1,000 (kit car) and 2,400 pounds (MGB, Triumph, TVR, Sunbeam, Lotus, Porsche and others). Unfortunately, time has not allowed me to check some of the build dates published here so please visually inspect anything you are considering purchasing before making the assumption that it will work for your application.

 

 

First, history of S10 and Camaro drivelines 1982-1995.

Chevrolet S10 and GMC S15 (later Sonoma)

1982- Introduction. 2.8L small bearing crank, rope seal. progressive 2 barrel Varijet II. Non-computer controlled distributor (except CA) Good distributor to run when running any kind of carb system. Varijet II is kind of a nice carb. I ran one for years on my LB S15 2WD. Not good for fuel economy the way I drove, but had a nice feel to it when the secondary would open up! rated 110 BHP and 140 Ft Tq- felt good on a 2WD with a manual and removed the mechanical fan and other power robbing items.

1983- virtually unchanged.

84- early 85 small changes to the motor, hydraulic clutch. Mostly the same for our conversion reasons.

85.5-86 The first TBI systems and electronically controlled distributors.

87- first internal balanced motors. Note that a set of 3.1L pistons and crank can bolt directly in to a 2.8L block. Thus creating a 3.1L- exact same bore and same block. (The 3.1L is a 2.8L with a longer stroke!) Oil pan changes from old fashioned cork seal to a rubber seal that works better and longer. This also changes the shape of the front timing chain and water pump cover.

88-92 virtually unchanged. All TBI. Even to the last, a STOCK S10 was a 2.8L TBI. Never was the 3.1L or 3.4L placed in any S10 that ever made it to the dealership.

Not mentioned here: CW vs. CCW water pump rotation. Generically- 1982-1986(?) were CW rotation, whereas 97-92 were CCW. Systems went from complete v belt to hybrid to complete serpentine system. Valve covers were ALL stamped steel but very early ones had round corners that looked more like 1950's covers- neat for those who want a retro look. The later covers- about 1985 and on had squared off corners- these valve covers were used on all 1985 and later iron head motors- Camaro/S10 to 1995 and all GM Crate motor 3.4L motors.

ALL S-series pickups have a shifter located forward by 9" on the box compared to the Camaro T5. ALL of these housings are a very poor choice for MGB conversions but the tail housing could be used for a few different conversions such as a Spitfire conversion. 1982-198X had a 4.06 1st gear and 0.86 5th gear. 198X (probably around '88) to 1992 had 3.76 1st gear and 0.73 5th gear, just like the Camaro V6.

Bell housings- 1982-83 were cable clutch. 84-92 were all hydraulic.

 

 

Chevrolet Camaro and Pontiac Firebird - corporate cars. Sold differently by packaging different options. Drivelines identical.

Refer to S10 for minor engine changes first before reading this section...

1982 intro to the 2.8L V6 Camaro/bird. This first year used a cast iron 4 speed with a separate bell housing. All rods were external. Good possible conversion gearbox for someone looking for something d ifferent. Not good for an MGB conversion and heavy too.

83-84 Carb and distributor the same as the S10. Not sure of the curve of the distributor or the jets in the carb but all run about the same.

85 First MPFI. NOTE: While the pickup received the TBI (Throttle body injection) that looks like a carburettor, the Camaro received the trick MPFI (Multi-Port Fuel Injection) which has 6 injectors vs. the 2 that TBI provides, FP for TBI is around 13-16psi and the MPFI used up to 40 PSI in the early years. Power for the MPFI systems was higher then the TBI systems. The MPFI systems are the tallest system and the most difficult system to fit under the stock MGB bonnet.

86-89 virtually unchanged Except that the 87 model year received the internal balanced motor.

90-92 saw the 2.8L get a new crankshaft. This crank had a longer stroke creating the 3.1L engine by simply changing the piston and crankshaft. The same rods were used for all 2.8, 3.1 and 3.4L motors and are very strong.

93-95 L32 3.4L motor- almost a new motor. GM used the SFI (Sequential port Fuel Injection) which fires each injector individually for more power and economy while still remaining conversion friendly (something that cannot be said as easily about 1996 and later PCM's!)

While GM was up to this, they installed DIS ignition and deleted the antiquated distributor. The bore was changed 3.03mm larger then the old 2.8/3.1L blocks while the crankshaft remained the 3.1L crank.

<<NOTE: A 87-92 2.8L crank can be installed in a 3.4L to create a short stroke high revving motor with a set of custom pistons>>

The pulley arrangement on the stock 3.4L when the stock brackets are purchased with the motor is a very simple arrangement. BMC provides a pulley setup that compliments the factory L32 system.

Other unmentioned items: like the S-Series pickup, the oil pans, front covers, water pump direction V belt to serpentine systems and other items went through changes. Valve sizes and camshaft changes occurred in the mid 1980's as well.

One note on oil pans: There are a few items to look at in oil pans and noting that there were various year MGBs or other cars that are being converted these things should be highly considered... Early 62-75 MGB (Chrome bumper cars) with sub frames in the stock position have less clearance. Later 1976 RB MGBs have an extra inch of clearance. Camaro oil pans and S10 oil pans have a few differences. Generically, the early S10 2WD and the Camaro oil pans are the same but can cause a slight interference with the MG Subframe. The later pans do not have this issue and seal better on the block with modern tech- not cork!

The 4WD oil pan of the S-series will fit the MGB but the pan is built shallow in front and deep in the rear. If this pan is used, it should be noted that it will hang below the MGB subframe, as it will on most other automotive conversions. The S10 oil pan will usually be avoided for this reason- unless your willing to build a heavy belly pan to avoid punching the underside of the pan and loosing oil/oil pressure.

Another small point that I will mention is that the Camaro oil pan is just ever so slightly different from the S10 2WD pan. The S10 pan will fit into a Camaro, but the extra step in the middle of the pan (about 3 or so inches back) just hits on the S10 frame, thus the Camaro pan cannot be used in the S10- I know! My '95 3.4L SFI motor in my '82 S10 2WD is running a 1988 S10 2WD pan.

Camaro gearboxes varied a bit more. the super early 1983 cars possibly had different ratios, the 4 cylinder (2.5L) Iron Duke Camaros had a T5 with something around a 3.95 1st gear- a real odd box. MOST of the later T5 V6 boxes were 3.76 1st gear- about 1984 to 2002. Bell housings were interchangeable with 1983-1992 for the GM bolt pattern T5, Muncie and other patterns. The 1993-1995 was the same on the motor side but the gearbox pattern changed to the "ford" pattern. The 1995-2002 3.8L T5 might possibly fit the 93-95 bell housing but only operates with a VSS and cannot be converted back.

The 1983-1992 V8 T5 is a 2.95 1st and a much greater OD, but the 4th gear is still the same.

in 1986 OR 87 Ford went to the world class box. GM waited until 1988. Most will refer to the various T5 units as WC or NWC for pre and post world class units for rebuild kits and so on. Having a NWC is not a big deal. I run a lot of them without any issues.

Bell housings were all hydraulic. 1983-198X had the dual pocket that could potentially be used with the GM T5 and a starter on either side although the RWD block was only drilled for a starter on the passengers side just like an MGB.

Flywheels- built heavy. Far heavier then the S10 unit. Not a good unit for a light car such as the MGB. <"editors" note: Even the S10 flywheel is heavier then the MGB needs but for stock applications we sell a ready to install S10 unit and for those looking for the "right" weight, we have something well fitted albeit a bit more of a cost>

 

 

OTHER GM 660 V6 powered vehicles:

Isuzu Trooper (87?? to aprox 92??- 2.8L and 3.1L TBI), Jeep Cherokee carbureted (85-86), half of GM's FWD fleet appears to be powered by this motor at one time or another.

It is my opinion that for the MGB and other conversions that the easiest motor overall is the 3.4L out of the 1993-1995 Camaro. This motor is a serpintine system with the modern oil pan and sealing system, has DIS but still has iron heads. It produces the most power while still remaining in RWD stock format. This allows a person to easily run the starter in the stock location which allows for the auto or manual without retrofitting and specialty machining. This motor can be retrofitted with carburetion or updated with aluminium cylinder heads and pistons to match.

One conclusion to all this is that any of these motors will fit into any year MGB or other car BUT generically, the later the RWD motor the more power it produces and the easier it will be to fit all the sub systems- oil pan, intake system, pulleys and so on.