I have a 1985 Fleetwood (rear wheel drive) with a blown HT4100 garbage engine in it.

I am not putting another 4100 in this car.

Can anyone tell me what GM engines will bolt up to a 1985 THM440 T4 transmission?

Thx, Mike

if it has the 60deg v-6 bolt pattern then there is a 3400 crate engine that makes 190hp. there are carb manifolds available or you can get a jy 3400 with all the computer goodies that would be a much better setup but would be more work. this is from wikipedia, i wouldnt invest any money until i get a few different sources to verify. seems more likely to me a big car would have the 3800 pattern but logic doesnt always apply. it doesnt say anything about the engine mounts either

HT-4100

A new lighter V8 engine was rushed into production for 1982, the HT-4100 (option code LT. It was a 4100 cc V8, designed for rear wheel drive and longitudinal front wheel drive applications sharing the same transmission bellhousing pattern as Buick, Oldsmobile, Chevy, and Pontiac rear and front wheel drivetrains for 2.5 L 4-cylinder and 2.8, 3.1, and 3.3 L V6. A transverse front wheel drive version was originally slated for 1983 and a new line of downsized Cadillac sedans, however, delays in the downsizing program shared with Buick and Oldsmobile postponed the introduction of those models until 1985.


HT stood for High Technology. For its time, the engine and its electronic control module (ECM) were quite sophisticated, despite having a throttle body injection system (as opposed to port fuel injection.) Like the 6.0/368" DFI engines before it, the HT4100 used an ECM that incorporated a detailed on-board computer. Every parameter of engine performance could be displayed on the Electronic Climate Control panel while the car was being driven. The HT4100 also pioneered other design features including replaceable cylinder sleeves, high operating temperature for emission control (210 degrees, compared to 180 in earlier engines), free circulation of coolant between the block and the heads, and bimetal construction that mounted heat-tolerant cast-iron heads onto a weight-saving aluminum block. The engine had a bore of 3.465 in (88.0 mm) and stroke of 3.307 in (84.0 mm), for a total displacement of 4.1 L (250 cu in). It initially was equipped with throttle-body fuel injection, with output of 135 hp (101 kW) at 4400 rpm and 190 lbf·ft (260 N·m) of torque at 2000 rpm.

In 1982 the HT4100 was the standard engine for the longitudinal front-wheel-drive Eldorado and Seville. It was also placed in many rear-wheel-drive DeVilles, and was available for the Fleetwood.

The HT4100 was prone to failure of the intake manifold gasket due to scrubbing of the bi-metal interface, aluminum oil pump failure, cam bearing displacement, weak aluminum block castings and bolts pulling the aluminum threads from the block. It may not have been the most successful engine to sit under the hood of a Cadillac, but potential buyers were no more satisfied with the other two engines available at the time, the V8-6-4 and the Oldsmobile 5.7 L Diesel. Reliability issues soiled the reputation of the HT4100. As a result, the V8 Oldsmobile gas engines were a popular and straightforward conversion.

personally i would just get a chevy bolt pattern 200 or 700r4 and then you can use any sbc that fits your goals and wallet.

Thank you. I have read many articles on what and what will not fit this trans. I have also read wikipedia. Looks to me like the only choice I have is to put another 4100 in it or change the trans,
drive shaft....etc....

Thx Mike

A Pontiac 301HO or an Olds 350.
I think just about any B.O.P. engines will fit just got to move the motor mounts is all and i would look for a carbed engine with HEI.

I stand corrected
2.0L (OHV I4), 2.2L (OHV I4), 2.5L (OHV "Iron Duke" I4), 2.8L (60* V6), 3.0L (90* V6), 3.1L & 3100 (60* V6), 3.3L & 3300 (90* V6), 3.4 & 3400 (60* V6), 3500 (60* V6), 3.6L (60* V6), 3800 (90*V6), 3.9L (60* V6), 4.1L V8, 4.5L V8, 4.9L V8

Just do yourself a favor and do a chevy 350 with a turbo 350/400 trans or 700r4

thats what im saying, change the trans 700 or 200r4 with chevy bolt pattern, i went the other way 700 to 400 on my firebird its not a big deal. then you can get a 350 that has twice the power and probably better mileage too. and a million times more reliable.