I am going to document the engine swap I did in my 73 LeMans. The car was originally equipped with a Chevrolet 350 from the factory. This engine ran perfectly but I wanted more power and fun after 7 years of ownership.
A good running 454 became available when site founder Canadian Poncho sold his 1969 Laurentian and I was able to obtain this engine in May of 2011. I started the swap on September 24, 2011 and used 4 weekends to do it, about 22 hours in total. Prior to actual work some research was required.
Because my car was designed with a Chevrolet engine the swap would be straight forward enough however parts needed to be obtained. I looked to the 1973 Chevelle SS454 for guidance on Oil Pan and Headers. The 454 also requires an externally balanced flex plate which I obtained from Summit Racing. Headers are Patriot 2" x 36" into 4" collectors coated in Cast Blast. Oil Pan is a stock replacement for the 1973 Chevelle SS454 with dipstick on the passenger side.
I assumed I would require the Chevelle big block fan shroud but in this case the LeMans factory shroud has worked out perfectly.
Parts that I transfered from the 350 small block are as follows: carburetor, distributor, coil, starter, power steering pump, alternator. I also obtained a very nice OEM clutch fan that works nicely. Radiator hoses and heater hoses were reused with little to no trimming.
My goal was to have an installation that appeared to be factory and period correct in apperance. I therefore used OEM parts with the exception of the headers. I retained the basic emmissions equipment that was on the small block, PCV and charcoal canister. Underhood decals and stickers were purchased from NPD in Michigan, Canadian oil change instructions, Canadian coolant warning, Tonawanda #1 valve cover decal and 73 SS454 emissions decal.
Exhaust system used was the one on the car, the headers reduce to 2 1/2 inch pipe into Turbo Cherry Bomb mufflers exiting through reproduction 1973 Pontiac Lemans/GT/GTO Chrome extensions.
First you have to get the old engine out. My advice is to have one or two friends to help out here especially with the hood removal. We used a china marker to trace the location of the hinges and bolts on the hood. Putting it back on was a snap and it closed and fit properly first time. The more things you can remove the easier it will be to pull the engine out. Engine itself is held in by 11 bolts, two for mounts 6 on bellhousing and 3 at flex plate. Remember to drain the fluids.
-- Edited by 73SC on Thursday 3rd of November 2011 04:10:32 PM
Ray, surprised you left the dist. cap on when "jerking" out the SBC. usually they hit the firewall & get smashed!!! I remove it from dist. & just lay it forward. You either got lucky or know another way of not breaking it????? OR Real carefull!!!!
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Some times I wake up GRUMPY, but today I let her sleep in !!!!!!!!BLACKSTOCK Ont.
That never seemed like an issue as there was plenty of clearance at the firewall. The LeMans engine compartment is pretty darn big, even with the 454 in place there is room to do you buisness with spark plugs and belts and what not.
One thing I did was jack the car up about 6 inches to gain access to the bellhouse and flywheel bolts and rather than jerk out the engine we lowered the car and it disconected real smoothly without endangering the distributor.
The removal process was done on a Saturday and finished on a Sunday morning. It took us about 5 hours in total. Of course we had about 8 visitors and had to have a few pops while listening to Willie's Roadhouse.
That is probably the best part, friends and shooting the breeze while you work.
Keeping your work area tidy and clean is essential as well as organizing the bolts and fasteners and clips you remove. A digital camera is essential as we used it to take photos of assemblies prior to removal and this was very helpful when putting it all back together.
-- Edited by 73SC on Thursday 3rd of November 2011 08:43:54 AM
The car sat for about two weeks due to other committments but I did manage to degrease, clean and paint the engine compartment during that period as well as clean up the parts that would be used from the small block, paint brackets and sorted out pulleys.
Crane was useful for painting various parts, Headers got Cast Blasted and brackets etc got cleaned up and painted.
Parts were transfered to the big block. A new fuel pump and oil pump and pick up was used. While the oil pan was off we made sure the bottom end looked good and torqued the main bearing caps and rods to spec. A neighbour who is a mechanic brought us his Snap On torque wrenches, things of beauty just like surgical tools.
Hoisted and ready to set in place. The placement of the oil sending unit was a topic for considerable discussion. This is the placement on the engine when I got it and when the engine is dressed and installed it is invisible to te eye and accsss from under neath is very clear. I decided to leave well enough alone as I was getting a good running engine and wanted to get it in then running. The PS pump protects it as well. The traditional placement to the rear by the oil filter is near impossible to acccess with headers. Those engine mount ears are directly from the small block.
Dropping in place.
Header install was very time consuming, about three hours, but once in they fit great. We had to get the car up about two feet to do it and raise the engine 3 inches. This is when I snapped the tranny dipstick top off, my only casualty. Drivers side required trimming of the engine mount ear and removal of oil filter. Passenger side required starter removal. Headers go in from underneath car. Once on the engine lowered onto the mounts with a nice click and we slid in the bolts an torqued them down.
-- Edited by 73SC on Friday 4th of November 2011 12:14:12 AM
Worth noting is my philosophy on this project. I knew the engine was a runner and coming from a trusted source so my idea all along was to get it in the car then shake it down for relaibility. I also took the view that I would buy parts and fix problems as they arose. To this end I stayed with the THM 350 and rear end that was in my car. Do these need upgrading ? probably - so that goes on the TO DO list. For now I can enjoy a huge upgrade in performance and fun.
The only mods to the engine were Edelbrock intake and Carb plus headers. The engine is a GMC 7.4 ltre rated at 230 Net HP and 360 lb ft torque as installed in a one ton single exhaust Dually. This translates to about 325 Gross HP before headers, duals and intake add ons.
For my use this was plenty of power and with mods is most likely on par with an LS4 or LS5. The 1973 LS4 was rated at 245 Net HP and this engine has that well covered. The 1972 LS5 was rated at 230 Net HP with single exhaust and 270 Net HP with dual exhausts and I would think this engine is north of that considering the effects of headers and intake. I have big block build books which show dyno gains with headers of between 50 & 75 HP so I feel very comfortable in making the LS4 & LS5 comparisons. For interest sake 270 Net HP translates to 365 HP under the pre 1972 SAE standard.
The actual performance of the car bears this out as it is near impossible to launch as is without lighting up the rear. My new Cadillac DTS has 292 net HP and the Rat Powered LeMans with 2.73's is actually bigger and would make minced meat out of the powerful Caddy. Even last night on a cool November evening I was doing 30 mph and accelerated swiftly and the tires broke loose and spun until I backed out.
All the time I wanted a factory appearing installation and period correct modifications. To that end I sourced some OEM parts to complete the look. A GMC grile callout used on less that 150 Sprint 454 SP's replaces the original small block call out using same placement holes in grille and a 1970 Pontiac 454 air cleaner decal which was also a very low use item. GMVVS documents for the Green Monster show less that 300 454 Pontiac and Chevrolet B Body's were made in 1970. Underhood decals were sourced form NDP to complete the project and Air Cleaner decal from Osborne Reproductions.
What do I foresee as possible items to address going forward?
My throttle cable is too short so I'll need a Big block cable, at that point the carb should be able to fully open to wide open throttle, it's kind of scary thinking it isn't right now.
I need to get some decent wires that will withstand the heat of the headers. I have pretty much landed on PerTronix Stock Look Flame Thrower wires just need to source them.
Radiator is original two core and I'll keep an eye on that for proper cooling, may need to upgrade to 3 or 4 core but so far so good.
Front springs were an area I was told would need replacing however the car has an improved stance without being too low and steering response and feel is much better with the added weight upfront. Headers have scraped the driveway ramp a couple of times but I'm getting used to how not to.
I may consider reconnecting the trans kickdown one I get used to the added torque.
A posi rear end is a must although the 2.73 gears seem ok to me. There is so much low end power that the engine can overcome this gearing and for now with a 1:1 final drive ratio the highway gears will assist with fuel consumption. OEM offered 3.08 and 3.42 ratios so I will likely be on the lookout for a posi but I am not complete sure about getting a lower gear.
Car revs at 2250 doing 70 mph which is pretty good for fuel economy I would think.
That's it for now, hope the thread is useful for anyone doing or thinking about a small block to BIG BLOCK swap.
-- Edited by 73SC on Tuesday 8th of November 2011 11:35:49 PM
the large oil pressure sending unit is the type to be used with an oil guage. If you just had an idiot light with a much smaller sending unit, you may have been able to use the regular position above the oil filter.
the large oil pressure sending unit is the type to be used with an oil guage. If you just had an idiot light with a much smaller sending unit, you may have been able to use the regular position above the oil filter.
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Yes I have a full factory guage cluster in my car. It is a rare option to say the least. Mine has been modified a bit when I installed a 160 mph Trans Am speedo. Firebird and LeMans share the same basic cluster.
Clean Shaven head is 65Camino and he refers to his footwear as safety sandles
I forgot to mention oil pump priming. This is essential once engine is together. An oil pump priming tool is needed and costs 20 bucks. You attach it to a high speed drill and put it down the distriuitor hole and engage the pump drive. If you hook up an oil pressure gauge you wiill see the pressure you get. It is also a good way to ensure you have set your oil pump pickup at the proper hieght. The idea is to oil the upper valve train prior to initial start up. You need to be patient but eventually the oil will start to flow up the push rods and into the rockers etc... Most engine builders recommend this procedure and you can find You Tube videos to help you with this.
-- Edited by 73SC on Thursday 3rd of November 2011 10:56:11 PM
'64 Parisienne CS "barn find" - last on the road in '86 ... Owner Protection Plan booklet, original paint, original near-mint aqua interior, original aqua GM floor mats, original 283, factory posi, and original rust.
I was very concerned about this aspect of the swap. My car sat high in front with the small block especially when I took a lot of weight off the front in the form of aluminum intake and some unnecessary underhood parts.
The car does sit lower now, perhaps an inch but it is level front to rear now. The extra weight is noticable in the steering which now feels much better and stable and I like how the car handles with the extra weight
The springs may settle over the winter but for now I have no concerns with ride hieght. The header collectors are not all that low either. I think time will tell so this is an area to watch.
I will try and get a photo of the car this weekend and post it so we can see what I am talking about. I don't plan on putting it away anytime soon this year come to think of it I should be heading out for a run right now.
It sounds like the engine swap has rekindled your love for the LeMans Ray. I was worried about you after you went to Woodward talking about how old cars were crap. Welcome back Ray. Welcome back.
It sounds like the engine swap has rekindled your love for the LeMans Ray. I was worried about you after you went to Woodward talking about how old cars were crap. Welcome back Ray. Welcome back.
A 4 hour trip on super hot August day in non air conditioned car does strange thinks to a guy. There is no doubt that these old cars can not hold a candle to what is produced today in comfort, ride, safety, performamnce and quality. Remember I drive a $72,000 Cadillac everyday and my midsize mid priced qustionable quality LeMans is not in the same league. Besides, Hillar made me do it.
-- Edited by 73SC on Thursday 10th of November 2011 10:20:04 PM
the large oil pressure sending unit is the type to be used with an oil guage. If you just had an idiot light with a much smaller sending unit, you may have been able to use the regular position above the oil filter.
________________________________________________
Yes I have a full factory guage cluster in my car. It is a rare option to say the least. Mine has been modify a bit when I installed a 160 mph Trans Am speedo. Firebird and LeMans share the same basic cluster.
Clean Shaven head is 65Camino and he refers to his footwear as safety sandles
I forgot to mention oil pump priming. This is essential once engine is together. An oil pump priming tool is needed and costs 20 bucks. You attach it to a high speed drill and put it down the distriuitor hole and engage the pump drive. If you hook up an oil pressure gauge you wiill see the pressure you get. It is also a good way to ensure you have set your oil pump pickup at the proper hieght. The idea is to oil the upper valve train prior to initial start up. You need to be patient but eventually the oil will start to flow up the push rods and into the rockers etc... Most engine builders recommend this proceedure and you can find You Tube videos to help you with this..
-- Edited by 73SC on Thursday 3rd of November 2011 03:36:29 PM
Ray, it's very easy to make the prime tool. one is to use an old dist with the guts stripped out & gear removed from shaft. attch. drill to tops of shaft & spin it up, or you can use a length of round stock & flatten lower end to engage oil pump & do the same. Last one is what I made up for the enginges I have done over the past few yrs. Works great just get ready for the 1/2" drill to "torque" when the pressure starts, nearly twisted drill & me around the engine!!!!
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Some times I wake up GRUMPY, but today I let her sleep in !!!!!!!!BLACKSTOCK Ont.
Just took daughter #1's BF for a run, he was laughing the whole time. I put down a smoke show and unknown to me he had his BB going. I asked him to email it to me. He has the camera pointing out front but you will get the idea. Coolest thing is you can hear me lift off after about 100 feet of tire shredding.
-- Edited by 73SC on Thursday 3rd of November 2011 09:30:08 PM
