Crank work / Cam work Dave at Puma help please?
Discussion
Hi folks, hoping Dave at Pumaracing picks this one up as generally on these matters he tends to be a bit of a guru.
I have a pair of MGCs with the 2912cc C series engine, it's a funny old engine being a redesign of the old Austin healey six intended to surpass it in many ways but as standard it just didn't. What it does however do is breath far better than it's A and B series cousins due to having a 12 port head and with a bit of work can prove a nice base for an engine although it is never going to set the world alight.
90% of people just do a bit of breathing work to the top end usually with a cam and triple carb conversion, for pretty obvious reasons, however the engine isn't actually particularly well balanced as standard, I have got a spare engine sat here which I am starting to break down with the intention of building in to a fast road engine to swap between the cars.
I'm not new to building engines so will be doing the build myself entrusting the machining work to engineering companies.
1. Who can I trust to do a good bore and hone on the block? It has a wear ridge and the engines have a tendency to breathe a bit anyway so no point in using the block as is, I'm based in Yorks at the moment (although moving to cambs in a couple of months) and just want someone who can be trusted to do the job right and do it once. Is it necessary to use one of these plates which clamps up in place of the head when boring a big cast iron 6 (think it's called a torque plate to replicate the forces applied to the block when the head is torqued up)? If so what do I ask for?
2. Stamping bearing caps, is there any harm in stamping the conrods and caps so I don't mix them up, I know everyone does it but is it good practice?
3. Crank lightening and balancing, I'd like the crank working over a bit, for a fast road engine (believed to be a forged crank, probably an EN40) what would you advise in the way of lightening the crank? There is next to no information on this out there unlike an MGB. Also much more importantly I want to get the crank, damper pulley and flywheel balanced as I believe this is where the roughness is coming from, who can be trusted to balance the assembly better than factory (I've read your horror story Dave where they came back worse than sent) and I want the pulley and crank balancing together but the flywheel balancing seperately (long story) is that going to be an issue?
I have a pair of MGCs with the 2912cc C series engine, it's a funny old engine being a redesign of the old Austin healey six intended to surpass it in many ways but as standard it just didn't. What it does however do is breath far better than it's A and B series cousins due to having a 12 port head and with a bit of work can prove a nice base for an engine although it is never going to set the world alight.
90% of people just do a bit of breathing work to the top end usually with a cam and triple carb conversion, for pretty obvious reasons, however the engine isn't actually particularly well balanced as standard, I have got a spare engine sat here which I am starting to break down with the intention of building in to a fast road engine to swap between the cars.
I'm not new to building engines so will be doing the build myself entrusting the machining work to engineering companies.
1. Who can I trust to do a good bore and hone on the block? It has a wear ridge and the engines have a tendency to breathe a bit anyway so no point in using the block as is, I'm based in Yorks at the moment (although moving to cambs in a couple of months) and just want someone who can be trusted to do the job right and do it once. Is it necessary to use one of these plates which clamps up in place of the head when boring a big cast iron 6 (think it's called a torque plate to replicate the forces applied to the block when the head is torqued up)? If so what do I ask for?
2. Stamping bearing caps, is there any harm in stamping the conrods and caps so I don't mix them up, I know everyone does it but is it good practice?
3. Crank lightening and balancing, I'd like the crank working over a bit, for a fast road engine (believed to be a forged crank, probably an EN40) what would you advise in the way of lightening the crank? There is next to no information on this out there unlike an MGB. Also much more importantly I want to get the crank, damper pulley and flywheel balanced as I believe this is where the roughness is coming from, who can be trusted to balance the assembly better than factory (I've read your horror story Dave where they came back worse than sent) and I want the pulley and crank balancing together but the flywheel balancing seperately (long story) is that going to be an issue?
You certainly don't need a torque plate on a cooking engine like that. Can't help with who to use for boring/honing though.
I hate seeing stamped rods and caps. I lightly engrave a number on them with the edge of a tiny mounted stone in a Dremel so as not to create any stress risers.
Don't waste your money lightening the crank. It will achieve nothing. Similarly I've never seen OE balancing on any production engine that wasn't perfectly good enough for road use. Lightening and rebalancing the flywheel is all I'd suggest. If you spend the money you've saved on the crank on a set of 1 gram digital scales you can at least check the pistons and rods yourself.
I hate seeing stamped rods and caps. I lightly engrave a number on them with the edge of a tiny mounted stone in a Dremel so as not to create any stress risers.
Don't waste your money lightening the crank. It will achieve nothing. Similarly I've never seen OE balancing on any production engine that wasn't perfectly good enough for road use. Lightening and rebalancing the flywheel is all I'd suggest. If you spend the money you've saved on the crank on a set of 1 gram digital scales you can at least check the pistons and rods yourself.
Thankyou I was planning to do the rods and pistons myself, I had my suspicions about the worthiness of lightening the crank, and will take on board your advice and leave it well alone, in every other sense the cranks are fine and don't suffer from oil starvation issues etc. So will be a good place to save a bit of money. The flywheel certainly does need some work though it is insanely heavy.
I've also decided to stay with a standard cam profile (although if I find as I suspect I might the cam I have which is from an Austin 3 litre as opposed to a C is either damaged or a gentler profile than the C one I may well have a very mild grind done on it if it's capable of being reground, if not I believe blanks are still available.
I think I'm going to use a local engineering firm that have been around a long time, the last engine I had built was done by Oselli and I have to say has been fantastic, but this one is a lot less fussy than that one and I think this company will be more than capable (and hopefully a fair bit cheaper!).
Many thanks for your advice it's been helpful.
I've also decided to stay with a standard cam profile (although if I find as I suspect I might the cam I have which is from an Austin 3 litre as opposed to a C is either damaged or a gentler profile than the C one I may well have a very mild grind done on it if it's capable of being reground, if not I believe blanks are still available.
I think I'm going to use a local engineering firm that have been around a long time, the last engine I had built was done by Oselli and I have to say has been fantastic, but this one is a lot less fussy than that one and I think this company will be more than capable (and hopefully a fair bit cheaper!).
Many thanks for your advice it's been helpful.
Shaving weight off the crank should change the characteristics of the engines feel and the way it puts down power on and off the throttle. The benefits can be very rewarding depending on the engine and its application. I wouldn't rule it out. In fact I'd positively embrace it to the point I'd research it to death to find out if it's worthwhile for the engine and your intended use.
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