MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Newbie - A silly question about exhausts?

Firstly... to let you all know. I am very much a mechanical/automotive novice. So please bear this in mind with the following question.

I have a 1967 mgb roadster. Bodywork has been done for me. Just a few things to put back together. It is in pieces (mechanically) I have being on a steep learning curve putting it back together. My question relates to the exhaust.

I am about to reinstall the radiator and replaced cooling system rubber hoses etc. Once done, I am going to try and start the engine. I don't have the exaust system from beyond the inlet manifold on the engine. Can I still start the engine without the bulk of the exhaust system? If I can, what should I expect to happen to the running of the engine when it turns over?

If I shouldn't I guess I will have to sort out the exhaust first?

Maybe a silly question... but thought I would give the BB a go to see if I should or shouldn't do this.

Many thanks all
Chris
Chris

You can start the engine with just the exhaust manifold in place but it will be very noisy!
Chris at Octarine Services

There are NO stupid or silly questions. That's how we all learn.

rick
rick ingram

Chris-
With no backpressure some of the cool intake charge will go right past the hot exhaust valves. Don't run the engine for long or you will risk warping the exhaust valves.
Steve S.

Thanks guys for the fast reply.

Rick... thanks for the encouragement!

Steve... how long do you think is ok to run the engine? I just want to see that it still runs once I have all the other bits on. A minute or so?

Thanks
Chris
Chris

Hi Chris , Welcome to the place and enjoy your stay.
Nice to see another from South of the Equator!

Cheers , Pete.
Peter Thomas

Chris,
Any reason you think it might not run? My 2p: you're going to have to get an exhaust sometime soon aren't you? In the meantime, if there is a problem, you'll never hear any subtle tell-tales of disaster over the cacophony without one. If there's not a problem, you may as well have waited....I'd be inclined to be patient for a bit longer, check any work you've done if you have a doubt, and then run it up to full temperature when you have a system in place. You could leave it loose if you think it's going to have to come off again.
You will definitely want to wait if you've got a new cam as you'll have to break it in (full instructions in the archive, just register) and that means running the engine for 20 minutes at 2-2500rpm from the first turn of the key.
Steve Postins

Hi Chris

My first thought is to let it rip, make a bloody great noise while you have a chance. I can't resist the temptation myself.

Steve P has a point though, with all that noise, how will you tell if everything is ok. And if you have a new cam and followers, best to run them in from first start.

I dont think that you need to worry about damage to the exhaust valves, you will not be working the engine hard.

Cheers
Ian F
Ian Fraser

Hi Guys,

Thanks for all the replies. Makes me feel most welcome!

Steve... as to your query if the engine will fire or not. It was working ok prior to bodywork restoration (when much of the car was dismantled). But that was about 4 years ago. I am hoping all is ok for a new start.

Ian... Yeah. I am really tempted to just get in there and get it started as soon as I have the cooling system etc reinstated. may be a month or so away though.

I don't have a new cam. Everything is original. Was running sweetly before restoration was started though.

Thanks for the relies guys.
looking forward to the day she hits the road again!

Chris

Chris

Chris, before you try to start your car you need to check the carbs! After sitting so long, the pistons may be sticking which will prevent the engine from running well - or at all. Unscrew the dampers from the tops of the carbs and top them off with engine oil. Revove the air filters and push the pistons up with your fingers to make sure they slide smoothly and both pistons return at approximately the same rate. I just faced the same issue with my Spring startup, so I thought I'd mention it.
Welcome to the BBS! Hope to see you around more!
Jeff
Jeff Schlemmer

I hope you don't live next door to me(lol)
Good luck
Regards
Roger
Roger T

Yep, everything the others say is fine. It will make a HUGE noise (wear ear defenders), but should run OK. The one thing I wanted to mention is that you might get flames out the open end, so make sure there's nothing flammable nearby.

Mike
Mike Howlett

Generally listen to Steve S. He is very knowledgeable.
J.T. Bamford

Chris, if you decide to fire it without the exhaust you should probably wait until around 11pm so that your neighbors will get to enjoy the full sound of a finely tuned MG. You also won't hear them as they come looking for you with rocks and clubs, so that will also be a surprise. ;-)
Bill Young

Chris. I am in exactly the same situation. Bringing a car back on line after a many year lay up. In addition, I installed a CB exhaust manifold on the RB car, so it will need some adapting. Since I wanted to be able to run the engine periodically while doing other things, I cut the old exhaust system to approximate mate with the new downpipe and connected the two of them via a flexible exhaust pipe. Not a perfect seal, but it does allow me to start and run the engine, both for tuning and general exercise, without worrying about excessive noise. Flex pipes are available in most auto parts stores where they are sold as a general replacement item.

Les
Les Bengtson

Hi guys,

Sounds like I will need some serious ear protection!
Will do it when the rest of the family wake (around 6am). The sound of the MG has gotta be better than an alarm clock!

Jeff... Thanks for the tips on the carbs. Will take a good look at those too.

Can't wait till I get her started again!

Chris

This thread was discussed between 09/05/2006 and 11/05/2006

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.