Running question-Well running poorly

[Deleted member 8566]

So I bought a good used block from a friend of mine, it had been rebuilt and put in a TF, my friend is a purist and pulled the engine for his B and to put the proper TF engine back in his car but then sold the engine to me.

I know the block is good. Great oil pressure, good sound, no issues there.

Here is where the problems do come in and I will try to give as much information as possible but I am at a point where I am racking my brain.

So in order to make sure I have no more challenges with my 1980 B, I have really taken my time and not cut any corners. All the wiring is new in the car and EVERYTHING electrical works properly. The distributor was recently rebuilt by Jeff at Advance so I know it is good. Same goes for the HS4 SU carbs, they have been rebuilt recently and are good. They have also been synchronized and adjusted in from what we can tell is properly. Also the valves were just adjusted too.

The car starts and idles just fine, temp. is now better than perfect (this was not the case until recently and I will go back and elaborate.) The timing was set just as the manual says at 10 degrees at 1500PRM.

When my previous engine gave out a hole was blown in my resonator (or front muffler) and I have not had the car run well enough for me to get it to a shop to get that fixed. I don't know if that could be affecting my running, I'm sure someone will let me know.

Anyway, when I test drive the car around the block, pick up is decent until the the throttle is opened wider, then I can hear and feel a lot of hesitation and inconsistency. What I hear comes out as a popping noise from the resonator and what I feel is the car trying to die.

One thing that is important is that we were having an issue with air trapped in the cooling system and the car getting hotter. After a few times of the needle moving into the hot range, we did a lot of investigating and found out the thermostat was stuck shut. I am wondering if I have a bad head gasket now over this, although aside from running issues when the throttle is fully opened, I don't notice any of the other "obvious" head gasket symptoms.

I am wondering if there are any thoughts or ideas or anything else I should check. If there is anything else that needs clarification, please let me know.

Justin

 

[LarryK]

Change the thermostat and cut off the resonator. With working thermostat and no resonator ( to free the exhaust of possible blocking ) see if the temp falls back in place and the engine runs better. Clogged exhaust can force overheating too!

 

[JPSmit]

Is there oil in the carb dashpots? Sounds a lot like what happens when mine get empty, or timing.

 

[trrdster2000]

Justin, check to floats, sounds like a starvation problem and lean can cause overheating.
John is right also.

Good luck, Wayne

 

[blueosprey90]

No expert here, but

1. I like the idea of the clogged exhaust system. I have a fairly open side pipe exhuast with just a small glass pack muffler. To meet sound restrictions, I have tried both an exhaust pipe insert and a "spark arrestor" on the tip of the exhaust. Both turned out to be terrible robbers of performance!

2. I agree that you might be running lean at higher rpms, but not sure why you would be "backfiring". That suggests a misfire. Double check your valve lash. If that looks ok, run the car until it runs poorley for a few minutes, then shut off and coast in for a stop. Check the fuel level floats, check the spark plug color. May help determine if you are lean or rich.

3. I think you should check your timing at 3,000 rpm. With a Mallory dual point distributor, I have my MGA timing at six degrees (6°) at idle, 32° at 3000 rpm. If 1500 rpm is your idle, I would think it too high.

Good luck.

 

[Stewart]

try resetting the timing.

12 to 16 degrees at 850rpm with the vacuum advanced disconnected and plugged. The 10 degrees at 1500 would be perfect stock restrictive setup.

 

[drooartz]

All good suggestions here, and I'll add that it's worth running a compression and leak down test as well. Let us know how it turns out.

 

[JPSmit]

Oh, and, don't assume any component is good just because it has been rebuilt - don't ask me how I know. Seriously though, things can always get joggled in transit, or something is missed. The usual suspects who rebuild stuff are outstanding (and I have met/used them) but everything is suspect until proven otherwise.

 

[blueosprey90]

So we have a newly built engine. It is in a TF that your friend bought. Your friend pulled the engine because he is a purist. But how did the engine run in the TF? Is he a purist because the engine ran like crap?

I picked this up on another forum last December relative the the MGA 1600 engine. Do you have a workshop manual? Check it for this test -

For the MGA there is a test to check valve timing. Section A.15 "Checking Valve Timing" in the MGA manual.

You set the #1 inlet valve to .060" with engine cold, and then turn the engine until the valve is just about to open. The notch on the crankshaft pulley should be at the TDC pointer on the timing cover. If the notch is not at the TDC pointer, your cam shaft and crankshaft sprockets are missaligned. Probably in the rebuild.

A missalighnment of one sprocket is maybe 15 degrees. That would explain poor performance (lack of compression). A two sprocket misallignment is even worse and might explain the backfiring. Can be fixed by removing the timing cover without removing the engine.

Easy test and worth considering.

 

[PAUL161]

OK, you've had a lot of good advice, if you still have an issue, I'll throw in my 2 cents worth.
1/ Make sure you have oil in the carb dampers!
2/ Make sure the vacuum chamber pistons are moving freely. They've been known to hang up.
3/ Make sure the valves are gaped properly, not to tight, loose is better, just noisy.
4/ Make sure ignition timing is right on. If Jeff rebuilt the dizzy, then you have no shaft wobble.
5/ If none of that works, pull the timing chain cover and check the cam timing
6/ Last I can think of is cam lobe wear / bad cam! Check lobes with dial mic on rockers for consistency.
Beyond that, without being there, I'm lost. PJ