All Activity

I think I just didn't get all the air out of the system. Runs cool now. What I didn't know is my car was a late production with a 400 in it! I put the harmonic balancer and flexplate from that engine on the 350. If I didn't have bad luck, I'd have none at all. I changed out the balancer for the correct one. But I need a transmission shop to change the flex plate. I've been told it can be done with the engine in the car, and that the transmission can be unbolted and moved back enough to drop the flexplate. I hope they are correct as that is what I told the shop that will perform the job!

Thanks very much -is there a way to fix it or do I need a new one?

Another possibility is that the starter solenoid is sticking. Sticking in the retracted position would account for nothing happening when you turn the key. Then, sticking in the engaged position when the engine starts could account for the noise, as it would be the same effect as holding the key in the start position.

Actually the 299 R3 was not stroked, it was just .060 over. The proof is the R3 crankshaft drawing shows that it is for the 299 and 304 engine.

SOLD 07/19/2025

Thanks Gunslinger appreciate it

Check all the connections for tightness and corrosion…both hot lead and ground. It may require disconnecting everything…cleaning it all and reconnecting everything tight. You might also do a starter draw test and see how many amps the starter is drawing. The noise may be the starter bolts have loosened and a shim is loose or gone…BTDT. The starter itself may be dry and needing rebuilding or replacing.

Battery reads 100% charged but 2 issues First issue is sometimes I turn the key and it is absolutely dead. Then moments later I can start it. Second issue is when it does turnover sometimes I get a shrill type sound of two pieces of metal rubbing together right before it starts. Any help would be greatly appreciated. Thank you everyone. Kevin A83

Apparently the frame is broken so ordered one from Dan Booth that was taken from another vehicle. Then runner and vent window will have to be swapped.

If you part it out, I might need a few for my own ‘75. If not, should be interesting.

THEY WERE OFF A C3 CORVETTE.... MAN, DO I EVER LIKE THEM. YOU ARE CORRECT... I FOUND OUT THEY ARE Sanderson Headers CC5-158-BEC -... $700 ..... THANKS FOR YOU INPUT....BB

The transmission only needs to be moved rearward 3-4” to install the new flex plate. Any reputable transmission / repair shop should be able to do that.

RQB3263.... WHEN I INSTALLED THE 700R4 IN 3263 THE TH350 CAME OUT AND 700 BACK IN 3 HRS ROUND TRIP WITH ONE HOTRODDER THAT KNEW WHAT HE WAS DOING AND ME....AND A BORROWED TRANS JACK.... ... SO NO NEED TO PULL THE ENGINE ...BILL IN FLORIDA

Can anyone tell me the brand of headers these are?

PS… those 400’s had so much torque they broke the frame under the engine mount on several Avanti ll’s!

I understand… but I did not mean to pull the engine trans together…Last time I did a job like that, I unbolted the engine from the trans, and left the transmission in place… Not too bad a job with the Chevy engine… a bit harder with the larger Studebaker V8! Ther 400 CI engines were factory installed as standard equipment in Avanti ll’s from ‘71 thru about ‘77… I’m guessing on the years.

I agree on pulling the engine/tranny together. Problem for me is, I can't find a hoist with a boom long enough to reach the center of the engine. This last swap was very difficult to do with the short boom I had to work with. It took 3 people with a lof of muscle to push the engine forward at an angle on the hoist. I looked at the 72 specs on Bob Johnson's page and it showed only a 350 engine. Probably where the confusion lay. Was the 400 a special option?

Well that’s all in all good news!…..Your 350 should run smooth as silk with the 400 parts changed out…. Yes, the trans can be pulled back without engine removal, but if it were me, I think I’d pull the motor….Pretty easy with a Chevy in an Avanti!

I wish to thank all the smart people for enlightening me on this subject. After comparing the harmonic balancer on my engine, it is indeed from a 400ci. The guy that sold me the car thought it was a 350 and so that is the long block I installed. So I have to change out the balancer and the flex plate. I only ran the engine for less than an hour and pray I have not damaged it!!. Last question is can the trannie be dropped with the engine in place on an Avanti? Or do I have to pull the engine? I'd like to just take it to a transmission shop to change the flex plate.

Yes…A0136 is correct about that front damper if your Avanti originally had the 400 CI engine…and a ‘72 would have.

I don't know which engine was in the car before. I have no information on it. The flex plate mounted with 3 flanges to the torque convertor. I have been waiting for over a month to get the build sheet I ordered. It still has not come yet.

Jim Did your 72 Avanti still have the 400 Chevy engine. If it did the 400 is externally balanced using a different front dampener and flex plate than the 350 used. You will need to install the 350 dampener and flex plate. Steve.

I don't know about that. I purchased it from Powertrain Products. I was just a professionally rebuilt Chevy 350 long block minus only the manifolds, water pump and harmonic balancer. I bolted the crankshaft to my flexplate and that to the transmission assy.

Jim What did you find was causing the overheating? Steve.

Is the new engine one of the external balance units?… If so, you may not be using the correct flex plate.