Posted By: Bubba C
1970 340 Question - 07/05/08 07:46 PM
Does any one know how many pounds of compression my 70 340 should have give or take when using a cylinder pressure gauge?
Thanks, Bubba
Thanks, Bubba
1970 340 Question
Posted By: autoxcuda
Re: 1970 340 Question - 07/05/08 08:02 PM
Lots of different factors to give you a better idea of the range.
I know the engine guys will need to know:
What cam does it have?
Stock heads?
What pistons does it have?
I know the engine guys will need to know:
What cam does it have?
Stock heads?
What pistons does it have?
Posted By: Bubba C
Re: 1970 340 Question - 07/05/08 08:39 PM
The engine has never been torn down. Its all factory.
Bubba
Bubba
Posted By: autoxcuda
Re: 1970 340 Question - 07/05/08 08:59 PM
The factory manual just lists the minimun at 110 with max variation at 40 psi.
I've got stock original pistons in my 68 340 with MP 761 mild cam (should be less than stock static compression. I got around 130-140 psi and it's a well worn motor.
IMHO, At least a leak down test needs to follow the compression test to determine a "rebuild or not" decision.
Another not too hard indication of inside worn engine parts: In a small block you can pull the lifters with just taking the valve covers and rocker arm rails off. That less than 20 bolts. Then you could look for worn lobes and beat valve tips.
I've got stock original pistons in my 68 340 with MP 761 mild cam (should be less than stock static compression. I got around 130-140 psi and it's a well worn motor.
IMHO, At least a leak down test needs to follow the compression test to determine a "rebuild or not" decision.
Another not too hard indication of inside worn engine parts: In a small block you can pull the lifters with just taking the valve covers and rocker arm rails off. That less than 20 bolts. Then you could look for worn lobes and beat valve tips.
Posted By: GODSCOUNTRY340
Re: 1970 340 Question - 07/05/08 09:05 PM
Just checked my Son's, trying to isolate a miss, they were all between 140 & 150 psi. ('69 340 with stock pistons, X heads).
Posted By: Bubba C
Re: 1970 340 Question - 07/05/08 09:11 PM
You guys will never believe this but my son and I just checked this one and it has 175 lbs per cylinder. It has 2.02 J heads.
Bubba
Bubba
Posted By: autoxcuda
Re: 1970 340 Question - 07/05/08 09:33 PM
Quote:
You guys will never believe this but my son and I just checked this one and it has 175 lbs per cylinder. It has 2.02 J heads.
Bubba
Makes sense, they havea tighter (than aftermarket) overlap cam and high compression. Especially if it still has original type steel head gaskets.
Posted By: Bubba C
Re: 1970 340 Question - 07/05/08 09:38 PM
Heres my next question: It has a 4639sa carter carb...Is that factory and whats the cfm?
Bubba
Bubba
Posted By: autoxcuda
Re: 1970 340 Question - 07/05/08 09:50 PM
Quote:
Heres my next question: It has a 4639sa carter carb...Is that factory and whats the cfm?
Bubba
68-70 340 carter AVS carbs are accepted by most people as around 625 cfm.
google search: carter carb part numbers
or I think there is a list of part numbers on the moparts archieve section.
Did you just buy this car or something??
Posted By: Bubba C
Re: 1970 340 Question - 07/05/08 10:04 PM
Yes I just got my hands on it a couple days ago. Ive built a few but I never knew what the compression on stock 340's was suppose to be or any thing about the stock carbs.
Thanks for all the help guys! Maybe some times I can return the favor!
Bubba
Thanks for all the help guys! Maybe some times I can return the favor!
Bubba
Posted By: autoxcuda
Re: 1970 340 Question - 07/05/08 10:23 PM
Quote:
Yes I just got my hands on it a couple days ago. Ive built a few but I never knew what the compression on stock 340's was suppose to be or any thing about the stock carbs.
Thanks for all the help guys! Maybe some times I can return the favor!
Bubba
Cut us a deal when it goes up for sale.
Posted By: Bubba C
Re: 1970 340 Question - 07/05/08 10:47 PM
What is your definition of a deal?(on the 70 340) I have a 72 block and a 73 block both 30 over I'll take $250.00 each for them. I still havent been able to identify the carb. I know its a Carter but I dont know the cfm.#4639sa.
Posted By: RobX4406
Re: 1970 340 Question - 07/05/08 10:55 PM
Quote:
I know its a Carter but I dont know the cfm.#4639sa.
69 340 AT, AC carb.
Likely about 625cfm
So do I get a free 340 for answering the quiz???
Posted By: Bubba C
Re: 1970 340 Question - 07/05/08 10:58 PM
GOOD ONE! I wish I could...
Posted By: autoxcuda
Re: 1970 340 Question - 07/05/08 11:36 PM
Quote:
What is your definition of a deal?(on the 70 340) I have a 72 block and a 73 block both 30 over I'll take $250.00 each for them. I still havent been able to identify the carb. I know its a Carter but I dont know the cfm.#4639sa.
Sounded like this motor was attached to a car. What car is it in? Pics? Sounds like an interesting find.
Posted By: Bubba C
Re: 1970 340 Question - 07/06/08 12:13 AM
Heres the story: A guy called me because he knew I'm a MoPar man. He says I got an old Plymouth if you wanna look at it. I said sure. When I got there it was a rusted out 66 Fury 2 door. I raised the hood and saw a 4 barrell. I started checking closer...and what do ya know! A 70 340 in a fury! I bought the whole car and kept the engine and tranny...oh and the 742 case 3.23 Sure Grip! I think the engine came out of an E body.