Anyone know much about LA 360 engines ?

[pearljam724]

I have a rebuilt LA 360 with a 4 barrel carb in my Coronet. I think there were a few Dusters that came with that motor to my understanding. I know a lot of trucks and vans did too. Those engines originally came with a 4 barrel Quadra jet carb I believe. Does anyone know the cfm on those original 4 barrel Quadra jets that were on 360’s ?

 

[mopar 3 B]

Yours has no id tag? If it does just run the number.

 

[Greg Ducato]

Quadrajets were 750cfm, in extreme cases for GM performance applications they were 800cfm.

 

[pearljam724]

I’m running a 650 cfm thunder series carb. I know it’s a small block motor. It’s mildly camed. But, something isn’t quite right with my carb set up I believe. It may need calibrated. But, why would modern carb manufacturers suggest only a 600 or 650 cfm carb on an engine such as mine and 750 cfm carbs were originally used ?

 

[pearljam724]

Yours has no id tag? If it does just run the number.

Yes, it does. I can only access it with a phone video from its location under driver side manifold. It’s hard to see. I can only make out 360 near the end.

 

[toolmanmike]

650 is plenty for that engine. The Thermoquads (and the few Qjets that were used) had big numbers but just because of the huge secondary butterfly's. They only opened as far as needed and rarely would you use all 850 cfm.

 

[pearljam724]

I need help identifying the engine. Please excuse because I have no lift. Even if I did, it’s tough to get in there for a good look. I tried many angles with a camera and this is the best I could decipher. I believe the number is 3413496-1-360
I can’t catch it in a pick. But, there is a big number 6 just to the right of those numbers. About 3-4 times the size as I listed. I thought these engines have a build date code just above these numbers ? There definitely is not and it’s definitely a LA motor.

 

[BeepBeepRR]

3418496 – 1971-1974, 360 LA-series small-block There is not a 3413496 in the list.

Here are some intake casting numbers to look for.

3418681 340-6 1970 Alum. AAR & T/A
2951185 318-2 1970-71
3512100 340-4 1971
3614025 340-4 1972
3671918 340-4 1972 Calif. Emissions
3671918 340-4 1973
3512099 340 1971-73
3698437 360-4 1973
3698434 360-4 1974
3698435 360-4 1974

Looked on this site here.. No Rochester carbs in the list. Doesnt mean it wasnt a thing. However is your intake a spread bore or a square bore? Also is it cast Iron or aftermarket aluminum? http://www.thecarburetorshop.com/Kdodge.htm

 

[pearljam724]

What do you mean by spread or square bore ? It’s an aftermarket Edelbrock intake. So, I assume it’s aluminum ? What else can I look for to identify the exact engine and build date ? I didn’t build it, I bought it as is. I was told it was a 360. I thought that was true, simply based on the 360 at the end of that identification number. So, I had no reason to believe it wasn’t. But, just recently I wanted to start digging further. I was hoping to at least find the build date.

 

[Darter6]

There should be a cast in number showing the date of birth on the block. Photo is for reference.See date 10-26-84. This would be found on the other side of the block from the photo you posted.

Carter Carburetors (Thermoquad) went out of business and Chrysler started using Rochester Quadrajets by 1985.My 88 D 350 Ram had one.

 

[pearljam724]

I understand what you said about the build date casting. That’s what I was looking for. But, I though it was on driver side right above the number and picture I posted. But, there’s nothing. No foul play that I can see either. You’re saying it’s on passenger side ? I ll look

 

[pearljam724]

Ok, I found 2 - 1 - 72 on passenger side. So that’s obviously build date. Plus 2 more of those very large 6’s on passenger side. That’s it. I’d like to properly identify the casting number to be sure of what it is if anyone can help. I just want to know if it is infact a 360 and not a 318.

 

[BeepBeepRR]

Spread bore



square bore

 

[YY1]

the 360 made it's debut in 1971 C body cars

in 1974, it replaced the 340 as the performance small block in Challengers, Road Runners, etc

for a 71/72 motor it may have been a 2 barrel

in a 74 and up HP car it likely would have had a Carter Thermoquad

 

[Photon440]

Quadrajet was used from '86-91. 74-85 used Thermoquad, 71-73 were 2bbl only.

 

[pearljam724]

Spread bore

View attachment 792762

square bore
View attachment 792763

Hard to tell with my carb on. Mine quite isn’t shaped like either of those. It’s completely flat on fender sides under carb. So, I’m assuming that’s a square bore.

 

[BeepBeepRR]

If they don't get larger towards the rear then yes its a square bore. The holes where the carb sits is what makes it either one. Spread bore is for Q-jet style carbs. Square bore is for carter/edelbrock style carbs.

 

[pearljam724]

Quadrajet was used from '86-91. 74-85 used Thermoquad, 71-73 were 2bbl only.

Being I have a 72. Maybe I’m over carbureted. I don’t know if that would be the case being I have a fuel regulator set at 6.5 pds. I don’t think so, but not sure.

 

[pearljam724]

I found and matched the identification. It’s 3418, not 3413496. It is infact a 1972 - 360. What that engine was used in, I don’t know ? Next I want to check to see what heads I have. Maybe I can get a little performance gain swapping to aluminum heads ? Pretty sure, these are original cast steel.