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2V not 4V...
#1
So I feel like a dope. Took the car for a drive today, felt great went great. When I got back I was checking the temperatures in the engine bay and found the stamp on the edelbrock intake. I hadn't been able to see it before. At first I thought it said "ZV." Nope. It says 2V! What does this mean? I think it means I have the wrong engine for this car. That sucks. What would it take to turn this back into a 4v engine?
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#2
What does it say on front of you're motors heads? On the front corners of the heads should be stamped a 2 or 4...2 meaning 2v ...4 meaning 4v....Could be wrong intake on 4v heads...Could be 2v intake on 2v heads on original 4v block..All counts what has been done over the years...Check the front of the heads..And motor block numbers...But block numbers are hard to see.
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#3
hyena429;121871 Wrote:What does it say on front of you're motors heads? On the front corners of the heads should be stamped a 2 or 4...2 meaning 2v ...4 meaning 4v....Could be wrong intake on 4v heads...Could be 2v intake on 2v heads on original 4v block..All counts what has been done over the years...Check the front of the heads..And motor block numbers...But block numbers are hard to see.

Ok, so the heads both say 2 on them. Where do I look for the block?

I can't find a serial number on the block, but on the driver's side just above the bellhousing lower right of the block there is a number 2. Does this mean 2-bolt main or 2 valves? Where else do I look for a serial on the block?
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#4
Went great because you have a 2v intake on 2v heads. While there are some differences in 2v vs 4v blocks on some of the high performance blocks, the bore and stroke is the same. There were 4 bolt mains on some 4v's but not all. There were some wtih peened rods and stronger bolts but not all. There were some with nodular iron cranks but not all. And of course there were some 4v's that had different cams with mechanical lifters ...but it would be unlikely that you would have a Boss engine that someone would only take out the top end and leave a racing block in the car and put 2v heads on it. The 2v is a very strong engine that produces great power when slightly modified (like your edelbrock 2750 alum intake) and produces that power at a lower rpm. I believe that stock torque ratings were very close between 2v's and 4v's and the 4v hp ratings were advertised at rpm's more than 500rpm higher than where the 2v peaked. I believe a 2v with 2:75 gears would be preferable to a 3:75 4v for any trip on the highway for more than 50 miles, and for a street car with an automatic the 2v with better intake and carb, plus a dual exhaust will perform just as well as the 4v's do in original factory form. The Boss 351 is a different story of course. By 72 the 4v's higher rpm needs made the engine much less attractive than he specs on the 71's. and anything that is a Cleveland is better than anyhing that is a windsor.

Your vin will tell you what the car had originally.
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#5
wwhite72;121878 Wrote:Went great because you have a 2v intake on 2v heads. While there are some differences in 2v vs 4v blocks on some of the high performance blocks, the bore and stroke is the same. There were 4 bolt mains on some 4v's but not all. There were some wtih peened rods and stronger bolts but not all. There were some with nodular iron cranks but not all. And of course there were some 4v's that had different cams with mechanical lifters ...but it would be unlikely that you would have a Boss engine that someone would only take out the top end and leave a racing block in the car and put 2v heads on it. The 2v is a very strong engine that produces great power when slightly modified (like your edelbrock 2750 alum intake) and produces that power at a lower rpm. I believe that stock torque ratings were very close between 2v's and 4v's and the 4v hp ratings were advertised at rpm's more than 500rpm higher than where the 2v peaked. I believe a 2v with 2:75 gears would be preferable to a 3:75 4v for any trip on the highway for more than 50 miles, and for a street car with an automatic the 2v with better intake and carb, plus a dual exhaust will perform just as well as the 4v's do in original factory form. The Boss 351 is a different story of course. By 72 the 4v's higher rpm needs made the engine much less attractive than he specs on the 71's. and anything that is a Cleveland is better than anyhing that is a windsor.

Your vin will tell you what the car had originally.

Thanks man. I have been and still am impressed with how the car performs. That is not what I am worried about. I totally agree that the car has great torque and power. It just sucks because the VIN is for a 351c-4v Mach 1. But this is clearly not the right engine. I was just thinking if it only took heads and an intake to turn it back into a 4v I would put that on the long term goals list. But looking at the block and reading a bit more I am definitely going to stick with what I have.

It also makes me feel a little better about really romping on the engine and getting after it. If I mess it up too bad, no big deal. Put a more original engine in and call it happy days. until then I will just enjoy what i have.

I guess I can still call it a mach 1 just not an M-code.
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#6
So the owner blew up the original 4v reving it to reach peak HP and replaced it with a 2v! Im pretty sure you can drop on 4v heads and an intake. The exhaust manifolds will have to match also. Thats a good amount of coin for not a lot of return. Better to wait until you do a completely new engine if thats what makes you happy. Doesnt sound like you are chasing concours with this car though. BTW there is a guy named Jon Kaase that is a genius and he competes and wins in Engine Masters using the 400m engine, which is an engine that has never ever been given a compliment. He also sells the awsome CHI 3v heads for our engines that is a hybrid of the 2v and the 4v and will allow you to build your engine to dyno at 700hp if you think you need it. I dont
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#7
wwhite72;121882 Wrote:So the owner blew up the original 4v reving it to reach peak HP and replaced it with a 2v! Im pretty sure you can drop on 4v heads and an intake. The exhaust manifolds will have to match also. Thats a good amount of coin for not a lot of return. Better to wait until you do a completely new engine if thats what makes you happy. Doesnt sound like you are chasing concours with this car though. BTW there is a guy named Jon Kaase that is a genius and he competes and wins in Engine Masters using the 400m engine, which is an engine that has never ever been given a compliment. He also sells the awsome CHI 3v heads for our engines that is a hybrid of the 2v and the 4v and will allow you to build your engine to dyno at 700hp if you think you need it. I dont

I don't either. The car is definitely not concours. So not worried there. and the car will likely sit in the garage a lot. i am active duty Navy and about to deploy again so not a lot for anyone to enjoy there except the outside.

Do you think this changes something for my engine running rich issues? Maybe something is mismatched?
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#8
No. I believe you have a vacuum leak.
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#9
[/quote]

Thanks man. I have been and still am impressed with how the car performs. That is not what I am worried about. I totally agree that the car has great torque and power. It just sucks because the VIN is for a 351c-4v Mach 1. But this is clearly not the right engine. I

I guess I can still call it a mach 1 just not an M-code.
[/quote]

There are several M Code engines where at some time in life the 4V heads were taken off for what ever reason and replaced with 2V heads and intake. Some say the 2V heads are more driver friendly, I don't know since I haven't driven it with the 4V heads on it. My M Code is one of them. I know it's the original M Code engine since the partial serial number on the engine matches the M Code Vin# on the car. I even went so far as to check the Vin# under a fender to make sure the Vin# on the dash hadn't been swapped out. I have a set of 4V date matching closed chambered heads I plan on putting on it to make it original again, but the darn thing is running so great with the current set up I'm in no hurry to do it. But people who know the engines will say "That can't be an M Code, those are 2V heads" then I have to explain everything once again. LOL

Bottom line, you may have a M Code engine where someone replaced the heads and intake, check your engine serial number.

Jim

Jim

M code 71 Mach 1, 351 4V Cleveland, Ram Air (not factory), C6 Trans, 3.5 rear
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#10
Besides, your VIN says it's an M-code Mach 1 so that's what it is. Mine is an F-code Sportsroof, no matter what decals I put on it or what engine I throw in there.

Steve



[Image: 25yvyp3.jpg]
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