I have a 1969 Mach 1, it has a the stock motor. But the block is bad, Because someone bored it 50 thousands over. the heads are in great shape. My Grandfather has a 1974 351w with bad heads. can I put these two together and have good (stock) horsepower?
They will go together. Your 69 casting cylinder heads are about the best stock OEM castings Ford made, aside from a GT40 cylinder head. Like any OEM head with press in rocker arm studs, they tend to pull out with age. Its a good idea to replace them with screw in rocker arm studs during a rebuild. Aside from that, there are some subtle differences that can effect performance.
1) You need to be aware of different compression ratio's. 4-barrel 69 351W was 10.7:1 and had flat top pitons with valve reliefs. The 2-barrel 69 351W had dished pistons and I think was 9:1 CR. I don't know what the 74 351W CR was. Probably close to 9:1.
2) The 69 351W cylinder head has a 60 CC combustion. 71 and later 351W cylinder heads have 64CC combustion chambers.
3) The 69 and 70 351W block have a 9.48" deck height. The 71 and later 351W motors have a 9.503" deck height.
To summarize, you can do the swap without any fitment issues. If your 69 is a 4-barrel motor the end result will be a lower compression ratio motor and have less power. I watched my older brother go through that way back in high school. If your 69 is a 2-barrel motor the end result will be about the same.
Best Regards,
Mike
the 74 engine is a 2 barrel, and the 69 is a 4 barrel, so if i read you right, 69 and the 74 block are the same, but the heads are different. I just want to be at the factory horsepower (300).
Yeah, it can get confusing. Ford wasn't consistent with a lot of things.
Yes the combination will fit. But no, they re not the same. First, the heads are different, 69 had 60 CC combustion chambers and 74 had 64 CC combustion chambers. Second, your 69 4-barrel has flat top pistons and 10.7:1 compression ratio and the 74 has dished pistons and probably 9:1 compression ratio. Third, your 69 has a 9.48" tall deck height and the 74 has a 9.503" tall deck height.
So, what will happen is the finished motor of your 69 heads and the 74 short block, will have a lower compression ratio that your current 69 4 barrel motor has. Result is The new motor with 69 heads and 74 short block will have less power than the complete 69 4-barrrel motor has. This power loss is assuming your 69 motor has flat top pistons like it originally did and the 74 motor has dished pistons like it originally did.
Have fun. Hope this helps.
Best Regards,
Mike
Thanks for the help! I found another block with heads. it is a 1969 351w casting # on the block C90E-6015-A . Its not the numbering match, but its the right year so engine parts will be easy to find.
Mine is that way as well, not numbers matching, but at least the correct year block and heads. The 69 and 70 351W block is supposed to be stronger than all the newer years in the main bearing area which is good. The only thing to be aware of when rebuilding is the shorter deck height of 9.48" for 1969 and 1970 vs. 9.503 for 1971 and newer. The difference in parts is the pistons for the shorter 9.48" deck height 351W motors have a shorter compression height than pistons for the 9.503" deck height motors. Compression height is the distance from the top of the piston to the centerline of the piston's wrist pin. Many engine builders are unaware of that 351W difference and buy the wrong pistons.
Best Regards,
Mike
Thanks mike I will keep that in mine! and write that down in my note book that I have on the mustang.