If anyone is interested in this combo, here it is. I built this engine combo more then once and it was one of the best Street Strip combos that I have ever done for the money.
351W Long rod engine, using 351M / 400M rods.
There was an article on this combo that used forged TRW pistons L2446 I think and fly cut the top .062” or whatever it takes to bring the deck to zero. I used this piston once and all the skirts either cracked or broke away altogether. It didn’t do any collateral damage, luckily. Funny thing was, you could take one of the broke off skirts from one piston and put into another, it fit like it was from that piston.
I talked to a friend of mine, about this problem, that built Chevy engines and he had the same problem in two different Chevy engines, which was without fly cutting the tops. I think once you get to the 400 HP mark, that’s too much for this piston.
So, I would suggest special ordered JE, Ross, Wiseco ect… What piston height ordered would depend on the year of the block. 1969-70 is 9.480 and 1971 and up is 9.503. I set the piston to deck at +.005” above the deck.
The compression ratio would depend on the valve pockets and head gaskets, which is as long as you use the 1969 – 1970 351W head. If I remember correctly, the chambers are 60cc. Felpro makes at least two head gaskets, one is 8.5cc and the other is 9.5cc.
The cylinder heads I was using were 69 & 70 351W’s. With 1.94” intake & 1.60” exhaust, ported with 1.6 roller rockers.
The rods are 351M/400M. The rod length for a 351W is 5.956” and the Modified rod is 6.580”, .624” longer. This changes the rod ratio from 1.70:1 stock 351W to 1.88:1. What happens with a longer rod engine is the piston hangs at TDC longer, more time to burn the fuel. Also, I was able to run 42 to 46 deg total timing on pump gas.
To make the Modified rod work you would need to take .050” off the big end, .025” off each side. There is a boss on the little end that needs to be removed as well, to keep the rod boss from hitting the piston. It’s up to the builder whether or not the rods are full floating or pressed fit.
I imbalanced the engine, 48% / 52% lighter reciprocating weight.
The cam used was a Comcams part # 32-000.5
Valve adjustment .020” intake & .022” exhaust
Duration @ .050” 244 / 248
Lift .578 intake & exhaust
Lobe separation 112
Seat pressure 145# closed
The compresson ratio was 10.8:1
Through the exhaust, you could hardly hear this cam at idle, it sounded like a stock 5.0 Mustang. With street tires, mufflers and 2 ½ exhaust out the back, the car ran 11.80’s and got 19 to 21 mpg on the hwy, 19 with the A/C on. This particular vehicles was a 1988 Mustang with no weight removed, I think it weighted in at 3400 lbs.
I am sure the car with more tuning would run deep into the 11.50’s and the street drivability was like a stock 5.0 Mustang. He did me wrong and I stopped working on his car, so I don’t really know how much more was in this setup.
If I ever change my 1985 SVO to an eight cylinder, this is the setup I will use. I really like it.
Whoops, almost forgot... The rod bearings need to be 351C. I have used King bearings with very good luck.
[This message has been edited by Buster (edited 06-08-2002).]
[This message has been edited by Buster (edited 03-07-2004).]