I have a 90 formula 350 that I bought and it looks like the engine has internal problems, I cant get it to turn over with any speed even with a new starter. I know the car was driven hard and gut feeling says something is torn up on the lower end. I have a few good mid 70s 350s, can I take the 90 heads and TPI and put them onto the older 350? I know I will lose the roller cam setup but will the newer stuff work ok with the old shortblock? Would I use the older 350 pushrods with the 90 rocker arms?

 

I used newer center bolt valve cover heads on a 76 400. Worked fine. I used the old 400 pushrods. I think you have to use the old 350 flywheel to match your balancer also. There's some different balance on the flywheels from the one piece rear main seal engines, I think.

 

The 90 heads will bolt up just fine to the 70's block. One thing you need to watch out for is the chamber size of the heads. If they are the small 58cc heads it may raise the compression ratio of the older block to untolerable levels. You didn't say which pistons the older block has and I'm not real current as to what newer heads have what cc's. Just giving you a friendly warning as to the possible problems. I have an older 70 block that I built into a 383. I'm using the AFR heads that I had made mainly to the later 80's (88 - 89) style so I could retain the centerbolt and the serpentine belt setup. They have been shaved to about 64 66 cc, I caan't recall exactly which now, but I'm pushing about 10.5 c.r., give or take a few.

The roller lifters are longer than the older style flat tappet lifters due to the roller, so yes, you should use the older pushrods. Might not be a bad idea to retain the older rockers themselves too. Now sure it would really make a differance though.

The only problem I can predict ahead of time would be the angle of the center 2 intake bolts. I can't recall if the 90's TPI had the revised angle. I think they did. If so, just take a drill and carefully elongate the intake holes. Most aftermarket bases (Edelbrock, Accel) have both angles made into their bases.

 

Thanks for the replys! I will be taking the complete 90 top end including the heads and complete TPI setup and serpentine and putting them on a 73 350 block which is currently around 8.5 compression stock. I have to check the casting number on the 90 350 TPI heads to check the chamber size, hopefully they would work ok with the dished 350 pistons. Sounds like it will work ok! Thanks again.

 

The later 350's used a dished 4 valve relief piston which is listed as ablout 8.5 - 1 but I've heard due to manufacturing tolerances are actually less. The heads should work out okay. I think the heads on those 350's were usually in the 76cc area. You might end up with 9 or 9.5 - 1 cr. That's about right.

Sounds like you're good to go!

 

thanks again! One last thing, is there a tapped boss on the older block that will accept the knock sensor? Maybe a core plug or something I have to remove?

 

Yup, sure is. One on either side down at the bottom. That's where I have mine.

 

Great! Thanks again.

 

You will have to change the flywheel AND the starter. Your current flywheel is smaller as is the starter. They were put on the '87 and up engines with the roller setup as well as the '86 non-roller engines (weird setup that year). With the older block you will have to get the larger flywheel for the older years AND the larger starter to go with it.

 

thanks,
the 350s I have are all complete and have the larger 168 tooth flexplate. I assume the 700r4 bellhousing has enough clearance for the larger flexplate, if not I have earlier 153 tooth flexplates as well so no problem there. I am just happy this is going to work!

 

I'm not too sure what tooth flywheel I have on mine but it clears .... on one side of the bell housing, there's literally about 1/2 inch clearance but it clears and that's what matter.