Need some help with Dart Blocks
 

Hey guys and gals,

This is a little different from the norm here but I have a 1980 Mazda Rx7 which I put my 66’ Stang engine in for a mock up but now I am getting ready to start the monster engine for which will be a 351W. This is car is primarily for racing on street course so I am building a beefy engine.

Here’s my question(s) – I am going to be using a Dart engine block and am looking at what the original deck height of the 351W would have been because they offer a 9.2 and a 9.5 deck height engine. I know there would be a compression difference with the two and I do plan to add on a turbo for a few extra pounds and am confused on which one I should get.

1. Would it still be safe to run 9.2 height with a turbo or would that be to much pressure and would the 9.2 cause any knocking of the valves with piston?

2. What is the stock deck?

3. And how much of a compression difference is there between 9.2 and 9.5

All the parts I am using in the engine will be rated at a min. of 750 – 1000 horsepower.
One more here. Stroke length, they show a max of 4.250 but what was the standard on a production 351. I will go with the 4.125 bore which I really only see as a Chevy piston size. With that bore and a 4.250 stroke I would be running a 454 cubic inch engine. Here is the page in case yall’ want to look at it. My goal horsepower is 860hp with 750 at the wheels. This is a serious build up which I plan to spend $13,000.00 on over the next 3 years. Any help would be much appreciated.
http://www.adperformance.com/index.p...roducts_id=542 – Engine block
http://www.itpapulling.com/ci_calc.html - For fun

Re: Need some help with Dart Blocks
 

Man, you're all over the place here.

[1] The 9.2 vs 9.5 deck height.....the 9.5 was the '69 block. As far as turbo pressure and hitting valves. The compression ratio is determined by the piston height/dome/dish and the size of the combustion chamber. The combined height of the piston/rod assembly is where the deck height will come into play. Rule of thumb is More boost, less CR.

Where the piston is in the bore has to be checked with the deck. The piston crown can be taller to fit the longer 9.5 deck height. This measurement should always be checked when building an engine to see if the piston, when at TDC, is above the deck or below it.

The valves will only hit if you don't have enough clearance, once again this is dependent on the piston dome/dish, valve size and cam lift. When building an engine you check this with clay.

[2] 9.5--1969 9.2--others

[3] Answered above

Lastly, 351W stock stroke is 3.5 inches. Maximum overbore is .060, most usually are .030. To get a thin wall Ford V-8 to .125 I think you'll find is damn near impossible. Just not enough metal to do it on a stock block. I have built a 426 cu in 351W. And as with a 289,302 or 351 .060 engines usually have a hot running problem.

My $.02