1994 351W Roller Engine Question

[BlownFiveLiter]

The 1994 should be hypereutectic pistons, if it followed the same lines as the 302 did from 93-01. You could most definitely notch the pistons. Isky sells a tool that you can remove the intake valve and use your valve guide as a guide for the notching tool. I seem to recall it being in the $150-175 range though. I bet you could find a set of forged Probe, or Keith Black pistons with large enough reliefs for a couple hundred bucks more.

D.Hearne, you mentioned this before, so I figured I'd post it now. SummitRacing.com has a compression calculator right on their site. I've never used it, to test it for accuracy, but figured it was worth a link.

 

[PoppyMod]

^AW

If the stock heads on this engine are 64cc what will the AFR 205 head with 58cc combustion chambers do to the compression and drivability?

There are numerous CR calculators online, to get close. However, for true CR, you need not only the bore and stroke specs, but, the piston had CCs, the chamber CCs (advertised is not always correct) and the CCs around the circumference of the piston from the top ring land to the piston top, also the compressed height of the head gasket.
This will help you determine static CR, Dynamic will be dertermined by the cam events and is more important, at times, than static.
Happy Motoring!

 

[D.Hearne]

As the pistons are likely hypereutectics, I wouldn't notch em for clearance. Either bolt the 205's on and actually measure the valve clearances or buy pistons that will definately clear.

 

[Rick 91GT]

The others are right, the pistons are hypereutectic and I wouldnt notch them unless you have to if they were forged the Isky tool works well. I made my own piston notcher years ago from an old junk e7 head I had, works well in a pinch and I can braze the cutters on for any valve size.

The downside to swapping pistons is you will be basically doing a rebuild, new rings, bearings and hone...At that point I'd consider a stroker kit.

Compression will change by about .8-.9 with the 58cc AFR head, the stock chambers will most likely range from 62-64cc.

 

[armand67Fstback]

Thanks everyone your input has been very helpful. So I took most of the motor apart and saw a small amount of sand on the rods and on the pistons. I am thinking the engine originated from a farm truck. I also found out that the engine is from 1997, because the lifter retainers had a F7....code on them.

Since I need a reliable engine with no sand inside I am going to build a 408W stroker. In researching heads why are the Vic Jr. 210cc hydraulic cam SBF heads so much more affordable than AFR 205cc heads? It is about $1400 for the 210cc vic Jr heads and $1840 for the AFR 205's.

 

[D.Hearne]

"E7" denotes an 87 part. The block casting numbers will tell you what year/day/month it was cast. This is a number/letter/number combination cast somewhere near the enginerring numbers (which will be F4TE on a 351W roller block. The first number is the year, the letter is the month code and the last number(s) is the day of the month. The month code goes alphabetically starting with "A" for January, ending with "M" for December, skipping the letter "I".

 

[armand67Fstback]

D.Hearne, thanks for the explanation, in reading it I realized the lifter retainer has an F7 code not E7.

 

[armand67Fstback]

Can anyone explain the benefit of the scenarios below if I am going naturally aspirated on a 408W?

1. Flat top piston and a large combustion chamber head. (72cc combustion chambers)
2. Dished piston and small combustion chamber head. (58cc combustion chambers)

I am aiming for low 10s compression ratio, thanks for the input.

 

[PoppyMod]

Can anyone explain the benefit of the scenarios below if I am going naturally aspirated on a 408W?

1. Flat top piston and a large combustion chamber head. (72cc combustion chambers)
2. Dished piston and small combustion chamber head. (58cc combustion chambers)

I am aiming for low 10s compression ratio, thanks for the input.

Are you asking , if for example, you want to plan for a CR of 10.6, is there any advantage in achieving this, using flat tops vs. dish pistons?
There are numerous debates of why dished pistons have a huge following. I, for one, am running 10.6 CR in my 334 using dual valve relief flat tops aqnd making 392 RWHP in a street warrior.

 

[armand67Fstback]

PoppyMod, yes that Is what I am trying to figure out. Will either be more powerful or more efficient?

 

[PoppyMod]

PoppyMod, yes that Is what I am trying to figure out. Will either be more powerful or more efficient?

OK, That's where I thought you were going, but, had to make sure. There has been a great debate on this in another forum, which, if you PM me I'll direct you. Only because, I 'm not sure of the policy here regarding such activity as simply posting a link.
So, PM me.