Thread: pistons in for the test fit

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Well here i have the pistons in for the test fit and every thing looks good. the piston to deck was good too at .015 for quench. I am going to have the shop take .005 off to cleen it up because it looks like wood grain
well where are the pics.....

that looks like it has never been cut. here is how they come out when i do them this is one getting a hair cut

PAT how do u get the pic's to show up?
and pat my block has what looks like scratches gowing form the front to the back all most looks like grain on wood what would causes them? i am going to have it milled .005 to cleen it up or shud i just go for for the hole thing and do .010????

from what i could see it looks like a stock mill job .sometimes they have grain or chop. i just deck two big block and one 351 C block i have never seen a big block that was not off end to end and only needing 005 to be at side to side square deck tru to main cam center line.you may find that when they cut it they may have to go the full .010 to be clean . on the BHJ true-deck i have had to go past that to get them right . the world block and darts i have cut off 004 and still seen chop from when whey get cut new. your machine shop will know when he make the first pass on the deck if its clean. very seldom are they square end to end or side to side center to the mains and cam centers.i have seen them off as much as 010 and when i am done less then .002. to load photos just go to advanced and you will see where you can add them it will say mange attachments

now i am lost i had a nuther guy on a diffrint thred tell me this!

Hi heads up!!

Those are TRW slugs and are designed around the stock width pin bosses from G.M. The width on the factory rods runs between 1.050" and 1.060".

With all G.M. components That leaves enough room between the pin bosses and the rod pin cheeks.

However, the rods in your photo appear to be either Eagle "SIR's" or Scat's "ICR's", either way I would recommend looking closer at the gaps between the pin bosses.

The Eagles' average 1.125"/1.130" across, I have no numbers handy for the Scat's, but they are probably similar. If this is the case by you, remember you need at least .060" clearance on both sides to be "safe"!

Very important! The pin bosses (on the pistons) are usually "tapered" at the tops, it would be wise to check the "room" at the top of the rod-eye, not at the bottoms!!! Most of those rod-eye cheeks themselves (on the rods) are
"straight" from top to bottom and this will have a 'wedge" effect from the bottom of the pin to the top.

(Add) It does appear to be L2328F's, if that's correct, it means they are
"pressed"!

Thanks, Gary in N.Y.

P.S. It's sometimes very hard to make judgement calls from photo's, they can be very deceiving at times, but your clearances look very close as I stated! I also can't make out the full piston number, but if they're pressed pins, you MAY need to disassemble them for a correction. The amount removed, if any will have little to no effect on the balancing. In other words, you will not have to rebalance!!

Double P.S. Just caught my eye, almost missed it!!! Factory 2 B.M. with "flow notches", you probably could have made a "heads-up" trade for a spankin' brand new G.M. Bow-Tie iron piece. At least around here it would have been possible. Just guessin' but it's probably a "3902406" block? Error, wrong oil filter base, has to be '68 or later, still valuable to the resto guys!



in reply to what he said:
the pistons are P/N:TRW-L2328F30 "pressed" the rods are Eagle "SIR"
i tried to measure the pin slide and it look like it is coming out at .055
the i can slide a .003 feeler gage in between the piston skirt and cylinder walls

what are you asking he said 060 and your at .055 that close it will work put pistons in the block say #1and #2 turn it and see how much room you have looking down it the bottom of the pistons and look at the side to side you have from side of the rod and piston if its still over 040 i would run it . there is no way i would pull it down for a added.010 . for the piston to wall i have run more then that. if they are coated thats about there i would put them in at

but pat he is telling me i need at least .060" clearance on both sides i have .055 totle

so u are saying .003 between the piston skirt and cylinder walls is ok?

Originally Posted by BBMonte

but pat he is telling me i need at least .060" clearance on both sides i have .055 totle

so u are saying .003 between the piston skirt and cylinder walls is ok?

if there coated pistons yes but if your beating the hell out of it abit more never hurts . what size feeler gauge can you get between the big end of the rods how much there ? if i had more room on the pin per side then i had rod clearance i would run it .but check all of them

all this crap about clearance / tolerances is making me rip the last of my hair OUT!!!!

i should have just stuck with computer lol J/K


P.S. this is my first build up

None of us geezers have enough hair to pull out. Please don't go there. Pat is stressing what we all believe in. Geometry, geometry, geometry. Get it down, and the thing will run forever.

what the hell are "flow notches"????

Originally Posted by BBMonte

what the hell are "flow notches"????

well i think he is trying to say were the deck is cut out for ...valves/ chamber notches

ok thats what i was thinking

i think this guy is pulling your chain on that some one would give you a new bowtie block for your 396 ? block.i just pick one up on e-bay for less than 100.if he can give me names with numbers? for that much coin i will find him some blocks

Lol Pat! Love the dancin goat on your posts!
I happen to know a great barbershop for big blocks! lol
and heck a bowtie block for trade! gee what a guy!
The block in the pic looks great but then again what else could you expect from Rats by Pat inc.