Thread: Engine Building Question

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This board is loaded and I mean just loaded with guys who are a vast pool of knowledge on building an engine "RIGHT". So with that thought I have a question, elementary granted, but a question that needs an answer none the less.

What with the economy like it is, there are so many good cars out there for sale that it isn't even funny. A deal came along for me I simple could not pass up. I am and have been for many years a real fan of 55 Chevy post cars. When this latest one was offered to me I simple could not pass it up. Very nice looking car-- The color is not to my taste but you can't have everything-- it has a brand new interior and is in fantastic shape. Almost an orginal car, it has had a small block engine change a few years ago and a turbo 350. The engine it has now is a pretty anemic 305, absolutly stock I believe with the exception of Headers and intake manifold and a Edelbrock carb.

I have no use for the 305 and I do have a 010 casting 4 bolt 350 setting in the shop I got "with" another project a few years ago. I also have a set of 186 casting Double hump heads with a fresh port and polish, these are 2.02/1.60 heads, screw in studs push rod guide plates etc. these heads are very fresh and ready to go.

I opened up the 350 today ( never had looked inside this motor before) and it does have a fresh low milage build on it. It is .030 over with some brand probably TRW flat top 'cast" pistons, fresh rod and main bearings and the crank looks fresh as well it is a .010/.010 crank. I checked the end gap on the rings and it will need new rings. I also checked the cylinder taper and it is very minimal less than a .001.

This brings me to the question. I would like to replace those TRW pistons with something a little better. I have always rebuilt an engine from the bottom up, took the block in to be bored and took the pistons in for the final fit and hone. This time I have what appears to be a pretty fresh block that is now .030 over can I buy a set of .030 pistons and use them as they come? This is what I would like to do, any problems with this somewhat of a shortcut??

Roland

alway fit the pistons to the cylinder,one companies +30 might be more or less than what you have plus forged pistons use different clearances than cast.if you just throw them in without fitting them you will soon have a nightmare on your hands.

take your time do it right so you will not have to do it over.

Good News on the ’55. I’ve always liked the ’55-‘57’s and they defined an era of hot rods that lives on and on.

You mentioned the economic times, here’s a thought – why not re-ring the pistons that are in the engine now? A .001 taper is really good and certainly acceptable! If they are TRW (or any “name” brand) they are probably a step above stock and you can’t beat the price. I know everyone has their preference for pistons, but in the cast arena, the TRW’s would be a good solid bet. Cast pistons get a bad rap and they’re fine for most street uses. While you have the pistons out, I’d recommend you freshen the bore with a quick/light hone to break any glaze. Spend the money you’d invest on pistons in new bearings, good gaskets (I’d use Fel-Pro Performance head gaskets) and a good timing set. Slap those dandy heads on and you’ll have a nice motor for the ’55.

You didn’t mention cam – but this would be a good time to consider it. Be careful not to go “lumpty-lump” without some additional research. Let us know what rear end and tires you’re running and if the TH350 is a stocker and I’m sure TechInspector can produce a dyno simulation that will help with a cam selection. The double humps with 2.02/1.60’s breathe pretty well but it’s easy to over cam any engine and you’ll be disappointed with low end. Unless you’re going for all out “drag race boogie” it’s better to be somewhat conservative on the cam side as most boulevard cruisers live in the 1500 – 4000RPM range.

I like the Performer RPM with a 780 QJet for intake – just my opinion. I’ve done tons of Edelbrock carbs and while they are a good dependable and easy to tune component, the thunder in the QJet secondaries is more in line with a ’55 hot rod – my opinion.

Keep us up to speed and post some pictures. Again, congrads on the great score.

Regards,
Glenn

Glenn, That is actualy a pretty good idea and I think I will following your suggestion. As to the Cam, I did in fact get in touch with Tech, and asked him for his recommendation for a cam. He graciously ( as usualy) did his computer dyno thing and came up with a recommendation, I fully plan on following his advice to the letter on the cam.

This 55 is a pretty nice little car, not perfect by any means, but I am much more into driving my Hot Rods than having other people critique them while I set in a lawn chair and watch. So it suits me right down to the ground. I have put a set of wheels and tires on it, and today I spent the day working on the stance, I think I have the stance thing down pretty good. Future plans are for a Big Block, but I just finished the Engine Swap from hell putting a Early Hemi into my 49 Ford F-1. I need a rest from engine swaps for a while...

here's a couple of pictures.

Roland

I would have expected a slew of answers to this thread, but in their absence, I'll weigh in.

You didn't say what the ring gap is, but it may not be as critical as you may think. As engine builders and hot rodders, we put a motor together with a certain gap so that the end gaps will not butt together as the rings gets hot and expand. As the motor is operated in the first days of its life, the very rough peaks and valleys of the bore are worn down to a smoother plane and ring end gap expands out to whatever it will be for most of the remainder of the motor's service life. So, whatever the ring gap is now, it will be again as soon as the wear-in process is completed with a honed bore and new rings.

What would I do? I'd re-install the rings on their respective pistons, re-install the pistons in their respective bores, install the cam and lifters I suggested in the PM along with the Victor Reinz head gaskets and drive it until it breaks or needs a rebuild.

hell looks nice .you know there is a guy i know that has a 427 hyd roller cam 060+ over from intake to pan.with many new parts .as for cast pistons i use them they work fine

Looks good Roland - I knew Richard would set you right on a good cam.

I had to wipe the drool off my computer after seeing your rod Roland. I absolutely LOVE '55 Chevys. I too would someday like to have a big block (572 maybe?) '55 shoebox...with a 4 or 5 speed stick like yesteryear, to go with my chopped, "Z-ed", and slammed, full roller, 496" BBC, '40 Chevy Sedan. There I go drooling again! Nice car, that '55.


Tom

I have a similar 350 awaiting a rebuild. It has one split piston skirt that will have to be delt with. Not sure if one piston can effectively be replaced, or if a new set is a better idea?

What was the cam suggestion?

Originally Posted by SBC

I have a similar 350 awaiting a rebuild. It has one split piston skirt that will have to be delt with. Not sure if one piston can effectively be replaced, or if a new set is a better idea?

What was the cam suggestion?

o yes better look at your piston to wall sounds loose for cast pistons they will not hold up to loose piston to wall if you had a split piston?????????

Thanks Pat - didn't realize the split piston was probably indicative of a bad/excessive clearance.

Hey Tech - would you please PM the cam you suggested? Still trying to leaning the theory behind cam selection based on static CR and other variables. Thanks -

Originally Posted by SBC

I have a similar 350 awaiting a rebuild. It has one split piston skirt that will have to be delt with. Not sure if one piston can effectively be replaced, or if a new set is a better idea?

What was the cam suggestion?

Nova, While I am no expert as witness my asking for advice on this subject. I believe that there is a lot that should go into "cam selection". The cam that Tech advised me on will work in my motor, may not be the one for you. now with that said "TECH's" advice was this, and was based on the following.
350 4 bolt block .030 over using the "existing" TRW cast pistons and with heads casting #3927186, with 2.02 intakes/1.60 exhausts, Ported and polished, bowls blended, gasket matched screw in studs and guide plates these heads are 64cc and have been milled .010 and the cc volumn NOW is a verified and matched 63 cc's. The cam was a http://www.compcams.com/Cam_Specs/Ca...x?csid=87&sb=0

That is a link to the spec sheet of the cam. Now also this cam was going into a realitive heavy car (55 Chevy) with a Turbo 350 and stock converter. Tech advised me that this cam would tend to load up some with the stock converter and a 2200 stall was recommended, however I do have a 4 speed swap planned for this car this winter and it will be fine with the 4 speed.

I have purchased this exact cam and sense Comp Cams does not recommend using the stock valve train components I bought the complete cam and kit that comes with springs, retainers, and timing chain and gears. The cam came in on Friday and I am looking forward to getting it into the motor and making this swap.

I have decided to go with the cast pistons and just freshen everything up with the exception of the cam and kit. I'm going to drive it till it quits and then do a proper rebuild from the ground up.

Roland

when building a very mild engine there s is things your going to look at with lower CR engine and what RPM range your going to be at .head .intake.cfm. EX. CR . trans number of gears .rear gear .tire size. weight of car or truck . all play in to this so there only going to be very few cams that stand out . the big deal were cams come in at. what your are willing to do if you want a big cam hi rpm engine hi hp engine for the street? most do not want the added parts needed to make a big cam work or the RPMs and just stuff it in thinking it going to work at lower speed it just may be a big pig. so there is many cams grinders out there that make RV cams thats were i start. after you have built over 100+ engine or less you start to see were there is some cam grinders just re package cams coming from one or only a hand full of big grinders that may bump the numbers on the cam very small amounts to call it theres

Thanks Roland. For the benefit of others on the board, I also recommended paying attention to this list of failure points with a flat tappet cam. Oil formulations have changed and extreme pressure lubricants are no longer part of the formulation in off-the-shelf motor oils, so we must use extreme caution in the installation and wear-in of valve actuation components. The Extreme Energy camshaft series is particularly prone to failures due to the additional loading involved with the lifter coming up off the base circle onto the opening ramp very quickly. It's nothing you have to be really afraid of if you pay attention to all the cautions I have laid out and pay attention to using all the matched components that the cam grinder recommends. I recommended to use only 1.5 rockers arms with this cam and also advised Roland to adhere to the list I provided. Here's the list....
http://www.crankshaftcoalition.com/w...ips_and_tricks

There are numerous offerings of extreme pressure lubricants on the market. Here, for example, is one from Crower that I would trust. Just add one of these 4 oz bottles to the oil on break-in and one with each subsequent oil change.
http://www.summitracing.com/parts/CRO-86092/

Bottom Line: Use all components that the cam grinder recommends for the cam you are purchasing, pay attention to the tips and tricks listed above for installation of flat tappet cams and lifters and use an aftermarket oil additive in your off-the-shelf oil or use a dedicated racing oil in which you can verify the content of extreme pressure lubricants.

This information is applicable only to small block Chevies and other "valve-in-line" type motors. I suspect that Pat McCarthy has built more big block Chevies than all of us combined and he will not use a flat tappet cam in a BBC. That's good enough for me, so be advised. Use only a roller cam in a BBC.

i would not trust many 4oz bottles from any one .buy the break in oil from brad pen or joe gibs and use it thats what i do when i build a flat lifter cam engine. as theres so much detergente in the oils now. were your bottle of zddp may just sit in the botton of the oil pan .you want a fast burn zinc but any oil with a leve of detergents can block it from working .as for adding zinc just buy a oil thats made with zinc in it so you will know it will work. but when all done you can buy hyd roller cam kits for $400 or less then your flat lifter cam and never worry about break in....or a detergent oil good luck