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Piston/Cam suggestions for my 388

5K views 72 replies 6 participants last post by  HotRodDinosaur 
#1 ·
388 .60 over block
6.0 rods
cast crank
.200 dome pistons KB hyper
RHS 220cc iron heads, ported 64cc chamber

Just recently sold my track car and put this in my s10 in my av.. lifted 4x4
Took out the big cam and went with a hydrauilic comp 240/246 .509 .513
Took off the Dart intake and went with a performer rpm

Obviously this isn't a pump gas engine and i'm wanting to drive it more and looking to change pistons and possibly cam, even though ill prob drive it less than 50 miles a month, im sick of dealing with race gas and heavy timing etc..

I can't give exact numbers for clearances as the motor is still together but when i built this years ago i was figuring right around 12.4 to 1 comp

Also i must add this is an externally balanced engine, and i would like tips on re-weighing piston/rods

Thanks you guys
 
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#4 ·
I don't think you necessarily need a big block but I do think selling what you have and building what you need from scratch may be a better option.

you'll need pistons, rings, a balance, maybe a hone, a cam, etc. You already have close to a grand in parts there which could be spent on a different engine.

The next trick will be finding someone to buy your engine at a price you can live with. Put the Dart intake back on and hope and pray you can get a grand for the engine.
 
#7 ·
I completely agree to use the motor in a different application, but we just moved to an area where we can drive on the beach and the closest track is 2 hrs away, and i have two 406s that i think would suit my track needs better anyway. I guess im just saying that im changing the pistons.. Lol
 
#14 ·
If you match the weights you'll be fine, BUT its highly unlikely your new pistons will weigh as much as your old ones. Try to at least stay within 1% of total bobweight. If you know the pistons PN's you should be able to make a phone call and get the approximate weights for each piston.

I still think its a dumb move to tear apart a good engine and discard good parts- but to each their own.
 
#15 ·
Thanks, well i just can't see getting back to the track anytime soon and that's really what the motor was made for..
The truck was basically one of my first beginner level fab projects and it makes sense to use it, etc. Yeah i figured i could match weights, i just wasn't quite sure of the technicalities with possibly weighing piston/rod together and match weights, or just simply have pistons matching each others weights.
I understand wrong motor/wrong application and that, but it wouldn't make sense to sell it, maybe make sense to build a mild 350 but then the 388 would just sit
 
#16 ·
For instance, if my new pistons weighed a gram or so less, how would that translate on a balance machine? Would you add weight to the flywheel? Possibly need a new flywheel? Or would heavier pistons enable me to use.the old flywheel and drill it.
It's been a few years since dealing with this and just trying to wrap my head around it.
 
#17 ·
if you're within a gram you're better than most balance jobs.

I'm thinking you'll likely be at least 30 grams light, which will be fine if they all match, ideally you'd pull some weight off the crank though. just try to find pistons as close to your current piston spec weight if you can- removing the dome will mean you'll likely end up lighter unless they are some thick pistons or you started with hollow domes. The other option is to just leave the pistons you have and run E85 if thats available in your area.
 
#18 ·
Ok, let me ask because i don't have much.exp with e85. T
Do you think the engine will likely want less timing on it? One of my other reasons for lowering compression is to get back in the neighborhood of 14 initial where im at about 20 now for it to run. I know i can get a retard box for hot starts but figured id be fine with a dish piston.
 
#19 ·
less compression will require MORE timing. your cam duration being so high is what is causing you the need to run 20 degrees, which honestly probably isn't enough.

E85 will require the same timing, but you shouldn't have any issues with only 20 degrees initial, you may need a new starter or to check your wiring/battery.

btw, 12.5:1 is no problem for E85- switching fuels may be your cheapest way out of your current situation.
 
#22 ·
Yeah it just seemed strange, i was running flat tops and a bigger cam in the past and it seemed like it used less timing 15/36 , I don't really have much of an issue with hot starts, new deep cycle battery, new high torque starter, heavy duty battery cables etc.. I'll check my total again but i know it's right at 39,40, i guess the sensible thing to do is just get a 16 or 18 degree stop bushing, im running a msd billet mech advance dist.
 
#32 ·
The problem with this is that E85 does not store well. It's probably the biggest drawback of E85- you need to make sure the place you get fuel has a fresh supply or test it. You can get small test kits that make it a relatively quick chore to do though.

As for running E85, some people change nothing more than the jets- but that is not the correct way to do it. All the carb circuits should be revised. Also, it is somewhat corrosive to rubber fuel lines, but don't think it'll melt one front of your eyes. Some fuel pumps will also see corrosion, the older the pump the more likely it will be to fail.
 
#33 ·
Yeah by doing it the correct way and revising the carb, replacing rubber lines, and potential storage issues with the fact the truck may sit for a month with no use when im out of town etc.. I may just deal with mixed gas until winter months and pull the engine for inspection and possible piston change. Ill try to get some time to read up on the kerosene, but any quick drawbacks or advantages?
 
#39 ·
Yeah, i think he must mean kerosene by itself rather than at a ratio, my truck has a 12 gallon fuel cell so i wouldn't be opposed to trying it if i could figure out a ratio , and im sure it doesn't add octane so does it help lubricate the cylinders to help control pinging damage?
 
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