Honda Prelude Forum - PreludeDriver.com

Will a B20A3 head bolt on a B21A1 block? I know it's a carb head but were we race the rules say we can not run a twin cam or a 16 valve engine. I was looking to get a stronger lower end and more cubic inchs if I can do this.

My head is ported and I will put a bigger cam and better carbs than stock. Just looking to increase cubic inchs andf make a stronger lower end.

Will the flywheel and trans bolt up.


Thanks

Hey Race77,

I have alerted Syn and Spiffy about your post. That's more their area than mine.

Glad to have you on the site. Hope we can asnwer your questions.

Josh

Thanks I'm looking at doing this soon. I just picked up the B21A engine today. It looks like it will swap out I think. All I need to do is find a good set of flatslide carbs and have a cam made for it and i think it should rock.

Thanks for the response.

Race,

Thanks for visiting here.

I've been thinking about your question for a while now, and as far as I know (but don't take my word alone) the block and head you specified should match up. The head bolts should for sure be the same, but make sure that the slots in the water jacket and the oil pisser also line up.

Your project is interesting to me. Perhaps you could post a topic and let us know about your progress?

Thanks for visiting, and please ask us any other questions you might have.

Thanks for the input. Here is where I'm at. I have the engine ready to be pulled out of my donor car. The cam is being grind as we talk. Still looking for carbs not sure if I want to try 4 carbs or 2. Leaning towards 4 32 to 38 mm carbs. The factory carbs are 36 mm 2 of them. In the next couple of weeks I will know if evreything lines up I think it will. Still not sure about the clutch and flywhell yet. This combo I feel has the potenial to make good hp with a higher compression engine.

Thanks Bob.

Race77,

Sounds awesome. I'm really interested in hearing how this all turns out because I've often thought about trying my hand at tuning a carbed engine. Post up some pictures if you have them, and be sure to keep us all updated on your progress.

I think you should go with the 4 carbs, as long as you can be sure of reliable fuel mixtures across all four. What are you going to do to filter air? Are you just going to put screens on the carb venturis, or do you have an airbox set up?

Try and get the compression as high as you can since this is an naturally aspirated engine. 11:1 would likely be a good number to shoot for. Your head has a smaller bore than the block you've chosen though, so your piston edges can't come above the block deck. You're going to get a wicked squish zone with this setup, which will really help combustion not create as many hot spots.

Have you thought much about what pistons, rings, rods, etc you're going to use?

Hi thanks for the rely. I was doing to use the orignal block and pistons. It should yeld me around 10 to 10.2 to 1 compression. I'm trying to due four carbs but getting hard to find right combo or I will use the two carb set up with bigger carbs for more air flow and a ported intake. Still waiting fotr the cam set up from the cam shop.

Thanks Bob.

Hi just wanted to let everyone know that I did use a 12 vavle carb head on a b21 block and a cam with two factory carbs and it runs great. Looking to try another cam for more rpm currently running at 7k looking to turn 7'500 k.

That is awesome!

Thanks so much for letting us know how it went. Any chance you could put up some pictures?